Yong Tzyy Jeng - Master of Engineering Science Dissertation 2015

8/18/2019 Yong Tzyy Jeng - Master of Engineering Science Dissertation 2015

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PREPARATION AND CHARACTERIZATION OF

CONTROLLED RELEASE FERTILIZERS USING

ALGINATE-BASED SUPERABSORBENT POLYMER

FOR PLANTATIONS IN MALAYSIA

YONG TZYY JENG

MASTER OF ENGINEERING SCIENCE

FACULTY OF ENGINEERING AND GREEN

TECHNOLOGY

UNIVERSITI TUNKU ABDUL RAHMAN

MAY 2015


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PREPARATION AND CHARACTERIZATION OF CONTROLLED

RELEASE FERTILIZERS USING ALGINATE-BASED

SUPERABSORBENT POLYMER FOR PLANTATIONS IN MALAYSIA

By

YONG TZYY JENG

A dissertation submitted to the Department of Petrochemical Engineering,Faculty of Engineering and Green Technology,

Universiti Tunu Abdul !ahman,in partial fulfillment of the re"uirements for the degree

of #aster of Engineering $cience#A% &'()


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ABSTRACT

PREPARATION AND CHARACTERIZATION OF CONTROLLED

RELEASE FERTILIZERS USING ALGINATE-BASED

SUPERABSORBENT POLYMER FOR PLANTATIONS IN MALAYSIA

Yong Tzyy Jeng

$uperabsorbent polymers *$APs+ ere synthesised through graft-

copolymerisation of acrylic acid *AA+ and acrylamide *A#+ onto sodium

alginate *.aAlg+ using ammonium persulfate *AP$+ as initiator, N , N /-

methylenebisacrylamide *.#BA+ as crosslining agent and calcium chloride

*0a0l&+ as precipitating agent1 The $APs ere synthesised using different

molar ratio of AA and A# monomers2 3)4(), 5'46'2 ))47)2 7'48'2 &)45) and

three different concentration of 0a0l&2 (#, and 6#1 $elf-prepared pure

fertili9ers ith .P: ratio of ()4()4() ere imbedded in the $APs1 The effect

of molar ratio of AA and A# and the concentration of 0a0l& on the selling

capacity, biodegradability and rate of release of fertili9er ere investigated1

;nfrared spectroscopy shos a successful grafting of AA and A# onto .aAlg

bacbones1 The grafting efficiency and grafting percentage of AA and A# onto

.aAlg ere found increasing as the concentration of A# increased1

Furthermore, thermogravimetric analysis *TGA+ shos that the grafting of AA

and A# had improved the thermal stability1 Differential scanning calorimetry

*D$0+ shos that the T g has increased as the concentration of A# increases

and this can be proven by


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shos that the crystallinity of grafted polymers could be influenced by the

increment concentration of 0a0l&1 =n the other hand, scanning electron

microscopy *$E#+ as done on the grafted polymers and it can be deduced

that the surface of grafted polymer as more compact ith less folds and

pinholes as the concentration of A# increased1 This directly affected the

selling capacity, biodegradability and release rate of fertili9er from graft

polymers1 ;n addition, the ater retention of soil also improved ith the

addition of graft polymers into soil sample1

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ACKNOWLEDGEMENT

This dissertation ould not have been done ithout the help and

guidance of many hom in one ay or another contributed their valuable

assistance in the preparation and completion of this study1 ; am e>tremely

pleasure to convey my deepest gratitude to them in my humble

acnoledgement1

First of all, ; ould lie to e>press my utmost gratitude to my main

supervisor, Dr %amuna #unusamy and co-supervisor, Dr 0hee $ee %ong for

their advice, supervision and guidance throughout this research pro?ect1 Their

patient and effort in e>plaining the concept of this research or and their

suggestions as ell as papers riting correction are very much appreciated1

; gratefully acnoledge Universiti Tunu Abdul !ahman for

providing me research grant, IPSRRMCUTARRFC!-!! that allos me to

carry out my research smoothly1 Besides, ; ould also lie to sho my

appreciation to Felda $ungai, Felda Gunung Besout ( @ & and Felda Trola

$elatan for providing the oil palm soil1

; ould also lie to e>press my gratitude to UTA! laboratory officers

for providing me their technical assistance during my research or1 #any

thans to #r =oh :eng Fei and #r Foong ee ip from Faculty of $cience for

their technical assistance in $E# and

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:elly ong *previously from Faculty of Engineering and Green Technology+

for their help1 Besides that, ; also oe my thans to my ?unior, #r ee #eng

:eong for aiding me in running FT;! to analyse my samples in Faculty of

Engineering and $cience, :uala umpur1

astly, ; ould lie to e>press my deepest gratitude to my family for

alays supporting me and encouraging me in these fe years and my

girlfriend, #iss .g $u Ting ho as alays there for me through the good

times and bad1

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FACULTY OF ENGINEERING AND GREEN TECHNOLOGY

UNI"ERSITI TUNKU ABDUL RAHMAN

Date4

PERMISSION SHEET

;t is hereby certified that YONG TZYY JENG *;D .o4 !#AGM$$$##+ hascompleted this dissertation entitled P!EPA!AT;=. A.D

0A!A0TE!;AT;=. =F 0=.T!=ED !EEA$E FE!T;;E!$

U$;.G AG;.ATE-BA$ED $UPE!AB$=!BE.T P=%#E! F=! PA.TAT;=.$ ;. #AA%$;AH under the supervision of Assoc1 Prof1 Dr1

%amuna #unusamy *$upervisor+ from the Department of PetrochemicalEngineering, Faculty of Engineering And Green Technology, and Asst1 Prof1

Dr1 0hee $ee %ong *0o-$upervisor+ from the Department of 0hemical$cience, Faculty of $cience1

; hereby give permission to my supervisors to rite and prepare a manuscriptof these research findings for publishing in any form, if ; did not prepare itithin si> *8+ months times from this date, provided, that my name is included

as one of the authors for this article1 Arrangement of names ill depend on mysupervisors1

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APPRO"AL SHEET

This dissertation entitled PREPARATION AND CHARACTERIZATIONOF CONTROLLED RELEASE FERTILIZERS USING ALGINATE-

BASED SUPERABSORBENT POLYMER FOR PLANTATIONS IN

MALAYSIA% as prepared by %=.G T%% E.G and submitted as partial

fulfillment of the re"uirements for the degree of #aster of Engineering $cience

at Universiti Tunu Abdul !ahman1

Approved by4

*Assoc1 Prof1 Dr1 %amuna #unusamy+ Date4IIIIIII11

$upervisor

Department of Petrochemical Engineering

Faculty of Engineering and Green Technology

Universiti Tunu Abdul !ahman

*Asst1 Prof1 Dr1 0hee $ee %ong+ Date4IIIIIII11

0o-supervisor

Department of 0hemical $cience

Faculty of $cience

Universiti Tunu Abdul !ahman

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LIST OF TABLES

T&'(e P&ge

61( !ecipe for graft copolymerisation of .aAlg- g polyJ*acrylic 75

acid+-co-acrylamideK

61& !ecipe for gelatinisation of superabsorbent polymer 7L

71( Grafting percentage and grafting efficiency of AA and A# 8(

onto .aAlg *.aAlg4 AAMA# N 84&(+

71& ;nflection points and eight loss percentage of .aAlg and 3'

its ) selected grafted polymers

716 ;nflection points and eight loss percentage of .aAlg and 3&

its 6 selected grafted polymers

717 Oalues of T g and T m of .aAlg and ) selected grafted 38

polymers

71) Oalues of T g and T m of 6 selected grafted polymers 35

718 The release factors * K +, release e>ponents *n+ and (((

determination coefficients *r &+ from release data of )

selected fertili9er-imbedded grafted polymers

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LIST OF FIGURES

F)g*+e P&ge

&1( *(,7+--D-mannopyranuronic acid *#+ ((

&1& *(,7+-Q--gulopyranuronic aicd *G+ ((

&16 0hain conformation of #G bloc (&

&17 #odel of sodium alginate (6

&1) #odel of calcium alginate (7

&18 Egg-bo>H model ()

&15 Acrylamide *A#+ and Polyacrylamide *PA#+ (3

&13 Acrylic Acid *AA+ and Poly*acrylic acid+ *PAA+ (L

&1L 0opolymerisation of macromonomers *Braun et al 1, &&

&'')+

&1(' 0opolymer grafted from polymer < *Braun et al 1, &6

&'')+

&1(( Grafting of groing chain % onto polymer bacbone &6< *Braun et al1, &'')+

&1(& Ammonium persulfate2 *.7+&$&=3 &5

&1(6 Thermal ;nitiation of AP$ &3

&1(7 N , N /-methylene bisacrylamide *.-#BA+ 6'

&1() 0rosslined Polymer 6(

&1(8 ining sites of N , N /-methylenebisacrylamide 6&

&1(5 0rosslining mechanism of cellulose-based $AP by 66

.-#BA *Cang, &''5+

61( Gelatinised .aAlg paste 7)

61& Product gelas dropped from separating funnel to 78

beaers ith different concentration of 0a0l&

616 $pherical grafted polymer beads ere formed in the 73

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0a0l& solution617 Fertili9er-imbedded grafted polymer beads )'

61) $oil Burial Test $et-up *Phang et al 1, &'((+ )7

71( *a+ $chematic diagram of grafting of AA and A# onto )L

.aAlg

71( *b+ $chematic diagram of crosslining of AA and A# 8'

71& Grafting percentage and grafting efficiency of AA and 8(

A# onto .aAlg

716 ;! spectrum of Pure .aAlg 87

717 ;! spectrum of e>trapure A# 8)

71) ;! spectrum of AA 88

718 ;! $pectrum of grafted polymer A6 83

715 ;! $pectrum of grafted polymer B6 8L

713 ;! $pectrum of grafted polymer 06 5'

71L ;! $pectrum of grafted polymer D6 5(

71(' ;! $pectrum of grafted polymer E6 5&

71(( Peas overlapping vs concentration of A# beteen 56

the avenumber of (7(8 R (6&5 cm-(

71(& ;! $pectrum of grafted polymer A( 5)71(6 ;! $pectrum of grafted polymer A& 58

71(7 ;! $pectrum of grafted polymer A6 55

71() Ceight loss of pure .aAlg and ) selected grafted 53

polymers *A6, B6, 06, D6, and E6+

71(8 Ceight loss of 6 selected grafted polymers *A(, A& 3(

and A6+

71(5 T g and T m values of pure .aAlg and ) selected grafted 36

polymers

71(3 T g and T m values of 6 selected grafted polymers 38

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71(L


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grafted polymers in soil as a function of time7165 Cater retention behaviours of soil sample ith ((&

fertili9er-imbedded grafted polymers *FA6, FB6, F06,

FD6 and FE6+ and plain soil sample *Blan+ as a

function of time

7163 Cater retention behaviours of soil sample ith ((6

fertili9er-imbedded grafted polymers *FA(, FA& and

FA6+ and plain soil sample *Blan+ as a function of

time

716L FE$E# #icrograph of grafted polymer A6 at >6)' (6)

magnification

717' FE$E# #icrograph of grafted polymer B6 at >6)' (6)

magnification

717( FE$E# #icrograph of grafted polymer 06 at >6)' (68

magnification

717& FE$E# #icrograph of grafted polymer D6 at >6)' (68

magnification

7176 FE$E# #icrograph of grafted polymer E6 at >6)' (65

magnification7177 FE$E# #icrograph of grafted polymer FA6 at >6)' (63

magnification

717) FE$E# #icrograph of grafted polymer FB6 at >6)' (63

magnification

7178 FE$E# #icrograph of grafted polymer F06 at >6)' (6L

magnification

7175 FE$E# #icrograph of grafted polymer FD6 at >6)' (6Lmagnification

7173 FE$E# #icrograph of grafted polymer FE6 at >6)' (7'

magnification

717L Plot of log * M t /M + versus log *t + of nitrogen *.+ (7(

71)' Plot of log * M t /M + versus log *t + of phosphorus *P+ (7(

71)( Plot of log * M t /M + versus log *t + of potassium *:+ (7&

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LIST OF APPENDICES

A,,en-). P&ge

A Preparation of &''t1S .P: fertili9er in ratio (66

()4()4() and its calculation

B $E# of grafted polymers at >6)' magnification (6)

0 $E# of .P:-imbedded grafted polymers at >6)' (63

magnification

D Plot of log * M t /M + versus log *t + of nutrients (7(

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LIST OF ABBRE"IATIONS

AA acrylic acid

Alg- g -P*AA-co-A#+ alginate- g -polyJ*acrylic acid+-co-acrylamideK

A# acrylamide

A. acrylonitrile

AP$ ammonium persulfate

0a&Mcalcium *;;+ ion

0a0l&1&&= calcium chloride dihydrate0#0 carbo>ymethylcellulose

0=D chemical o>ygen demand

-0==- carbo>ylate

-0== carbo>ylic acid

D$0 differential scanning calorimtery

G *(,7+-Q--gulopyranuronic acid

;P. interpenetrating netor

;! ;nfra-red

;UPA0 ;nternational Union of Pure and Applied

0hemistry:Br Potassium bromide

Da iloDalton

Pa :ilopascal

# *(,7+--D-mannopyranuronic acid

m monomer molecule

#( chain initiating species

mPa1s millipascal seconds

.aAlg sodium alginate

.aAlg- g -P*AA-co-A#+ sodium alginate- g -polyJ*acrylic acid+-co-

acrylamideK

.-#BA .,./-methylenebisacrylamide

PAA poly*acrylic acid+

PA# polyacrylamide

P! phosphate roc

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P##A poly*methacrylic acid+

POP polyvinylpyrolidone

! initiator radical

rpm revolutions per minute

$AP superabsorbent polymer

$E# scanning electron microscopy

$emi-;P. semi-interpenetrating netor

$GF simulated gastric fluid

$ sodium humate

$;F simulated intestinal fluid

TGA thermogravimetric analysis

t1S eight percent

-ray diffraction

microlitre

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TABLE OF CONTENTS

Page

ABSTRACT ))

ACKNOWLEDGMENTS )/

PERMISSION SHEET /)

APPRO"AL SHEET /))

DECLARATION /)))

LIST OF TABLES ).

LIST OF FIGURES .

LIST OF APPENDICES .)/

L)01 OF ABBRE"IATIONS ./

CHAPTER

!2$ INTRODUCTION !

(1( ;ntroduction (

(1& Biodegradable $uperabsorbent Polymers &

(16 Polysaccharides 6

(17 Polysaccharides for $uperabsorbent Polymers 7

(1) Problem $tatements 8

(18 =b?ectives of !esearch $tudy 8

#2$ LITERATURE RE"IEW 3

&1( Polymer, 0opolymer and Graft 0opolymer 3

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&1& Alginates L&1&1( $ource of Alginic Acid L

&1&1& 0hemical $tructure of Algnic Acid ('

&1&16 Physical Properties of Alginate (6

&1&17 Applications of Alginate ()

&16 Poly*acrylic acid+ and Polyacrylamide (5

&17 Graft 0opolymerisation &'

&171( Advantages of Graft 0opolymerisation &'

&171& #ethods for $ynthesis of Graft 0opolymerisation &&

&1) 0hain Groth Polymerisation &)

&1)1( !adical 0hain Polymerisation &)

&1)1&1 Thermal ;nitiation Using Ammonium Persulfate &5

as ;nitiator

&18 0rosslining &L

&181( 0rosslining of Gels by 0opolymerisation 6(

&181& N , N / #ethylene Bisacrylamide 6&

&15 Preparation of Biodegradable $APs 6)

&13 !ecent Development of Applications of $APs 6L

42$ MATERIALS AND METHODOLOGY 55

61( #aterials 77

61& $ynthesis of Biodegradable $APs 77

61&1( Gelatinisation of $odium Alginate 77

61&1& Graft 0opolymerisation of PolyJ*acrylic acid+-co- 7)

acrylamideK onto $odium Alginate *Phase (a+

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61&16 Precipitating of Product $olution *Phase (b+ 78616 $ynthesis of 0ontrolled !elease Fertili9er Using 73

$uperabsorbent Polymers

617 0haracterisation )'

6171( Grafting Efficiency Determination )'

6171& ;nfrared $pectroscopy *FT;!+ )(

61716 Thermogravimetric Analysis *TGA+ )(

61717 Differential $canning 0alorimtery *D$0+ )&

6171) 61718 $tudy of $urface #orphology using $canning )&

Electron #icroscopy

61715 $elling 0apacity of $APs )6

61713 $oil Burial Test )6

617131( 0ollection of $oil )6

617131& #icrobial Degradation Using Ceight )7

oss Test

6171316 !ate of !elease of Fertili9er in $oil ))

6171317 #easurement of Cater !etention in $oil )8

52$ RESULTS AND DISCUSSION 63

71( Grafting of AA and A# onto .aAlg *.aAlg4AAMA# N )3

84&(+ and its Grafting Percentage and Grafting Efficiency

71& ;dentification 0odes 8&

716 Fourier Transformation ;nfrared $pectroscopy *FT;!+ 8&

717 Thermogravimetric Analysis *TGA+ 53

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71) Differential $canning 0alorimtery Anlysis *D$0+ 3&718 715 #orphological Analysis L'

7151( $urface morphology of grafted polymers ithout L'

.P: fertili9ers

7151& $urface morphology of .P: fertili9er imbedded L6

grafted polymers

713 #easurement of $elling 0apacity L)

71L Biodegradability Test *Ceight oss Test+ LL

71(' !ate of !elease Behaviour of .P: Fertili9er ;n $oil ('(

71(( Cater !etention of $oil ((&

62$CONCLUSIONS !!6

REFERENCES !!3

APPENDICES !44

>>


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CHAPTER !2$

INTRODUCTION

!2! In1+o*71)on

The cultivation of high yield crops re"uires ade"uate supply of nutrients

for sustained and better crop performance and yield1 Thus, fertili9er and ater

are important factors that limit the production of agriculture, so it is e>tremely

important to improve the utili9ation of ater resources and fertili9er nutrients

hich are the highest variable costs items in crop production budget1

According to the statistics provided by the #alaysia Government

Agency, Fertili9er ;ndustry Association of #alaysia *FIAM+, the consumption

of .P: fertili9er for oil palm plantations in #alaysia for year &''3 alone is

around (1&3L million tonnes1 Besides that, the analysis report from The Corld

Ban also shos that the fertili9er consumption on arable land in #alaysia is

about ()5'15' ilograms per hectare hich is e>tremely high1

oever, about 7'-5'S of nitrogen, 3'-L'S of phosphorus and )'-

5'S of potassium of the applied normal fertili9ers is lost to the environment

and cannot be absorbed completely due to the fact that it ill be ashed or

leached out by rain ater, causing not only substantial economic and resource

losses but also very serious environmental pollution *Trenel, (LL52 $aigusa,

&'''+1

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As a solution for this problem, controlled release fertili9er using

biodegradable superabsorbent polymer is the best idea to be developed not only

can release the nutrient contents gradually in order to save its consumption but

also can minimi9e environmental pollution *Cu and iu, &''3+1

!2# B)oeg+&&'(e S*,e+&'0o+'en1 Po(y8e+0

About L'S of traditional superabsorbent polymers are petroleum-based

and used in disposable articles1 #ost of them are disposed in landfills or by

incineration *:iatam?ornong, #ongolsaat and $onsu, &''&+ that can

cause serious environmental pollution1 Thus, it is the common consensus that

non-biodegradable aste has to be evaded, and biodegradable products have to

be fully-utili9ed as much as possible under reasonable economical and

ecological conditions in order to build a friendly environment that can lead

sustainable development for a country1

Therefore, in recent years, synthesis of biodegradable superabsorbent

polymers *$APs+ is attracting researchers/ interest in polymer-based production

due to their e>clusive environmental benefits1 Among them, carbohydrates

have attracted huge groing interest for the development of biodegradable

$APs1

Biodegradable $APs are loosely crosslined netors of hydrophilic

polymers that can absorb, sell and retain a very large volume of ater or

other biological a"ueous fluids up to thousands times of their on eight for

&


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certain period and the fluid absorbed is hardly removable even under some

pressure1

#oreover, the macromolecules of these polymers are able to brea

don into smaller compounds or completely degrade in biologically active

environment *Baer et al1, &''L+1 The biodegradation process is not only

caused by microorganisms, but also through hydrolysis and o>idation process

in biological environment *0osgrove et al 1, &''5+1 Because of their e>cellent

characteristics, biodegradable $APs had been idely used not only in

agriculture and horticulture but also in other applications1

!24 Po(y0&779&+)e0

0arbohydrates are e>tremely abundant due to their incorporation more

than L'S of the dry mass of all biomass, and more than L'S of carbohydrate

mass is in the form of carbohydrate polymers hich are polysaccharides

*ohuriaan and $horolahi, &''7+1 Polysaccharides, hich are the

stereoregular polymers of monosaccharide, are distinctive ra materials1 The

uni"ueness of polysaccharides is that they are natural, affordable and available

orldide1 Being stable, hydrophilic and amenable to both chemical and

biochemical modification *0rini, &'')+ caused polysaccharides to be largely

e>ploited for decades in numerous applications1

;n addition, polysaccharides carry e>cellent biological and chemical

properties too1 These include biodegradability, non-to>icity, high chemical

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reactivity, biocompatibility, polyfunctionality and adsorption capacities1 The

e>traordinary adsorption property of polysaccharides involve high hydrophilic

characteristic of the polymer due to hydro>yl groups of glucose unit, a large

number of functional groups such as acetamido, primary amino andVor

hydro>yl groups, high chemical reactivity of the functional groups and fle>ible

structure of the polymer chain *0rini, &'')+1

!25 Po(y0&779&+)e0 Fo+ S*,e+&'0o+'en1 Po(y8e+0

$uperabsorbent polymers *$APs+ ere first introduced into the

agriculture and diaper industries about four decades ago *=midian et al 1, &'')+1

$ince then, the application of $APs have been e>tended to other industries due

to their primary concern4 e>cellent ater-holding ability1

$APs are structurally crosslined hydrophilic polymer netors hich

can highly sell after absorbing a large amount of ater or a"ueous saline

fluids, practically (' to (''' times of their original eight or volume

*!ama9ani-arandi et al 1, &''8+, in short periods1 $APs are not dissolved in the

media due to their three-dimensional structure1 The electrostatic repulsion force

of the ionic charges of the polymer netors stimulates the selling by

dissociation of the carbo>ylic group *-0==.a or -0==:+ in the solution

*:aradag and $araydin, &''&+, alloing the ater to penetrate into the matri>1

The desired features of $APs include high selling rate, high selling

capacity and e>cellent strength of sollen gel *:abiri et al 1, &''62 !ama9ani-

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arandi et al 1, &''8+1 The ater absorbency of a $AP is greatly affected by its

composition, molecular eight, degree of crosslining, the molecular

conformation of the polymer and by the properties of li"uids to be absorbed

*0hen and Tan, &''8+1

Usually $APs are synthesised using acrylic monomers such as acrylic

acid, salts of the acrylic acid and acrylamide *=midian et al 1, (LL3+1 $APs are

produced ith acrylic acid as ey material in commercial field1 *anthong et

al 1, &''8+1 Due to the e>cellent selling behaviour, $APs ere used in some

ater absorbing applications such as feminine napins, disposable diapers,

absorbent pads, agriculture, horticulture and cosmetic1

;n recent years, various applications of $APs are still being e>panded to

many fields such as horticulture, agriculture and sealing composites, drilling,

medicine, fluid additives, artificial sno etc1 *i and Cang, &'')+1 Oan de

Oelde and :ieens *&''&+ mentioned that the applications found in medical

field can be divided into three common categories4 ound closure and healing

products, surgical implant devices and drug delivery systems1

Diapers or other absorbent articles incorporated ith biodegradable

$APs might be disposed in municipal composting facilities or directly flushed

don the toilet to degrade at municipal asteater treatment plants or degrade

in domestic septic tans1 Therefore, $AP manufacturers have paid their

attention to develop biodegradable $APs in order to fulfill the groing demand

for biodegradable products1

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!26 P+o'(e8 S1&1e8en10

The problem statements of this research study are as follos4

*i+ The nutrients from the fertili9ers are leached out during rain1 Plants

such as oil palm and rubber trees are unable to fully assimilate most of

the nutrients released from fertili9ers1

*ii+ E>cessive loss of fertili9ers to the environment result substantial

economic and resources losses1

*iii+ Unabsorbed nutrients release from fertili9er cause environmental

pollution1

!2: O';e71)/e0 o< Re0e&+79 S1*y

The ob?ectives of this research study are as follos4

*i+ To synthesise a biodegradable $AP derived from sodium alginate,

namely crosslined .aAlg- g -P*AA-co-A#+1

*ii+ To study the effects of the molar ratio of monomers *AA and A#+ and

the concentration of precipitating agent *0a0l&+ on the selling

capacity of the sodium alginate-based $APs1

*iii+ To characteri9e the grafted $APs by determining the functional groups,

thermal stability, surface morphology, crystallinity, glass transition

temperature and melting temperature, biodegradability through Fourier

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transform infrared *FT;!+, thermogravimetric analysis *TGA+, scanning

electron microscopy *$E#+, scanning calorimetry study *D$0+ and eight loss test using soil burial,

respectively1

*iv+ To formulate controlled release fertili9ers using .aAlg-based $APs1

*v+ To study the release rate of .P: fertili9er from biodegradable $APs

through soil burial test and the ater retention of the plantation soil

samples1

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CHAPTER #2$

LITERATURE RE"IEW

#2! Po(y8e+= Co,o(y8e+ &n G+&cess of )''' gVmol1 The repeating

chemical units hich mae up a polymer are named as monomer molecules1 A

polymer is then a substance ith high molecular mass composed of molecules

ith repeating chemical structural unit, or monomers, hich are connected

strongly by chemical covalent bonds1

#acromolecules are classified according to different criteria1 The

criterion is according to the number of different types of monomers *Braun et

al 1, &'')+1 omopolymers are the polymers hen they are produced from a

single type of monomer1 ;f there is a second or third type of monomer involved

in the polymer synthesis, the products are named as binary, ternary, I

copolymersH1 Different arrangement of monomers in copolymer chains are

categori9ed into alternating-, bloc-, statistic- and graft-copolymers1

Graft copolymer is one ind of copolymer in hich one or more blocs

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of homopolymer X are grafted onto main chain of homopolymer Y 1 This means

that a branched copolymer ith one or more side chains of a homopolymer X

attached to the homopolymer Y bacbone1 The grafted copolymer is given a

name by mentioning the main chain first, ith the ord - graft -H in beteen

the names of the corresponding homopolymers1 For e>ample4 polyY - graft -

poly X *=dian, (LL(+1

#2# A(g)n&1e0

#2#2! So*+7e o< A(g)n)7 A7)

Alginic acid is a natural acidic polysaccharide e>tracted from phylum

Phaeophyta hich is bron algae1 ;t e>ists as the most abundant

polysaccharide in the bron algae hich consists up to 7'S of the dry matter

*Draget, &''L+1 The e>tracts of polysaccharides from marine macroalgae are

named as hydrocolloids or phycocolloids because they sho colloidal

properties hen dissolved in ater and are e>tracted from phyos *the Gree

ord Wphyos/ refers to seaeed+ *eis et al 1, (L33+1

Even though this polysaccharide is found in all ind of species of bron

seaeeds *0handia et al 1, &'')+, the main species of commercial purposes are

Ascophyllum nodusum, Durvillaea antartica, Eclonia maima,

!aminaria digitata, !aminaria hyper"orea, !aminaria #aponica, !essonia

nigrescens, Macrocystis pyrifera, and $argassum spp *0ui and Cang, &''8+1

Besides that, Davis et al 1 *&''6+ also mentioned that alginic acid can also be

found in the family %orallinaceae of the red algae * phylum &hodophyta+1

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Alginate appears ithin the inner layer of the cell all matri> and in the

mucilage or intercellular matri> as a gel containing barium, calcium,

magnesium, sodium and strontium ions *Davis et at 1, &''62 Draget, &''L+1 As

the ma?or structural polysaccharide of bron seaeed, alginate carries its

fle>ibility in order to conduce to the strength of the cell all1 The abundance of

alginic acid alters beteen ('S and 7'S of the dry eight of untreated bron

algae1 This alteration depends on the seasonal variation and the depth at hich

the bron algae gro in the ater *Davis et al 1, &''62 $abra and Decer,

&''7+1

#oreover, alginic acid is also synthesi9ed as capsular polysaccharides

by to types of soil bacteria, A'oto"acter vinelandii and Pseudomonas

aeruginosa *!obyt, (LL32 Draget et al 1, &'')+ in addition to be in natural

bron seaeeds that can be found in the shallo aters of temperate 9ones1

All the commercial alginates are e>tracted from algae sources *Draget, &''L+1

Even if the mechanism involved in producing alginate is not nouveau, but the

fact that these bacteria-synthesised alginic acid corresponds to alginates from

bron algae is incontrovertible1

#2#2# C9e8)7&( S1+*71*+e o< A(g)n)7 A7)

Alginic acid is an unbranched bloc copolymer consisting of to

distinct monosaccharide residues, *(,7+--D-mannopyranuronic acid *#+

*Figure &1(+ and *(,7+-Q--gulopyranuronic aicd *G+ *Figure &1&+1 Though

!obyt *(LL3+ mentioned that the amounts of # and G are in the ratio of &4( for

('


32/183

most alginic acids, the ratio of the uronic acids can deviate idely ith the

algal species, type of tissue, habitat, season and age of the plant *!obyt, (LL32

0handia et al 1, &'')2 eal et al 1, &''3+1

F)g*+e #2!> ?!=5@--D-8&nno,y+&n*+on)7 &7) ?M@

F)g*+e #2#> ?!=5@--L-g*(o,y+&n*+on)7 &)7 ?G@

Draget et al 1 *&'')+ described that the polymer can be described into

three distinct portions through partial acid hydrolysis1 The repeating units of the respective # and G molecules form the homopolymeric #- and G- blocs1

These homopolymeric regions of #- and G- blocs are separated in proper

order by alternating repeating units of # and G *so-called the #G blocs+

*Figure &16+1

((


33/183

F)g*+e #24> C9&)n 7onylic form *-0==+, hereas, it is non as the alginate or

sodium alginate if the acid groups are in the carbo>ylate form *-0== -+ *Figure

&17+1 Glicsman *(L)6+ stated that alginic acid is insoluble and thus the

sodium, potassium and ammonium salts are more preferable for industrial area

and food purposes1 Among all of these salts, sodium alginate is the compound

that most idely used in most of applications1

(&


34/183

F)g*+e #25> Moe( o< 0o)*8 &(g)n&1e

#2#24 P9y0)7&( P+o,e+1)e0 o< A(g)n&1e

Generally, the molecular masses of alginates range beteen )'' and

(''' Da1 They are soluble in hot and cold ater1 Their solubility is affected

by some factors such as p, concentration of solution, ions in solution, the

presence of divalent ions *#oe et al 1, (LL)+ and ionic forces *!iou> et al 1,

&''5+1 The viscosities of alginates could reach up to )''' mPa1s for ( t1S of

solution1 Alginate solutions are non as pseudoplastic, therefore a drop in

viscosity is e>pected as higher shear is applied1 0oncentration of polymer, si9e

of polymer, temperature and rate of shear are those non physical variables

that can influence the flo characteristics of alginate solutions, hile chemical

variables lie monovalent salts, polyvalent cations, p and se"uestrants *eis

et al 1, (L33+1

Alginates gels are ell-non to be cold setting if compared ith other

gelling polysaccharides1 This denotes that alginate gels are independent of

temperature but the inetics of the gelling process may be strongly altered by a

(6


35/183

temperature change1 Being non-e"uilibrium gels, alginates are dependent upon

the history of formation1 Therefore, the properties of the gel product ill be

modified if the gelation process falls on different temperature *Draget, &''L+1

The thermoirreversibility of alginate gels also shos that the gels are thermally

stable and thus they can only be heat-treated ithout melting though they may

degrade in the end *0ui and Cang, &''8+1

The most noteorthy physical properties of alginate is its selective

binding of multivalent cations *Draget et al 1, &'')+1 $odium ions in sodium

alginate ill be substituted by the divalent metal ions henever it interacts

ith divalent metal ions1 The polysaccharide is then crosslined by the divalent

metal ions *such as barium, cadmium, calcium, cobalt, copper, lead, nicel,

strontium or 9inc+ to form gels1 Among all of these divalent ions, calcium is

most fre"uently used to form gels *Figure &1)+1

F)g*+e #26> Moe( o< 7&(7)*8 &(g)n&1e

!obyt *(LL3+ mentioned that the alginate gels formation and the affinity

force of divalent cations are predominately due to the presence of G residues1

(7


36/183

The binding sites for the calcium ions are believed to be formed by to a>ially

lined G residues1 That se"uence of G beteen to or more alginate molecules

builds a gel netor of calcium to crosslin the alginate molecules1 This is

non as the egg-bo>H model, since the calcium ions resembled eggs fitting

into a bo> made by the alginate chains *Figure &18+1

F)g*+e #2:> Egg-'o.% 8oe(

#2#25 A,,()7&1)on0 o< A(g)n&1e

$abra and Decer *&''7+ stated that about )'S of alginate has been

used in the food industry and this has itnessed the fast groing demand of

alginates in the global maret1 The alginates used in the food industry are

products mostly from harvested bron algae, and global maret for this

polysaccharide is appro>imately 6',''' tons1

Although alginates do not carry any nutritional value, there are still

often used as additives to modify and stabilise the te>ture of foods1 Due to the

ability of gel formation and stabilising a"ueous mi>tures and emulsions *Torres

()


37/183

et al 1, &''5+, alginates are idely used as additives in foods such as dessert

gels, baery products, salad dressings, beverages, fabricated foods, dairy

products and fro9en desserts *eis et al 1, (LL3+ through the ability of

viscosifying, stabilising, emulsifying and gelling a"ueous solutions1 Alginate is

also used in ice cream maing in order to prevent crystallisation and shrinage,

therefore giving a more homogenous product *$abra and Decer, &''7+1

$ome to>icology studies have already verified the high safety level of

alginates in food industry1 The U1$1 Federation of American $ocieties for

E>perimental Biology *FA$EB+ established the alginates as generally

recogni9ed as safeH in year (L3&1 The European common maret *E0+

regulations and the 0ode> Alimentarius 0ommission of the United .ations

Food and Agriculture =rganisationVCorld ealth =rganisation also legali9ed

the application of alginates in food industry *eis et al 1, (L33+1

Furthermore, alginates are also idely used in medical applications1 ;t

acts as an assisting agent in human-health for some decades1 Thomas *&''7+

revealed that the salts of alginic acid have a very long history in the ounds

management and large amounts of alginates are used for the e>uding ounds

treatment lie pressure ulcers, leg ulcers and infected surgical ounds1 =ther

than traditional ound dressings, alginates are also applied in dental

impression material and in some formulations to prevent gastric reflu> *Draget

et al 1, &'')+1

The drastic increment in the usage of alginate in the medical field

(8


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started ith the acnoledgment of its usage as a scaffold for encapsulation

and immunoprotection of transplanted cells1 According to Cong *&''7+,

alginates are non as immobilisation matrices in various biotechnological

processes1

$abra and Decer *&''7+ stated that calcium alginate gels is the most

idely used medium to immobili9e living cells lie bacteria, algae, yeast, and

animal and plant and cells1 The immobilisation of living cells is accomplished

in a single-step procedure through cells entrapment ithin calcium alginate

gel-spheres under very mild conditions and therefore it is compatible ith most

cells *Draget et al 1, &'')+1 From production of ethanol by yeast, to production

of monoclonal antibodies by hybridoma cells, to mass production of artificial

seed by entrapment of plant embryos, the use of this immobilisation techni"ue

is immense1

;n addition, Cong *&''7+ also stated that alginate has been used to

immunoprotect recombinant cells delivering tumor-suppressing agents and

groth hormone1 0ell types lie chondrocytes, islets, bone-marro stromal

cells, fibroblasts, myoblasts, idney cells and epithelial cells have been

achieved as stable cultures in alginate beads1

#24 Po(y?&7+y()7 &7)@ &n Po(y&7+y(&8)e

The polymers and copolymers of acrylic acid *067=&2 ;UPA0 name4

prop-&-enoic acid2 common synonyms4 vinylformic acid, acroleic acid, propene

(5


39/183

acid, ethylenecarbo>ylic acid, propenoic acid+ and acrylamide *06) .=2

;UPA0 name4 prop-&-enamide2 common synonyms4 acrylic amide, &-

propenamide+ are categorised in the acrylic family of polymers1

Polyacrylamide *Figure &15+ is used as flocculants in papermaing,

mining and treatment of municipal drining ater and industrial astes

hereas the crosslined polyacrylamide is also used in gel electrophoresis

*=dian, (LL(+1

Poly*acrylic acid+ *Figure &13+ is used as adhesives, crosslined ion-

e>change resins, and it is found useful as dispersants for inorganics pigments in

paint1 Furthermore, it is used as flocculants to aggregate suspended particles in

metal recovery and clarification of aste and potable aters1 =ther than that, it

is also used as thicening agent to increase the viscosity of a solution ithout

modifying its properties and also improve the suspension and emulsion hich

can increase the stability of related product *=dian, (LL(+1

F)g*+e #2> A7+y(&8)e ?AM@ &n Po(y&7+y(&8)e ?PAM@

(3


40/183

F)g*+e #23> A7+y()7 A7) ?AA@ &n Po(y?&7+y()7 &7)@ ?PAA@

PAA is generally acnoledged as a polyelectrolyte hich has been

idely utilised in the area of site-specific drug delivery to specific regions of

the gastrointestinal tract1 oever, due to its great ater solubility, PAA hich

acts as drug carrier, has been restricted to a certain level because of the

dissolution before the drug can be delivered1 uang et al 1 *&''5+ mentioned

that PAA is normally crosslined ith organic cross-liners to form

interpenetrating netors *;P.s+ to overcome this disadvantage, but this seems

to have some limitation in the morphology and properties such as

morphological inhomogeneity and mechanical eaness in the systems1

%in et al *&''3+ cited uang et al 1 *&''5+ as proving that the carbo>ylic

acid groups in PAA allo it to build different types of intermolecular

interaction such as hydrogen bonding, electrostatic force and dipole-ion ith

other polymers, especially ionic natural polysaccharides1 After some various

investigations from researchers, the selling property of the hydrogels is

greatly affected by these mentioned interactions, and hence the PAA hydrogels

are applied in pharmaceutical purposes, especially in drug delivery systems1

(L


41/183

#25 G+&posure of this site to a

monomer *an et al 1, &''6+1

#252! A/&n1&ge0 o< G+&tent *ee et al 1, &'')a+1

hu et al 1 *(LL8+ described that the polymer grafting allos the

conversion of commodity-based polymers to value-added specialty polymers1

For e>ample, the grafting of maleic anhydride oligomers onto polyolefins *P=+

to enhance the adhesive properties of the polymers to metals and glass fibers

grafting of elastomers, the grafting onto polypropylene *PP+ to improve the

&'


42/183

impact strength for applications in the automobile industry and the grafting of

highly charged ionic polymers onto high molecular eight polyacrylamide

*PA#+ to have better flocculation effects1

Alginate-based graft copolymers are getting more important due to their

high potential in industry1 The ide availability of vinyl and other monomers

implies that the polymer grafting is a poerful method to affect substantial

modifications to alginate properties and thus e>pand its applications and

utilisation1 ;YZlan et al 1 *&'('+ also mentioned that the desired properties could

be introduced by graft copolymerised of vinyl monomers onto alginate1 A

variety of types of side chains leads the development of application of

alginates1

The grafting of vinyl monomers such as methyl acrylate *Patel et al 1,

(LLL+, acrylamide *Tripathy et al 1, (LLL2


43/183

#252# Me19o0 Co,o(y8e+)0&1)on o< 8&7+o8ono8e+0 ?B+&*n et al 2= #$$6@

The second ay of synthesising graft copolymers is named as grafting

formH1 The long chain branches are formed hen the active sites brought forth

at the polymer < bacbone initiated the polymerisation of monomer % *Braun

et al 1, &'')+ as shon in Figure &1('1 The radical center on the polymer <

bacbone could be ith irradiation using UO radiation or ith any other high

energy radiation such as electron beam radiation1

&&


44/183

F)g*+e #2!$> Co,o(y8e+ g+&


45/183

from hydro>yl group of the polysaccharide to generate alo>y radicals on the

substrate and results in active centres on the substrate to initiate radical

polymeri9ation reaction of A# and form to a graft copolymer1

#eanhile, $abotain et al 1 *&''L+ carried a free radical graft

copolymerisation of poly*methacrylic acid+ *P##A+ onto carbo>ylmethyl

starch *0#$+ at 5'[0, using bis-acrylamide as the crossliner and persulfate as

an initiator1 The authors studied the e"uilibrium selling studies in en9yme-

free simulated gastric and intestinal fluids *$GF and $;F, respectively+1 They

found that the selling and hydrolytic behaviour of the hydrogels as

dependent on the content of #AA group, hich resulted an increase in gel

selling in $;F or a decrease in gel selling in $GF1

Tripathy et al 1 *(LLL+ had grafted PA# onto .aAlg using a ceric ion

initiated solution polymerisation techni"ue at &5\([01 $i> graft copolymers

had been prepared ith a variation in the number and length of grafted PA#

chains1 The results shoed that graft copolymers containing longer PA#

chains ere having the highest flocculation-efficiency1 After fe years, ygen demand *0=D+ and colority in dyeing

asteater1

&7


46/183

#26 C9&)n G+o19 Po(y8e+)0&1)on

0hain groth polymerisation or addition polymerisation is a techni"ue

here activated species *initiators+ add onto active centers of groing polymer

chain1 The molecules are lined together through double or triple chemical

bonds or are cyclic and having sufficiently high ring strain1 Braun et al *&'')+

stated that the chain groth polymerisation is divided into three different

categories based on the mechanism of initiation, hether the chains initiation

occurs via ionic *0ationic or anionic+, radical or coordinative-acting *hich

can be found in transition-metal mediated polymerisation+ initiators1 Ebeele

*&'''+ also mentioned that those initiators are regularly but inaccurately

identified as catalysts and it is noteorthy that those initiators are used up in

the reaction, hereas catalysts are regenerated at the end of the reaction1

As the initiation system, hich is made up of redo> system that could

generate radicals in the initiation step in this research study, the chain groth

polymerisation naturally proceeds through the radical polymerisation pathay1

ence, only radical polymerisation is going to be described in the folloing

section1

#262! R&)7&( C9&)n Po(y8e+)0&1)on

Braun et al *&'')+ stated that there are three distinctive inetic steps

involved in free radical chain reaction4 initiation step, propagation step and

termination step1 =nce the active centers are produced in the initiation step, the

&)


47/183

reaction ill immediately propagate rapidly through the action of

macroradicals or macroions until the termination stage that forms inactive

macromolecules is accomplished1

The initiation step of free radial chain polymerisation involves to

reactions4 formation of initiator radical *hich is the rate-determining step in

initiation stage+ and addition of the initiator radical to monomer1 The initiator

radicals of chain reactions are produced by the hemolytic dissociation of the

relatively ea covalent bond in the initiator to ac"uire a pair of initiator or so-

called primary radicals, !1 The primary radical, ! then binds together ith

the first monomer molecules *m+ to form a ne radical, # ( *chain initiating

species+1

=dian *(LL(+ described that the rapid groth of #( by the consecutive

additions of hundreds or thousands of monomer molecules indicated the

beginning of the propagation step1 Cith each addition of monomer molecules,

there is a ne radical that is larger by one monomer unit than the previous

primary radical is formed1

The reaction continues to propagate at the reactive chain ends in the

chain-reaction polymerisation1 ;t only stops during the termination reaction

hereby the reaction deactivates the chain ends or causes the monomer to be

completely consumed1 According to =dian *(LL(+, the termination reaction

could either happen by molecular reaction beteen radicals by combination

*coupling+, or disproportionation in hich a -hydrogen radical of one radical

&8


48/183

centre is shifted to another radical centre1

Braun et al 1 *&'')+ cited Buchhlo9 and Graham *(LL3+ as proving that

both disproportionation and combination reactions are inetically

indistinguishable1 The only difference of these to termination reactions

depends on the products formed1 The combination reaction produces a single

polymer chain hereas the disproportionation reaction generates in to chains,

each ith half the molecular mass of the product from recombination1

#262# T9e+8&( In)1)&1)on U0)ng A88on)*8 Pe+0*(ydisulfuric acid, ammonium

pero>ydisulfate+, hich is an inorganic pero>o compound, is used in the initial

stage of this research study1 ;t is a thermal initiator that decomposes at high

temperature1

F)g*+e #2!#> A88on)*8 ,e+0*(


49/183

to monomer+ could be thermally decomposed into radicals *Figure &1(6+ that

can initiate the polymerisation reaction even at lo temperature at 6']0 *Braun

et al 1, &'')+, therefore it is non as a thermal initiator1

F)g*+e #2!4> T9e+8&( In)1)&1)on o< APS

The decomposition of persulphate ions in the polymerisation reaction

*initiation stage+ proceeds according to E"uation &1( R &16 *!udin, (LLL2 Braun

et al 1, &'')+1 Each initiators molecule decomposes to produce to types of

primary radicals *sulphate and hydro>yl radicals+1 !udin *(LLL+ suggested that

these radicals or ell at the temperature range of 7' to L' ]0, hereas

Braun et al 1 *&'')+ also proposed that the desired temperature for every

polymerisation reaction is at the temperature range of 7' to L' ]0 for the

radicals1

28


50/183

$&=3&- ^ &=$=6- II *&1(+

=$=6- M &= ^ $=7- M = 11111111 *&1&+

& = ^ &= M _ =& II1 *&16+

#2: C+o00()n)ng

;t is orth mentioning that the crosslins/ nature significantly affects

the properties of $APs1 Elastic gels are formed hen $APs absorb any li"uid

*e1g ater+1 The gel formed is then a soft, deformable solid composed of the

e>panded polymer chains and ater *Buchhol9 and Graham, (LL3+1 ;onic,

covalent and hydrogen bonds are the three ma?or bonding types that connect

the polymer chains together to form ionic, covalent and physical gels1

Buchhol9 and Graham *(LL3+ stated that there are to methods to form

covalent gels2 the first type of covalent crosslins are introduced via

condensation or addition reaction hen a di- or tri- functional reagent reacts

ith performed polymer chains, for instance the carbo>ylic acids, hereas the

second type of covalent crosslins are formed through a free-radical initiated

addition polymerisation hen a di-, tri-, or tetra-vinyl monomer such as N , N /-

methylenebisacrylamide *.-#BA+ *Figure &1(7+ is used to copolymerise the

ma?or monomer, for instance, AA1

&L


51/183

F)g*+e #2!5> N = N -8e19y(ene')0&7+y(&8)e ?N-MBA@

Due to the association of unlie charges, ionic crosslins are produced

through reaction of a polyvalent ion of opposite charge and the charged

polymer chains1 ;f ionic crosslins compared to covalent crosslins, the

placement of the crosslins is less affected by the chemical structure of the

crossliner because the bond is formed by ion association1 The main

disadvantage of ionic gels is that the ion e>change might happen beteen the

ionic crosslins and the ionic components present in the li"uid, as the result,

the nature of the crosslins and behavior of the $AP are modified1 #oreover,

Buchhol9 and Graham *(LL3+ also stated that the incorporation of the crosslin

and the final structure of the $AP are difficult to control due to the rapid

interionic reaction1

Physical gel is formed hen the hydrogen bonds are formed beteen

segments of one chain ith the segments of another chain1 Due to the presence

of polypeptide chains, the gelling of gelatin solution is a typical e>ample of

physical gel hich allos the strong hydrogen bonds forming beteen their

chains1 Physical crosslins have their disadvantage as ell1 Aside from the

reduction of the mass efficiency of the crossliner due to the e>tension of the

multiple segments of the polymer chains, simple heating of the polymer can

6'


52/183

also demolish the crosslins *Buchhol9 and Graham, (LL3+1

#2:2! Ge(0 C+o00()n)ng 'y Co,o(y8e+)0&1)on

$mall amounts of crossliners are certainly re"uired in order to modify

the properties and characteristics of superabsorbent polymers1 0rosslining

agents are used to introduce crosslins or so-called intermolecular bridges

beteen polymer chains1 Unlie branched polymer in hich the side groth of

each polymer chain is terminated before the polymer chain could have a chance

to interconnect ith another polymer chain in a crosslined *Figure &1()+

polymer, the groing polymer chains are chemically bonded *Ebeele, &'''+1

F)g*+e #2!6> C+o00()ne Po(y8e+

Buchhlo9 and Graham *(LL3+ had ranged the copolymerisable

crossliners in superabsorbent polymers idely from functional compounds

* N , N /-methylenebisacrylamide, allymethacrylate and diacrylate esters+ to tri-

functional compounds *(, (, (-trimethylol-propanetriacrylate and triallylamine+

and to tetra-functional compounds *tetraallylo>yethane+1

6(


53/183

The efficiency of crosslining agents relies on respective factors and

there are steric hindrance and reduced mobility at the site of pendant double

bonds, solubility of the crossliner in the monomer mi>tures and the tendency

of a crossliner to undergo intermolecular addition reaction, for e>ample4

cyclopolymerisation *Buchhol9 and Graham, (LL3+1

#2:2# C+o00()n)ng o< 9y+oge(0 )19 N = N -8e19y(ene')0&7+y(&8)e

The bifunctional compound N , N /-methylenebisacrylamide * N -#BA,

05(' .&=&, ;UPA0 name4 N -J*Prop-&-enoylamino+methylKprop-&-enamide+ is

a most often used ater soluble crosslining agent1

A ne macro-radical, hich has four reactive sites, is produced from .-

#BA crossliner in any polymerisation reaction involving the crosslining

agent *Figure &1(8+ due to the poly-functionality of .-#BA *$ingh et al 1,

&''5+

F)g*+e #2!:> L)n)ng 0)1e0 o


54/183

synthetic polymers *PAA and PA#+ used in the synthesis of the $AP in this

research study1 As a result, a three-dimensional netor is formed1

From the research article presented by Cang *&''5+, the author

proposed that in the synthesis of cellulose-based $AP ith .-#BA as the

crosslining agent, the polymeri9ation mechanism is shon in Figure &1(51

Cith this epistemology, the mechanism of the crosslining reaction beteen

.aAlg-based $AP and .-#BA in this research study could be developed1

F)g*+e #2!> C+o00()n)ng 8e79&n)08 o< 7e((*(o0e-'&0e SAP 'y N-MBA

?W&ng= #$$@

$AP hydrogels are synthesised from synthetic polymers ithout natural

polymers that have AA as the main component1 :abiri et al 1 *&''6+ carried out

their research regarding the effect of the concentration and type of crossliner

on the porosity and adsorption rate of highly porous $AP hydrogels formed

from high concentration of AAVpotassium acrylate a"ueous solutions using .-

#BA and (,7-butanedioldiacrylate as crossliners1 ;t as concluded that both

crossliners shoed same effects on ater absorbency in distilled ater and

saline1 The gelation time decreased ith increasing concentration of the

crossliner especially .-#BA1

66


55/183

#ahdavinia and co-orers *&''7+ graft copolymerised AA and A#

onto chitosan using potassium persulfate *:P$+ as a free radical initiator in the

presence of .-#BA as a crossliner1 The concentration of .-#BA and ratio of

AAVA# on the ater selling capacity had been investigated1 The authors also

revealed that the hydrogels e>hibited salt-sensitivity and cation e>change

properties1

;n year &''5, $ingh and co-orers synthesised psyllium *common

name for the plant genus Plantago+ and PA# based hydrogel polymeric

netors in the presence of N -#BA as crossliner1 The authors found that the

e"uilibrium selling as dependent on both structural features of the polymers

and selling environment1 The increase of concentration of .-#.BA in the

polymeric netors as found to result the decrease of selling capacity1

;n &''3, %in and co-orers prepared a series of hydrogels through

graft copolymerisation of AA and .aAlg by using N -#BA as a crossliner1

The dynamic selling e>perimental results shoed that an e>traordinary

overshooting effect as revealed in the selling process of P*.aAlg- g -AA+

hydrogels in the buffer solutions at p ` 71'1 The authors ascribed that the

phenomenon to a cooperative physical crosslin hich as caused by the

formation of hydrogen bond beteen the carbo>yl groups of the hydrogels1

The selling capacity decreased due to hydrogen bond crosslining and thus

resulted the ater e>pulsion during the dynamic selling process1

9eroglu and Birdal *&''L+ proposed meso-&,6-dimercaptosuccinic

67


56/183

acid-0e*;O+ redo> couple for crosslining polymerisation of A# ith .-#BA

as crossliner in acid a"ueous medium1 The authors concluded that the selling

ratio and rate of selling of the hydrogels in distilled ater decreased ith the

increase of concentration of the acid, initiator and crossliner1

Cang and Cang *&'('+ synthesised a p-sensitive semi-

interpenetrating netor *semi-;P.+ $AP composed of .aAlg- g -poly*sodium

acrylate+ *.aA+ netor and liner polyvinylpyrolidone *POP+ via free-radical

solution polymerisation1 Ammonium persulphate and .-#BA ere used as the

initiator and crossliner, respectively in this reaction1 The authors concluded

that the introduction of POP and the formation of the semi-;P. structure

improved the selling capacity and rate of selling of the hydrogel1

#2 P+e,&+&1)on o< B)oeg+&&'(e SAP0

;n order to save the environment from synthetic polymers, graft

copolymerisation of synthetic polymer on natural polymers such as starch and

.aAlg as introduced as an alternative method to produce $APs1 As a result of

this, countless research papers on syntheses of such $APs sarmed the

research literature orld1 Basically, these $APs could be categorised into

crosslined and non-crosslined $APs and these to categories of literatures

are shon as ne>t fe paragraphs1

There ere some research articles hich focused on syntheses of

polymer ithout using any crossliner1 ;n Bra9il, Da $ilva et al 1 *&''5+

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synthesised a cashe- g -PA# polymer at 8' [0 by a radical polymerisation

using :P$ as the redo> initiator under nitrogen atmosphere1 A series of graft

copolymers as prepared by varying the concentration of A# and eeping the

concentrations of the initiator and polysaccharide at constant1 The authors

concluded that even ith a lo acrylamideVgum ratio, high percentages of A#

conversion *S0+ and grafting efficiency *SE+ ere still obtained1

;n &''L, %ang and co-orers carried out the synthesis of

carbo>ymethylcellulose *0#0+- g -PA# in an a"ueous medium by using

ammonium persulphate and sodium sulfite redo> system as initiator1 The

effects of reaction conditions, such as monomer concentration, initiator

concentrations, initial reaction temperature, and p value, on the eight-

average molecular eight of the copolymers ere investigated, and the optimal

conditions for the grafting reaction ere established1

Pour?avadi et al 1 *&'('b+ graft copolymerised polyacrylamide-co-poly-

&-acrylamido-&-methylpropane sulfonic acid *PA#-co-PA#P$+ chains onto

.aAlg through a free radical polymerisation method, to produce novel types of

highly selling hydrogels1 The results shoed that the biodegradable $AP

could successfully deliver a drug to the intestine ithout losing any drug in the

stomach and thus acting as potential candidate as an orally administrated drug

delivery system1

;n addition, there ere some articles hich focused on the syntheses of

crosslined-$APs too1 0hen and Tan *&''8+ synthesised a novel

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carbo>ymethylchitosan- g -PAA $AP through graft polymerisation of AA onto

the carbo>ymethylchitosan chain and subse"uent crosslining1 ;n the

polymerisation reaction, ammonium persulphate and .-#BA ere used as

initiator and crosslining agent1 =ptimisation conditions for $AP ith the

highest selling ratio ere found by studying the selling ratio of the polymer

synthesised under different conditions1

;n &''8, anthong and coorers prepared biodegradable $APs by

graft copolymerisation of A#V;A onto cassava starch via a redo> initiator

system of AP$ and N , N , N /, N /-tetramethylethylenediamine *TE#ED+, in the

presence of .-#BA as crosslining agent, sodium bicarbonate as foaming

agent and a tribloc copolymer of *polyo>yethylene V polyo>ypropylene V

polyo>yethylene+ as a foam stabili9er They found out that the ater absorption

of $APs as affected by acrylamide-to-itaconic acid ratio, starch-to-monomer

ratio and concentration of the crosslining agent and iniatiator1

0hang et al 1 *&'('+ successfully synthesised novel $APs from

carbo>ymethylcellulose sodium *0#0+ and cellulose in the .a=Vurea

a"ueous system using epichlorohydrin *E0+ as crossliner1 The results

shoed that cellulose acted as a strong bacbone in the hydrogel to support it

for retaining the shape hile the 0#0 improved the si9e of pores1 The

ma>imum selling ratio in ater reached an e>citing level of (''' as the

hydrogels eep a stable appearance1

$pagnol et al 1 *&'(&+ developed superabsorbent hydrogel composite

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using cellulose nanofibrils and chitosan-graft-poly*acrylic acid+, in the

presence of .-#BA as crosslining agent and :P$ as initiator1 The authors

evaluated the crossliner and filler amounts ere the main factors controlling

the ater uptae1 Besides that, selling capacity as also improved by adding

cellulose nanofibrils in the polymerisation reaction1

iu and coorers *&'(6+ synthesised a chitin-based acrylate

superabsorbent by grafting copolymerisation chitin and acrylic acid ith AP$

and .-#BA as initiator and crossliner, respectively in .a=Vurea solution

ithout nitrogen protection1 The authors revealed that chitin hich possesses

more hydrophilic group in the graft copolymerisation reaction, significantly

enhanced the ater absorption of the product1 Acrylic acid as e>pected to

simplify the procedures and reduce the ater consumption hereas .a= and

urea play the role of solvent and reaction reagents1 Thus, the final product

e>ists as a hydrogel ithout e>cess reagent emissions, hich is conductive to

reducing the environmental pollution1

Ge and Cang *&'(7+ prepared chitosan-acrylic acid $APs through

thermal reaction ithout or ith .-#BA and potassium pero>ydisulfate as

crossliner and radical initiator respectively, under air or nitrogen atmosphere1

The authors concluded that $APs ere successfully synthesised by the thermal

reaction ithout using radical and crossliner in air at atmospheric pressure1

The results also shoed that the yield of thermal reaction in air as similar to

reaction in nitrogen atmosphere *radical and crossliner ere used+ and the

thermal reaction ithout using crossliner and initiator as suggested since

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both of them are harmful or to>ic to human body and environment1

#23 Re7en1 De/e(o,8en1 o< A,,()7&1)on o< SAP0

.oadays, many researchers are focusing their or on obtaining

environmentally friendly $APs, such as starch, cellulose and .aAlg-based, to

be implemented in diaper application, medical, tissue engineering application,

drug delivery system and controlled release fertili9er system1

$afaa et al 1 *&'(&+ developed a ne superabsorbent system in diaper

industry using Tara gumVacrylic acid *TGVAAc+ via gamma irradiation1 The

results shoed that the presence of Tara gum ith acrylic acid in the hydrogel

had caused an increase in the crosslin density1 This as proven as there as

an increase in the elastic modulus1 Thus, a higher elastic modulus value

signified a more rigid structure of TGVAAc hydrogel1 From the selling

capacity result, TGVAAc hydrogel shoed that pressure *'18.Vm&+ did not

change its selling capacity in urea *ma?or component of urine+ solution up to

8 hours1

Upadhyaya et al 1 *&'(7+ successfully provided a comprehensive

introduction to various types of carbo>ymethyl chitosan *0#0$+ based on

formulation for delivery of therapeutic agents and tissue regeneration and

preparation procedures and applications in different tissuesVorgans1 The results

revealed that 0#0$ has improved the dissolution of rate of many otherise

poorly soluble drugs and thus can be e>ploited for bioavailability improvement

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of drugs1 ;n addition, therapeutic agents such as anticancer, anti-inflammatory,

antibiotics, antithrombotic, proteins and amino acids have been incorporated in

0#0$-based system effectively to increase the bioavailability and to achieve

the targeted controlled release1

Bhattacharya et al 1 *&'(6+ prepared an interpenetrating polymer

netor *;P.+ hydrogel microspheres of >anthan gum *acin hydrochloride *0;P!=+1 The

results revealed that the formulation hich containing loer amount of

glutaraldehyde gave a higher rate of release1 This confirms that the formation

of a denser netor structure can reduce the selling and the rate of drug

release from the $AP matri>1

#ogoYanu and Grume9escu *&'(7+ emphasi9ed that the dressing

protects in?ury and contributes to the recovery of dermal and epidermal tissues

in the ound healing process1 The results concluded that polysaccharides *e1g1

chitin, chitosan, alginates, heparin, chondroitin+, proteoglycans and proteins are

used e>tensively in ounds management1 This is due to their biocompatibility,

biodegradability and similarity to macromolecules recogni9ed by the human

body1 Furthermore, by electrospinning techni"ue, some synthetic polymers lie

biomimetic e>tracellular matri> micro or nanoscale fibers based on

polyglycolic acid, polyactic acid, polyacrylic acid, poly-ɛ-caprolactone,

polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol, e>hibit in vivo

and in vitro ound healing properties and enhance epithelialisation1

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iang, iu and Cu *&''5+ synthesi9ed a $AP hich possessed the

coreVshell structure hich is urea formaldehyde *UF+ and polyphosphate

potassium, and the poly*acrylic acid-co-acrylamide+Vaolin respectively1 The

results shoed that its ater absorbency as up to L(gVg in tap ater1 The $AP

contained ((16, &(1( and 318 t1 S for ., P and : respectively1 The .P:

nutrient release of the $AP as not above 5)S on the 6' th day and this

concluded that it had a good slo release property in soil and ater holding

ability and ater retention properties of the soil could be greatly improved1

Availability of fertili9er and ater resource to crops could be improved

simultaneously1

Cu, iu and iang *&''3+ prepared a double-coated slo-release .P:

compound fertili9er ith $AP using *acrylic acid+Vdiatomite *AAVDT+ hich

contains urea, chitosan and ater-soluble granular fertili9er .P: hich ere in

the outer coating, the inner coating and the core respectively1 The double

coated $AP as undergone its selling test and it as found that it could sell

5) times of its on eight at room temperature for & hour1 Besides, the $AP

contained 3175S of potassium, 31)(S of phosphorus and ()155S of nitrogen

through AA$ and elemental analysis1 The results shoed that the slo release

ratio of the effective nutrient in it as not e>ceeding 5)S on the 6'th day1 This

can be concluded that chitosan and diatomite in the production of coating

material can reduce the production cost and the techni"ue is environmental-

friendly1 ;ts slo release property could be useful in agricultural and

horticultural purposes1

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Cu and iu *&''3+ prepared a three-layer structured $AP hich is

chitosan-coated nitrogen, phosphorus and potassium compound fertili9er1 The

three layer structures included the core hich as ater-soluble .P: fertili9er

granular, the inner coating hich as chitosan and the outer coating as

poly*acrylic acid-co-acrylamide+1 The results shoed that the chitosan-coated

$AP had a good control release property since the release of .P: nutrients did

not e>ceed 5)S on the 6'th day1 ;n addition, the product could improve the

ater holding ability and retention property of the soil1

hong et al 1 *&'(&+ synthesi9ed an eco-friendly $AP using modified

sugarcane bagasseVpoly *acrylic acid+ embedding phosphate roc

*#$BVPAAVP!+ in order to improve the ater-fertili9er *.P:+ utili9ation

ratio1 The result shoed that #$BVPAAVP! had an e>cellent ater absorption

capacity hich achieved 7(7gVg in distilled ater and )) gVg in '1Lt1 S of

.a0l solution, a preferable sustained-release property and this could also

mitigate the environmental contamination1

hong et al 1 *&'(6+ synthesi9ed an agricultural $AP based on

sulfonated corn starchVpoly *acrylic acid+ embedding phosphate roc

*$0$VPAAVP!+ due to the difficulty of utili9ation of plants since phosphate

roc is abundant1 The result shoed that $0$VPAAVP! possessed an e>cellent

sustained-release property of plant nutrient and the $0$VPAA improved the

release of phosphorus nutrient1

emvichian et al 1 *&'(7+ synthesi9ed a $AP by using radiation-induced

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grafting of acrylamide *A#+ onto carbo>ymethyl cellulose *0#0+ and this

$AP as loaded ith potassium nitrate *:.=6+ as an agrochemical model

hich has a highly potential of controlled release system1 The results shoed a

very high selling ratio of (L'gVg of dry $AP1 oever, the selling ratio and

control release rate of :.=6increased ith decreasing of A# and irradiation

dose1

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CHAPTER 42$

MATERIALS AND RESEARCH METHODOLOGY

42! M&1e+)&(0

Graft copolymeri9ation process for this research as carried out by

using sodium alginate *.aAlg+ as polymer bacbone hich as provided by

!@#, U:1 Acrylic acid *AA+ and acrylamide *A#+ ere used as monomers1

Both of them ere supplied by $!, ;ndia1 N , N /-methylenebisacrylamide *.-

#BA+ as used as crosslining agent hile ammonium persulfate *AP$+ as

used as initiator1 Both ere obtained from $!, ;ndia1 0alcium chloride

dihydrate, 0a0l&1&&= as used as precipitating agent hich as obtained

from !@#, U:1

For .P: fertili9er preparation, e>tra pure urea and potassium chloride,

hich ere purchased from $!, ;ndia, ere used to produce nitrogen and

potassium respectively and phosphate roc poder, hich as obtained from

0hina .ational Analysis 0enter, 0hina, as used to produce phosphorus1

These three main elements act as the resources for .P: fertili9er1

42# Syn19e0)0 o< B)oeg+&&'(e SAP0

42#2! Ge(&1)n)0&1)on o< So)*8 A(g)n&1e

81' g of sodium alginate as dispersed in ()' ml distilled ater1 The

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system as heated at 3' \ & [0 ith mechanical stirring, using an overhead

metal stirrer at (''' rpm for 6' minutes to form a homogenous, gelatinised

.aAlg paste *shon in Figure 61(+1

F)g*+e 42!> Ge(&1)n)0e N&A(g ,&01e

42#2# G+&


67/183

in Table 61(1 At this phase, the ratio of AA and A# on graft polymers as

varied and the effect on the properties of grafted polymers ere studied1

42#24 P+e7),)1&1)ng o< P+o*71 So(*1)on ?P9&0e !'@

After (&' minutes of polymeri9ation reaction, the product gel as then

precipitated by dropping the product gel from a separating funnel into a beaer

ith different concentration of 0a0l& solution *Table 61&+ under stirring to form

the final product hich is in spherical bead form *Figure 61& and 616+1 These

grafted polymer beads ere then dried overnight in an oven at 8']01

F)g*+e 42# P+o*71 ge( &0 +o,,e


68/183

T&'(e 42!> Re7),e


69/183

F)g*+e 424 S,9e+)7&( g+&ed .P: poder

as then transferred into the .aAlg-g-polyJAA-co-A#K solution1 The mi>ture

as then stirred vigorously until uniform and sloly transferred from a

separating funnel to beaers ith (#, and 6# 0a0l& solution1 The

spherical grafted polymer beads ere left in the 0a0l& solution for half an hour

to ensure complete gelling1 The beads ere then taen out from the solution,

rinsed tice ith distilled ater and dried at 8']0 overnight1 The fertili9er-

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imbedded grafted polymer beads *Figure 617+ ere formed1

T&'(e 42#> Ing+e)en10 *0e


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F)g*+e 425> Fe+1)()ze+-)8'ee g+&


72/183

grafted polymer and eight of monomers respectively1

4252# Inimately (' mg of grafted polymers ere eighed

into 5' alumina crucible and heated from room temperature to ))' [0 at a

heating rate of (' [0Vmin under minimum LL1LLL)S purity nitrogen purge of

(' mVmin1

)(


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42525 D)

accelerating voltage of 61' O1 The grafted polymers ere coated using

platinum before scanning1

)&


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4252 Se(()ng C&,&7)1y o< SAP0

A non mass of each grafted polymers ere immersed in tap ater

inside the beaer ith a glass cover and alloed to sell for 3 hours at room

temperature1 The sollen sample as then removed from distilled ater at (

hour interval by filtering through a (''-mesh sieve to remove non-absorbed

ater1 The samples ere then dried in conventional oven overnight at 8']0 and

eighed1 The ater absorbency as calculated gravimetrically as shon in

E"uation 616 *iang, iu and Cu, &''52 hang and Cang, &''52 Cu and iu,

&''32 Phang et al 1, &'((+1

2 m

&

m

(

m(

IIIIII *616+

here m( and m& are the mass of the dry samples and the sollen samples,

respectively1 2 is grams of ater per gram of dried sample1

42523 So)( B*+)&( Te01

425232! Co((e71)on o< So)(

#alaysia oil palm soil is a type of loamy soil hich contains a

combination of microorganisms and some organic materials such as rooted

leaves, ood chips, old manure, compost and etc, hich help in the groth of

oil palm trees1 The oil palm soil as found to be slightly acidic, p )1531

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By employing random sampling method, four oil palm soil samples

ere collected from four different oil palm plantations, Felda Trola $elatan

Pera, Felda $ungai :lah Pera, Felda Gunung Besout ( Pera and Felda

Gunung Besout & Pera1 A plastic pail as used to enclose the soil samples up

to to third of its volume1 The pail as loosely capped using pins-holed

aluminium foil for gas e>change2 the samples ere ept at room temperature

for one ee1

425232# M)7+o')&( Deg+&&1)on U0)ng We)g91 Lo00 Te01

$oil burial test to evaluate the biodegradation of superabsorbent grafted

polymers as conducted for L' days1 The grafted polymers ere eighed and

rapped ith stainless steel ire mesh *6&)+ in order to minimi9e the loss of

the polymer fragments during the soil burial process1 Each grafted polymer as

buried appro>imately )cm beneath the surface of the soil as shon in Figure

61) and the oil palm soil as maintained at 6' t1S of ater holding capacity

by eighing and adding ater if necessary throughout the test *Phang et al 1,

&'((+1

F)g*+e 426> So)( B*+)&( Te01 Se1-*, ?P9&ng et al 2= #$!!@

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At least three grafted polymers of each sample ere used in the test to

obtain its average reading1 The grafted polymers ere transferred out from soil

at different time intervals *(', &', 6' , )', 5' and L' days+1The grafted

polymers ere then put in an oven at 8'[0 overnight after ashed to remove

all the debris and planton microorganism1 The eight of dried grafted

polymers as taen1

The eight loss as determined using the E"uation 6174

1! S m' mt IIII111 *617+m'

Chere 1!0 is eight loss in percentage, m3 is the initial mass and mt is the

final mass1 An average of three measurements as taen *Franco et al 1, &''7+1

4252324 R&1e o< Re(e&0e o< Fe+1)()ze+ )n So)(

To study the controlled-release behavior of fertili9er-imbedded graft

polymer beads in oil palm soil1 (' grafted polymer samples ith different ratio

of AA and A# ith different concentration of 0a0l& as buried in palm soil1

The samples ere ept in a )'' ml beaer and properly covered *Figure 61)+

and incubated for different periods at room temperature1 Throughout the test,

the oil palm soil as maintained at 6' t1 S of ater holding capacity by

eighing and adding ater if necessary1

After 6, 5, (7, &(, &3, 6), 7&, 7L, )7 and 8' days of incubation periods,

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the remaining of grafted polymers ere removed from oil palm soil and

ashed ith distilled ater to remove all debris and planton microorganism

and then dried at room temperature overnight to estimate the content of ., P

and :1 For (' measurements, (' beaers ere prepared at the same time1 The

remaining amount of ., P and : as estimated using :?eldahl method of

distillation *Abraham and !a?aseharan, (LL8+ and atomic absorption

spectrophotometer *AA$+, respectively1

The release results ere analy9ed by using an empirical e"uation to

estimate the value n and K as follos *Al-ahrani, (LLL2 Peng, hang and

:ennedy, &''8+4

IIIIIII *61)+

IIIIIII *618+

Chere M t /M is the release fraction at time t , n is the release e>ponent and K is

the release factor1

4252325 Me&0*+e8en1 o< W&1e+ Re1en1)on )n So)(

) grams of fertili9er-imbedded grafted polymers as ell mi>ed ith

&'' g of dry soil *belo &mm in diameter+ and ept in a cup and then &'' g of

tap ater as sloly added into the cup and eighed *1 4+1 A controlled

e>periment, i1e1, ithout fertili9er-imbedded grafted polymer *plain soil

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sample+, as also carried out1 The cups ere maintained at room temperature

and eighed every ) days *1 i+ over a period of &' days1 The ater retention

percentage *1&0+ o

Yong Tzyy Jeng - Master of Engineering Science Dissertation 2015

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