30 OCTOBER 2015 - Green Fund | Supporting Green Initiatives€¦ · · 2016-04-19LITERATURE...

DEVELOPMENT OF SUSTAINABLE BIOBASED COMPOSITE PRODUCTS FROM AGRICULTURAL BIOMASS

1

Development of Bio-based Composite

Products from Agricultural Wastes/

Crops Residues for Applications in

Automotive sector, Green Packaging and Green Buildings in South Africa

Development of Sustainable Biobased Composite Products from Agricultural Biomass

Sudhakar Muniyasamy

30 OCTOBER 2015


2

Development of Sustainable

Biobased Composite Products

from Agricultural Biomass


3

This Research Report was prepared under the Research Funding Programme, ‘Research and Policy

Development to Advance a Green Economy in South Africa'

By:


4

GREEN FUND

RESEARCH AND POLICY DEVELOPMENT TO ADVA NCE A GREEN ECONOMY IN SOUTH A FRICA

GREEN ECONOMY RESEA RCH REPORTS

The Government of South Africa, through the Department of Environmental Affairs, has set up the

Green Fund to support the transition to a low-carbon, resource-efficient and pro-employment

development path. The Green Fund supports green economy initiatives, including research, which

could advance South Africa’s green economy transition. In February 2013, the Green Fund released a

request for proposals (RFP), ' Research and Policy Development to Advance a Green Economy in South

Africa’, inviting interested parties with relevant green economy research projects to apply for research

funding support. The RFP sought to strengthen the science-policy interface on the green economy by

providing an opportunity for researchers in the public and private sectors to conduct research which

would support green economy policy and practice in South Africa. Sixteen research and policy

development grants were awarded in 2013. This peer-reviewed research report series presents the

findings and policy messages emerging from the research projects.

The Green Economy Research Reports do not represent the official view of the Green Fund,

Department of Environmental Affairs or the Development Bank of Southern Africa (DBSA). Opinions

expressed and conclusions arrived at, are those of the author/s.

Comments on Green Economy Research Reports are welcomed, and may be sent to: Green Fund,

Development Bank of Southern Africa, 1258 Lever Road, Headway Hill and Midland 1685 or by email to

[email protected].

Green Economy Research Reports are published on:

www.sagreenfund.org.za/research

Please cite this report as:

Sudhakar Muniysamy, Asanda Mtibe, Tshwafo Motaung, Osei Ofoseu and Asis Patnaik. “Development of

sustainable biobased composite products from agricultural wastes/biomass in South Africa”. Green Economy

Research report (2015).

Prepared by Dr Sudhakar Muniyasamy of the Council for Scientific and Industrial Research (CSIR)

http://www.sagreenfund.org.za/research


5

TABLE OF CONTENTS

SUMMARY ............................................................................................................................. 6

INTRODUCTION ............................................................................................................ 7

Waste Management in South Africa ................................................................................................................... 7

Environmental issues of plastics wastes in South Africa .................................................................................... 7

LITERATURE REVIEW ................................................................................................ 9

OBJECTIVES ...................................................................................................................... 11

METHODOLOGY/DESIGN .......................................................................... 12

Extraction and characterization of cellulose from bio-residues ................................................................... 12

RESULTS AND DISCUSSION ...................................................................... 14

Task 1: Extraction and characterization of cellulose from bio-residues ....................................................... 14

Task 2: Preparation, processing and characterization of micro and nano cellulose based

biocomposites ....................................................................................................................................................... 23

Task 3: Study of the biocomposite materials for automotive, packaging and green Building

applications............................................................................................................................................................ 28

CONCLUSIONS ........................................................................................................... 33

WAY FORWARD ......................................................................................................... 33

ACKNOWLEDGEMENTS ................................................................................. 34

REFERENCES ..................................................................................................................... 34

Annexure 1 ...................................................................................................................... 36

Design and development of natural fibre reinforced roof sheet ................................................................. 36

Annexure 2 ...................................................................................................................... 37

Design and development of bio-fibre reinforced ceiling tile ........................................................................ 37

Annexure 3 ...................................................................................................................... 40

Development of thermal and sound insulation materials for building industries ....................................... 40


6

Annexure 4 ...................................................................................................................... 47

Development of thermal and sound insulation materials for building industries and their

biodegradation studies ........................................................................................................................................ 47

SUMMARY

The present study investigates value added utilization of agricultural biomass residues derived

from sugarcane bagasse and maize stalks for the development of sustainable biobased polymer and

bio-composite materials for specific uses in automotive parts, green buildings and green packaging

applications in South Africa. Based on the present study objective, the experimental part has been

divided three main tasks i) extraction and characterization of cellulose from bio-residues; ii) preparation

and characterization biodegradable biobased materials and biocomposites; iii) identifying biomaterials

potential applications in interior transporation parts, green building and green packaging to substitute

to certain petroleum based counter parts.

In this first experimental task mechanical, chemical extraction and bleaching pretreatment

techniques were explored for extracting cellulose and obtaining micro and nano cellulose materials for

preparing micro and nano biocomposites. Chemical compositions, mechanical properties,

morphology and dimensions of the isolated micro and nano cellulose of the sugarcane bagasse and

maize stalks were examined before and after purification using a TAPPI standard, Raman spectroscopy,

Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD, thermogravimetric analysis (TGA),

scanning electron microscopy and atomic force microscope (AFM). In this second experimental task,

biodegradable polymer biopolymers from renewable resources were used as a polymer matrix to use

cellulose natural fibres as reinforcement for preparing biobased composite materials, since it is made

from renewable resources (agricultural feedstock) with the benefit of compostable, recyclable and

energy recoverable. In this task a conventional melt extrusion and injection molding techniques were

implemented for developing this micro and nano crystalline cellulose based green composites

followed by its characterization of mechanical, thermal, chemical properties using various tensile,

flexural, TGA and DSC analyses. Also in this task, detailed biodegradation studies of developed

biobased materials and its bio-composites were tested in natural environments in terms of the potential

impact of biomaterials when they enter to waste streams such as landfill, compost and marine waste

conditions. In this study third experimental task, the obtained results were analysed its potential

applications and developed prototypes and validation studies were carried out according to

international norms and standards.

These experimental results demonstrate that low cost and higher thermal stability micro and

nano crystalline cellulose fibres from maize stalk residues and bagasse were approached to produce


7

bioplastic/microcrystalline cellulose fibre biocomposites. The approach consists of integrating green

treatment of natural fibre, process engineering and optimization. This green treatment resulted in micro

and nano crystalline cellulose withstanding the high temperature of melts processing successfully. The

physical-chemical and biodegradation behaviour results shown the optimized biocomposite made

from maize stalk residue and sugarcane bagasse natural fibres have potential opportunities to replace

certain non-biodegradable petroleum-based counterparts with added advantages of compostability

and low carbon economy. Also, this study results found a new outlet for maize stalk and bagasse from

agricultural waste which can help in viability to create a new generation of biobased industrial

products with signification value and economic benefit to agricultural farmers in South Africa.

Keywords: Agricultural natural fibres, cellulose, biopolymer and bio-composites

INTRODUCTION Waste Management in South Africa

Land fill fees and costs are ever increasing and the demand to recycle waste is increasing in South

Africa. Agricultural waste is one of the largest segments of the nationwide waste problems. These large

volumes of agricultural waste threaten surface water and groundwater quality in the event of waste

spills, leakage from waste storage facilities, and runoff from fields on which an excessive amount of

waste has been applied as fertilizer. The objectives of recycling are to save resources as well as reduce

the environmental impact of waste by reducing the amount of waste disposed at landfills. In many trials

in South Africa including the United States of America, animals utilize approximately 40% of maize stalk

residues and the remaining crop residue is waste. Sugarcane baggase is another fibrous matter that

remains after sugarcane stalks are crushed to extract their juice. It has found its use as a biofuel and in

the manufacturing of pulp and building materials. It has also been used over the recent years in the

production of biomaterials. The burning of baggase fibre became a major concern as far as

atmospheric pollution thus it has become necessary to implement new uses of the fibre. There is

currently no economic value for the sugarcane baggase available in South Africa. In anticipation of

the environmental pollutants, the research objectives were focused on the value added applications

of the polymers by extracting biopolymers from agricultural waste materials mainly used for potent

applications in automotive, building, and environmental applications. The total global natural fibre

composites market is anticipated to witness good growth and reach approximately US$ 27.4 billion 2016

with an 11% per annum increase in the next five years. The composite market is expected to

experience substantial growth in the future with new developments in various sectors [1].

Environmental issues of plastics wastes in South Africa

The new environmental regulations globally necessitated the global research community to conduct

research and development for new eco-friendly materials as an alternative to non-biodegradable


8

materials, particularly conventional plastics from fossil-fuel origin which creates serious environmental

pollution and greenhouse gas emission. In this respect, worldwide researchers have committed to

conduct value added research on eco-friendly biomaterial products in support of bioeconomy and

waste management strategies for new industry development in order to contribute to national GDP as

well as to align with the global competitive strategies.

The SA government has developed a policy framework to support research, development and

innovation to promote local manufacturing and industry development. The Department of Science

and Technology (DST) and Trade & Industry (the dti) are the lead Government Departments with a

mandate to ensure South Africa fully exploit the commercial potential arising from the use of biobased

materials for various industrial applications. One of the major challenges faced by the recycling sector

over the past decade, according to Plastics South Africa, is their inability to perform as a viable

alternative to plastic waste disposal problems. Plastics SA is committed to a policy of achieving zero

plastic waste to landfill as determined by the Waste Management Act. The South Africa Government in

its Industrial Policy Action Plan (IPAP) strategy document, identified the key industrial sectors critical to

improving the country’s GDP and associated job creation potential. Table 1 below profiles those sectors

in which some of the components could be replaced by composites and biomaterials to comply with

environmental legislation. The issue of biodegradability and recyclability of these composite and

biomaterials products will be of primary importance in enhancing the global competitiveness of the

local manufacturing sector.

Table 1. R&D focus and opportunities for composite and biocomposite for each identified sector.

IPAP

focused

sector

Aerospace Automotive Rail transport

Equipment

Renewable

Energy

Agro-

processing

Plastics

Contributio

n to SA

GDP

* R3.4bn (7%

of GDP)

R44.2 billion

(2.54% of

GDP)

* R7.7bn (16.

% of GDP)

R50 bn (-

R7bn trade

deficit)

Sector

objective

Substantially

diversify and

deepen the

components

supply

chain.

Substantially

diversify

and

deepen the

component

s supply

chain.

Metal

fabrication,

capital and

rail

transportatio

n equipment

Increase

local

content on

renewable

energy

components

Value

addition of

waste

streams to

increase

beneficiati

on

Address

environment

al concerns

regarding

plastic

manufacturi

ng and

waste

disposal

Opportuniti

es for

composite

and

biocomposi

te materials

Increase use

of

composite

and

biocomposit

e materials

for the

manufacturi

ng of high

Developme

nt of

lightweight

materials

automotive

interiors

parts to

reduce the

energy

Developmen

t of

lightweight

composite

and

biocomposit

e materials

body panels

with superior

Increase use

of bioplastic

production

and

manufacturi

ng

Extraction

for high

value

additives

(biopolyme

rs) and

cellulose

nanowhisk

ers for food

Developmen

t of

biodegrada

ble polymers

for use in

plastic

manufacturi

ng.


9

performanc

e, low cost,

lightweight

and

reduced

carbon

footprint

advantages.

consumptio

ns.

performance

functionality

(flame

retardant,

toughness,et

c.)

packaging

a and

filtration

application

s.

* No authentic data available

LITERATURE REVIEW

The worldwide production capacity for bio-based materials is predicted to increase from

approximately 1.4 million tons by 2015 to 6 million tons by 2019. This is account for an annual growth rate

of 32.7% during this five year period. Forecast shows that in 2016 large production of biobased materials

will occur in Asia (46.3%) and South America (45.1%) followed by Europe (4.9 %) and North America

(3.5%). The market share of bio-based biodegradable plastics and composite materials market is

dominated at about 90% currently [1]. The growth drivers and global production capacities of

biobased biodegradable and non-biodegradable materials are shown in Fig 1.

(a) (b)

Figure 1: Growth drivers (a) and global production capacities (b) of bioplastics and composite material

products by market segment (Source: European Bioplastics 2015).

Government legislations and incentives are also strong drivers towards the manufacturing of biobased

products. The Japanese Government has set a goal that 20% of plastics consumed in Japan should be

from renewable resources by 2020. Germany used bioplastic for beverages containers made from

more than 75% renewable resources until the end of 2012 [2]. Similarly, many companies have

mandated an increased use of renewably sourced materials in their products for market differentiation,

reduced environmental footprint, or weight reduction (i.e., automotive) purposes. For example, Toyota

has set the goal of using renewable or recycled material in 20% of its resin parts by 2015. The bioplastics


10

and their composites are also expanding into higher value/higher performance applications such as

single use products, semi durable compostable plastics and durable end uses such as automotive

returns to the future [3-5].

In South Africa sugarcane is grown in 14 cane-producing areas extending from the Eastern Cape

Province through the coastal belt and Kwa-Zulu-Natal midlands to the Mpumalanga lowveld.

Moreover, 14 million supply areas produce about 22 million tons of sugarcane on average each season

[6]. This has prompted increasing interest towards efficient use of agro-industrial by-products to reduce

agricultural wastes produced every year which poses potential pollution problems to the environment.

In addition, agricultural by-products are produced in millions of tons annually worldwide as waste from

agro-based processing and agricultural activities which litter the environment and result to waste

problems [7, 8]. One of the by-products produced in large quantities by sugar and alcohol industries is

sugarcane bagasse (SB) which is commonly discarded as agricultural waste or burned for energy

supply in sugar and ethanol mills [9]]. Both alternatives are, however, pollutant and inefficient in making

use of the chemical energy available in the biomass and still harm the environment.

One of the remarkable alternative solutions in resolving the impact of agricultural by-products on the

environment is the amount of research dedicated to the fractionation of agricultural biomass into

constituents such as lignin, hemicellulose and cellulose in what is best described as bio-refinery.

Sugarcane bagasse residue from refining process of sugarcane has been utilized as a raw material in

several processes and productions such as pulp and paper production [10]. Bagasse consists of 28.6%

hemicellulose, 23.5% lignin, 40-50% cellulose, 1.3% ash and 2.8% other components [11]. The high

content of cellulose suggests the possibility of using the SB as a source of cellulose and further for

extraction of nanowhiskers. A variety of pretreatments have been applied for the extraction of cellulose

from sugarcane residue. These include organic and inorganic solvent; chemical treatment; physical

processes such as grinding; biological pretreatments using bacterial and fungi; and diluted acids and

bases [7, 8, 12].

Cellulose is the most abundant natural homopolymer and renewable resource on earth. It is made up

of bundles of fibrils called microfibrils. However, individual fibril consists of crystalline region and

amorphous domains. CNCs are the rod shaped crystalline part remained after the removal of the

amorphous domains [13]. CNCs can be either extracted by enzyme or microbial hydrolysis [14] and

acid hydrolysis [15]. However, sulphuric acid hydrolysis is one of the preferred methods for the

extraction of CNCs from cellulosic materials due to the formation of sulphate charges on the surface of

the material which helps in stabilizing the suspension [15, 16]. On the other hand, CNFs are extracted by

means of mechanical treatment such as high shear homogenization [17], mechanical grinding [18], a

combination of mechanical actions and enzyme hydrolysis [18], and a combination of mechanical

actions and chemical method [18]. The diameters of these CNCs and CNFs are in the nano scale (<100

nm) range with the lengths in micron size [17]. CNCs and CNFs offer advantages such as high aspect

ratio, high surface area per unit volume, high strength and stiffness.


11

OBJECTIVES

The specific aim of this project is to develop value added biomaterials from agricultural waste residues

(maize stalks and sugarcane bagasse) that are abundantly available in South Africa. This is to replace

petroleum based non-biodegradable materials that pose serious environmental problems due to land

fill. Agricultural wastes are traditionally land-filled or burned but according to national environmental

management regulations (ACT NO 39 of 2004) this practice now has been prohibited as it is an

environmental hazard that generates greenhouse gas emissions and possible leaching of toxic

chemicals into surrounding ground and water sources. In addition, significant costs are incurred by

industry for transporting waste to landfill and maintaining landfill sites. Therefore, the development of

innovative technologies to maximise recovery and beneficiation of agricultural waste streams in a

sustainable way has become imperative for the industry. South African sugar mills produce 3 tons of

wet bagasse for every 10 tons of crushed sugarcane. Bagasse is generally burnt for generation of

power for the sugar mill but studies have indicated that more than 50% of this residue is available from

sugar mills for conversion to value-added products. The South African maize industry is the largest in

Africa employing nearly 169000 maize farmers and workers. The annual production of maize in South

Africa is around 8 million tons, cultivated in nearly 3 million hectares of land. Maize waste residues

comprise of cobs, leaves and stalks; currently small amounts of these residues are being used by

farmers as feed for livestock and the rest of these are largely under-utilized. Reports suggest that for

every 1 kg of dry corn grains processed, about 0.15 kg of cobs, 0.22 kg of leaves and 0.50 kg of stalks

are produced as waste residues.

Waste residues from forest and agricultural streams offer the following advantages:

Widely available and offer the least cost biomass option

Renewable resource that has a steady and abundant supply, especially those biomass

resources that are byproducts of agricultural activity

Carbon neutral, can displace fossil fuels and helps reduce greenhouse gas emissions while

closing the carbon cycle loop.

Agricultural wastes/residues can also be a source for providing additional income to

agriculturists without compromising the production of main food and even non-food crops.

This project dealt with the diversification of agricultural wastes from landfills. The use of waste products

such as bagasse and maize stalk residues as a suitable raw material feedstock for beneficiation into

high value products such as functionalized bio composite products for potential applications was

investigated.

This project has the following overall objectives:

I. To develop sustainable and affordable green composite materials that can substitute certain

petroleum based composite materials with added advantage of eco-friendliness and reduced

greenhouse gas emission.

II. To utilize agricultural waste such as (maize stalks and sugarcane bagasse) to develop value

added industrial biobased polymer and composite products.


12

III. To create a new generation of biobased structural materials with significant value and

economic benefit to agricultural farmers for potential applications in Automotive, Packaging and

Green Buildings in South Africa (Fig 2).

Figure 2. Overview of R& D initiative of this project

METHODOLOGY/DESIGN

This project has the following implementation tasks (Table 2)

Table 2. Project implementation tasks

Task

No Activities

1 Extraction and characterization of cellulose from bio-residues

2 Preparation, processing and characterization of micro and nano cellulose based

biocomposites

3 Study of the biocomposite materials for automotive, packaging and green Building

applications

Extraction and characterization of cellulose from bio-residues

The post-harvested agricultural biomass (maize stalks and sugarcane bagasse) were grounded into a

coarse powder by Hamermeul. The grounded powder was then weighed and dried in an oven at 50 ºC

overnight and treated with 1.5% NaOH, 1.5% NaClO2, and 1.5% KOH, respectively, for 1 hour. Each

treatment was repeated four times with repeated washes using deionized water to remove excess

chemicals and to achieve a neutral pH.

Extraction of cellulose nanocrystals (CNC)

Cellulose obtained biomass (maize stalks and sugarcane bagasse) after KOH treatment was hydrolyzed


13

using 50% acid concentration under a strong agitation of 1000 rpm, at 40 ºC for 30 min, keeping

acid/pulp ratio at 20:1 (ml/g). The hydrolysis process was terminated by adding 10-folds (1000 ml) of

deionized (DI) water. The suspensions were then centrifuged at 8000 rpm for 10 min and dialyzed with

deionized water for 3 days until the pH was neutral. Subsequently, the suspension was dispersed by

ultrasonication for 1 minute. Finally, the suspensions were stored in a refrigerator at 4 ºC with the

addition of few drops of chloroform to avoid fungal growth.

Extraction of cellulose nanofibers (CNF)

Cellulose pulp (2%) was agitated in a mechanical blender [Silverson L4RT (England)] at 35000 rpm for 15

minutes. Then, the dispersed suspension was ground using a supermass colloider [MKCA6-3 (Masuko

Sangyo Co, Ltd., Japan)] at a speed of 1500 rpm for 20 minutes until a gel-like substance was

achieved.

Characterization techniques

Morphology studies

FEI Quanta 200 (FEI Co., Eindhoven, the Netherlands) environmental scanning electron microscope

(ESEM) operated at an accelerating voltage of 20 kV was utilized to capture images. The samples of

the untreated and chemical treated (NaOH, NaClO2 and KOH) maize stalks were coated by gold prior

to ESEM analysis. Furthermore, atomic force microscope (AFM), [Veeco Multi Mode instrument

equipped with nanoscope V controller] was utilized to measure the dimensions of CNCs and CNFs. For

the analysis of CNCs and CNFs, a droplet of the aqueous suspension containing CNCs and CNFs was

dried on a mica surface prior to capturing images on AFM.

Birefringence studies

The aliquots of CNCs and CNFs were placed in sample vials. The vials were placed in front of a source

of polarized light and photographed using a DX Nikon camera.

Thermal stabilities

Thermogravimetric analysis was carried out on a thermogravimetric analyser (Perkin Elmer,

Buckinghamshire, UK) at a heating rate of 10 ºC/min using nitrogen as purge gas. The TGA programme

was conditioned to increase the temperature linearly from room temperature to 700oC under nitrogen

flow. The temperature of the sample was monitored and the loss in weight of the sample was

expressed in terms of percentage weight loss.

Crystallinity

The X-ray diffraction (XRD) profiles of the untreated and chemical treated (NaOH, NaClO2, and KOH)

maize stalk residues, CNCs and CNFs were measured using BRUKER AXS (Germany) X-ray Diffractometer

D8 Advance equipped with PSD (Position sensitive detector) Vantec-1 detector and Cu-Kα radiation

(λKα1=1.5406Å). Scattering radiation was detected in a 2θ= 5-90º at a rate of 1 second per step. The

amorphous peak and crystallinity peak are usually observed in XRD pattern. To quantify XRD results,


14

crystallinity index (CI) was determined from peak height method: In this method CI is calculated from

the height of the 002 peak (I002) and the height of the minimum (IAM) between the 002 peak and the

001 peak.

Chemical analysis

The spectra of the untreated and chemical treated maize stalks were obtained using FTIR-ATR Perkin-

Elmer 4000. All samples were scanned over a range of 4000-600 cm-1 with an average of 4 scans with a

resolution of 4 cm-1.

RESULTS AND DISCUSSION Task 1: Extraction and characterization of cellulose from bio-residues

The cellulose obtained after chemical treatment was weighed and the results confirmed that only 36%

yield was achieved. Alkali and bleaching treatments remove the amorphous lignin and hemicelluloses

which are cementing the cellulose [19]. Dilute alkali treatment solubilizes lignin and hemicellulose, while

bleaching treatment removes lignin. Visually, the white material was produced after treatment with

alkali and bleaching agent which indicates that a greater part of non-cellulose compounds were

removed after these treatments. Consequently, maize stalks treated with KOH should have higher

cellulose content in comparison to that of treated with NaOH and NaClO2 due to the removal of non-

cellulosic components.

Fig 3 FTIR results showed the presence of non-cellulosic materials by C=O, C=C and =C–O–C functional

groups at, and1252 cm-1. The peak at 1725 cm-1 represents stretching vibrations of the acetyl and

uronic ester groups of the hemicellulose or ester linkage of carboxylic group of ferulic and p-coumaric

acids of hemicellulose or lignin. The peak at 1521 cm-1 corresponds to aromatic stretching vibrations in

lignin, while the band at 1252 cm-1 is commonly seen when ether, ester and phenol groups are present.

These peaks disappeared after chemical treatment indicating the removal of non-cellulosic lignin and

hemicellulose. Other peaks were seen in all spectra which correspond to cellulose.


15

Figure 3. FTIR spectra of the untreated and chemical treated (NaOH, NaClO2 and KOH) maize stalk

residues.

Figure 4 shows morphology images of untreated and treated maize stalk. The untreated maize stalks

displayed a bundle of fibres which were bonded together by non-cellulosic components (lignin,

hemicellulose and extractives) (Figure 4A). It was seen that chemical treatment of the fibres induced

defibrillation of fibre bundles therefore reduces the size of fibres and roughens the surface of the maize

stalks.

Figure 4. ESEM images of A) untreated, B) NaOH treated, C) NaClO2 and D) KOH treated maize stalk

residues.


16

Figure 5 shows X-ray diffraction patterns of untreated and treated maize stalk residues. The reflection

peak at 2θ= 22.56º becomes more intense upon chemical treatment; this indicates the increase in

crystallinity of the material presumably due to the removal of non-cellulosic amorphous material

induced by chemical treatments. The untreated maize stalks as anticipated displayed a low crystallinity

index (Table 3) as compared to chemically treated (NaOH, NaClO2 and KOH) samples. This could be

due to the fact that the untreated maize stalks contain non-cellulosic amorphous materials (lignin,

hemicellulose, pectin and waxes)[20]. CNCs displayed the highest crystallinity index relative to CNFs

due to the removal of amorphous domains.

Figure 5. X-ray diffraction patterns of 1 untreated maize stalk, 2 NaOH treated maize stalks, 3 bleached

maize stalks, 4 CNFs, 5 KOH treated maize stalks and 6 CNCs.

Table 3. Crystallinity indices of the untreated and chemical treated (NaOH, NaClO2, and KOH) maize

stalks, CNFs and CNCs.

Sample Crystallinity (%)

Untreated maize stalks 53.8

NaOH treated maize stalks 64.0

Bleached maize stalks 66.1

KOH treated maize stalks 70.5

CNFs 66.4

CNCs 72.6

Figure 6 shows thermos gravimetric analysis (TGA and DTG) of untreated and treated maize stalk. The

DTG curve of the untreated maize stalks displayed a small hump at 191 ºC next to a main degradation

peak. This could be due to the presence of non-cellulosic components i.e. hemicellulose [21]. After

chemical treatment, the small hump disappeared (Figure 6B), which indicate the removal of non-

cellulosic components. From the DTG curve (Figure 6B) it was noticed that after chemical treatment the


17

prominent of cellulose peak shifted to higher temperatures with the increasing intensity of the peaks. It

was also noticed that the untreated maize stalks showed higher char residue as compared to the

chemical treated maize stalks. This could be due to the presence of lignin or cellulose-lignin complex.

Figure 6. A and B are TGA and DTG profiles of the untreated and chemical treated maize stalks.

AFM and birefringence studies.

Figure 7 shows AFM and birefringence studies of CNC and CNF in suspensions. CNFs displayed a web

structure with diameters ranging from 4 to 10 nm while CNCs exhibit a rod like shape with diameters

ranging from 3 to 7 nm and the lengths were in microns ranging from 150 to 450 nm. The aspect ratios

of CNCs were estimated to be ranging between 50 and 64.

Figure 7. A) and C) shows AFM images of CNCs and CNFs and B) and D) are birefringence of

suspensions containing CNCs and CNFs.

The presence of birefringence in suspension containing CNCs is the evident of the good dispersion of

CNCs in water [20]]. No birefringence (static or flow) was observed for CNFs suspension (Figure 7D). This

could be due to the structure of CNFs (Figure 7C) which tends to agglomerate due to the lack of


18

negative charges on the surface of CNFs fibrils [18]]. The birefringence in suspension containing CNCs

(Figure 7B) was not strong enough due to the presence of larger particles in the suspension which were

not hydrolyzed therefore resulting in weak birefringence [22].

Cellulose extraction from Sugarcane bagasse :

The chemical compositions of untreated sugarcane bagasse (SB), SB passed 500 times in a

supermasscolloider (SMC500), cellulose extracted by bleaching from SMC500 (SMC500C), cellulose

extracted directly from SB (C) and C passed 500 times in a supermasscolloider (C500SMC) are shown in

Table 4. The results reveal that there was a drastic increase in cellulose content from 49.75 to 98.9% and

a drop in hemicellulose and lignin contents to 2.60 and 0.41%, respectively. Prior to the chemical

treatment and for efficient isolation of the cellulose nanofibers, the mechanical treatment was

essentially inevitable to secure reasonably high cellulose content and at the same time lower lignin and

hemicellulose contents of the fibres. This may suggest that SMC provided more exposure of the

remaining lignin and hemicellulose which were removed by the chemical treatment for SMC500 and

water for C. All samples treated with SMC showed a slight increase in cellulose, while lignin and

hemicellulose slightly decreased. SMC500C revealed highest cellulose content followed by C500SMC

and C consecutively. Similar observations were reported on the isolation of cellulose nanofibers from

empty fruit bunches (EFB) and raw EFB via chemo-mechanical treatments. However, in our case high

amount of cellullose was obtained when SB was exposed to mechanical treatment followed by

chemical treamtment (SMC500C).

Table 4. Fractions of principal constituents of sugar cane bagasse before and after treatments

Sample Lignin (%) Cellulose (%) Hemicellulose (%)

SB 2.20 ± 1.34 49.75 ± 1.14 48.41± 0.75

SMC500 1.80 ± 0.13 55.90 ± 0.18 42.80 ± 1.81

SMC500C 0.50 ± 1.10 98.90 ± 0.18 2.60 ± 1.31

C 0.70 ± 0.51 94.0 ± 0.11 4.80 ± 0.12

C500SMC 0.41 ±0.52 96.5 ± 0.22 2.60 ± 1.31


19

The logical physical breakdown of the cell wall of sugar cane bagasse samples is evident from SEM

images obtained after each treatment (Figure 8). SMC500 (Figure 8B) fibres revealed a reduced

average diameter (approximately 10µm) and a reduced quantity of lumps on the surface, relatable to

pectin and wax, compared to SB (Figure 8A). On other hand, SMC500C(Figure 8C) revealed a further

reduced sheet-like fibrils average diameter (approximately 2 µm) which looked bonded to each other,

unlike C(Figure 8D) which indicated certain fibrillation with loose fibrils. Similar to SMC500C, C500SMC

(Figure 8E) showed a sheet like fibrils mostly spirally shaped with average diameter of 6 µm. It seems as

though supermasscolloider at 500 passes has a potential to fibrillate SB or cellulose into sheet form.

Figure 8. SEM images of SB (A), SMC500 (B), SMC500C(C), C(D) and C500SMC (E).

Figure 9 represents the FTIR spectra SB, SMC500, SMC500C, C and C500SMC obtained from sugarcane

bagasse. The SB and SMC500 samples show typical peaks of sugarcane bagasse around 3500 cm-1,

2921cm-1, 2852 cm-1, 1722 cm-1 and 1243 cm-1 which are attributed to the –OH stretching, C-H aliphatic


20

axial deformation in CH2 and CH3 groups from cellulose, lignin or hemicellulose, C=O group from acetyl

from hemicellulose and aromatic skeletal vibrations of lignin and hemicellulose respectively [23]. The

disappearance of these peaks was observed from all treated fibres due the removal of lignin and

hemicellulose. Compared to SB, the SMC500 spectra are more particularly those at 1508 and 1243 cm-

1,which are attributed to C=C aromatic vibration and C-O bond respectively together with the

absence of C-H aliphatic axial deformation peak. This observation could be attributed to partial

removal and/or exposure of both lignin and hemicellulose as suggested in chemical composition

analysis (Table 4). It was further observed that when a chemical treatment was applied after

mechanical treatment (SMC500C), a significant removal of lignin and hemicellulose led to a

disappearance of the peak at 1508 cm-1 as well as the C-H aliphatic axil deformation [24]. In fact, the

disappearance of the C-H aliphatic axial deformation peak in SMC500 and SMC500C, suggests that

the compounds containing this functional group could easily be removed when starting with the

mechanical treatment as opposed to a direct treatment with the chemicals. Furthermore, the

appearance of an intense peak at 1637 cm-1 attributed to absorbed water is a typical peak related to

pure cellulose which has a strong affinity of water. Therefore, the results imply that when fibres are

subjected to a mechanical treatment first, the more lignin and hemicellulose would be exposed to the

fibres surface due a breakdown of the fibre cell wall. The slight difference observed form the SMC 500

and SMC500C spectrum compared to C and C500SMC suggests that the supermasscolloider has

somehow changed the molecular structure of the cellulose fibres compared to chemical treatment.

Figure 9. FTIR spectra of SB, SMC500, SMC500C, C and C500SMC obtained from sugarcane

bagasse.


21

X-ray diffractograms of SB, SMC500, SMC500C, C and C500SMC are shown in Figure 10, while the

crystalline index in Table 5. The diffractograms show a major diffraction peak around 2θ = 22.2°, which

is attributed to cellulose I crystallographic plane (002) [8, 23]. A broad diffraction peak was also

observed between 2θ = 15° and 16° which is ascribed to the crystallographic plane (110) of cellulose.

The mechanical treatment revealed a slight decrease in crystallinity index for SMC500 compared to SB,

whereas an extraction of cellulose (sample C) led to an improvement in crystallinity index (Table 5). The

similar trend, however using a ball milling, of the mechanical treatments was obtained by Zhao et al.,

[25] and was related to a reduction in a long range order. Furthermore, mechanical grinding is able to

physically destroyed cellulose crystals and brake cellulose chains, resulting in small crystals with short

chain length. The same could be possible in our study; however SEM and FTIR results suggested that

either the exposure or the removal of lignin and hemicellulose could be responsible for the varying

crystallinity. In the case of the extracted cellulose (sample C) by chemical treatment, this may be

attributed to the dissolution of cementing materials, such as lignin and hemicellulose, by chemical

treatments, thereby increasing the crystallinity of C (79.5%), as shown in Table 5. Higher crystallinity of

extracted cellulose from all treatments (Table 5) was obtained in this study as compared to bleached

EFB fibres (67.12%) reported by Jonoobi et al., [26]. Wherein, a percentage crystallinity of about 75-78%

was gained for both mechanical and chemical treatment of raw SB fibre, which exhibits an effective

purification process by removing and/or exposing lignin, hemicellulose, and others waxy materials.

Figure 10. X-ray diffractograms of SB, SMC500, SMC500C, C and C500SMC obtained from

sugarcane bagasse.


22

Table 5. Crystallinity index of sugar cane bagasse before and after treatments

Samples Crystallinity indexa (%) Crystallinity indexb (%)

SB 58.5 ± 9.2 64.0 ± 4.2

SMC500 55.5 ± 5.0 57.0 ± 5.7

SMC500C 70.0 ± 0.0 78.5 ± 3.5

C 73.0 ± 2.8 79.5 ± 2.1

C500SMC 68.5 ± 0.7 75.0 ± 2.8

a Crystallinity index determined by XRD deconvolution method

b Crystallinity index determined by XRD peak height method

The thermal degradation and derivative curves of untreated SB together with its chemically and

mechanically treated counterparts are presented in Figure 11. SB and SMC500 revealed two

degradation steps at low thermal stability compared to celluloses which showed single degradation

step as confirmed by derivative curves. SMC500C indicated highest thermal stability than all celluloses

followed by C and C500SMC respectively. The two degradation steps and low thermal stability could

be attributed to the presence of substantial amount of hemicellulose and lignin which are known as

catalysts for thermal degradation of plant fibres [23]. The increase in thermal stability of SMC500C

suggests that the supermasscolloider exposed lignin and hemicellulose which were easily removed by

the chemical treatments as indicated in Table 4 and FTIR (Figure 9). Therefore, exposing pure cellulose

which is thermally stable and has high degree of structural order obtained by the two treatments. It

seems as though somehow the mechanical treatment minimise the interaction between cellulose,

lignin and hemicellulose which could promote the removal of lignin and hemicellulose by chemical

treatments as confirmed by FTIR results. Those which were not mechanically treated contained higher

amount of lignin and hemicellulose which are catalytic to thermal degradation, hence they are

thermally less stable than the treated ones. It is clear that applying SMC on cellulose (C500SMC)

destroyed cellulose crystals and broke cellulose chains, resulting in small crystals with short chain length,

hence the observed decrease in thermal stability as compared to SMC500C.


23

Figure 11. Thermal analysis of raw SB and mechanically and chemically treated SB (a) TGA

curves, (b) DTG curves.

Task 2: Preparation, processing and characterization of micro and nano cellulose based biocomposites

The following bioplastics materials listed in Table 6 has been investigated to develop biodegradable

green composite materials.

Table 6. Bioplastics used in this study for development of biodegradable green composite

materials

Test Sample Nature of sample /trade name Source

Poly butylene adipate-co-terephthalate

(PBAT) Biopolymer/Ecoflex BASF, Germany

Poly hydroxybutyrate-co-valerate (PHBV) Biopolymer (PHB88/HV12) GoodFellow, UK

Poly lactic acid (PLA) Biopolymer- 1001 Injection

moulding Cereplast, USA

Poly lactic acid (PLA) Biopolymer/3001D and 3052D Nature works, USA

Polybutylene succinate adipate (PBSA) Biopolymer /Bionelle1020 and

3020

Showa Polymer,

Japan

Table 7-8 and Fig 12-13 show thermo-mechanical properties of test materials were characterized by

thermal such as differential scanning calorimetry (DSC) and thermal gravimetric Analysis (TGA) and

mechanical testing tensile, flexural and impact etc.

Table 7. Thermal properties of pristine biopolymer samples as determined by DSC and TGA analysis.

Test Sample Tm (2nd heat) Tg Tonseta) Max Deg T Residue weight

(°C) (°C) (°C) (°C) (%)

Maize stalk residue N.A N.A 175.0 313.7 26.9

Extracted Cellulose N.A N.A 260.4 357.5 14.8

PBAT 116 -35.0 405.7 468.1 4.1


24

PHBV 162.9 n.d 322.9 355.5 0.8

PLA 1001 162.55 55-60 305.88 364.9 10.2

PLA 3001D 174.89 55-60 370.5 431.8 0.8

PLA 3052D 161.15 55-60 400.1 454.5 0.8

PBS 1020 114.0 -35.0 345.9 395.1 0.01

Figure 12. DSC analysis of different biopolymer a) first heating scan, b) cooling and second heating

scan

a) b)

Figure 13. TGA analysis of different biopolymer a) weight loss and b) derivative weight


25

Table 8. Mechanical Properties of bioplastics used in this study.

The analyzed results suggested, bioplastics have some drawbacks and several advantages in

comparison to conventional thermoplastic non-biodegradable PP. The bioplastics drawbacks are very

expensive and too brittle in nature and are not suitable for some applications. However, it has several

advantages; bioplastics are derived from agricultural wastes, renewable, biodegradable, recyclable,

reducing greenhouse gas emission and no carbon foot print etc [27-31]. Perhaps, the production costs

of bioplastics are not still completive to petrochemical plastic market [29-31]. The development of

biodegradable biocomposites with a biopolymer matrix and natural fibres are the new generation of

green composites materials and their biodegradation makes it possible to retain the whole carbon

content and save primary resources [2]. Therefore, in the present study have been proposed, by

making a blend tough biodegradable polymer with low cost natural filler such as MCC green

composite that will exhibit strength and rigidity of comparable to commodity plastics and display good

thermomechanical behaviour. Based on these approaches we have developed several strategies to

carryout research experiments as listed in the project implementation tasks.

Modification of bioplastics by blending with an optimized amount of a tough biodegradable

polymer

Improved adhesion of the developed bioplastics matrix with the MCC for high performance

biocomposite formulations as targeted applications

Incorporate high MCC into the biocomposite formulation

Sample

Tensile

yield

Strength

(MPa)

Tensile

Modulus

(MPa)

%

Elongation

Maximum

Flexural

Stress

(MPa)

Flexural

Modulus

(MPa)

Impact

Energy

(J/m)

MFI

(g/min)

Commercial Poly

propylene (PP) 27 752 100 35 1124 20-100 8

PHBV –

PHB88/HV12-

Goodfellow

40.0 2800 6 65 2900 18 5

PBAT - Ecoflex 16.0 68.6 500 4.72 101.4 229 9.4

PLA-

1001Cereplast 49.6 3590 5.1 80 3360 40 8

PLA – 3052D

Nature works 62.0 3750 3.5 108 3600 16 14

PBS –1020

Bionelle 35.0 600 200 32 700 31.8 25.3


26

Brittle biopolymer with tough biopolymer will be grafted with compatibilizer

Sample preparation, processing and characterization

Before processing of the various materials, each polymer was stored in a convection oven at 80˚C

overnight to ensure that the materials did not contain any moisture before being extruded. The

processing conditions varied with the polymer type blend. Attempts such as blending of biopolymers

and addition of fillers have been used subsequently to enhance the properties of biopolymers. Blending

is a way of improving properties and achieving property combinations required for specific

applications, allowing considerable improvement in the impact resistance of brittle polymers, etc.

Processing biopolymers and bio-composites is very challenging. Thus we needed to optimize certain

parameters before processing, such as temperature (Table 9-10). If the samples were processed at

temperatures leading to degradation of the polymer, inaccurate results would be observed.

Optimized processing parameters

Table 9. Temperature Parameters for Processing Materials on the CTE Twin Screw Extruder

Materials Processed Zone 1

(°C)

Zone 2

(°C)

Zone 3

(°C)

Zone 4

(°C)

Zone 5

(°C)

Zone 6

(°C)

Melt

Tempe

rature

(°C)

CPLA 1001 175 180 185 185 180 175 170

PLA 3001 D 175 180 185 185 180 175 170

PLA 3052 D 175 180 185 185 180 175 170

cPLA/PBS 1020 160 170 175 180 175 170 160

PBS 1020/ PBAT 134 150 155 155 155 150 130

PBS 1020/PBAT 134 150 155 155 155 150 130

cPLA/PBS 1020 + baggase 155 170 175 180 175 170 160

Table 10. Temperature Parameters for Processing Materials on the BOY Injection Moulding Machine

Materials Processed Nozzle

(˚C)

Front

(˚C)

Centre

(˚C)

Rear

(˚C)

Back Press

(˚C)

PBAT 160 155 155 150 5

PLA 3001 D 205 205 195 165 5

PLA 3052 205 205 195 165 5

cPLA 1001 170 170 160 150 5


27

PBS 1020 120 130 130 122 5

PBS 3020 100 115 105 105 5

PBS1020 ; PBAT; cPLA 160 155 150 145 5

PBS 1020 120 130 130 122 5

cPLA/PBS 1020) 155 155 150 145 5

cPLA/PBS 1020 155 155 150 145 5

cPLA + PBS + Baggase 155 150 150 145 5

cPLA + PBS + Baggase 155 150 150 145 5

Characterization

Tensile Properties

Five specimens from each biopolymer, biopolymer blend or bio-composite were tested for mechanical

properties after they were conditioned at room temperature (25 ˚C) for 2 days. The tensile test was

carried out using an Instron Tensile Tester, in compliance with the standard ASTM D 638 at room

temperature (25˚C).

Flexural Properties

In testing the flexural properties of the biopolymers, biopolymer blends and bio-composites, five

samples were tested after being conditioned at room temperature (25˚C) for 2 days. The flexural test

was carried out using an Instron Tensile Tester, in compliance with the standard ASTM D 790 - 90 at room

temperature (25˚C).

Biopolymer melt processing

Upon the processing of biopolymer and bio-composite blends, we encountered some challenges. The

completion of each formulation takes relatively a week. After the moulding of the biopolymer

materials, the samples had to be reconditioned for at least 48 hours or 2 days before testing, this takes

up time. The processing parameters need to be greatly considered as to prevent any damage to the

biopolymer, biopolymer blend or bio-composite.


28

Task 3: Study of the biocomposite materials for automotive, packaging and green Building applications

Figure 14. Tensile strength and elongation at break for the unblended biopolymers: (A) PBAT, (B)

PLA 3052, (C) cPLA 1001, (D) PLA 3001D, (E) PBS 1020 and (F) PBS 3020.

Figure 14 shows the tensile properties of the biopolymers. PBAT (14A) shows a tensile strength of

16.49 MPa and an elongation at break of 938.61 %. PLA 3052 (14B) shows a tensile strength of 53.85

MPa and an elongation at break of 4.71%, while cPLA 1001 (14C) shows a tensile strength of 35.51

MPa and an elongation at break of 12.62% and PLA 3001D (14D) has a tensile strength of 56.61 MPa

and an elongation at break of 4.15%. PBS 1020 (14E) shows a tensile strength of 32.05 and an

elongation at break of 555.16%, whilst PBS 3020 (14F) shows a tensile strength of 22.6 and an

elongation at break of 848.58%. PBAT was found to have a relatively high elongation at break, with

the lowest tensile strength, which proved to be flexible. PLA 3052 and PLA 3001D had high tensile

strengths and exceedingly low elongation at break, which proved that the biopolymers were

brittle. The behavior of the PBS shows that as the elongation increased, the tensile strength

decreased, as seen with PBS 1020 and PBS 3020.


29

Figure 15. Tensile strength and elongation at break of (70/30) biopolymer blends: (A) cPLA/PBS 1020, (B)

cPLA/PBS 3020, (C) cPLA/PHBV, (D) cPLA/PBAT, (E) PBS 1020/PBAT, (F) PBS 3020/PBAT, (G) nPLA/PHBV

and (H) nPLA/PBAT.

Figure 15 shows the tensile properties of the biopolymer blends. Blend (15A) showed a relatively high

tensile strength and low elongation at break, thus there was a change in the elongation of the PBS

1020. Blend (15B) showed a low tensile strength and elongation at break, thus the tensile strength was

affected. Blend (15C) showed a lower tensile strength and elongation. Blend (15D) had a very low

tensile strength and blend (15E) had a relatively high elongation at break and tensile strength, the

flexibility of the PBAT affected the elongation of this blend. The low mechanical properties of blend A

were found to be the most desirable as they impart the required properties for packaging applications.


30

Figure 16. Tensile and elongation at break for cPLA/PBS 1020 biopolymer blends: (A) cPLA/PBS 1020

(70/30), (B) cPLA/PBS 1020 (60/40) and (C) cPLA/PBS 1020 (50/50).

Figure 16 shows the tensile properties of the blend which achieved the desirable properties. The

biopolymer blend was then prepared in different ratios to achieve the most suitable properties. Thus

from figure 16, blend (16A) shows an exceedingly low elongation at break and high tensile strength.

Blend (16B) shows an increase with the elongation at break and a slight decrease in the tensile strength

of the biopolymer blend. Blend (16C) showed a huge increase in the elongation at break and a

decrease in the tensile strength. One great achievement made in this study was managing to increase

the elongation at break even though the tensile strength was decreasing. This is being due to other

studies failing to increase the elongation at break. Other studies always showed a decrease in the

tensile strength with a decrease in the elongation as well.


31

Figure 17. Tensile strength and elongation at break for the bio-composites: (A) cPLA/PBS 1020 +

Baggase (95/5), (B) cPLA/PBS 1020 + Baggase (90/10) and (C) cPLA/PBS 1020 + Baggasse (85/15).

Figure 17 shows the tensile properties of the bio-composite blend. We noticed that as the weight

percentage of the sugarcane baggase was increased, there was a decrease in the elongation at

break. Blend (17A) showed a very low tensile strength, whilst there was not much change in blends

(17B) and (17C). This is where we suspected that the biopolymer blend was incompatible with the

sugarcane baggase as there were also pores in the test specimens after testing.

Figure 18. Flexural strength and flexural modulus for bio-composites: (A) cPLA/PBS 1020 + Baggase

(95/5), (B) cPLA/PBS 1020 + Baggase (90/10) and C cPLA/PBS 1020 + Baggase (85/15).

Figure 18 shows the Flexural properties of the bio-composites. The sugarcane baggase has an effect on

the Flexural Modulus of the bio-composite blends, as the flexural modulus increased with increasing

sugarcane baggase content.


32

Table 15. Mechanical Properties of bioplastic blend and micro crystalline cellulse fibre biocomposite

materials.

Our preliminary characterizations had shown that the bioplastic blend PHBV/PBAT and PBS/PBAT have

an elongation at break of more than 250-550 % and basically shows a non-break behavior while impact

testing (Table 15). This is main the blend was considered as a good candidate for the matrix of

microcrystalline/bioplastic composites. Accordingly, it has been tried 20% micro crystalline MCC with

such a “tough” matrix, and characterized with mechanical tests (Table 15). As observed, addition of

20% MCC decreased the mechanical performance of the bioplastic dramatically, especially the tensile

modulus and impact strengths (Table 15). The 20% MCC into bioplastic blend system 1 and 3 (Table 15),

is improving the interfacial adhesion between MCC and the bioplastic, both tensile and impact

strengths were improved significantly, e.g. the impact strength was improved from 29 to more than 75

and 139 J/m depending on the bioplastic blend (Table 15). The analyzed results suggested, it is

necessary to optimize other binary blends with different ratios of PHBV/PBAT, PBS/PBAT and PLA/PBAT

and analyzing their properties to compare with obtained results and finding out the right binary blend

system for making bioplastic/MCC biocomposites for targeted application. One significant outcome of

the targeted optimized composite from maize stalk residue is that such a green composite have the

potential of substituting their petroleum-based counterparts such as polypropylene (PP) with added

advantages of compostibility and low carbon economy. Also, this part of project, various agricultural

waste and biomass based composite materials were also tested for green building applications. This

technical information is reported in annexure 1, 2, 3 and 4.

Annexure 1 : Design and development of natural fibre reinforced roof sheet

Annexure 2 : Design and development of bio-fibre reinforced ceiling tile

Annexure 3 : Development of thermal and sound insulation materials for building industries

Annexure 4 : Development of thermal and sound insulation materials for building industries and their

biodegradation studies

Sample

Tensile

yield

Strength

(MPa)

Tensile

Modulus

(MPa)

%

Elongation

Maximum

Flexural

Stress

(MPa)

Flexural

Modulus

(MPa)

Impact

Energy

(J/m)

PHBV/PBAT blend (80/20)

Bioplastic blend 1 24.5 1170 289 34.1 1110

Non-

break

PHBV/20% MCC 18.0 2100 1 35 2200 29.8

Bioplastic blend 1 (PHBV-

PBAT) /MCC(80/20) 16.3 970 10.2 27.7 1090 75

PBS/PBAT blend (70/30)

Bioplastic blend 2 46.0 250 550 18 400

Non-

break

PBS/PBAT blend (60/40)

Bioplastic blend 3 43.0 250 530 15 400

Non-

break

PBS/PBAT blend 3 (60-

40)/MCC 20% 20.0 1500 350 21 750 139.8


33

CONCLUSIONS

In this work, finely ground particles of sugarcane bagasse and maize stalk residues were extracted into

micro and nano crystalline cellulose fibres by various chemical and mechanical treatments. The

extracted cellulose fibres were analysed using thermal degradation analysis and structural

characterizations. The thermal degradation results suggest that the extracted cellulose fibre has higher

thermal stability (~250-350°C) than untreated sugarcane bagasse and maize stalk residues (~180 °C).

The structural characterization of cellulose fibre results suggested, the chemically treated natural fibres

has higher crystallinity behaviour as compared to mechanically treated cellulose fibres, these results

indicated that it has potential to withstand high temperature of melts processing successfully.

Conventional melt extrusion and injection moulding techniques were implemented for developing

extracted micro and nano crystalline cellulose based green composites. The optimized green

composite materials and products have the potential of substituting their petroleum-based plastic

materials such as polypropylene (PP) with added advantages of biodegradability and low carbon

emissions for both durable and short time used disposable products applications.

WAY FORWARD

• The project outcome support South Africa waste management strategies as well as in the

South Africa Bio-economy strategies. This preliminary R&D results are indicating there is potential

opportunities for creating valued added biobased products from agricultural waste with economic

benefit, replacing petro based products and reduced greenhouse gas emission. It also offers

opportunities to farmers, chemical and plastic industries, as well as industrial users and recycling

companies, which will have an impact on the socio-economic scenario in South Africa.

• The knowledge outcome of this project (lab scale results) suggests a further experimental study

on the technology demonstration is required for field trials to adopt the industrially prevalent process

engineering for real-world applications. The following studies are required for next level demonstration:

(i) to demonstrate the PLA based natural fibres biocomposite for successful moulding of returnable and

non-returnable bio-crates and validation as per manufacturing industry process requirements; (ii)

techno-economic feasibility studies of final validated bio-crates for direct and indirect benefit analysis

such as cost-benefit, technology, biobased market etc. The outcome knowledge will assist South Africa

to transition towards low carbon economy. This project may attract more funding from the TIA, DTI and

IDC to create more green jobs for the next generation of scientist and engineers and to improve

economic growth in South Africa.


34

ACKNOWLEDGEMENTS The authors would like to thank the financial support from Green Fund grant, an environmental finance

mechanism implemented by the Development Bank of Southern Africa (DBSA) on behalf of the

Department of Environmental Affairs (DEA); the Department of Science and Technology –

Biocomposite Centre of competence (BCoC) programme for 2014/015.

REFERENCES [1] Bioplastics. E. Press release: European Bioplastics: Fivefold growth of the bioplastics market by 2016.

October 10, 2012. . Available at: http://eneuropean-bioplasticsorg/blog/2012/10/10/pr-bioplastics-

market-20121010/ (Last accessed November 2013). 2013.

[2] Babu RP, O’Connor K, Seeram R. Current progress on bio-based polymers and their future trends.

Prog Biomater. 2013;2:1-16.

[3] Faruk O, Bledzki AK, Fink H-P, Sain M. Biocomposites reinforced with natural fibers: 2000–2010.

Progress in Polymer Science. 2012;37:1552-96.

[4] John MJ, Thomas S. Biofibres and biocomposites. Carbohydrate polymers. 2008;71:343-64.

[5] Reddy MM, Vivekanandhan S, Misra M, Bhatia SK, Mohanty AK. Biobased plastics and

bionanocomposites: Current status and future opportunities. Progress in Polymer Science.

2013;38:1653-89.

[6] Graham M, Haynes R, Meyer J. Soil organic matter content and quality: effects of fertilizer

applications, burning and trash retention on a long-term sugarcane experiment in South Africa. Soil

biology and biochemistry. 2002;34:93-102.

[7] Shaikh HM, Pandare KV, Nair G, Varma AJ. Utilization of sugarcane bagasse cellulose for producing

cellulose acetates: Novel use of residual hemicellulose as plasticizer. Carbohydrate polymers.

2009;76:23-9.

[8] Pereira PHF, Voorwald HCJ, Cioffi MOH, Da Silva MLCP. Preparation and characterization of

cellulose/hydrous niobium phosphate hybrid. BioResources. 2010;5:1010-21.

[9] Lima MA, Lavorente GB, da Silva HK, Bragatto J, Rezende CA, Bernardinelli OD, et al. Effects of

pretreatment on morphology, chemical composition and enzymatic digestibility of eucalyptus bark:

a potentially valuable source of fermentable sugars for biofuel production–part 1. Biotechnology for

biofuels. 2013;6:1.

[10] Sun J, Sun X, Zhao H, Sun R. Isolation and characterization of cellulose from sugarcane bagasse.

Polymer Degradation and Stability. 2004;84:331-9.

[11] Maddahy N, Ramezani O, Kermanian H. Production of nanocrystalline cellulose from sugarcane

bagasse. Proceedings of the 4th International Conference on Nanostructures (ICNS4)2012. p. 12-4.

[12] Sun J, Sun X, Sun R, Su Y. Fractional extraction and structural characterization of sugarcane

bagasse hemicelluloses. Carbohydrate polymers. 2004;56:195-204.

[13] Rosa M, Medeiros E, Malmonge J, Gregorski K, Wood D, Mattoso L, et al. Cellulose nanowhiskers

from coconut husk fibers: Effect of preparation conditions on their thermal and morphological

behavior. Carbohydrate polymers. 2010;81:83-92.

[14] Satyamurthy P, Vigneshwaran N. A novel process for synthesis of spherical nanocellulose by

controlled hydrolysis of microcrystalline cellulose using anaerobic microbial consortium. Enzyme and

microbial technology. 2013;52:20-5.

[15] Neto WPF, Silvério HA, Dantas NO, Pasquini D. Extraction and characterization of cellulose

nanocrystals from agro-industrial residue–Soy hulls. Industrial Crops and Products. 2013;42:480-8.

[16] Fahma F, Iwamoto S, Hori N, Iwata T, Takemura A. Effect of pre-acid-hydrolysis treatment on

morphology and properties of cellulose nanowhiskers from coconut husk. Cellulose. 2011;18:443-50.

[17] Zhao J, Zhang W, Zhang X, Zhang X, Lu C, Deng Y. Extraction of cellulose nanofibrils from dry

softwood pulp using high shear homogenization. Carbohydrate polymers. 2013;97:695-702.

[18] Qing Y, Sabo R, Zhu J, Agarwal U, Cai Z, Wu Y. A comparative study of cellulose nanofibrils

disintegrated via multiple processing approaches. Carbohydrate polymers. 2013;97:226-34.

[19] Henrique MA, Silvério HA, Neto WPF, Pasquini D. Valorization of an agro-industrial waste, mango

seed, by the extraction and characterization of its cellulose nanocrystals. Journal of environmental

management. 2013;121:202-9.


35

[20] Silvério HA, Neto WPF, Dantas NO, Pasquini D. Extraction and characterization of cellulose

nanocrystals from corncob for application as reinforcing agent in nanocomposites. Industrial Crops

and Products. 2013;44:427-36.

[21] Li R, Fei J, Cai Y, Li Y, Feng J, Yao J. Cellulose whiskers extracted from mulberry: A novel biomass

production. Carbohydrate polymers. 2009;76:94-9.

[22] Oksman K, Etang JA, Mathew AP, Jonoobi M. Cellulose nanowhiskers separated from a bio-residue

from wood bioethanol production. biomass and bioenergy. 2011;35:146-52.

[23] Kumar A, Negi YS, Choudhary V, Bhardwaj NK. Characterization of cellulose nanocrystals produced

by acid-hydrolysis from sugarcane bagasse as agro-waste. Journal of Materials Physics and

Chemistry. 2014;2:1-8.

[24] Abdel-Halim E. Chemical modification of cellulose extracted from sugarcane bagasse: Preparation

of hydroxyethyl cellulose. Arabian Journal of Chemistry. 2014;7:362-71.

[25] Zhao H, Kwak JH, Wang Y, Franz JA, White JM, Holladay JE. Effects of crystallinity on dilute acid

hydrolysis of cellulose by cellulose ball-milling study. Energy & fuels. 2006;20:807-11.

[26] Jonoobi M, Khazaeian A, Tahir PM, Azry SS, Oksman K. Characteristics of cellulose nanofibers

isolated from rubberwood and empty fruit bunches of oil palm using chemo-mechanical process.

Cellulose. 2011;18:1085-95.

[27] Thakur VK, Thakur MK, Gupta RK. Review: raw natural fiber–based polymer composites.

International Journal of Polymer Analysis and Characterization. 2014;19:256-71.

[28] Thakur VK, Thakur MK, Raghavan P, Kessler MR. Progress in green polymer composites from lignin for

multifunctional applications: A review. ACS Sustainable Chemistry & Engineering. 2014;2:1072-92.

[29] Keshavarz T, Roy I. Polyhydroxyalkanoates: bioplastics with a green agenda. Current opinion in

microbiology. 2010;13:321-6.

[30] Razza F, Innocenti FD. Bioplastics from renewable resources: the benefits of biodegradability. Asia‐Pacific Journal of Chemical Engineering. 2012;7:S301-S9.

[31] Soroudi A, Jakubowicz I. Recycling of bioplastics, their blends and biocomposites: A review.

European Polymer Journal. 2013;49:2839-58.


36

Annexure 1

Design and development of natural fibre reinforced roof sheet

The past MSM Nonwoven and Composite group’s Bio-build R&D project focused among others on

development of R&D technology platform and associated scientific technical expertise in the

manufacturing processes involved in moulding natural fibre reinforced roof sheet using vacuum

assisted resin transfer moulding (VARTM).Based on the outcome of experimental study on the suitability

of the VARTM technology for large scale production, MSM Nonwoven and Composite group

collaborated with Modek Translucent Roof Sheeting Company to use the CSIR needle-punched

nonwovens fabrics to mould roof sheets. Modek uses glass fibre as a reinforcing material in a

continuous laminating roof sheet manufacturing process to supply the local construction market.

Nonwovens and resin

The natural fibre nonwovens were blended with 10 wt % polypropylene fibres as carrier fibres and

polyester bioresin was used as matrix.

Agave/Polypropylene blends nonwoven with area weight 250 gsm.

Kenaf/Polypropylene blends nonwoven with area weight 250 gsm.

Equipment and the moulding process

The Modek equipment consists of three sections; the first section is where fibre is spread onto a plastic

sheet which acts as a conveyor. The second section consists of resin infusion system where resin is

infused and spread into the fibre to ensure resin saturation. The third section consists of a series of ovens,

46 m long with temperature range of 50oC – 75oC, where moulding into shape and curing of the

composite is achieved. The cured composite comes out of the oven as a solid piece which is then cut

into the required length.

The nonwoven was spread onto a thin plastic sheet belt and infused with the polyester resin. The

moving conveyor moves the fibre with resin to the next stage where the resin is properly spread onto

the fibre ensuring resin saturation of fibre is achieved. The saturated fibre proceeds into the ovens,

where the wet fibre is moulded into shape and cured.

Mechanical Tests

Mechanical tests to determine the tensile properties of some of the natural fibre roof sheets were

conducted. They were tested according to ISO 527 – 1 & 4 standard test methods.

• 250 gsm Agave – Polypropylene blend

• 250 gsm Kenaf – Polypropylene blend

The results obtained are given in the table below;

Table 1: Experimental data for the natural fibre reinforced composite roof sheets

Sample Tensile

(MPa)

Modulus (MPa) Resin Weight

Fraction

Fibre Weight

Fraction

250 gsm Agave 12.82 2621.73 0.88 0.12

250 gsm Kenaf 19.47 2757.64 0.88 0.12

It can be seen from the diagrams above that the Kenaf fibre reinforced composite roof sheets has

better tensile properties than their Agave counterparts. In this study 90% raw materials are derived from

renewable resources (biomass) alternative to petroleum and glass fibre materials.


37

Annexure 2

Design and development of bio-fibre reinforced ceiling tile

MSM Nonwoven and Composite group’s Bio-build R&D project development of R&D in the

manufacturing processes involved in moulding natural fibre reinforced ceiling tile using vacuum

assisted resin transfer moulding (VARTM). The technology has been developed for other applications

and this study will prove the feasibility of the technology and the viability of the product. The aim is to

manufacture the product with materials that have a higher percentage of sustainability and

biodegradability with lower greenhouse gas emissions.

Materials

The reinforcement is a 350gsm needle-punched South African source flax fibre mat produced by the

CSIR. This was chosen as an alternative to the traditional glass fibre chop-strand mat used for producing

ceiling tiles. Bio-resin has been chosen as an alternative to the current epoxy due to the content of bio-

mass within the material (21%-30%) with a 2:1 ratio of epoxy to hardener.

Manufacturing technology

Vacuum assisted resin transfer moulding (VARTM) is a composite manufacturing process whereby

reinforcement is place onto a mould (after being dried at 80°C for 24hours) and bagged with tacky

tape to create a closed system with and inlet and outlet. The outlet is connected to a vacuum pump

and the inlet to the liquid resin source.

Method 1

The vacuum pump is switched on and the inlet closed to check for proper closed system with no leaks

and left for 4 hours prior to resin infusion to stabilize the environment. After the environmental

stabilization period is finished, the resin is mix in the advised proportions and mixed thoroughly for a

homogeneous mixture. An inhibitor is proportionally added in replacement of the hardener to create

the optimal viscosity and gel time. The inlet is placed into the resin mixture and opened to start the

transfer of resin into the mould with the fibre bed. A drip bucket is connected between the outlet and

the vacuum source to collect extra resin after it has passed through the mould. When the resin is at this

point, the inlet is closed and the vacuum left on for an hour at which point the outlet is closed and the

vacuum switched off and left for 24 hours. The following diagram represents the entities of the

manufacturing process:


38

Method 2

This method is similar to the first except that the resin mixture is placed onto the fabric prior to bagging

and then the vacuum is switched on for 4 hours.

Fibre to Weight ratio

The fibre was weighed after the dehumidifying period and before being placed in the mould. The

panel was then weighed after the moulding process to find out how much resin is in the composite.

Method 1

Fibre content: 152.08g

Final panel weight: 839.7g

Fibre to resin ratio

18.1 : 81.9

Method 2

Fibre content: 181.85

Final panel weight: 2400g

Fibre to resin ratio:

7.5 : 93.5


39

Images

Method 1 Method 2

Conclusion

Both methods were successful in producing a panel that could be used as a ceiling tile. Unfortunately

the optimum fibre to resin ratios was not obtained due to the manufacturing method. The first method

was an improvement to the second, but not at the ideal fibre to resin ration of around 50:50. This is

partly because of the use of the inhibitor. The inhibitor was not used for the second method and thus all

the resin was not drawn out of the closed mould due to the high viscosity. The first method was an

improvement because of the addition of the inhibitor, but further work is required to obtain the

optimum mixture ratios.

The final product is one step closer to the optimum product, but there are important factors to consider

when assessing the product and the technology. The material selection is deemed to be correct for the

application, although the non-woven does not give homogenous properties throughout the panel

since there are areas of different fibre content. This is not critical to the product since the product is to

be used as a tertiary structure in the building.

The technology is considered to be not ideal for the product because of the slow turnover of product

verse cost for the application. Large scale producers would manufacture large quantities of ceiling tiles

in one day, whereas, this product is limited to the amount of product that can be produced on a daily

basis. There is also a need for more reliable product in terms of fibre to weight optimization. Therefore

we would recommend that the ceiling panel also be fabricated using the Modek manufacturing

process.


40

Annexure 3

Development of thermal and sound insulation materials for building industries

Introduction

Clay bricks, has been used in the construction of shelters for thousands of years, and approximately 30%

of the world’s present population still live in earthen structures (Cofirman R, 1990). Earth is a cheap,

environmentally friendly and abundantly available building material permanently. It has been used

extensively for wall construction around the world, particularly in developing countries (Ren KB, 1995).

Home brick-makers of Turkey and the Middle East have long been using fibrous ingredients like straw to

improve the tensile strength of mud bricks for millennia (Paksoy S, 2000). The onward march of

urbanisation and the continuous growth of industrialisation throughout the world together with the

increasing living standards have turned the creation of the built environment into a rising threat to the

natural environment. Buildings account for one-sixth of the world’s freshwater withdrawals, one-quarter

of its wood harvest and two-thirds of its material and energy flows. Those effects had prompted a vast

number of projects and initiative on energy efficiency and low cost housing in South Africa.

As part of the effort to reduce greenhouse emissions in the South African building sector, the CSIR Build

Environment (BE) approached CSIR Materials Science and Manufacturing (MSM) to design and

develop bio-composites for building envelope applications. This report will be on a bio-brick whose

mortar could, as well, be used for different applications of bio-wall panels.

Materials

1.Sugar cane bagasse (SB)

Table Fractions of principal constituents of sugar cane bagasse.

Sample Lignin (%) Cellulose (%) Hemicellulose (%)

SB 2.78 ± 1.34 48.75 ± 0.14 46.41± 0.75

2. Hardener/cement and Clay

Chemical components

Compound Cement (%) Clay (%)

SiO2 20.1 59.10

Al2O3 5.2 27.50

Fe2SO3 3.9 3.66

CaO 64.1 0.18


41

MgO 2.2 1,09

Na2O - 0.39

SO3 1.2 5.25

TiO2 - 0.63

Na2O+ K2O 1.4 -

K2O - 1.96

Experimental

1. Sugar cane bagasse was washed with tap water, dried, resized by screening through sieves of

1mm.and soaked in water for 2hr. 2kg of clay was dispersed in water together with 774.8g of

hardener to form homogenous mixture. The mixture was then mixed thoroughly with 2.4 kg

cane bagasse and moulded into a brick by compression to form Sample 2. A reference brick

without the hardener was also formed (Sample1).

Reference

Cofirman R, Agnew N, Auiston G, Doehne E. Adobe mineralogy characterisation of adobes from

around the world. In: Proceedings of 6th international conference on the conservation of

earthen architecture, Las Cruces, NM; 14–19 October, 1990.

Ren KB, Kagi DA. Upgrading the durability of mud bricks by

impregnation. Build Environ 1995;30:432–40.

Paksoy S. M.Sc. Thesis of the University of Cukurova, Adana; p. 78,

2000, unpublished [in Turkish].

Sound Transmission Loss Test

4 samples numerically numbered in the Table below containing 0g, 193.7g, 387.4g and 774.8g

respectively with clay and SB kept constant were tested in order to understand a trend followed by the

product.

Sample Type: 4 Different Samples of Bricks made from Bio-degradable material.


42

Testing Procedure: 5 random specimens are cut form each sample, each specimen should be a

cylinder to fit perfectly (no spaces) in a testing tube. Samples were conditioned (60+/-5 RH and 20+/-3

Degrees Celsius) for 24hrs before testing.

Sound Transmission Loss Testing: The standard was developed by the instrument manufacturers, LMS

Belgium. It uses 2 impendence tubes, 4 microphones, a speaker and a digital frequency analyser. The

frequency range of the instruement is 50-5700Hz.

Instrument: LMS Acoustic Tester, Belgium.

Results

Sample Average STL (dB)

1 47.25

2 42.49

3 32.90

4 21.59

The results show average STL for the frequency range of 50-5700Hz. Sample 1 had the highest STL value

(47.25dB) which means that it is the best in the tested samples in terms of being a sound barrier. Sample

4 was the worst at 21.59dB. See Graphs below:

Sample 1


43

Sample 2

Sample 3

Sample 4


44

FLAME RETARDANT REPORT

. SAMPLE DETAILS:

Sample 1 – Bio-based brick specimens 6 x100 mm x 100 mm samples

Sample 2 – Bio-based brick specimens 6 x100 mm x 100 mm samples

2. SAMPLING PROCEDURE:

All samples were supplied by Dr. Motaung. Samples were received on 09.03.2015.

3a. LABORATORY TESTING & METHOD:

Reference: ISO 5660-1 – Japan building Standards Law requirment.

3b. TESTING CONDITIONS:

All samples were tested as received, but after conditioning for a minimum of 24 hours at 21 C ±

3 C, and 50 % ± 5 % RH (Constant humidity chamber)

Cone calorimeter:

Sample specimens were wrapped according to ISO 5660-1 prior to testing

Equipment: Dual Cone Calorimeter

Manufacturer: Fire Testing Technology (FTT), UK.

Located in Fire Testing Laboratory, CSIR, Port Elizabeth, South Africa

C-factor calibration: 10.03.2015

Heat flux setting: 50 kW/m2

Test duration: 5 minutes (300 seconds)

Specimen orientation: Horizontal, with retainer frame

Examine: Peak Heat Release Rate (PHRR), Total Heat Release (THR), and specimen surface

after testing for compliance with requirements of classification for Fire Retardant samples (5

minute test time)

Sample 1 – 3 specimens tested

Sample 2 – 3 specimens tested

4. TEST RESULTS

The Japanese Building Standards Law was chosen for testing of the bio-based brick samples as

it is one of the few international standards for construction materials that make use of the cone

calorimeter as a test instrument. Materials are classified according to a set of criteria (Table 1).

The criteria are the same for each of three classes, but the test duration is different. Specimens

are tested according to ISO 5660-1, using a heat flux of 50 kW/m2.

Table 1 Japanese Building Standards Law classification

Classification Test duration

(min)

Peak heat Release rate

(kW/m2)

Total Heat Release

(MJ/m2)

Noncombustible 5 <200 <8

Quasi Noncombustible 10 <200 <8

Fire Retardant 20 <200 <8

In addition, there should be no cracks or holes on test specimens at the end of the test.

The results of the cone calorimeter testing is given in Table 2


45

Table 2. Cone calorimeter results

Peak heat Release rate

(kW/m2)

Total Heat Release

(MJ/m2)

Specimen after test

Criteria <200 <8 No holes or cracks

Sample 1 105 15.5 Some small holes

Sample 2 54 11.1 Few small cracks and

holes

These results relate only to the behavior of the specimens of the product under the particular

conditions of test; they are not intended to be the sole criterion for assessing the potential heat

release rate of the product in use.

A plot of the total heat Release (THR) is given in Figure 1. Figure 2 shows an example of the

specimens after test.

Figure 1. Total Heat Release Rate (Cone calorimeter, 50 kW/m2)

Figure 2. Left: Sample 1 after testing, Right: Sample 2 after testing

For information purposes, other cone calorimeter results are also included (Table 3).


46

Table 3. Additional cone calorimeter results.

Sample 1 Sample 2

Time to ignition (s) 32 38

Time to flameout (s) 108

(2 specimens started

flaming again before

the end of the test)

53

Average Heat Release Rate (kW/m2) 52 36

Average Mass loss Rate (g/s) 0.046 0.037

Average CO yield (kg/kg) 0.074 0.086

Average CO2 yield (kg/kg) 0.64 0.48

Total Smoke Release (m2/m2) 8.9 4.3

5. COMMENTS

According to the Japanese Building Standards Law, both brick samples would be classified as

“unclassified’ as both had a Total Heat Release greater than that allowed. Both samples also showed

some signs of cracks and holes. The Peak Heat Release Rate of both samples was lower than the limit.

Sample 1 produced more smoke and burnt for a longer period compared to sample 2.

In South Africa, materials, components and elements used in buildings are tested against SANS 10177,

and the bricks would need to be tested against this standard for a rating before use in South Africa.


47

Annexure 4

Development of thermal and sound insulation materials for building industries and their biodegradation

studies

Introduction

Thermal insulation of a building plays an important role in energy savings from reduction in heat gains

and losses through the building. A properly insulated building requires less heating and cooling during

winter and summer, respectively thus directly reducing the electricity cost. Much of the heat losses are

through the ceiling. Also noise has been identified as a major health hazard which significantly

decreases productivity in various environments. Noise pollution must be controlled in hospitals, homes,

shopping mall and offices in order to improve the quality of life. Therefore, a demand for better

noise/sound absorbing (acoustic) and thermal insulation materials is increasing in order to minimize its

negative effects.

This technology development work discusses the development of thermal and sound insulation

materials for applications in building industries, which can perform dual functions simultaneously. The

products developed in this work are in the form of sandwiched needle- punched nonwoven mats.

These mats are made from Polyester (PET) (derived from the recycled plastic bottles) and waste sheep

wool fibres. The products were evaluated for areal density, acoustic properties and thermal

conductivity. An extensive biodegradability study was conducted to analyse the conversion of organic

carbon into carbon dioxide by composting method for 50 days.

2. Materials and Methods

Sample preparation

A double layer sandwich structure consisting of a layer of polyester (PET) and waste wool (WW) was

developed. The layer combination for the first sample being 50/50 in weight of polyester and waste

wool, respectively and identified as 50PET/50WW. The target weight of the sample was 1000 g/m2. In

total 2 samples of 8 meters length were prepared as nonwoven dual sandwich. Each layer was

prepared by carding the fibres, cross-laying followed by light needle-punching at needle penetration

depth of 3 mm. The separate layers of 500 g/m2 were then joined by needling the layers at a needle

penetration depth of 7 mm to form a dual layer. The second sample was three layered. It was a

sandwich combination of PET outer layers and WW wool as the core layer. The sample compositions

being 25PET/50WW/25PET with target areal weight of 1000 g/m2.


48

Figure 1: (a) Schematic representation of the two layers sandwich structure (b) an actual sample

obtained from the experimental trials

Figure 2: (a) Schematic representation of the three layers sandwich structure (b) an actual sample

obtained from the experimental trials

The specifications of the fibres were: Polyester (PET): linear density 6.7 dtex, staple length 38 mm.

Waste wool blend: (WW): fibre diameter 28.6 μm (CV = 101.9%), staple length 38 mm,

The fire resistance properties of the products were enhanced by applying foam of fire retardant (FR)

(5% by weight), mixture of di-ammonimum phosphate and sodium tetraborate only at the surface. This

is an additional protection layer as per the fire requirements, although these fibres have inherent fire

resistance.

Property Evaluation

Samples were tested for thermal insulation, acoustic and bio-degradation properties.

1. Areal weight: Areal weight was measured using 5 cut samples of 20 cm x 20 cm dimensions an

electronic scale.

Table 1: Insulation Fabric Areal Weight

Sample ID Areal weight (g/m2)

50PET/50WW (WWP) 1115

25PET/50WW/25PET 1021

Thickness: Thickness of the samples was measured according to ASTM D5729-95 with a digital thickness

gauge under the weight of 1 kPa.

Table 2: Insulation Fabric Thickness

Sample ID Thickness (mm)

50PET/50WW (WWP) 8.339


49

25PET/50WW/25PET 8.044

Thermal conductivity: Laser Comp Fox 314 heat flow meter instrument was used for measuring thermal

conductivity as per the standard ASTM C518 and ISO 8301. Sample size was 300×300× (thickness). In this

test, sample was placed between two solid plates. The temperatures of the plates are kept at 3 levels

during the testing. These levels are set point 1, 2, and 3. Test temperature for set point 1 is -5 °C. Test

temperature for set point 2 is 15°C. Test temperature for set point 3 is 35°C. Test periods for set points 1,

2, and 3 are 110 minutes, 100 minutes, and 95 minutes. For each temperature the thermal conductivity

was measured and the average value is reported. Direction of heat flow was upward during the

testing.

Table 3: Insulation Material Thermal Conductivity

Sample ID K value (thermal conductivity/ mWm-

1k-1)

50PET/50WW (WWP) 0.03580

25PET/50WW/25PET 0.03203

4. Acoustic properties: Acoustic property of the samples was measured according to the ASTM E1050

standard, using 2-microphone impedance tube method.

Table 4: Insulation Material Acoustic properties

Sample ID

Frequency Range

50-2000 2000-5700 50-5700

50PET/50WW (WWP) 0.16 0.50 0.39

25PET/50WW/25PET 0.10 0.68 0.51

Overall, sample 50PET/50WW absorbed 39 % of the incident noise in the tested range between 50-5700

Hz. Sample 25PET/50WW/25PET absorbed 51 % in the same range. The performance of these samples

can be further enhanced if processing is optimised. In the initial samples, layers were observed to

delaminate hence a higher needling penetration depth was selected which reduced the fabric

thickness to about 8 mm from a target of 15 mm. Optimised setting can achieve higher fabric integrity

and thicknesses giving much improved performances.


50

Figure 3: Sound absorption curve for sample 50PET/50WW

Figure 4: Sound absorption curve for sample 25PET/50WW/25PET

5. Biodegradation

In order to study the biodegradability of the samples, the surface layers sprayed with chemicals (fire

retardant and silicon coating) was peeled off by hand and the remaining sample (90%) was subjected

to biodegradability testing. In this study, biodegradation test was carried out in 3 months old well

aerated compost, derived from mushroom farm consisting of straw/hay/mulch and chicken manure.

Further, the compost was sieved to a size below 0.8 mm to obtain uniform size of compost for testing

biodegradability of samples as per ASTM D6400 standard. Biodegradability of WW, PET and WWP

(50PET/50WW) was carried out.

Biodegradation results

The elemental analysis of the samples used for biodegradation studies is shown in Table 5 and

compostability test is shown in Table 6. WW sample mainly consist of carbon, followed by nitrogen,

hydrogen and sulphur, whereas PET mainly consists of carbon.


51

Table 5: Elemental analysis results of test samples.

Sample code N [%] C [%] H [%] S [%]

WW 16.34 43.42 3.59 1.08

PET 2.06 63.09 2.74 0

WWP 10.54 52.06 5.78 0.86

Note: All the results are average of two test samples.

Compostability tests

Table 6 : Organic carbon content and theoretical carbon dioxide (CO2)t of test samples and reference

sample analysed in the compost respirometric test.

Run Sample code Amount

[mg]

C

[%]

C [mg] (CO2)t

[mg]

Biodegradation (%) in 50

days

1 WW 4601 43.42 1997.75 7325.10 83.0

2 PET 5230 63.09 3299.61 12098.56 27.2

3 WWP 4173 52.06 2172.46 7965.70 69.7

4 Cellulose

(Reference)

5092.1 42.3 2153.96 7897.85 67.4

Figure 5: Biodegradation results of test samples under compost conditions


52

A maximum level of biodegradation of 83% for 50 days was observed for WW sample. However, an

acceleration phase was carried out for the WWP sample after 10 days of incubations and they were

approaching similar biodegradation behaviour to that of micro-crystalline cellulose powder, i.e.

reference samples (Fig. 5). Comparing with other test samples, the observed biodegradation behaviour

for PET sample was slow. Biodegradation results of the samples under compost conditions in terms of

carbon conversion into CO2 emissions indicate about 60-70% biodegradation in the case of WWP mats

in 50 days incubation time. Whereas, during the same time period, the observed biodegradation was

about 83 in 100% WW mats and 30% in case of 100% PET mat.

Conclusion : These mats are alternative materials for green building applications.


53

Date post:	22-Apr-2018
Category:	Documents
Upload:	vominh
View:	220 times
Download:	4 times

30 OCTOBER 2015 - Green Fund | Supporting Green Initiatives€¦ · · 2016-04-19LITERATURE...

Documents