Effect of Seawater on Ageing of Polyester Composites and ... · P 12 Kerem KÜÇÜK Master Thesis...

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Effect of Seawater on Ageing of Polyester

Composites and Study of Aged Composite Polymer

Kerem KÜÇÜK

Master Thesis

presented in partial fulfillment of the requirements for the double degree:

“Advanced Master in Naval Architecture” conferred by University of Liege

"Master of Sciences in Applied Mechanics, specialization in Hydrodynamics,

Energetics and Propulsion” conferred by Ecole Centrale de Nantes

developed at l’Institut Catholique d’Arts et Métiers (ICAM), Nantes

in the framework of the

“EMSHIP”

Erasmus Mundus Master Course

in “Integrated Advanced Ship Design”

Ref. 159652-1-2009-1-BE-ERA MUNDUS-EMMC

Supervisor:

Prof.Dr. Eric Le Galle La Salle, ICAM, Nantes

Isabel Guillanton ,ICAM ,Nantes

Reviewer: Prof. Philippe Rigo, University of Liege

Nantes , February 2017

http://www.icam.fr/icam/

P 2 Kerem KÜÇÜK

Master Thesis developed at ICAM, Nantes

Effect of Seawater on Ageing of Polyester Composites and Study of Aged Composite Polymer

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“EMSHIP” Erasmus Mundus Master Course, period of study September 2015 – February 2017

Table of contents

ABSTRACT .............................................................................................................................. 5

ACKNOWLEDGEMENTS ................................................................................................... 10

CHAPTER 1. INTRODUCTION ......................................................................................... 12

1.1 Motivation .................................................................................................................. 12

1.2 Objectives and scopes ................................................................................................ 13

CHAPTER 2. LITERATURE REVIEW ............................................................................. 14

2.1. Introduction ................................................................................................................... 14

2.2 Moisture absorption phenomena .................................................................................... 14

2.3. Fickian Diffusion ........................................................................................................... 15

2.4. Langmuir model ............................................................................................................ 18

CHAPTER 3. SEAWATER AGEING OF THE GLASS/POLYESTER COMPOSITES

.................................................................................................................................................. 19

3.1 Introduction .................................................................................................................... 19

3.2 Experimental details ....................................................................................................... 20

3.2.1. Fabrication of composite plates .............................................................................. 20

3.2.2. Preparation of Seawater for Accelerated Ageing Test ........................................... 22

3.2.3. Accelerated ageing test ........................................................................................... 23

3.2.4. Flexural test of aged composite plates ................................................................... 31

3.2.4.1.: Preparation for flexural test ................................................................................ 31

3.2.4.2. Flexural test ......................................................................................................... 34

CHAPTER 4. ANALYSIS OF RESULTS ........................................................................... 37

4.1. Introduction ................................................................................................................... 37

4.2. Results of the seawater diffusion to polyester composite plates ................................... 37

4.3. Results of the flexion test after ageing .......................................................................... 42

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CONCLUSION AND GENERAL PERSPECTIVES ......................................................... 47

Appendix A: TECHNICAL DRAWING OF COOLER FOR 130 C TEST ..................... 48

Appendix B: RESULTS OF THE FLEXURAL TESTS .................................................... 49

Apendix C: TECHNICAL DRAWING OF PRESS FOR RECYCLING ......................... 51

REFERENCES ....................................................................................................................... 59


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List of figures

Figure 1:The example of relation between temperature and relative humidity in air ............. 12

Figure 2:Relationship between environment temperature and penetration activity on the

solute by a solvent ................................................................................................................... 14

Figure 3: Moisture sorption locations and mechanisms in polymeric composites [Wong, K. J.,

2013] ........................................................................................................................................ 15

Figure 4:Illustration of Fickian diffusion ................................................................................ 17

Figure 5:Prepared metal template of fiber coupons (145 x 145 mm) ...................................... 20

Figure 6:Illustration of cut coupons and at the end of the fabrication process ....................... 21

Figure 7:Coding system of the composite plates ..................................................................... 22

Figure 8:Accelerated Ageing Test Environment-1 ................................................................... 24

Figure 9:Accelerated Ageing Test Environment-2 ................................................................... 24

Figure 10:Cooler design and realization of the design for 130 C° ageing test ....................... 25

Figure 11:Placement of test plates inside of the container-1 .................................................. 26

Figure 12:Placement of test plates inside of the container-2 .................................................. 26

Figure 13:A view of the collected rust in the cooker after ageing process .............................. 27

Figure 14:Taken examples to analyze in spectrophotometer (polyester resin, catalyst and rust

taken from ageing water) ......................................................................................................... 28

Figure 15:Spectrophotometer result of the cured resin analyzed ............................................ 29

Figure 16:Spectrophotometer result of the extract from solvent ............................................. 29

Figure 17:Spectrophotometer result of the dried powder made from example taken from aged

water ......................................................................................................................................... 30

Figure 18:Comparison of the results from spectrophotometer results of the examples

collected ................................................................................................................................... 30

Figure 19:Some part of the cleaned plates after ageing process ............................................. 33

Figure 20:Example of cut plate for flexural testing ................................................................. 33

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Figure 21:Packaged specimens of composite plates for flexural test ...................................... 34

Figure 22:Flexural test equipment ........................................................................................... 34

Figure 23:Demonstration of flexural test................................................................................. 35

Figure 24:Weight change of the 80 C degree composite plates by time in percentage for the

first period ................................................................................................................................ 37


first period ................................................................................................................................ 38


first period ................................................................................................................................ 38

Figure 27:Diffusivity coefficient of ageing at 80 C° accelerated ageing test .......................... 39

Figure 28:Comparison of mass change between 3 different temperatures for first period ..... 39


second period ........................................................................................................................... 40


second period ........................................................................................................................... 40


second period ........................................................................................................................... 41

Figure 32:Comparison of mass change between 3 different temperatures for second period 41

Figure 33:80 C Ageing Young modulus degradation according to time period and position . 43

Figure 34:80 C ageing degradation of resistance against flexural stress according to time

period and position ................................................................................................................... 43

Figure 35:100 C Ageing Young modulus degradation according to time period and position44



Figure 37:130 C Ageing Young modulus degradation according to time period and position45



Figure 39:Delaminated 130 C° ageing test samples ............................................................... 46


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List of tables

Table 1: Composition of the artificial seawater for ageing test .............................................. 23

Table 2: 3 point flexural test standard for flexural test according to ISO 14125 .................... 31

Table 3:Full length, support length and thickness proportions according to ISO 14125 ....... 32

Table 4:Width proportions of specimen for flexural test according to ISO 14125 .................. 32

Table 5:Errors of first period flexural tests ............................................................................. 42

Table 6:Errors of second period flexural tests ......................................................................... 42

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ABSTRACT

The work presented in this study is both the effect of sea water on mechanical performances of a

polyester composite, its adhesion during the ageing process and the mixing compatibility of

thermoplastic with polyester composite after ageing. Samples are made from 16 plies of biaxial woven

[0°/90°] glass fibers and polyester resin with a hand lay-up process at room temperature. Sea water

ageing of a polyester composite and the effect of diffusion of water on the mechanical properties of the

composite material are studied in three different accelerated conditions which are 80°C, 100°C and 130

°C. For ageing process, artificial seawater was prepared proportionally. The objective is also to compare

accelerated ageing condition with ambient condition which is found in literature to confirm this method.

Figure 1: Moisture sorption locations and mechanisms in polymeric composites [Wong, K. J., 2013]

The wet and dry composite samples are tested with three point flexural tests and there will be a

comparison between dry flexural strength of the material and aged ones. The recycling process, which

is the last process of the study, is mixing crushed polyester composite with thermoplastic material and

checking the compatibility and eligibility of the material with thermoplastic. The aim of this study is to

determine, the change of mechanical properties of polyester composite and to check the possibility of

the recycling of the polyester composites after a life cycle.

Keywords: Moisture absorption; Ageing Composites; Composite Recycling; Mechanical Property

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ACKNOWLEDGEMENTS

First of all, I would like to express my sincere and heartfelt thanks to Professor Hervé

LeSourne to make this study possible for me. Thanks to his supports and positive energy, I

encouraged to finish my thesis.

I am indebted to Professor Eric Le Galle La Salle and Isabelle Guillanton who are all

the time suggested a solution when I had a problem during my study and thanks to their positive

energy and approach I am really grateful them for their willingness and for share their

knowledge with their high patience and guidance through my studies at ICAM, Nantes.

Sincere appreciation is extended to Yoann Etourneau and Alex Lejeau who are always

there whenever I need their help and I am appreciated for their willingness to help me and to

make everything easy for me during my master thesis study in ICAM.

I would like to thanks Professor Philippe Rigo for his helps and guidance during the

EMSHIP program.

I’m gratefully appreciate to all my friends in EMSHIP 6th cohort friends to make me

feel pleasure of knowing new people from different cultures and friendship.

Last but not least, I am deeply thankful to my mother Dilek KÜÇÜK and my father

Veysel KÜÇÜK for their endless support from the begining and I am indepted to their

encouragement and guidance to find the right way in my life.

This thesis was developed in the frame of the European Master Course in “Integrated

Advanced Ship Design” named “EMSHIP” for “European Education in Advanced Ship

Design”, Ref.: 159652-1-2009-1-BE-ERA MUNDUS-EMMC.


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CHAPTER 1. INTRODUCTION

1.1 Motivation

There is a long history about the use of fiber-reinforced polymer (FRP) matrix

composites in marine environment. Glass fiber reinforced polymer (GFRP) composites

have been commonly used, started to be preferred instead of wood in marine applications,

since the 1950’s. [P.Davies and Y.D.S. Rajapakse eds., 2014] Due to their high specific

strength, stiffness and low density advantage against metals, they turn benefits the industry

in cost saving. During the entire service life time, marine structures are exposed to different

daily changing (Figure. 1.1.1) in different environmental conditions, according to climate

differences, such as light, temperature, humidity and corrosive environments.

Figure 1:The example of relation between temperature and relative humidity in air: [Borra,

S. ,n.d..]

The effect of these parameters causes the degradation of the mechanical properties of

fiber reinforced composites after some time period because of their sensivity against

environmental parameters with cyclic loads on materials. This effect reveal an important

fact which is durability of the material.


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In leisure marine industry, most of the vessel are using glass fiber reinforced polyester

and so far, not much polyester boats ended their life time. In the upcoming years, the

quantity of life time service expired boats will increase. Because of their chemical content

and material behaviors, stocking expired materials will be a problem, both space and

environmental point of view. Also, due to the low cost value of the glass fibers, it is really

hard and expensive to recycle glass fiber reinforced polyesters in an economically efficient

way; so new solutions are required to recycle and to take industrial, financial and

environmental benefits.

Purpose of this work, to support study the possibility of recycling polyester composite

with a thermo-mechanical solution or a recycling method which has been developed by

ICAM and partners and which is in production now. This industrial solution is currently

used for industrial waste of polyester composite. The thermo-mechanical recycling in a way

very interesting to evaluate of these aged polyester composites, especially polyester

composites in marine industry at the end of their service life. The recycling process will be

performed between mi-January to end of the February.

1.2 Objectives and scopes

The aim of this study is to contribute to the knowledge of the change of the

mechanical behavior of polyester composite structure with effect of sea water which is

under ageing. During ageing process, the moisture absorption and corresponding changes

on mechanical behavior is studied with glass/polyester composite. The objectives include:

i. The quantification of the sea water ingression in glass/polyester laminates at

different temperature levels ;

ii. The determination of the change of flexural property of the glass/polyester

composite at different temperature levels;

The material scope of this study is only for glass fiber and polyester composite. Glass

fibers used are biaxial woven with [0/90]16 stacking sequence. Required specimens are

produced by hand lay-up process. Accelerated ageing tests are made under 80 C°, 100 C° and

130 C° with artificial sea water which was made by determined ingredients and demineralized

water.

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CHAPTER 2. LITERATURE REVIEW

2.1. Introduction

In this chapter, a general literature review given to introduce the background of the work.

2.2 Moisture absorption phenomena

When a polymer is exposed to an ambient fluid, the fluid diffuse in the polymer

[Weitsman, Y. J., 2012] until saturation. Also, according to [Hopfenberg HB, Frish HL. 1992]

,it is shown (Figure 2.2.1) how a solvent penetrate by different transport mechanism absorbed

below:

Figure 2:Relationship between environment temperature and penetration activity on the

solute by a solvent [Wong, K. J. , 2013]


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Figure 3: Moisture sorption locations and mechanisms in polymeric composites [Wong, K. J.,

2013]

Furthermore, according to Wong’s study it is shown (Figure 3) that there are many ways and

conditions that a polymer can absorb moisture and different mechanisms can occur during the

sorption process on polymeric composites.

2.3. Fickian Diffusion

In the Fickian diffusion, moisture can penetrate randomly into the materials at atomic

scale and using voids inside of the material (free volume). According to second law of Fick,

concentration changing by the time on concentration gradient. During the diffusion, there is a

minimum required size of free volume for a water molecule to diffuse and to be placed in voids.

[Pogany, G. A. ,1976] Also, during the diffusion, movements of the molecules are not directed

and they are completely free to move in every direction of the void (Brownian motion) (Figure

2.3.1.). While diffusion progressing, the speed of diffusion decreases and at the end, diffusion

stops when the moisture concentration gradient reaches equilibrium.

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Figure 2.3.1: Representation of the diffusion in one-dimension

At the constant diffusivity level, the diffusion is described by the following equation:

𝜕𝑐

𝜕𝑡=

𝜕

𝜕𝑧 (𝐷𝑧(𝑇)

𝜕𝑐

𝜕𝑧) = 𝐷𝑧(𝑇)

𝜕2𝑐

𝜕𝑧2 (2.1)

Where:

c= moisture concentration

Dz= moisture diffusivity (independent of distance,time and concentration)

When the water molecules are penetrating through a polymer, degradation by the

moisture occurs in the material. [Gu, H., & Hongxia, S. 2006] Also, plasticization and swelling

can occur due to debonding of Van Der Waals bonds between polymer chains by moisture.

[Wong, K. J., 2013]

As a conclusion, voids (spaces between molecules) are getting expanded by water

molecules and this will lead to a reduction of the interfacial strength of the polymer chains.

Also, the water molecules will move more freely inside of the polymer and this will decrease

the strength of the polymer. [Lv XJ, Zhang Q, Li XF, Xie GJ.,2008]

In general, the overall moisture absorption is described by level in percentage. To

show this percentage of instantaneous moisture content, M (t) can be expressed as:

𝑀(𝑇, 𝑡) = 𝑤−𝑤𝑖

𝑤𝑚 𝑥 100 (2.2)

Where:

w= instantaneous weight of the material

wi= initial weight of the material

wm= maximum weight of the material.

At the end of the moisture absorption, the plot of the Fickian diffusion is shown in

Figure 4 below:


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Figure 4:Illustration of Fickian diffusion

With the slope of the curve determined from the experimental data, the diffusivity is

described by the equation below:

𝐷𝑧 = 𝜋 [ℎ

4𝑀𝑚]

2 [

𝑀2−𝑀1

√𝑡2−√𝑡1]

2

(2.3) [Wong, K. J. , 2013]

where:

h= thickness of the material where seawater diffuse

Mm= Maximum moisture content

M1= Moisture content at time of t11/2

M2= Moisture content at time of t21/2

t1= First measurement time of the moisture content

t2= Second measurement of the moisture time

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While the moisture diffusion is the still on going, the diffusion surface can be in

rubbery state, and inside, the polymer can be still glassy state. Fickian diffusion assumes that

the solvent penetrates through polymer from outer rubbery region to inner glassy region. The

polymer segments are reaching new equilibrium state instantaneously. As a result, the internal

stress of the polymer at the rubbery state changed and relaxed. As a result of which polymer

reached a new mechanical equilibrium. [Frisch, H., Wang, T., & Kwei, T. ,1969]

2.4. Langmuir model

According to Langmuir model, instead of Fick’s diffusion, it assumes that the water

molecules are not diffusing freely. There are certain water molecules which are acting to the

active regions of resin by hydrogen bridges and become bound.

According to [Carter et al., 1978], absorbed moisture can be quantitatively explained by

assuming, absorbed moisture consist mobile and bound phase. Mobile molecule diffuse with a

factor of Dγ and absorbed and become bonded with probability per unit time γ. Molecules

became mobile from bound with probability per unit time β.

When the local weight fraction approach to the equilibrium M∞ when γn = βN as in

Langmuir theory. After exposure time t, the total moisture uptake is approximately is given by

[Carter et al., 1978] below:

𝑀𝑡

𝑀𝑠=

𝛽

𝛾+𝛽𝑒−𝛾𝑡 (1 −

8

𝜋2∑

𝑒

−(2𝑛+1)𝜋2𝐷𝑡/4ℎ2

(2𝑛+1)2∞𝑛=1 ) +

𝛽

𝛾+𝛽(𝑒−𝛽𝑡 + 𝑒−𝛾𝑡) + (1 − 𝑒−𝛽𝑡) (2.4)

Where:

Mt= Moisture content at the time

MS= Moisture content at saturation

N= number of the bound molecules per unit volume

n=mobile molecules per unit volume


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CHAPTER 3. SEAWATER AGEING OF THE GLASS/POLYESTER

COMPOSITES

3.1 Introduction

This chapter mainly discusses about the preparation and application of the ageing

process of the glass/polyester composite. During the service life a boat facing a lot of

environmental effect such as temperature, UV, biological environment, contact with liquids

and mechanical stresses. At the end of their service life, composite hulls of the boats are

ageing during 30-40 years period and according this low irreversible process, their

mechanical property is changing. The main purpose of this work is to simulate the real life

cycle of a boat hull until the end of the service life and observe how its properties changed.

Figure 3.1.1.: Illustration of the environmental effects on a boat [Castaing P., 1992]

Firstly, type of the resin and the glass fiber determined. Amount of the seawater for

the ageing test is calculated. Then amount of the contents are calculated. After fabrication of

the plates and preparation of sea water, accelerated ageing test performed. Finally, amount of

diffused seawater measured.

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3.2 Experimental details

3.2.1. Fabrication of composite plates

The materials used in this study are biaxial woven glass fiber (300gr/m2) and polyester

resin (orthophtalic polyester resin). Determination of the thickness of the composite plates are

provided by European norm NF EN ISO 14125 which is 4 mm thick. According to the

defined thickness of the plates, number of plies are calculated. Size of the plates are defined

according to size of the containers which are used for the accelerated ageing test performed.

Before fabrication of the plates, a metal template of the coupons (145 x 145 mm) (Figure 5)

prepared and coupons are cut from roll of glass fiber.

Figure 5:Prepared metal template of fiber coupons (145 x 145 mm)

To fabricate 4 mm thickness, 16 coupon are cut for each plate. All composite laminates

are fabricated using hand lay-up technique and cured at room temperature for 3 weeks before

being immersed in seawater. Weight proportion between glass fibers and polyester resin

decided to be %60 fiber and %40 resin in mass which are around ~115-120 gr fiber and resin


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according to fiber weight (~80 gr). At the end of the fabrication, one plate weight was around

~200gr and cured plate was around ~ 160gr. (the least plate were 156 gr and the heaviest plate

was 165gr). For each condition of the ageing test, 10 plates were fabricated, because of the

required amount (1.6 kg of composite) for the recycling process of the aged samples. Finally,

70 plates were fabricated in total (20 samples for each temperature level and 10 for non-aged

samples).

Figure 6:Illustration of cut coupons and at the end of the fabrication process

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At the end of the fabrication process, a code system generated to classify the

composite plates which is shown below in Figure :

Figure 7:Coding system of the composite plates

Where:

1. #1 is mentioning that it’s a test plate,

2. #2 of the coding is showing the testing temperature of the plate which is T1 for

80 C°, T2 for 100 C° and T3 for 130 C°,

3. #3 of the coding is showing the period of the ageing plates which is P1 for first

period plates and P2 for second period of the plates.

4. #4 of the coding is showing the number of the plate in defined temperature and

period which can change from 01 to 10.

3.2.2. Preparation of Seawater for Accelerated Ageing Test

We decided to make the seawater required for the accelerated ageing tests. Chemical

composition of the artificial seawater was calculated from chemical components set according

to 35 gr/l which is shown (Table 1) below:


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Composition

of Ions

# of mole Composition

of Salts

M salt g/mol Quantity For Salinity

35gr/l (gr)

Na+ 0,469 NaCl 58,5 27,4 25,0

Mg2+ 0,053 MgCl2 95 5,035 4,6

SO4- 0.028 Na2SO4 142 3,976 3,6

Ca2+ 0,0103 CaCl2 111 1,1433 1,0

K+ 0,0102 KCl 74,5 0,7599 0,7

- - Total - 38,4 35,0

Table 1: Composition of the artificial seawater for ageing test

After preparation of the composition (components prepared for 5 liters each time) ,

chemical ingredients are mixed with distilled water which has <5 µs/cm conductibility

3.2.3. Accelerated ageing test

Accelerated ageing tests were planned to be done 3 different temperature levels which

are 80C°, 100C° and 130C°. Also, for each temperature level, 2 periods were planned to test

composite plates. According both, to temperature and period plan, test environment were

prepared. (Figure 8 and Figure 9) Instead of the study of [Davies, Mazéas and Casari,2000]

and the study of [ Visco, Calabrese and Cianciafara,2008] and other studies like them, because

of the short time period, temperatures of the ageing tests are chosen higher than similar studies.

Result of the chosen temperatures, continuous ageing process could not carried out at 100 C°

and 130 C°.

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Figure 8:Accelerated Ageing Test Environment-1

Figure 9:Accelerated Ageing Test Environment-2

For 80 C° test, a heated sand bath was used for continuous testing condition. For 100 C°

and 130 C° tests, heating plates were used to carry out tests. 80 C° ageing test was carried out

until all day and night. However, because of the safety issues, 100 C° and 130 C° tests are

carried out only on day time.


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Also, to carry out the 130 C° ageing test along a day, a cooler (Figure 10) (Appendix

A1) designed for pressure cooker which is provided to condensate vapor of test water before it

evaporates. According to the designed cooler, pressure cooker was modified at ICAM

workshop.

Figure 10:Cooler design and realization of the design for 130 C° ageing test

Firstly, before starting ageing test, the weight of the each plate is measured to the

accuracy of 0.01 g and recorded. The plates are placed horizontally in containers. To increase

the contact between seawater and plates, there are 2 small aluminum plates placed between 2

composite plates (Figure 11 and Figure 12). During the ageing process, instead of 80 C° test

continuing with same seawater (no water loss), time by time newly prepared seawater was

added to 100 C° and 130 C° test’s water because of the evaporation. Also, because of the

production of the cooler for pressure cooker and the testing period difference of the 80 C°,100

C° and 130 C° tests as mentioned above, applied accelerated ageing time is different in each

test.

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Figure 11:Placement of test plates inside of the container-1

Figure 12:Placement of test plates inside of the container-2


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Until end of the accelerated ageing test, weight of the composite plates are measured

periodically and noted. Also, the thickness of the plates are measured but because of there was

no change of the thicknesses, after some time, thickness this according was stopped.

During the measurement periods, some weight loss occurred instead of increasing.

Besides that, color of the ageing water started to change day by day and some rusty particles

started to collect on the plates. (Figure 13) According to this situation, some rust examples

were taken from the water from 130 C° which was contained the most quantity of rust for

analysis.

Figure 13:A view of the collected rust in the cooker after ageing process

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Two method were tried to analyze the sample taken from the ageing test. First

immiscibility and, mix the water taken from the test with a solvent (dichloromethane).Thanks

to difference of the density of the water and solvent they are separated from each other. During

the mixing time, molecule was soluble in dichloromethane passed through to solvent. After

vaporization of the solvent, finally, the remaining liquid was tested in spectrophotometer to see

if there is some resin mixed inside of the ageing test water.

Secondly, sample of water was evaporated until they become a dried powder to be

analyzed. After evaporation process, samples are analyzed with a spectrophotometer to see what

could be inside of the ageing water. Also, some sample of polyester resin which were used in

the fabrication of the composite plates were measured by spectrophotometer to compare the

results in the spectrophotometer.

Figure 14:Taken examples to analyze in spectrophotometer (polyester resin, catalyst and rust

taken from ageing water)

The obtained spectra are, results are shown below:


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Figure 15:Spectrophotometer result of the cured resin analyzed

Figure 16:Spectrophotometer result of the extract from solvent

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Figure 17:Spectrophotometer result of the dried powder made from example taken from aged

water

Figure 18:Comparison of the results from spectrophotometer results of the examples

collected


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According to results of the spectrophotometer tests on, the water taken from ageing test,

polyester resin was found in the accelerated ageing water. Also, instead of extract taken from

solvent, dried powder example is having less characteristic of the polyester resin. According to

obtained results, we can say that, the loss of the resin on the surface of the plates is one of the

reason to loss of the weight in the aged plates.

During the testing process, first period of the plates for each temperature are taken after

3 weeks of the start date of accelerating test. Second period of the plates are taken after 3 weeks

of the first period plates but during the second 3 week period, ageing process could processed

for 10 days because of the official holiday of the institution and because of the safety issues,

test are stopped but composite plates are left in the sea water which is prepared. At the end of

the ageing process of the plates, all of the plates are collected from the container preparation

and submitted do flexural test is done.

3.2.4. Flexural test of aged composite plates

3.2.4.1.: Preparation for flexural test

After ageing process, to prepare the plates to flexural test, all of the plates are taken and

cleaned (Figure 19). To make a comparison in the flexural test, 1 bottom and 1 top plate taken

from each temperature and period of the ageing condition. In the total, there are 14 plates cut

(2x no aged, 2x first period plates for each temperature and 2x second period plates for each

temperature. According to Norm European ISO 14125 standards, composite plates are cut and

for each plate, 5 specimen of composite plates are prepared for flexural test and packaged

(Figure 20 and Figure 21).

According to 3 point test standards recommended dimensions are Class 3 chosen from

standard shown below:

Material Length of the test

piece

l

Distance Between

supports

L

Width

b

Thickness

h

Class III 60 40 15 2

Table 2: 3 point flexural test standard for flexural test according to ISO 14125

P 32 Kerem KÜÇÜK


According to standards, thickness of the specimens were required to be 2 mm thick but

both because of the recycling process after ageing (recycling process requires 1,6 kg of

composite material for each condition) and more realistic simulation of a boat hull, samples’

thicknesses are decided to be 4 mm instead of 2 mm. After the decision of thickness, new

dimensions are calculated according to standards which are shown below:

Class of Material Three Point Four Point

L/h l/h L/h l/h

I 16 20 16,5 20

II 16 20 16,5 20

III 20 30 22,5 30

IV 40 50 40,5 30

Table 3:Full length, support length and thickness proportions according to ISO 14125

Nominal thickness h

Width b (Class I) Width b (Class II)

1<h≤3 25 15

3<h≤5 10 15

5<h≤10 15 15

10<h≤20 20 30

20<h≤35 35 50

35<h≤50 50 80

Table 4:Width proportions of specimen for flexural test according to ISO 14125

According to proportions, samples’ dimension calculated 120 mm x 15 mm x 4 mm.

This calculations are done before fabrication process to produce all plates according to this

standards.


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Figure 19:Some part of the cleaned plates after ageing process

Figure 20:Example of cut plate for flexural testing

P 34 Kerem KÜÇÜK


Figure 21:Packaged specimens of composite plates for flexural test

3.2.4.2. Flexural test

The flexural test determines the deformability. Also, the test provides to calculate

elasticity modulus in bending Ef (Eq. 3.1), flexural stress σf (Eq. 3.2). After all of the test plates

are prepared, flexural tests are done. For the flexural test process,3 point flexural test equipment

prepared and INSTRON 4302 machine used with 10kN force shown below (Figure 22 and

Figure 23) :

Figure 22:Flexural test equipment


35


Figure 23:Demonstration of flexural test

Tests are made by 2mm/min arm speed.

The calculation of the elasticity modulus under bending Ef was made by:

𝐸𝐹 =𝑚𝐿3

4.𝑏.ℎ3 (3.1)

Where:

m= the gradient (i.e., slope) of the initial straight-line portion of the load deflection,

L= support span, (mm)

b= width of the test sample, (mm)

h= thickness of the test sample, (mm)

The calculation of the flexural stress σf was made by:

P 36 Kerem KÜÇÜK


σf = 3 𝐹𝐿

2.𝑏.ℎ2 (3.2)

where:

F= load at given point on the load deflection curve, (N)

L= support span, (mm)

b= width of the test sample, (mm)

h= thickness of the test sample, (mm)


37


CHAPTER 4. ANALYSIS OF RESULTS

4.1. Introduction

The objective of this study presented in this thesis to investigate the effect of the

seawater on mechanical property of the polyester composite. In this chapter, the results of the

accelerated seawater ageing tests are shown and discussed.

4.2. Results of the seawater diffusion to polyester composite plates

The figures demonstrates the mass change in percentage by hours in three degree and 2

period.


first period

0,00%

1,00%

2,00%

3,00%

4,00%

5,00%

6,00%

0,00 0,50 1,00 1,50 2,00 2,50 3,00 3,50 4,00 4,50 5,00

Mas

s C

han

ge (

%)

Immersion time (day^0,5)

Mass Change by Immersion by (day^0.5)

Sample 1

Sample 2

Sample 3

Sample 4

Sample 5

P 38 Kerem KÜÇÜK


Figure 25:Weight change of the 100 C degree composite plates by time in percentage for the first

period


first period

0,000%

0,500%

1,000%

1,500%

2,000%

2,500%

3,000%

3,500%

4,000%

4,500%

5,000%

0,00 1,00 2,00 2,65 3,00

Mas

s C

han

ge (

%)



Sample 1 Sample 2 Sample 3 Sample 4 Sample 5

0,00%

1,00%

2,00%

3,00%

4,00%

5,00%

6,00%

7,00%

8,00%

0,00 0,50 1,00 1,50 2,00 2,50 3,00 3,50

Mas

s C

han

ge (

%)

Immersion time (day^0.5)


Sample 1 Sample 2 Sample 3 Sample5 Sample 4


39


Figure 27:Diffusion speed of ageing at 80 C° accelerated ageing test

As it’s shown in the Figure 27, when the diffusion coefficient is calculated (Eq. 2.3),

diffusion speed is approaching through 0 because of diffusion state is reached to saturation.

Figure 28:Comparison of mass change between 3 different temperatures for first period

0

0,5

1

1,5

2

2,5

3

4,9 11,0

Dif

fusi

on

sp

eed

(%

)

Square Root of Time (t)^0,5

Diffusivity of ageing by h^0,5

Série1 Série2 Série3 Série4 Série5

0,00%

1,00%

2,00%

3,00%

4,00%

5,00%

6,00%

0,00 0,50 1,00 1,50 2,00 2,50 3,00 3,50 4,00 4,50 5,00

Mas

s ch

ange

(%

)

Immersion day (day^0,5)

Comparison of mass change between 3 temperature (1st period)

80 C°

100 C°

130 C°

P 40 Kerem KÜÇÜK


At the end of the first period of the ageing of polyester composites, periodic weight

measurement, the results are shown in Figure 28. The reason of the more data points in the 80

C° ageing condition is because of the safety issues, instead of 80 C° test,100 C° and 130 C°

ageing conditions could not carried out at the night time.


second period


second period

0,00%

1,00%

2,00%

3,00%

4,00%

5,00%

6,00%

0,00 0,50 1,00 1,50 2,00 2,50 3,00 3,50 4,00 4,50 5,00

Mas

s C

han

ge (

%)



Sample 1

Sample 2

Sample 3

Sample 4

Sample 5

0,00%

2,00%

4,00%

6,00%

8,00%

10,00%

12,00%

14,00%

16,00%

0,00 1,00 2,00 2,65 3,46 3,82

Mas

s C

han

ge (

%)



Sample1 Sample 2 Sample 3 Sample 4 Sample 5


41



second period

Figure 32:Comparison of mass change between 3 different temperatures for second period

According to results:

It is visible that, diffusion speed increasing with increase of temperature and solvent can

penetrate faster when temperature is higher. As we can see that, at 80 C test, weight of the

composite plates are started to change less than beginning of the test because they are getting

saturated condition. Also, instead of 80C and 100 C samples, 130C test samples started to lose

weight.

0,00%

1,00%

2,00%

3,00%

4,00%

5,00%

6,00%

7,00%

0,00 0,50 1,00 1,50 2,00 2,50 3,00 3,50

Mas

s C

han

ge (

%)



Sample 1

Sample 2

Sample 3

Sample 4

Sample 5

0,00%

2,00%

4,00%

6,00%

8,00%

10,00%

-0,50 0,50 1,50 2,50 3,50 4,50

Mas

s ch

ange

(%

)

Immersion day (day^0,5)

Comparison of mass change between 3 temperature (1st period)

80 C°

100 C°

130 C°

P 42 Kerem KÜÇÜK


4.3. Results of the flexion test after ageing

During the ageing tests, ambient temperature was really low compared to test

temperatures, because of the location of the laboratory where the tests have done. For this

reason, each test temperature were changed from the bottom to top inside of the containers. The

main reason of the difference of diffusion rate and mass change in the same condition ageing

group composite plates is this temperature difference. Chosen plates are taken from both from

the top and the bottom side of the periodic ageing group of composite plates to observe, how

the plates were actually affected by the temperature change. After ageing tests, flexural tests

are applied these different plates to see difference in different temperature level. The loss of the

Young modulus and the degradation on resistance against flexural stresses in different periods

shown below:

Table 5:Errors of first period flexural tests

Table 6:Errors of second period flexural tests

7% 5% 4%

Errors of First Period Flexural Tests

5% 9% 10%

80 100

Avg. Young Modulus E

130

Avg. Stress

Modulus Error(%)

Stress Error(%)

Moyenne

Ecart-Type

Moyenne

Ecart-Type

15422,37

1022,53

221,64

10,62

15659,2

719,08

290,64

25,52

15273,54

559,36

240,69

23,74


43


Figure 33:80 C Ageing Young modulus degradation according to time period and position


period and position

0,00

11,00

18,0016,00

43,00

0,00

5,00

10,00

15,00

20,00

25,00

30,00

35,00

40,00

45,00

50,00

NO AGEING 80 C 1st periodtop

80 C 1st periodbottom

80 C 2 ndperiod top

80 C 2 ndperiod bottom

Deg

rad

atio

n (

%)

80 C Ageing degradation of resistance against flexural stress according to time period and position

0,00

11,00

18,00 18,00

27,00

0,00

2,50

5,00

7,50

10,00

12,50

15,00

17,50

20,00

22,50

25,00

27,50

30,00



80 C 2 ndperiod top

80 C 2 ndperiod bottom

Deg

rad

atio

n (

%)

80 C Ageing Young modulus degradation according to time period and position

P 44 Kerem KÜÇÜK




period and position

0,00

9,00

18,00

14,00

39,00

0,00

5,00

10,00

15,00

20,00

25,00

30,00

35,00

40,00

45,00



100 C 2 nd periodtop

100 C 2 nd periodbottom

Deg

rad

atio

n (

%)


0,00

4,00

30,00

14,00

39,00

0,00

5,00

10,00

15,00

20,00

25,00

30,00

35,00

40,00

45,00





Deg

rad

atio

n (

%)

100 C degradation of resistance against flexural stress according to time period and position


45


,



period and position

In the graphs, same location plates are shown in same color. There is a visible effect of

the temperature on the degradation level. Especially high temperatures like 130 C, because of

0,00

11,00

21,0016,00

91,00

0,00

10,00

20,00

30,00

40,00

50,00

60,00

70,00

80,00

90,00

100,00

NO AGEING 130 C 1st period top 130 C 1st periodbottom



Deg

rad

atio

n (

%)


0,00

19,00

31,00

21,00

83,00

0,00

10,00

20,00

30,00

40,00

50,00

60,00

70,00

80,00

90,00

100,00





Deg

rad

atio

n (%

)

130 C Ageing degradation of resistance against flexural stress according to time period and position

P 46 Kerem KÜÇÜK


the increase of the diffusion coefficient, plates are ruptured by seawater shorter time than lower

temperature levels like 80C. At 130 C, in the second period of ageing, plates are delaminated

(Figure:39). Also, during the flexural test, it is observed that displacement level of the samples

under flexural force is decreased and applicable force to reach rupture state of samples are

decreased.

Figure 39:Delaminated 130 C° ageing test samples


47


CONCLUSION AND GENERAL PERSPECTIVES

The effect of the seawater on glass fiber /polyester composite plates is studied with

different temperatures (80C, 100C and 130C). After ageing test process, flexural test applied

on samples which are cut from aged plates.

According to test results, at 80 C° test, loss of the mechanical properties are linear with

the time. On the other hand, at 100 C° and 130C° test, this linearity is not exist anymore, because

of the difficulties of contact ageing by the time. During the ageing process, 80C° test

approached through saturation condition so after some time, weight increment decrease. At

100C° and 130C° test, weight increment continued longer than 80C° test but after some time,

weight loss occurred in both 100C° and 130 C° tests.

Concerning the study shows that at the thermal effect, an increase in temperature

accelerates the damage to the structure and causes a decrease in its mechanical properties. The

time is a factor that it also influences the process of degradation of the sample.

In summary, from the experiments carried out on this type of composite shows a strong

dependence on two main factors which are the temperature and the duration of immersion.

During the study, while accelerating process carried out, some security reasons are

caused some inequality on the ageing time. If there will be a new study on similar subject,

equality on ageing time is suggested for future to be more clear to explain the difference about

degradation between different temperature tests.

For the future work, thermo-mechanical recycling process will be carried out by ICAM

after heated mold production and applicability of the process will be discussed.

P 48 Kerem KÜÇÜK


Appendix A: TECHNICAL DRAWING OF COOLER FOR 130 C TEST


49


Appendix B: RESULTS OF THE FLEXURAL TESTS

Moyenne

Ecart-type

Minimum

Maximum

Moyenne

Ecart-type

Minimum

Maximum

Moyenne

Ecart-type

Minimum

Maximum

Moyenne

Ecart-type

Minimum

Maximum

Moyenne

Ecart-type

Minimum

Maximum

Moyenne

Ecart-type

Minimum

Maximum

Moyenne

Ecart-type

Minimum

Maximum

Results of the flexural test from first period samples-

PT

3P

10

1

-5,01

-5,21

-5,69

-5,07

-5,01

-5,32

14552,34

16067,43

-8,37

0,55

-8,74

-7,62

-5,79

-5,70

0,34

PT

3P

11

0

17064,11

13193,14

13924,09

14912,05

PT

1P

10

1P

T1

P1

10

PT

2P

10

3P

T2

P1

08

14694,34

16717,79

16717,79

15587,79

689,63

14912,05

12289,67

14190,52

13321,85

793,80

12792,76

14768,72

15504,38

15273,54

559,36

12792,76

15091,7

14552,34

15151,85

16067,43

15224,66

15572,63

15659,20

719,08

-5,1

-7,46

-7,45

-8,24

-7,72

-8,2

1123,82

12289,67

15224,66

14706,47

-5,07

-6,19

-4,99

0,71

-6,77

-4,99

-9,05

-7,62

-5,87

-5,60

0,31

-5,87

-5,07

-5,76

-5,7

-5,61

384,97

477,32

207,87

228,6

218,03

218,32

235,39

202,40

210,56

217,06

45,44

466,58

563,76

444,57

403,49

36,45

622,82

32,74

582,56

670,07

556,25

518,29

466,58

474,37

20,95

182,74

238,66

Displacement

Young Modulus

(Mpa)

(Standart)

(mm)

250,47

240,69

23,74

210,09

265,24

216,51

210,09

221,33

256,34

265,24

238,16

320,1

290,64

25,52

260,38

14995,17

407,79

417,45

432,76

417,45

-5,29

0,28

551,95 296,1

18021,67

423,47

13,63

17064,11 -5,45 441,88 235,39

15422,37

1022,53

221,64

10,62

Force

(N)

Sttress of the sample

according to applied force

(Mpa)

14750,11

15745,13

14557,31

-7,44

16402 -8,28

-7,21 631,68 313,59

17251,76 -7,69 578,69 302,90

669,85 0,51 32,45 7,74

186,34

186,34

14557,31

11,70

441,88

412,89

429,54

448,60

25,18

-5,69 407,79 207,87

14209,43 -5,57 418,42 205,09

13630,19 -5,77 424,81 208,51

14748,74

14269,14

-5,92

-5,10

380,14

420,94

197,79

320,1

217,06

175,95

211,84

24,47

175,95

230,52

238,16

563,76

530,47

406,45

479,58

47,99

618,8 293,73

209,08

14509,96 -7,53 465,24 203,84

14221,86 -6,31 483,23 210,72

406,45

529,67

670,07

513,29

529,67

448,6

0,71

-8,24

-6,31

-8,25

13193,14 -5,92 380,14

14096,3 -5,45 384,97 182,74

80

°C1

00

°C

13

0°C

14768,72 -6,77 477,32 238,66

13171,31 -5,43 413,7 206,85

606,98 269,37

14694,34 -9,05 582,56 260,38

635,71 309,6

15723,47

PLA

TE

S

NO

AG

EIN

G

631,68

553,03

551,95

582,29

574,5

296,1

300,38

313,59

308,21

296,21

16749,34

17372,66

18021,67

17713,15

16402

-8,28

-8,21

-7,32

-7,21

P 50 Kerem KÜÇÜK


Moyenne

Ecart-type

Minimum

Maximum

Moyenne

Ecart-type

Minimum

Maximum

Moyenne

Ecart-type

Minimum

Maximum

Moyenne

Ecart-type

Minimum

Maximum

Moyenne

Ecart-type

Minimum

Maximum

Moyenne

Ecart-type

Minimum

Maximum

Moyenne

Ecart-type

Minimum

Maximum

204,76

12548,10

Results of the flexural test from second period samples

551,95 313,59

16402 -8,28 551,95 296,1

18021,67 -7,21 631,68 313,59

15681,85 -4,56 351,68 182,54

204,56

11925,46 -5,2 405,91 180,48

13173,91 -4,43 448,06

(Mpa) (mm) (N) (Mpa)

12858,1 -4,62 366,18 178,33

11574,63 -4,59 354,37 161,27

17251,76 -7,69 578,69 302,90

NO

AG

EIN

G

-

16749,34 -8,28 631,68 296,1

17713,15 -7,21 582,29 308,21

16402 -7,44 574,5 296,21

17372,66 -8,21 553,03 300,38

18021,67 -7,32

669,85 0,51 32,45 7,74

PLA

TE

SDisplacement Sttress of the sample

Young Modulus (Standart) Force according to applied force

1272,03 -19,58 88,33 42,75

1657,64 -8,73 124,57 63,12

1508,65 -13,98 109,36 50,01

207,20 5,43 18,81

-4,72 587,12 271,41

11,37

- - - -

- - - -

544,17 235,43

PT

3P

21

0

1657,64 -19,58 124,57 63,12

1272,03

627,38 0,40 36,62 21,47

13843,69 -5,64 503,36 216,46

-13,63 115,17 42,75

1596,29 -8,73 88,33 44,17

15243,89

13

0°C

PT

3P

20

1

14975,62 -5,51 587,12 260,56

15243,89 -5,64 585,51 271,41

13923,73 -4,72 503,36 216,46

14536,76 -5,21 549,48 245,65

14696,88 -4,87 527,25 244,4

13843,69 -5,32

222,65

16844,24 -5,58 594,37 286,36

15403,84 -5,69 549,59 260,04

1104,54 0,10 53,29 24,82

PT

2P

21

0

14510,98 -5,75 561,88 250,84

14800,9

16844,24 -5,58 584,17 286,36

16337,9 -5,69 547,39 276,59

-5,61 460,14 222,65

14525,17 -5,83 594,37 263,77

14510,98 -5,83 460,14

402,15 194,84

14072,84 -5,29 392,92 183,52

15681,85 -4,56 411,01 194,84

14639,69 -6,47 406,45 194,16

10

0 °

C

PT

2P

20

1

11512,91 -4,79 411,01 170,49

13837,82 -5,41 393,29 175,58

1573,37 0,74 23,96 10,90

11512,91 -6,47 351,68 170,49

14691,91 -5,24

194,30

547,63 0,29 17,11 10,41

13894,75 -4,59 366,18 180,68

355,39 171,60

PT

1P

21

0

11925,46 -5,05 448,06 192,21

12073,37

12988,49 -5,20 444,03 204,76

12579,25 -4,43 405,91 180,48

-4,79 424,7 189,49

13173,91 -4,85 437,86

-4,86 432,11

80

°C

PT

1P

20

1

13894,75 -4,69 352,22 180,68

12557,32 -4,68 347,39 171,3

979,61 0,13 6,95 8,09

11548 -4,91 347,39 161,27

11548 -4,91 356,78 166,41

12486,56 -4,70


51


Apendix C: TECHNICAL DRAWING OF PRESS FOR RECYCLING

P 52 Kerem KÜÇÜK



53


P 54 Kerem KÜÇÜK



55


P 56 Kerem KÜÇÜK



57


P 58 Kerem KÜÇÜK


Declaration of Authorship

I declare that this thesis and the work presented in it are my own and have been generated by

me as the result of my own original research.

Where I have consulted the published work of others, this is always clearly attributed.

Where I have quoted from the work of others, the source is always given. With the exception of

such quotations, this thesis is entirely my own work.

I have acknowledged all main sources of help.

Where the thesis is based on work done by myself jointly with others, I have made clear exactly

what was done by others and what I have contributed myself.

This thesis contains no material that has been submitted previously, in whole or in part, for the

award of any other academic degree or diploma.

I cede copyright of the thesis in favour of the University of …..

Date: Signature


59


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[Borra, S. n.d..] What is the relationship between temperature and humidity? Retrieved

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temperature-and-humidity

[Weitsman, Y. J. ,2012] Fluid Effects in Polymers and Polymeric Composites. doi:DOI

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[Hopfenberg HB, Frish HL. 1992] Transport of organic macromolecules in amorphous

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[Wong, K. J. , 2013] Moisture absorption characteristics and effects on mechanical

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structures. NNT : 2013DIJOS031

[Pogany, G. A. ,1976] Anomalous diffusion of water in glassy polymer ; 17(8):690-694.

[Gu, H., & Hongxia, S. 2006] Delamination behaviour of glass/polyester composites after

water absorption.

[Lv XJ, Zhang Q, Li XF, Xie GJ.,2008] Study of the influence of immersion on the carbon

fiber/epoxy composites. Journal of Reinforced Plastics and Composites. 27(6): 659-666.

[Frisch, H., Wang, T., & Kwei, T. ,1969]. Diffusion in glassy polymers. II. Journal of

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[Carter, Harris G., and Kenneth G. Kibler, (1978) ] Langmuir-Type Model for Anomalous

Moisture Diffusion in Composite Resins. Vol. 12. N.p.: n.p. . Print. P. 118

[Chaaben, Rihem, and Mariem Bouaziz, (2016)] Etude du viellissement hygrothermique

d'un composite unidirectionnel. N.p.: n.p.,. Print. ISBN: 978-3-639-48353-6

[Castaing P. ,1992] Vieillissement des matériaux composites verre-polyester en milieu

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constituents. (n.d.). Retrieved November 10, 2016, from

https://www.soest.hawaii.edu/oceanography/courses/OCN623/Spring%202015/Salinity20

15web.pdf

[Davies, P., F. Mazeas, and P. Casari, 2000] . Sea Water Aging of Glass Reinforced

Composites: Shear Behaviour and Damage Modelling. N.p.: n.p.

[Visco, A. M., L. Calabrese, and P. Cianciafara , 2008] . Modification of polyester resin

based composites induced by seawater absorption. N.p.: n.p.

https://www.soest.hawaii.edu/oceanography/courses/OCN623/Spring%202015/Salinity2015web.pdf

https://www.soest.hawaii.edu/oceanography/courses/OCN623/Spring%202015/Salinity2015web.pdf

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