2-74-1343890128-Gen Engg - Ijget - Development - t Karthik - Unpaid

DEVELOPMENT OF ECOFRIENDLY TEXTILE COMPOSITES FROM

CALOTROPIS GIGANTEA BAST FIBRE

T.KARTHIK & P.GANESAN

Department of Textile Technology, PSG College of Technology, Coimbatore, India

ABSTRACT

In the latest years industry is attempting to decrease the dependence on petroleum based fuels

and products due to the increased environmental consciousness. This necessitates an investigation on

investigate environmentally friendly, sustainable materials to replace existing ones. Calotropis Gigantea

is a soft shrub that can grow in dry habitats and in excessively drained soils. In this work, stem fibre of

Calotropis Gigantea and PLA have been used as a reinforcement and matrix respectively and are

compared with Flax / PLA composites. The chemical treatments such as alkali treatment and acetylation

were done to improve the mechanical properties of the composites. The results showed that the

mechanical properties of Calotropis Gigantea were less than the flax fibre composites which is expected

due to better flax fibre properties compared Calotropis Gigantea. The suitable coupling agent and its

concentration can be used out to improve its mechanical properties. The Calotropis Gigantea composites

can be used as low end applications in automotive industry.

KEY WORDS: Ecofriendly, Calotropis Gigantea, Fibre-Reinforced Composite, Thermoplastics.

INTRODUCTION

The interest in using natural fibres such as different plant fibres and wood fibres as

reinforcement in plastics has increased dramatically during recent years. The need for materials having

specific characteristics for specific purposes, while at the same time being non-toxic and environmentally

friendly, is increasing, due to a lack of resources and increasing environmental pollution. Studies are

ongoing to find ways to use lingo-cellulosic materials in place of synthetic materials as reinforcing

fillers. Thus, research on the development of composites prepared using new fibrous materials is being

actively pursued.

Bio-fibres like sisal, coir, hemp, oil palm are now finding applications in a wide range of

industries. The field of bio-fibre research has experienced an explosion of interest, particularly with

regard to its comparable properties to glass fibres within composites materials. The main area of

increasing usage of these composites materials is the automotive industry, predominantly in interior

applications. Material revolution of this century may be provided by green composite materials.

Sustainability, ‘cradle-to-grave’ design, industrial ecology, eco-efficiency, and green chemistry are not

just newly coined buzz words, but form the principles that are guiding the development of a new

generation of ‘green’ materials.

International Journal of General Engineering and Technology (IJGET) Vol.1, Issue 1 Aug 2012 26-43 © IASET

27 Development of Ecofriendly Textile Composites from Calotropis Gigantea Bast Fibre

Although biofibre reinforced polymer composites are gaining interest, the challenge is to

replace conventional glass reinforced plastics with biocomposites that exhibit structural and functional

stability during storage and use and yet are susceptible to environmental degradation upon disposal. An

interesting approach in fabricating biocomposites of superior and desired properties include efficient and

cost effective chemical modification of fibre, matrix modification by functionalizing and blending and

efficient processing techniques. Another interesting concept is that of ‘‘engineered natural fibres’’ to

obtain superior strength biocomposites. This concept explores the suitable blending of bast (stem) or leaf

fibres. This research work explores the possibility of using bast fibre obtained from giant milkweed to

produce composites. The milkweed fibre is seen as a possible raw material for reinforcements in

composites. This work will increase the application of milkweed fibre in industrial textiles.

MATERIALS AND METHODS

Fibre Extraction

In hand extraction, the outer bark of the stem is initially removed from the half dried calotropis

gigantea followed by extraction of fibre through simple scraping with a sharp knife.

Analysis of Chemical Composition of Fibre

The fibre extracted was treated to determine the fibre composition.

Extractible Content

The air dried sample of 5g was weighed in an extraction thimble and placed in Soxhlet

extraction unit. A mixture of ethanol and toluene (1:2) was used as solvent and extraction process

continued for a period of five hours at 900 C. After extraction the sample was rinsed with ethanol and hot

water and dried up to constant weight at the temperature of 60°C. The extractibles were calculated as a

percentage of the oven dried test sample and the method has been repeated for each sample.

Lignin Content

Two grams of extracted sample were placed in a flask and 15ml of 72% sulphuric acid was

added. The mixture was stirred frequently for two and half hours at 25°C and 200ml of distilled water

were added to the mixture. Then the mixture was boiled for next two hours and cooled. After 24 hours,

the lignin was transferred to the crucible and washed with hot water repeatedly until becoming acid free.

The collected lignin was dried at 105°C and cooled down in desiccators and weighed. The drying and

weighing were repeated until constant weight.[17]

Holocellulose Content

Three grams of air dried stem fibre were weighed and placed in an Erlenmeyer flask and then,

160ml of distilled water, 0.5ml of glacial acetic acid and 1.5g og sodium chloride were added

successively. The flask was placed in water bath and heated up to 75°C for an hour and then additional

0.5ml of glacial acetic and 1.5g of sodium chloride were repeated two times hourly. The flask was placed

T.Karthik & P.Ganesan 28

in an ice bath and cooled down below 10°C. The holocellulose was filtered and washed with acetone,

ethanol and water respectively and at the end, sample was dried in oven at 105°C before weighed.

α –Cellulose Content

Two grams of holocellulose were placed in a beaker and 10ml of sodium hydroxide solution

(17.5%) was added. The fibres were stirred up by glass rod so that they could be soaked with sodium

hydroxide solution vigorously. Then sodium hydroxide solution was added to the mixture periodically

(once every five minutes) for half an hour. The holocellulose residue was filtered and transferred to the

crucible and washed with 100ml of sodium hydroxide (8.3%), 200ml of distilled water, 15ml of acetic

acid (10%) and again water successively. The crucible with α – cellulose was dried and weighed.

Hemicellulose Content

The content of Hemicellulose of stem fibre was calculated from the equation

Hemicellulose = Holocellulose – α-Cellulose

Physical Properties of Fiber

The untreated and treated fibers were tested to determine the physical properties.

Single Fibre Strength and Elongation

The single fiber strength, an average (±0.4) value for twenty five samples was determined using

instron instrument (5500R), on 15 mm fibre length fixed between the movable and fixed clamps provided

in the instrument. The weight of the above clamped fibre is sensed automatically by a microbalance

online with the equipment. The average single fibre strength (±0.5%) on twenty five fibre samples for the

raw fibres were measured using the above instrument as per ASTM standards using testing speed and

gauge length values of 100 mm/min and 100 mm respectively after conditioning the samples at the

standard temperature and relative humidity (27.0 ± 0.2 °C and 65 ± 1%). Stress–strain curves for the

fibres were recorded by performing the tests as described above on the random fibre samples.

Fiber Diameter

The diameters of the fibres were measured using the Projection Light Microscope (WESWOX,

Optic Model 385/385 A) with a magnification of 200x. Averages of fifty randomly chosen readings were

taken to compute the mean fibre diameter with an accuracy of ±1.5%. Longitudinal optical micrographs

of fibre samples with a magnification of 200 were photo- graphed on the Optical Microscope.

Moisture Regain

The conditioning oven is used to determine the moisture regain and moisture content of the

fibre. Two grams of the sample was taken in a bottle and placed in the main chamber. The oven was

switched on and the thermostat set at 110°C. Heating was continued for 2 h, the material weighed, and

the reading noted. It was again switched on and after heating for 30 min the material was weighed. This

was carried on till the values stabilized.


Then using the following formula the moisture content and moisture regain were calculated.

Weight of bottle + stopper = W1

Weight of bottle + stopper + sample (moist) = W2

Weight of bottle + stopper + sample (dry) = W3

Moisture regain (R) = (W2 - W3) x 100

(W3 -W1)]

Composite Fabrication

Manufacturing process of composites was done at Composite Fabrication Centre, IIT Madras.

The resin polylactic acid with synthetic bio-degradable mixture (BF 703 B grade) was used for the

composite preparation. Initially, fibres were chopped into 30-50 mm in length converted into web form

to get uniform distribution of the fibre. The prepared web was cut in 30×30 cm dimension and laid on the

mold surface. Polylactic acid resin and its mixture in granule form were randomly distributed and one

more web layer was spread to form a sandwich distribution. It was noted to spread aluminum foil sheet

above and below sandwich for proper composite releasing from the mold. Core was prepared to get a

volume fraction of fibre-resin in the ratio of 40/60 .Compression molding technique was used for

manufacturing fibre matrix composite. The melt temperature of the die was maintained at 180- 200ºC

and at a pressure of 40-60 bar and core material was allowed to remain in this condition for one hour.

After compounding the core compounds were allowed to cool in room temperature for 2 hours. The

sample conditions was followed to prepare composites of raw fibre , alkaline treated and acetylation

treated fibre of Calotropis and flax with PLA resin mixture and for compounding two samples were

prepared .

CHEMICAL TREATMENT

Alkali Treatment

In this process untreated calotropis gigantea stem fibres were dipped in 10% NaOH solutions at

room temperature for an hour maintaining fibre weight to liquor ratio of 1:50. After treatment, the fibres

were neutralized with 5% acetic acid solution and thoroughly washed with distilled water. The washed

samples were dried at 85ºC until obtaining a constant weight

Acetylation Process

The calotropis gigantea stem fibres were soaked in demineralised water for an hour, filtered and

placed in a round bottom flask, containing acetylating solution. Acetylating solution consist of 250 ml

toluene, 125 ml acetic anhydride (2:1) and a small amount of catalyst H2SO4. The process temperature of

acetylation was 60°C and duration was 30min. After modification, the fibre was washed periodically

with distilled water until acid free. Finally modified fibres were air dried for certain time and then at

85ºC until obtaining constant weight.


Testing of Composites

The fabricated composites were tested for various mechanical properties such as tensile, flexural

and impact testing.

Tensile Testing

Tensile test is to analyze the compression resistance (the property of a material to oppose its

change in dimension under compaction) and recovery properties (the property of a material to regain its

original dimensions after release from compaction).The results obtained are essentially dependent on the

type of compression fixture used. Also, the gauge length is conical, as if it is too long, the specimen will

buckle and flex, resulting in premature failure. If it is too short, then the proximity of the tabs will

adversely affect the stress state, resulting in artificially high values. Cylindrical in design, a small

specimen sits within a set of trapezoidal grips, encased in collars and an alignment shell. The gauge

length depends on the type of test material and varies between 12.7mm for longitudinal specimens and

6mm for transverse specimens.

Tensile testing utilizes the test specimen as Shown in the Fig. 1, it consists of two regions: a

central region called the gauge length, within which failure is expected to occur, and the two end regions

which are clamped into a grip mechanism connected to a test machine INSTRON 5500R. These ends are

usually tabbed with a material such as aluminum, to protect the specimen from being crushed by the

grips.

Fig: 1 Specimen Size for Tensile Testing

The test specimens were conditioned at 23±2 ºC, 50±5 % RH for at least 40 h according to

ASTM D-3039.Tensile properties of Calotropis Gigantea and flax composites were measured using an

Instron Universal Testing Machine Model 3365 in accordance with ASTM Standards D-3039. The

instrument was calibrated with a gauge length of 50 mm with a sample size of 300 ×25 mm. The test was


repeated for 5 times each for untreated, alkaline treated and acetylated specimens of Calotropis and flax

composites.

Flexural Rigidity

The flexural test measures the force required to bend a beam under three point loading

conditions. The data is often used to select materials for parts that will support loads without flexing.

Flexural modulus is used as an indication of a material’s stiffness when flexed. After molding, test

specimens were conditioned at 23±2 ºC, 50±5 % RH for at least 40 hours according to ASTM D-

790.Flexural properties of Calotropis Gigantea and flax composites were measured using an Kalpak

Universal Testing Machine Model (KIC-2-0200-C capacity 20kN) in accordance with ASTM Standards

D-790 as shown in the Fig. 2. The instrument was calibrated with a span length of 50 mm at a sample

size of 12 ×120 mm.

Fig: 2 Three-Point Flexural Rigidity Testing Machine

Impact Testing

Notched Izod Impact is a single point test that measures a materials resistance to impact

from a swinging pendulum. Izod impact is defined as the kinetic energy needed to initiate fracture and

continue the fracture until the specimen is broken. Izod specimens are notched to prevent deformation of

the specimen upon impact. This test can be used as a quick and easy quality control check to determine if

a material meets specific impact properties or to compare materials for general toughness.

Fig: 3 Izod Sample Geometry


The test specimens were conditioned at 23±2 ºC, 50±5 % RH for at least 40 hours according to

ASTM D-256. The result of the Izod test is reported in energy lost per unit of specimen thickness (such

as ft-lb/in or J/cm) at the notch ('t' in graphic at right ) as shown in the figure 3. Additionally, the results

may be reported as energy lost per unit cross-sectional area at the notch (J/m² or ft-lb/in²). Impact

properties of Calotropis Gigantea composites and flax composites were measured with an Frank Testing

Machine in accordance with ASTM Standards D-256.The sample composites were analyzed with a

gauge weight of 25J with a sample size of 13×65 mm. Both raw and NaOH treated fibre produced

composites of Calotropis and flax were tested

RESULTS AND DISCUSSIONS

The stem of giant milkweed plant has been collected from Sankari and Udumalpet. The outer

skin of the bark was peeled from the stems of the plant by hand and the fibre was extracted. The

extracted fibre was tested for fibre properties such as fibre length, fibre diameter, strength, elongation

and moisture regain. The fibre composition was determined by various experiments and the results are

discussed below.

Fibre Composition

The different elements in the fibres were calculated by

Percentage fibre composition = (a-b)/a× 100

Where a - Initial fibre weight, b - Extract weight

Table 1: Calotropis Gigantea and Flax Fibre Composition (%)

S. No Fibre

composition

Calotropis Gigantea fiber %

composition Flax fiber % composition

1 Wax content 2.98 1.57

2 Lignin 3.5 6.5

3 Holocellulose 79 65

4 α-cellulose 51.5 47

5 Hemicellulose 27.5 18

6 Ash 2.2 -

A good understanding of the composition of fibre is needed to develop fibre reinforced

composites. From the Table 1 it is understood that the fibre contains nearly 80% of cellulose content.

Thus the investigation shows that fibres obtained from milkweed stems have much higher cellulose and

lower lignin content than the flax fibres. The cellulose content of the milkweed stem fibres is much

higher than that in the flax fibres but lower than that of cotton. The milkweed stem fibres also have much

lower lignin content when compared with the flax fibres but higher than the lignin content in cotton. This

property makes it a suitable raw material to produce composites with adequate strength and durability.


The study showed us that, milkweed stems are very sensitive to the alkaline treatment.

Relatively mild treatments using alkali alone have produced milkweed stem fibres with high cellulose

content .In addition to the treatment conditions, the chemical composition of the milkweed stems

influences the amount of cellulose in the fibres obtained.

Physical Properties of Fibres

Fibre diameter

The fiber diameters of Raw, NaOH treated and Acetylated fibre samples are given in Table 2.

Table: 2 Fibre Diameter of Raw, NaOH Treated and Acetylated Fibre

SL.No Fiber Particulars Calotropis Gigantea

Dia (µm) Flax Dia (µm)

1 Untreated fiber 134.87 131.642

2 NaOH treated fiber 140.026 136.871

3 Acetylated fiber 139.738 135.942

From the results, it was observed that the diameter of fibre after alkaline treatment increases

due to the fiber swelling action in both calotropis and flax. It was also observed that the untreated fibre

surface was rough, exhibiting waxy and protruding parts. The partial removal of lignin content is

shown by change in colour of the fibre. After the acetylation treatments the non-cellulosic content

present in the fiber is removed and the fibrillation is more which leads to increased amount of surface

damage of the fiber. The hydroxyl group is replaced by the acetyl groups and this can also be the

reason for the decrease in moisture absorption. It can be seen that the variations in diameter after

acetylated treatment is very minute and not much significant in the fibers.

Single fibre strength

The fibre extracted from the stem of Calotropis stem was tested for its Single Fibre Strength

using INSTRON 5500R are given in Table 3.

Table: 3 Fibre Properties

Parameters Breaking

strength(g) Breaking Elongation (%)

Calotropis Flax Calotropis Flax

Raw Fibre 427.7 740.75 1.6 2.34

NaOH Treated 400.28 707.95 2.9 2.94

Acetylated 267.85 415.87 1.27 1.98


Milkweed stem fibres have strength higher than milkweed floss, similar to that of cotton as

determined in the stress–strain curves. However, the strength of the milkweed stem fibres is similar or

higher than that of other common bast fibres such as jute and the fibres obtained from various

agricultural by-products. Breaking elongation of the milkweed stem fibres is higher than that of

milkweed floss and most other bast fibres but lower than the elongation of the cotton fibres. The high

elongation of the milkweed stem fibres indicates that the fibres may have a higher microfibrillar angle

than the common bast fibres. The flax fibres have better fibre properties when compared to Calotropis

Gigantea as shown in Table 3. The NaOH treated fibres have less strength compared to raw fibres due to

partial removal of lignin and the acetylated fibres significantly losses the strength both in calotropis

gigantea and flax fibres due to breaking of –OH bonds and replaced with acetyl groups.

Moisture regain

The moisture regain of the fibres was determined according to ASTM standard method 2654

using standard conditions of 21°C and 65% relative humidity .The moisture regain of the Calotropis

Gigantea milkweed fibre and flax fibre are shown in Table 4.

Table: 4 Comparison of Moisture Regain Values of Calotropis Gigantea and Flax Fibre

Parameters

Calotropis Gigantea Flax

(% Moisture Regain) (% Moisture Regain) Raw Fibre 9.7 12

NaOH Treated 13.5 15.4

Acetylated 6.3 8.5

The alkaline treated fibers show a more moisture regain compared to untreated fiber. This can

be due to the removal of waxy content and other impurities like fat, proteins etc which reduces the

moisture absorbency. The reduction in moisture regain after acetylation process is due to the

modification of cellulosic fibres and hydroxyl groups of the cell wall replaced by acetyl groups, which

modify the properties of these fibers so that they become hydrophobic which could stabilize the cell wall

against moisture, improving dimensional stability and environmental degradation.

FTIR analysis of fibre

FT-IR microscopy is a well-established method for the chemical identification of particles or

contaminants and for visualizing the distribution of certain substances in complex compounds.


Table: 5 FTIR Chart

Fibre Component

Wave number (cm-1)

Functional Group

Compounds

4000-2995 OH Acid, Methanol 2890 H-C-H Alkyl, aliphatic Cellulose 1640 Fibre-OH Adsorbed water

1270-1232 C-O-C Aryl-alkyl ether

1170-1082 C-O-C Pyranose ring skeletal

1108 OH C-OH

4000-2995 OH Acid, methanol Hemicellulose 2890 H-C-H Alkyl, aliphatic

1765-1715 C=O Ketone and carbonyl

1108 OH C-OH

4000-2995 OH Acid, methanol 2890 H-C-H Alkyl, aliphatic 1730-1700 Aromatic 1632 C=C Benzene stretching ring Lignin 1613, 1450 C=C Aromatic skeletal mode

1430 O-CH3 Methoxyl-O-CH3

1270-1232 C-O-C Aryl -alkyl ether

1215 C-O Phenol

1108 OH C-OH

700-900 C-H Aromatic hydrogen

Due to the usage of modern focal plane array detectors, this technology has advanced to a new

imaging technique during the last few years. It allows for the measurement of even large sample areas

with a very high lateral resolution within a few minutes. The assignments of wave numbers for different

functional groups are given in the Table 5.

(a)


The effectiveness of chemical treatments carried out on the fibre was assessed by FTIR

spectroscopy, which yields the progress of the chemical reaction in time. The FTIR spectra of untreated,

alkali-treated and acetylated fibers are shown in the Fig.4. It can be noted that there is an absorption band

at~1700-1750 cm-1 and 1316 cm-1 for the treated fiber is reduced compared to the raw fibers. This shows

that there is partial reduction in the lignin content. The vibrations at 2880-2850 cm-1 indicate CH and

CH2 symmetrical stretching formed from the wax variations due to the treatment.

(b)

(c)

Fig: 4 FTIR of (a) Raw (b) Alkali Treated (c) Acetylated Fibre

Also the absorption at 1716 cm-1 is reduced which means the acid carbonyl absorption is

reduced indicating the corresponding reduction in hemicelluloses (xylans) content. Alkali treatment is

expected to reduce the hydrogen bonding in cellulosic hydroxyl groups by the removal of the carboxyl

group by the alkali, thereby increasing the OH concentration due to the changes in the spiral angle and


higher exposition of OH, when cellulose I changes to cellulose II. The increased intensity of the OH

revealed by FTIR results indicates that the alkali treatment was effective.

After acetylating reaction, new acetyl groups were added to cellulose, as indicated in curve,

with the vibrations at 1732 cm-1 (–C=O) and 1108.06 cm-1 (C=O). The spectrum of unmodified cellulose

shows an absorption peak at 1315 cm-1 attributed to the –C–H bending vibration. The spectra at 1240-

1350 indicate C=O aryl and C=O aromatic group indicating change in the lignin and cellulose part due to

the acetylation process. As the reaction progresses the content of acetyl groups increases which is

revealed by an increase in the intensity of the peak at 1732 cm-1.

Composite Fabrication

Manufacturing process of composites was done at IIT Madras, Composite Fabrication Centre.

Extracted fibre was compounded with Polylactic acid resin with its synthetic bio-degradable mixture in

compression molding manufacturing technique. A total of 12 samples were fabricated using raw, alkaline

treated, acetylated treated of calotropis gigantean (Fig. 5) and flax fibre along with PLA and its synthetic

biodegradable formulation mixture as matrix.

(a)

(b) (c)

Figure: 5 Calotropis Gigantea Fibre Composites (a) Untreated,(b) NaOH

Treated (c) Acetylated


Composite Testing

Tensile Testing

The results of tensile testing of calotropis and flax fibre composites are shown in Table 6 and

Fig.6.

Table: 6 Tensile Strength of Calotropis and Flax Fibre Composites

Material

Tensile Strength (MPa)

Calotropis Flax

Raw fiber 32 34.9

NaOH treated 35.07 37.2

Acetylated fiber 36.26 38.25

Two different surface modification methods (alkalization and acetylation) were applied on the

extracted fibre. Alkali treatment removes hemicelluloses, lignin from the fibre and became more

thermally stable than untreated fibres. Acetylation treatment on alkali treated fibres caused further

purification on the removal of hemicelluloses, lignin components from the fibre and the chemical

treatment also increases the fibre individualization (fibrillation).

Fig: 6 Tensile Properties of composites

From the table we are able to determine the tensile strength of composites were found to

increase with increasing degree of surface modification up to some extent and then decreased with

further increasing degree of chemical concentration. The increase in tensile strength could be due to the

more fibre-matrix interfacial strength because of the modified fibre surface and increased surface free

energy which shows increased tensile strength of composites. It shows that the alkali treated and

acetylated composites have higher tensile strength of about 9% and 12% compared to untreated fibre

composites respectively for calotropis gigantea fibre composites and about 6% and 9% for flax fibre

composites.


Flexural Testing

Flexural properties of untreated and treated fibre composites are shown in Table 7 and Figure 7

Table: 7 Flexural strength of Calotropis and Flax Fibre Composites

Material

Flexural Strength (MPa)

Calotropis Flax

Raw fiber 49.238 83.635

NaOH treated 52.435 85.241


Flexural testing gives a positive study into the structural comparison of the fibre structure.

Chemical treatment changes the amorphous regions and arrests the random movement of the fibrous

structure improving the elastic nature of the fibre. The improvement of flexural properties of treated fibre

composites is likely to be due to removal of outer surface. The possible reason for this improvement is

the alkalization helps to improve fibres hydrophobicity by removing hemicelluloses, lignin and other

cellulosic matters from the fibre. As a result compatibility between the fibre and resin were improved

which resulted superior mechanical properties. It shows that the alkali treated and acetylated composites

have higher flexural strength of about 6% and 8.5% compared to untreated fibre composites respectively

for calotropis gigantea fibre composites and about 2% and 6% for flax fibre composites. There is also

fibrillation and diameter reduction of fibre due to acetylation that may have influence on modulus

properties of composites. The flexural strength of flax composites are much higher than the calotropis

gigantean composites as shown in Fig. 7.

Fig: 7 Flexural strength of composites


Impact Testing

Impact properties of untreated and treated fibre composites are shown in Table 8 and Figure 8.

Table: 8 Impact strength of Calotropis and Flax Fibre Composites

Material

Energy (Joule)

Calotropis Flax

Raw fiber 0.895 0.909

NaOH treated 807 0.826


The impact strength of a composite is usually influenced by many factors, including the

toughness properties of the reinforcement, the nature of interfacial region and frictional work involved in

pulling out the fibre from the matrix. The nature of the interface region is of extreme importance in

determining the toughness of the composite. The impact testing shows a close relationship with both raw

and NaOH treated composite. It does not show much variation because the alkali treatment does not

change the load distribution properties of the fibre. Impact testing gives a close value between the

composites. Acetylation treatment decreases the impact strength of both calotropis and flax fibre

composites .This could be may be due to the brittleness increase of fibre matrix material and local

internal deformation in composite material.

Fig: 8 Impact Strength of composites

From the figure 8, it is observed that the calotropis gigantea and flax composites shows

more or less same impact properties. This shows that calotropis gigantea fibre can used in application

where flax is used. The impact strength properties are very important for the high end industrial


applications. However chemical treatment reduces the impact strength in the composite due to surface

damage. For applications preferring high impact properties it is recommended to use untreated fibre [17].

CONCLUSIONS

The concept of bio-based materials is now becoming a key important factor due to the ultimate

need to preserve our environment. Study into bio-composites investigated different matrix components

and research conducted found that polylactic acid and its synthetic bio-degradable formulation is a eco-

friendly matrix. The stem of Calotropis gigantea is a soft shrub that can grow in dry habitats and in

excessively drained soils. Stems of Giant Milkweed plant can be used to obtain natural cellulose fibers

with good strength and elongation. Study investigated the fiber composition and physical properties of

the extracted stem fiber and found that the fiber is having properties suitable for composite application.

The composite have been fabricated using calotropis gigantea stem fiber and the resin mixture

formulation of PLA using compression molding. The PLA resin mixture formulation was found to be

having a good bonding strength with the calotropis gigantea stem fiber. The resin formulation is having a

good adhesion property and is able to withstand high temperature. Further study in the composite

manufacturing found that hydrophilic character of the fiber affects the composite durability. To improve

the hydrophilic character the fiber was given chemical treatments. This research work also conducted

comparative analysis of the fiber diameter and mechanical properties of raw fiber and chemically treated

fiber.

From the research work, it is observed that the mechanical properties of calotropis gigantea

composites are slightly inferior compared to flax fibre composites due to better fibre properties of flax. It

is also clear that, the chemical treatments of fibres improved the adhesion between matrix and resin and

thus improved the mechanical properties of fibres.

REFERENCES

1. Alireza Ashori and Zaker Bahreini, 2009, “Evaluation of Calotropis Gigantea as a Promising

Raw material for fibre-reinforced Composite,” Journal of composites, Vol.43, pp. 1298-1303.

2. Narendra Reddy and Yiqi Yang, 2009, “Extraction and Characterization of natural cellulose

fibres from Common Milkweed Stems,”Biological Systems Engineering Papers and

Publication, pp. 2214-2216.

3. Amir Nourbakhsh, Alireza Ashori and Mojgan Kouuhpaayehzadeh, 2009, “Giant Milkweed

(CalotropisPersica) Fibers-A potential reinforcement Agent for Thermoplastics

Composites,”Journal of Reinforced Plastics and Composites,Vol.28, pp. 2143-2145.

4. Pushpanjali Prasad, 2006, “Physio-chemical properties of a non-conventional Fibre:Aak

(Calotropis Procera),” Journal of Textile Association, pp. 63-64.

5. Parmar M.S, Rao J.V, Mansi Bahl and Chitra Arora, “To Study Behaviour of Milkweed Fibres

collected from Different Regions”.


6. Sakthivel J.C, Mukhopadhyay S, and Palanisamy N.K, 2005, “Some Studies on Mudar Fibres,”

Journal of Industrial Textiles, Vol.35(1), pp. 63–76.

7. Sanjay K.Mazumdar PhD., “Composite Manufacturing-Materials, Products and Process

engineering”.

8. Ward J, Tabil L.G, Panigrahi S, Crerar W.J, Powell T, Kovacs,Alvin Ulrich A.J,“Tensile

Testing of Flax Fibres,”pp. 3-7.

9. Andrew B Conn and Warren J Bachelor,“Conversion of an Instron to mechanical testing of

single fibres,”pp. 1-3.

10. Jiri Militký,Dana Křemenáková, Gabriela Krupincová, and Josef Ripka, 2004,“Relations

between bundle and single fibre strength,” October 3-6, pp. 1-3.

11. Mohanty K, Misra M &Drzal L.T (Eds.), CRC Press,“Natural fibres, Biopolymers and

Biocomposites”.

12. Muhammad Jannah Bin Jusoh,“Studies On The Properties Of Woven Natural Fibres Reinforced

Unsaturated Polyester Composites”.

13. Horrocks A.R and Anand S.C,“Handbook of Technical Textiles,”Woodhead Publishing Ltd.

14. Rout J, Misra M, Tripathy S.S, Nayak S.K & Mohanty A.K, 2001, “ The influence of fibre

treatment on the performance of coir-polyester composites,”Composites Science and

Technology 61,pp. 1303-1310.

15. Sinha E & Rout S.K, 2009,“Influence of fibre surface treatment on structural, thermal and

mechanical properties of jute fibre and its composite,”Bulletin of Materials Science 32(1), pp.

65-76.

16. Viviana P.C., Claudia V., Jose M.K. & Analia V, 2004,“Effect of chemical treatment on the

mechanical properties of starch-based blends reinforced with sisal fibre,”Composite Material

38(16),pp. 1387-1399.

17. Bledzki A.K, Mamun A.A, Lucka-Gabor M, Gutowski V.S, 2008, “The effect of Acetylation on

Properties of Flax Fibre and its Polypropylene Composites,” Express Polymer letters, Vol. 2, pp.

414-416.

18. Maya Jacob John and Sabu Thomas, 2007, “Bio-fibres and Bio-composites,”pp. 346-347.

19. Yang H.S., Kim H.J., Park H.S., Lee B.J And Hwang T.S, 2006,“Water Absorption Behavior

and Mechanical Properties of Ligno-cellulosic Filler-Polyolefin Bio-Composites,” Composite

Structure, Vol. 72,pp.429–437.

20. David Roylance, 2000,“Department Of Materials Science And Engineering, Massachusetts

Institute Of Technology, “Introduction To Composite Materials,” March 24, pp. 1.


21. Jayaraman K, 2003, “Manufacturing Sisal-polypropylene composites with minimum fiber

degradation,”Vol.63, pp.367–374.

22. Donald Garlotta, April 2001,“Composites Science and Technology,” Journal of Polymers and

the Environment, Vol. 9, pp. 63-64.

23. Kabir M.M, Wang H, Cardona F &Aravinth T, “Effect of chemical treatment on the mechanical

and thermal properties of hemp fibre reinforced thermoset sandwich composites”.

24. ASTM, 2009, ”Standard Test Method for composites,” American Society for Testing and

Materials, chapter D1256, 790, 3039.

25. Mohanty A.K., Misra M., Drzal L.T, 2001,“Surface modifications of natural fibres and

performance of the resulting biocomposites,” Composite Interfaces, Vol.8, pp.313–343.

26. James S. Han and Jeffrey S. Rowell, “Paper and Composites from Agro-Based Resources”,

Chemical Composition of Fibers, Chapter 5, pp.8

27. Rahim Oraji, 2008, “The Effect of Plasma Treatment on Flax Fibres”, pp.7-53

Date post:	28-Oct-2014
Category:	Documents
Upload:	peacesoul
View:	35 times
Download:	0 times

2-74-1343890128-Gen Engg - Ijget - Development - t Karthik - Unpaid

Documents