ENHANCEMENT OF THE SORTPION PROPERTIES OF FOAM RUBBER BY 
INCORPORATING A SUITABLE ADSORBENT 
By 
T. O. Kumanayaka 
THIS THESIS WAS SUBMITTED TO THE 
DEPARTEMNT OF CHEMICAL AND PROCESS ENGINEERING 
OF THE UNIVERSITY OF MORATUWA 
IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE DEGREE OF 
MASTER OF SCIENCE 
L I B R A R Y 
UflllVERSiTV OF MORATUWA. SRI LANKA 
MORATUWA 
DEPARTMENT OF CHEMICAL AND PROCESS ENGINEERING 
UNIVERSITY OF MORATUWA 
MORATUWA 
SRI LANKA 
University of Mora tuwa 
87851 
FEBRUARY 2007 
^ 'I <P -S I 
8 7 8 5 1 
DECLARATION 
I certify that this thesis does not incorporate without acknowledgement any material 
previously submitted for a degree or diploma in any university and to the best of my 
knowledge and belief if does not contain any material previously published ,written or 
orally communicated by another person except ,where due reference is made in the text. 
T.O kumanayaka 
04/8216 
Certified by 
(Dr.Shantha Walpolage) 
Supervisor 
ACKNOWLEDGMENT 
From the beginning I would like to offer my grateful thanks to Dr.Shantha Walpolage, 
Senior lecture, Department of chemical and Process Engineering, University of 
Moratuwa, for his kind and patience, supervision and excellent guidance during the entire 
course of this project. 
My grateful thank also goes to Prof. Ajith de Alwis Head of the Chemical & Process 
Engineering Department, Dr Jagath Premachandra, Senior Lecturer and all other lectures 
of the Department of Chemical & Process Engineering, University of Moratuwa, who 
helped and encouraged me in various ways to complete this project successfully . 
Then I 'm very much thankful to the Wonderlight Consumer Products (Pvt.) Ltd. and 
Beco link (Pvt.) Ltd. for supplying raw materials for the project. 
I wish to thank Mr.M.A Hemachandra, Miss. A.S.Wahalathanthri and Mr. M.G.S.K.De 
Silva and special thank goes to Mr.Janaka Madushanka for their support given me in 
various occasions during the project period. 
I warmly remind my beloved parents and my husband Chamila Amaradiwakara for all the 
encouragement and the support given me as usual to success this project. 
Finally I would like to thank my friends, especially Sashmial Dissanayaka, Poornima 
Jayasingha, Gayan Bandara & Chinthaka Narangoda who were with me and gave their 
kind co-operation through out this project. 
1 
C O N T E N T S 
Acknowledgement i 
List of Tables vi 
List of figures viii 
Abbreviations ix 
Abstract x 
CHAPTER 1: INTRODUCTION 
1.1 Natural rubber latex foam 01 
1.2 Uses of Latex foam 01 
1.3 Filler incorporation to latex foam 02 
1.4 Objectives of the research 03 
CHAPTER 2 : LITRATURE REVIEW 
2.1 Polymer Latex 04 
2.2 Natural Rubber latex 04 
2.2.1 Composition of field latex 04 
2.2.2 Preservation of natural rubber latex 05 
2.2.3 Concentration of natural rubber latex 06 
2.3 Manufacture of natural rubber (NR latex foam) 07 
2.3.1 Manufacturing process of foam rubber 08 
2.4 Foam Economies 20 
2.5 Theoretical aspects of adsorption 21 
2.5.1 Factors affecting adsorption 21 
2.5.2 Adsorbents 22 
2.6 Activated Carbon 22 
2.6.1 Manufacture of activated carbon 23 
2.6.2 Pore structure of activated carbon 25 
2.6.3 Activated carbon structure and surface chemistry 26 
ii 
2.6.4 Application of activated carbon 28 
2.7 Zeolite 
2.7.1 Origin of zeolite 29 
2.7.2 Structure of zeolite 29 
2.7.3 Pore structure of zeolite 32 
2.7.4 Applications of zeolite 33 
2.8 Incorporation of adsorbent into natural rubber latex foam 34 
2.9 Applications of modified NR foam 35 
2.9.1 Applications in indoor air pollution 35 
2.9.2 Steps to improve the indoor air quality 37 
2.9.3 Modified NR foam applications in odour removing 37 
2.9.4 Physical adsorption 38 
CHAPTER 3: METHODOLOGY 
3.1 Experimental design . 39 
3.2 Testing of adsorbents 40 
3.2.1 Determination of pH 40 
3.2.2. Determination of Avg. particle size 40 
3.2.3 Determination of moisture content 40 
3.3 Methods of dispersion preparation 41 
3.3.1 Determination of the best preparation method 41 
3.4 Preparation of adsorbent dispersion with maximum TSC. & 
Investigate the Dispersion properties 42 
3.4.1 Preparation of dispersion with varying TSC % 42 
3.4.2 Determination of dispersion properties 43 
3.5 Determination of the best dispersions for making a stable latex compound 45 
3.5.1 Preparation of latex compound 45 
3.5.2 Determination of the properties of the basic latex compound 47 
3.5.3 Selection of the best adsorbent dispersion for making a 
Stable latex compound 49 
iii 
3.6 Determination of the effect of dosage of adsorbent for stable NR foam 50 
3.6.1 Stability of the latex compound at partially foam stage 51 
3.6.2 Chemical stability towards gelling agents 51 
3.6.3 Structure analysis of foam with different dosage of adsorbent 51 
3.7 Determination of physical properties 52 
3.7.1 Tensile strength 52 
3.7.2 Indentation hardness 53 
3.7.3 Density and shrinkage percentage 53 
3.7.4 Flame retardant property 53 
3.8 Determination of sorption capacity of modified NR foam with adsorbents 54 
3.8.1 Determination ammonia gas sorption capacity 54 
3.8.2 Determination of C 0 2 sorption capacity 55 
3.8.3 Determination of Acetone sorption capacity 55 
CHAPTER 4: RESULTS AND DISCUSSION 
4.1 Properties of selected adsorbents 56 
4.2 Preparation of adsorbent dispersions 57 
4.2.1 Selection of the best preparation for zeolite powder 57 
4.2.2 Selection of the best preparation for activated powder 57 
4.3 Preparations of adsorbent dispersions with maximum T.S.C 61 
4.3.1 Properties of dispersions with varying T.S.C. % 61 
4.4 Incorporation of adsorbent dispersions to NR latex compound 65 
4.4.1 Properties of basic latex compound 65 
4.4.2 Effect of adsorbent dispersions for the stability of latex compound 65 
4.5 Effect of dosage of adsorbent for preparing stable foam of NR latex 69 
4.5.1Detemination of stability of latex foam varying zeolite dosage at 
Partial foamed stage 69 
4.5.2 Chemical stability of latex compound with varying zeolite dosage 72 
4.5.3 Structure analysis of foam with varying zeolite dosage 75 
4.6 Physical properties of foam samples produced bb batch scale process 81 
iv 
4.7 Measurement of sorption property of modified latex foam 91 
4.7.1 Ammonia gas sorption of foam with adsorbents 86 
4.7.2 Carbon dioxide sorption of foam with adsorbents 96 
4.7.3 Acetone sorption of foam with adsorbents 99 
CHAPTER 5: CONCLUSIOS AND RECCOMENDATIONS 
5.1 Conclusions 102 
5.2 Suggestions for further studies 103 
REFERENCES 104 
v 
L I S T O F T A B L E S 
Table 2.1 A typical composition of field latex 05 
Table 2.2 Composition of Centrifuged latex concentrates 07 
Table 2.3 Effect of filler on some foam properties 20 
Table 2.4 Chemical analysis of major elements in zeolite 29 
Table 3.1 Formula for zeolte dispersions 42 
Table 3.2 Formula for activated carbon dispersions 43 
Table 3.3 Formula for latex compound with varying zeolite dosage 50 
Table 3.4 Formula for latex compound with varying activated carbon dosage 50 
Table 4.1 Properties of selected adsorbents 56 
Table 4.2 Properties of Zeolite dispersions 57 
Table 4.3 Properties of Activated carbons dispersions 58 
Table 4.4 Properties of zeolite dispersions series 61 
Table 4.5 Properties of activated carbon dispersions series 61 
Table 4.6 Properties of compounded latex 65 
Table 4.7 Results of coagulum formation test with 1% adsorbent dosage 65 
Table 4.8 Results M.S.T of latex compounds with 1% adsorbent dosage 65 
Table 4.9 Variation of chemical stability in latexYx compound with 1% adsorbent 65 
Table 4.10 Normalized foaming heights of latex compound at partially 
foamed stage for different dosages of zeolite 69 
Table 4.11 Normalized foaming heights of latex compounds at partially 
foamed stage for different dosages of activated carbon 70 
Table 4.12 Gel times of latex compounds series of zeolite 72 
Table 4.13 Gel times of latex compounds series of AC 73 
Table 4.14 Structure analysis of foam with zeolite adsorbent 75 
Table 4.15 Structure analysis of foam with AC adsorbent 79 
Table 4.16 Tensile strength of foam samples 82 
Table 4.17 Indentation hardness of foam samples 84 
Table 4.18 Density and shrinkage % of foam samples 86 
Table 4.19 Flame retardant property of foam samples 89 
vi 
Table 4.20 Ammonia gas sorption % of foam modified with zeolite 91 
Table 4.21 Ammonia gas sorption % of foam with 8% dosage of zeolite 92 
Table 4.22 Ammonia sorption capacity of foam with 85 dosage of zeolite 93 
Table 4.23 Ammonia sorption capacity of foam modified with AC 94 
Table 4.24 Minimum CO2 sorption % of foam with zeolite 96 
Table 4.25 Minimum CO2 sorption % of foam with AC 97 
Table 4.26 Acetone sorption % of foam with zeolite 99 
Table 4.27 Acetone sorption % of foam with AC 100 
vii 
LIST OF FIGURES 
Figure 2.1 Structure of Isoprene 04 
Figure 2.2 Schematic diagram of graphite lattice with a turbostratic structure 23 
Figure 2.3 Structure of carbonized and activated carbon 24 
Figure 2.4 Microscopic pore structure of activated carbon 25 
Figure 2.5 Functional groups on activated carbon surface 27 
Figure 2.6 Basic zeolite structure 30 
Figure 2.7 Crystallographic structure of zeolite 31 
Figure 2.8 Pore structure of zeolite 32 
Figure 3.1 Ball milled machine 41 
Figure 3.2 Mechanical stability tester 48 
Figure 3.5 Experimental design for ammonia sorption 54 
Figure 4.1 pH variations of dispersions 62 
Figure4.2 Particle size analysis of dispersions 63 
Figufe4.3 Coagulum content of latex compound with different adsorbents 66 
Figure4.4 M.S.T of latex compound with different adsorbents 67 
Figure4.5 Gel time of latex compound with different adsorbents 68 
Figure4.6 Normalized foaming heights of latex compound with zeolite 70 
Figure4.7 Normalized foaming heights of latex compound with AC 71 
Figure4.8 Gel time of latex compound with zeolite 73 
Figure4.9 Gel time of latex compound with AC 74 
Figure4.10 Foam samples with zeolite 78 
Figure4.11 Foam samples with zeolite 80 
Figure4.12 Tensile strength of foam samples 83 
Figure4.13 Indentation hardness of foam samples 85 
Figure4.14 Density of foam samples 87 
Figure4.15 Shrinkage % of foam sample 88 
Figure4.16 Flammability of foam samples 90 
Figure4.17 Ammonia sorption of foam with zeolite 92 
Figure4.18 Saturation & re sorption of foams with zeolite 93 
Figure4.19 Ammonia sorption % of foams with AC 94 
viii 
FigureA. 20 CO2 sorption % of foam with zeolite 
Figure4,21 CO2 sorption % of foam with AC 
Figure4.22 Acetone sorption of foam with zeolite 
Figure4.23 Acetone sorption of foam with AC 
ABBREVIATIONS 
TSC Total solid content 
MST Mechanical stability time 
AC Activated carbon 
ix