Effect of Maleic Anhydride-Grafted-polyethylene (MAPE) and...

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Effect of Maleic Anhydride-Grafted-polyethylene(MAPE) and Silane on Properties of RecycledPolyethylene/Chitosan Biocomposites

Salmah Husseinsyah , Azieyanti Nurain Azmin & Hanafi Ismail

To cite this article: Salmah Husseinsyah , Azieyanti Nurain Azmin & Hanafi Ismail (2013) Effect ofMaleic Anhydride-Grafted-polyethylene (MAPE) and Silane on Properties of Recycled Polyethylene/Chitosan Biocomposites, Polymer-Plastics Technology and Engineering, 52:2, 168-174, DOI:10.1080/03602559.2012.734362

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Effect of Maleic Anhydride-Grafted-polyethylene (MAPE)and Silane on Properties of Recycled Polyethylene/ChitosanBiocomposites

Salmah Husseinsyah1, Azieyanti Nurain Azmin1, and Hanafi Ismail21School of Material Engineering, Universiti Malaysia Perlis (UniMAP), Jejawi, Perlis, Malaysia2School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia (USM), NibongTebal, Penang, Malaysia

Chitosan-filled recycled polyethylene biocomposites were preparedusing an internal mixer. The effect of maleic anhydride-grafted-polyethylene (MAPE) and silane of recycled polyethylene (RPE)/chitosan biocomposites on tensile properties, water absorption,morphology and thermal properties of recycled polyethylene (RPE)/chitosan biocomposites were studied. The results of biocomposites withMAPE and silane improved the tensile strength and Young’s modulusbut reduced the elongation at break and water absorption. The pres-ence ofMAPE and silane show the evidence of better adhesion betweenfiller and matrix through scanning electron microscopy (SEM) study ofthe tensile fracture surface of biocomposites. The incorporation ofMAPE and silane also increased the crystallinity of RPE/chitosanbiocomposites.

Keywords Biocomposites;Chitosan;MAPE;Recycledpolyethylene;Silane

INTRODUCTIONSynthetic plastics such as polystyrene, polypropylene,

polyurethane, polyethylene and polylactides are used indaily life in food industry, biomedical field and agriculture.However, some of these polymers have disadvantages insuch applications, i.e., poor biocompatibility and releaseof acidic degradation products. A heavy environmentalpollution accompanies their uses, because they need hun-dreds of years to degrade, and the disposal of waste plasticshas become a serious problem. Biodegradable materialswere used as alternative to the petroleum-derived plastics.The natural polymers have undergone reevaluation regard-ing their ability to biodegrade. Natural biopolymers includ-ing starch, cellulose and chitosan were tested, alone orcombined with synthetic polymers, for the possibility toform a fully or partially biodegradable film. Most of thenaturally occurring polysaccharide, e.g., cellulose, dextran,

pectin, alginic acid, agar, agarose and carragenans, areneutral or acidic in nature, whereas chitin and chitosanare examples of highly basic polysaccharide[1–4].

In wanting to find substitute materials for plastic, thiscould involve a great cost and effort as it is much antici-pated that used plastic can be recycled again and reusedas their original product to prevent the waste of potentiallyuseful materials, reduces the consumption of raw materialsand reduces energy usage. Therefore, studies on recycledplastic are very important because they will help todecrease the amount of waste. Thermoplastics are poly-mers that soften upon exposure to heat and return to theiroriginal condition at room temperature. Because thermo-plastics can easily be shaped and molded into variousproducts such as bottles, jugs, and plastic films, they areideal for packaging. Moreover, virtually all thermoplasticsare recyclable (melted and reused as raw materials forproduction of new products), although separation posessome practical limitations for certain products.

Chitosan is a well-known abundant natural polymerderived from crustaceans exoskeleton with molecularformula, poly-(b-1!4)-2-amino-2-deoxy-D-glucopyranose,is used as a collective name for a group of partially and fullydeacetylated chitin [4–14]. Thus, chitosan contains a large num-ber of hydroxy and amino groups [15–18]and it is also classifiedas a natural polymer because of the presence of a degradableenzyme, chitosanase[3]. Chitosan is the second most abundantpolysaccharide in nature after cellulose[19–20]. Chitosan isnatural family biopolymer, biodegradable, nontoxic as wellas being a low-cost material. Therefore, these biopolymersare extensively used in many scientific and technologicalapplications such as medicine, pharmacology, biotechnologytextile and food industry, photographic films, as well as fiberand plastic applications.

A tremendous awareness of the suitability of usingnatural biopolymers for diversified applications in lifescience is increasing. Biopolymers are polymers that arebiodegradable. The input materials for the production of

Address correspondence to H. Ismail, Division of PolymerEngineering, School of Material Engineering, Universiti MalaysiaPerlis, 02600 Jejawi, Perlis, Malaysia. E-mail: [email protected]

Polymer-Plastics Technology and Engineering, 52: 168–174, 2013Copyright # Taylor & Francis Group, LLCISSN: 0360-2559 print=1525-6111 onlineDOI: 10.1080/03602559.2012.734362

168

these polymers may be either renewable (based on agricul-tural plant or animal products) or synthetic. Natural bio-polymers have several advantages, such as availabilityfrom replenishable agricultural or marine food resources,biocompatibility, biodegradability, therefore leading toecological safety and the possibility of preparing a varietyof chemically or enzymatically modified derivatives for spe-cific end uses. The effect of compatibilizer and some chemi-cal modification of chitosan filled thermoplastic compositeswere reported in our previous study[21–23].

The strong interfacial bonding strength obtained byimproving the compatibility between the hydrophilic fillerand hydrophobic matrix polymer can improve the physical,mechanical and thermal properties of the composite sys-tem[24]. Studies have been performed on surface modifi-cation or treatment using a compatibilizing and couplingagent for the purpose of making the polyolefin chainhydrophilic. MAPE and silane coupling agent have beenwidely used to improve the interfacial interaction betweenthe components in polymer blends and polymer compositesto maximize the physical properties. Their action producessignificant improvements in physical properties in variousthermoplastic systems. In this research was focused tostudy the effect chitosan loading and MAPE wit silaneon the properties of recycled polyethylene=chitosancomposites.

EXPERIMENTALMaterials

Recycled polyethylene (RPE) used was grade TitanleneLDF260GG, obtained from Titan Petchem (M) Sdn Bhd.The properties of recycled polyethylene is shown Table 1.Chitosan in powder form was obtained from Hunza Nutri-ceuticals (M) Sdn Bhd, Penang, Malaysia. The average par-ticle size of chitosan is 85.4 mm. The properties of chitosanis shown in Table 2. Compatibilizer, used in RPE=chitosancomposites was polyethylene-graft-maleic anhydride(MAPE), supplied by Aldrich (Malaysia) and the amountapplied is 3 php based on weight recycled polyethylene.Table 3 shows the properties of MAPE. The couplingagent used is a-methacryloxypropyltrimethoxysilane (SilaneA-174), supplied by Union Carbide (USA) and the amountapplied is 3 php based on weight of chitosan.

Mixing ProcessThe mixing of the biocomposites was carried out by

using Z-Blade mixer at temperature 180!C and rotor speed50 rpm. RPE and 3 php MAPE were charged into the mix-ing chamber for 10min until it completely melts. After10min the treated chitosan with silane was added and

TABLE 1Properties of recycled polyethylene

Recycled polyethylene

Melt Index 5 g=10minDensity 0.922 g=cm3

Melt temperature 160–180!C

TABLE 2Properties of chitosan

Chitosan

Physical properties. Appearance. Powder fineness

Off-white powderFiner than 120 mesh size

Chemical properties. Degree of

deacetylation. Solubility of 1%

chitosan in 1% aceticacid

. Viscosity

. Moisture content

. Ash content

> 90.0%> 99.0%

150–200mPa " s< 10.0%< 1.0%

TABLE 3Properties of maleic anhydride-grafted-polyethylene

Maleic anhydride-grafted-polyethylene

Chemical formula C8H10O3

Density 0.925 g=cm3

Melting point 120!CViscosity 500 cP (140!C)

TABLE 4Formulation of RPE=chitosan biocomposites with and

without MAPE and silane

MaterialsWithout

MAPE þ silaneWith

MAPE þ silane

Recycled polyethylene(php)

100 100

Chitosan (php) 0, 10, 20, 30, 40 10, 20, 30, 40Maleic anhydride-grafted-polyethylene,MAPE (php)a

– 3

Silane A-174 (php)b – 3

a3 php from weight RPE.b3 php from weight chitosan.

RECYCLED POLYETHYLENE=CHITOSAN BIOCOMPOSITES 169

mixing continued for 20min. The whole mixing progresswas conducted for 30min. The formulation used forRPE=chitosan biocomposites with and without MAPEand silane is shown in Table 4. To produce a 1-mm-thicksheet sample, sample of biocomposites were compressionmolded in an electrically heated hydraulic press com-pression molding machine model GT 7014 A with tempera-ture 180!C and pressure 170 kg=cm2. After compressionmolding, the samples were cut into dumbbell shapes byusing Wallace dumbbell cutter.

Measurement of Mechanical PropertiesTensile Test

The tensile test was carried out according to ASTM D638 using an Instron Tensile model 5569. The gauge lengthwas set at 50mm and the cross-head speed of testing was50mm=min at 25 $ 3!C. Tensile properties for 5 identicalsamples of each composition were measured and the aver-age values were reported. Tensile strength, elongation atbreak and Young’s modulus were recorded and automati-cally calculated by the instrument software.

Water AbsorptionRPE=chitosan biocomposites samples of approximate

dimensions 25mm x 20mm x 1mm were used for themeasurement of water absorption according to ASTM D570. The samples were oven-dried at 80!C for 24 h, andimmersed in distilled water at room temperature until aconstant weight was reached. A Mettler balance type wasused, with precision of $ 1mg. The percentage of waterabsorption, (Mt), was calculated according to the followingformula:

My ¼ WN & Wd

Wd' 100

where Wd ¼ Original dry weight and WN ¼ Weight afterimmersed.

Morphology StudyStudies of the morphology of tensile fractured surfaces

for RPE=chitosan biocomposites were carried out by usinga scanning electron microscopy (SEM) model JOELJSM-6460LA. SEM was used to examine qualitatively thedispersion of chitosan in RPE matrix. The fracture endsof specimens were mounted on aluminium stubs and sput-ter coated with a thin layer of palladium to avoid electro-static charging during examination.

Differential Scanning Calorimetric (DSC)Thermal analysis measurements of selected systems were

performed using a Perkin Elmer DSC-7 analyzer. Samplesof about 10–25mg were heated from 20 to 250!C using a

nitrogen air flow of 50ml=min and the heating rate of20!C=min. The melting and crystallization behavior ofselected biocomposites were also performed using a PerkinElmer DSC-7 (USA). The crystallinity (Xcom) of biocom-posites was determined using the following relationship:

Xcomð%crystallinityÞ ¼ DHf=DH!f ' 100%

where DHf and DH!f are enthalpy of fusion of the system

and enthalpy of fusion of perfectly (100%) crystalline PE,respectively. For DH!

f (PE) a value of 285 J=g was usedfor 100% crystalline PE homopolymer.

RESULTS AND DISCUSSIONEffect Filler Loading on Mechanical PropertiesTensile Properties

Figure 1 shows the effect of filler loading on tensilestrength of RPE=chitosan biocomposites with and withoutMAPE and silane. The results indicates that the tensilestrength for both biocomposites increase with increasingof filler loading. The increasing of tensile strength showsthe effectiveness of compatibilizer and coupling agentand, in turn, improving stress transfer between filler andmatrix. Biocomposites incorporated with MAPE and silaneimproved the strength of biocomposites because they cre-ated more filler-matrix contact with the presence of compa-tibilizer and coupling agent and therefore increased thepotential for bonding. It was clear that, to improve reinfor-cing effect of filler, the presence of silane as coupling agentwas important. The application of coupling agent and com-patibilizer in RPE=chitosan biocomposites was used toovercome the dispersion problem and to enhance theproperties of biocomposites by improving adhesionbetween filler and matrix.

Figure 2 shows the effect of filler loading on elongationat break of RPE=chitosan biocomposites with and without

FIG. 1. The effect of filler loading on tensile strength of RPE=chitosanbiocomposites with and without MAPE and silane.

170 S. HUSSEINSYAH ET AL.

MAPE and silane. The result shows the drastic decrease ofelongation at break with increasing of filler loading. Atsimilar filler loading, compatibilized and treated biocom-posites exhibitedlower elongation at break than uncompa-tibilized and untreated biocomposites. This indicates thatcompatibilizer and coupling agent imparts a greater stiffen-ing effect to biocomposites.

Figure 3 shows the effect of filler loading on Young’smodulus of RPE=chitosan biocomposites with and withoutMAPE and silane. The increase in Young’s modulus wasattributed to the increased stiffness and brittleness of bio-composites due to addition of chitosan. The biocompositeswith MAPE and silane exhibit higher Young’s moduluscompared to biocomposites without MAPE and silane.Significant improvement was more for high chitosan load-ing. Thus, the biocomposites with MAPE and silane give

better properties than biocomposites without MAPE andsilane. The presence of MAPE and silane give betterfiller-matrix adhesion and stress transfer at the interface.MAPE and silane have modified the inherent poor com-patibility between thermoplastic and filler. It is suggestedthat the higher efficiency of maleated polyethylene wasdue to more available anhydride group for reaction withhydroxyl group of treated chitosan with silane, andwithlonger hydrocarbon chain that entangle more effectivelywith RPE matrix.

Water AbsorptionFigure 4 indicates the curves of the percentage of water

absorption versus time of RPE=chitosan biocompositeswith and without MAPE and silane at 0, 20 and 40 php.Figure 5 shows the equilibrium water absorption ofRPE=chitosan biocomposites with and without MAPEand silane at different filler loading. The percentage ofwater absorption increases with increasing of filler loading.At similar filler loading, the presence of MAPE and silanereduced the amount of water absorption. The reduction inwater absorption with MAPE and silane treatment wasattributed to improve interfacial adhesion which reducedwater from entering the biocomposites.

Morphological StudiesFigure 6 shows the scanning electron micrograph of

chitosan that indicates the irregular shape of chitosan suchas particulate, fiber and flake morphology. SEM micro-graphs of tensile fracture surface of RPE=chitosan biocom-posites with and without MAPE and silane for 20 and 40php are shown in Figures 7–10, respectively. SEM micro-graphs of tensile fracture surface of RPE=chitosan biocom-posites without MAPE and silane at 20 and 40 phpchitosan are shown in Figures 7 and 8. The biocompositeswith 20 php of chitosan show ductile morphology.

FIG. 2. The effect of filler loading on elongation at break of RPE=chitosan biocomposites with and without MAPE and silane.

FIG. 3. The effect of filler loading on Young’s Modulus of RPE=chitosan biocomposites with and without MAPE and silane.

FIG. 4. The percentage of water absorption versus time of RPE=chitosan biocompositeswith andwithoutMAPEand silane at 0, 20 and 40 php.


FIG. 5. The equilibrium of water absorption versus time of RPE=chitosan biocomposites with and without MAPE and silane.

FIG. 6. Scanning electron micrograph of chitosan at magnification1000X.

FIG. 7. The SEMmicrograph of tensile fracture surface of RPE=chitosanbiocomposites without MAPE and silane at 20 php at magnification 200X.

FIG. 8. The SEM micrograph of tensile fracture surface of RPE=chitosanbiocomposites without MAPE and silane at 40 php at magnification 200X.

FIG. 10. The SEMmicrograph of tensile fracture surface of RPE=chitosanbiocomposites with MAPE and silane at 40 php at magnification 200X.

FIG. 9. The SEM micrograph of tensile fracture surface of RPE=chitosanbiocomposites with MAPE and silane at 20 php at magnification 200X.


In Figure 7 chitosan is not well dispersed in matrix. Pooradhesion can causes cracks and voids between matrix andfiller. The morphology of biocomposite at 40 php exhibitsrough surface with the presence of less voids and cavities.This indicates that the chitosan have better dispersion inRPE matrix. SEM micrograph of tensile fracture surfaceof RPE=chitosan biocomposites with MAPE and silaneat 20 and 40 php at magnification 200X are illustrated inFigures 9 and 10. The SEM micrograph of biocompositeswith MAPE and silane clearly show the less pulled-outtraces from the matrix. This result clearly demonstratedthe treatment of biocomposites provides strong interfacialadhesion and good wetting, which consequently resultedin better adhesion between filler and matrix.

Thermal PropertiesFigure 11 shows the curves of RPE=chitosan biocompo-

sites with and without MAPE and silane at 20 php ofchitosan. The thermal parameter of DSC for biocompositeswith and withoutMAPE and silane at different filler loadingis shown in Table 5. It can be seen in Table 5 that the value ofDHf(com) and percent crystallinity increase with increasing offiller loading. The results show that the biocomposites withMAPE and silane exhibit higher value of enthalpy and crys-tallinity. This may be due to the silane treated of filler whichare display strong molecular interactions with the compati-bilizer in matrix. The slight increase in crystallinity wasprobably due to covalent adhesion between filler and matrixwith presence of MAPE and silane.

CONCLUSIONBiocomposites from chitosan and recycled polyethylene

were prepared. The presence of MAPE and silane in RPE=chitosan biocomposites enhanced the tensile strength,Young’s modulus and cystallinity but reduced the elonga-tion at break and water absorption of biocomposites.SEM micrograph study proved that biocomposites withMAPE and silane improved the adhesion between chitosanand RPE matrix.

ACKNOWLEDGMENTThis research was supported by Ministry of Higher

Educational (MOHE) for providing FundamentalResearch Grant Schemes (FRGS).

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FIG. 11. Differential scanning calorimetric thermogram of RPE=chitosanbiocomposites with and without MAPE and silane.

TABLE 5DSC analysis of RPE=chitosan biocomposites with andwithout MAPE and silane at different filler loading

Sample Tm (!C)DHf(com)

(J=g)Xcom

(% crystallinity)

RPE=chitosan: 100=0 130 52.97 18.6RPE=chitosan: 100=20(uncompatibilizedand untreated)

124 113.3 39.8

RPE=chitosan: 100=40(uncompatibilizedand untreated)

123 129.3 45.4

RPE=chitosan: 100=20(compatibilized andtreated)

124 144.3 50.6


123 164.7 57.8


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Effect of Maleic Anhydride-Grafted-polyethylene (MAPE)and Silane on Properties of Recycled Polyethylene/ChitosanBiocomposites

Salmah Husseinsyah1, Azieyanti Nurain Azmin1, and Hanafi Ismail21School of Material Engineering, Universiti Malaysia Perlis (UniMAP), Jejawi, Perlis, Malaysia2School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia (USM), NibongTebal, Penang, Malaysia

Chitosan-filled recycled polyethylene biocomposites were preparedusing an internal mixer. The effect of maleic anhydride-grafted-polyethylene (MAPE) and silane of recycled polyethylene (RPE)/chitosan biocomposites on tensile properties, water absorption,morphology and thermal properties of recycled polyethylene (RPE)/chitosan biocomposites were studied. The results of biocomposites withMAPE and silane improved the tensile strength and Young’s modulusbut reduced the elongation at break and water absorption. The pres-ence ofMAPE and silane show the evidence of better adhesion betweenfiller and matrix through scanning electron microscopy (SEM) study ofthe tensile fracture surface of biocomposites. The incorporation ofMAPE and silane also increased the crystallinity of RPE/chitosanbiocomposites.

Keywords Biocomposites;Chitosan;MAPE;Recycledpolyethylene;Silane

INTRODUCTIONSynthetic plastics such as polystyrene, polypropylene,

polyurethane, polyethylene and polylactides are used indaily life in food industry, biomedical field and agriculture.However, some of these polymers have disadvantages insuch applications, i.e., poor biocompatibility and releaseof acidic degradation products. A heavy environmentalpollution accompanies their uses, because they need hun-dreds of years to degrade, and the disposal of waste plasticshas become a serious problem. Biodegradable materialswere used as alternative to the petroleum-derived plastics.The natural polymers have undergone reevaluation regard-ing their ability to biodegrade. Natural biopolymers includ-ing starch, cellulose and chitosan were tested, alone orcombined with synthetic polymers, for the possibility toform a fully or partially biodegradable film. Most of thenaturally occurring polysaccharide, e.g., cellulose, dextran,

pectin, alginic acid, agar, agarose and carragenans, areneutral or acidic in nature, whereas chitin and chitosanare examples of highly basic polysaccharide[1–4].

In wanting to find substitute materials for plastic, thiscould involve a great cost and effort as it is much antici-pated that used plastic can be recycled again and reusedas their original product to prevent the waste of potentiallyuseful materials, reduces the consumption of raw materialsand reduces energy usage. Therefore, studies on recycledplastic are very important because they will help todecrease the amount of waste. Thermoplastics are poly-mers that soften upon exposure to heat and return to theiroriginal condition at room temperature. Because thermo-plastics can easily be shaped and molded into variousproducts such as bottles, jugs, and plastic films, they areideal for packaging. Moreover, virtually all thermoplasticsare recyclable (melted and reused as raw materials forproduction of new products), although separation posessome practical limitations for certain products.

Chitosan is a well-known abundant natural polymerderived from crustaceans exoskeleton with molecularformula, poly-(b-1!4)-2-amino-2-deoxy-D-glucopyranose,is used as a collective name for a group of partially and fullydeacetylated chitin [4–14]. Thus, chitosan contains a large num-ber of hydroxy and amino groups [15–18]and it is also classifiedas a natural polymer because of the presence of a degradableenzyme, chitosanase[3]. Chitosan is the second most abundantpolysaccharide in nature after cellulose[19–20]. Chitosan isnatural family biopolymer, biodegradable, nontoxic as wellas being a low-cost material. Therefore, these biopolymersare extensively used in many scientific and technologicalapplications such as medicine, pharmacology, biotechnologytextile and food industry, photographic films, as well as fiberand plastic applications.

A tremendous awareness of the suitability of usingnatural biopolymers for diversified applications in lifescience is increasing. Biopolymers are polymers that arebiodegradable. The input materials for the production of

Address correspondence to H. Ismail, Division of PolymerEngineering, School of Material Engineering, Universiti MalaysiaPerlis, 02600 Jejawi, Perlis, Malaysia. E-mail: [email protected]

Polymer-Plastics Technology and Engineering, 52: 168–174, 2013Copyright # Taylor & Francis Group, LLCISSN: 0360-2559 print=1525-6111 onlineDOI: 10.1080/03602559.2012.734362

168

these polymers may be either renewable (based on agricul-tural plant or animal products) or synthetic. Natural bio-polymers have several advantages, such as availabilityfrom replenishable agricultural or marine food resources,biocompatibility, biodegradability, therefore leading toecological safety and the possibility of preparing a varietyof chemically or enzymatically modified derivatives for spe-cific end uses. The effect of compatibilizer and some chemi-cal modification of chitosan filled thermoplastic compositeswere reported in our previous study[21–23].

The strong interfacial bonding strength obtained byimproving the compatibility between the hydrophilic fillerand hydrophobic matrix polymer can improve the physical,mechanical and thermal properties of the composite sys-tem[24]. Studies have been performed on surface modifi-cation or treatment using a compatibilizing and couplingagent for the purpose of making the polyolefin chainhydrophilic. MAPE and silane coupling agent have beenwidely used to improve the interfacial interaction betweenthe components in polymer blends and polymer compositesto maximize the physical properties. Their action producessignificant improvements in physical properties in variousthermoplastic systems. In this research was focused tostudy the effect chitosan loading and MAPE wit silaneon the properties of recycled polyethylene=chitosancomposites.

EXPERIMENTALMaterials

Recycled polyethylene (RPE) used was grade TitanleneLDF260GG, obtained from Titan Petchem (M) Sdn Bhd.The properties of recycled polyethylene is shown Table 1.Chitosan in powder form was obtained from Hunza Nutri-ceuticals (M) Sdn Bhd, Penang, Malaysia. The average par-ticle size of chitosan is 85.4 mm. The properties of chitosanis shown in Table 2. Compatibilizer, used in RPE=chitosancomposites was polyethylene-graft-maleic anhydride(MAPE), supplied by Aldrich (Malaysia) and the amountapplied is 3 php based on weight recycled polyethylene.Table 3 shows the properties of MAPE. The couplingagent used is a-methacryloxypropyltrimethoxysilane (SilaneA-174), supplied by Union Carbide (USA) and the amountapplied is 3 php based on weight of chitosan.

Mixing ProcessThe mixing of the biocomposites was carried out by

using Z-Blade mixer at temperature 180!C and rotor speed50 rpm. RPE and 3 php MAPE were charged into the mix-ing chamber for 10min until it completely melts. After10min the treated chitosan with silane was added and

TABLE 1Properties of recycled polyethylene

Recycled polyethylene

Melt Index 5 g=10minDensity 0.922 g=cm3

Melt temperature 160–180!C

TABLE 2Properties of chitosan

Chitosan

Physical properties. Appearance. Powder fineness

Off-white powderFiner than 120 mesh size

Chemical properties. Degree of

deacetylation. Solubility of 1%

chitosan in 1% aceticacid

. Viscosity

. Moisture content

. Ash content

> 90.0%> 99.0%

150–200mPa " s< 10.0%< 1.0%

TABLE 3Properties of maleic anhydride-grafted-polyethylene

Maleic anhydride-grafted-polyethylene

Chemical formula C8H10O3

Density 0.925 g=cm3

Melting point 120!CViscosity 500 cP (140!C)

TABLE 4Formulation of RPE=chitosan biocomposites with and

without MAPE and silane

MaterialsWithout

MAPE þ silaneWith

MAPE þ silane

Recycled polyethylene(php)

100 100

Chitosan (php) 0, 10, 20, 30, 40 10, 20, 30, 40Maleic anhydride-grafted-polyethylene,MAPE (php)a

– 3

Silane A-174 (php)b – 3

a3 php from weight RPE.b3 php from weight chitosan.


mixing continued for 20min. The whole mixing progresswas conducted for 30min. The formulation used forRPE=chitosan biocomposites with and without MAPEand silane is shown in Table 4. To produce a 1-mm-thicksheet sample, sample of biocomposites were compressionmolded in an electrically heated hydraulic press com-pression molding machine model GT 7014 A with tempera-ture 180!C and pressure 170 kg=cm2. After compressionmolding, the samples were cut into dumbbell shapes byusing Wallace dumbbell cutter.

Measurement of Mechanical PropertiesTensile Test

The tensile test was carried out according to ASTM D638 using an Instron Tensile model 5569. The gauge lengthwas set at 50mm and the cross-head speed of testing was50mm=min at 25 $ 3!C. Tensile properties for 5 identicalsamples of each composition were measured and the aver-age values were reported. Tensile strength, elongation atbreak and Young’s modulus were recorded and automati-cally calculated by the instrument software.

Water AbsorptionRPE=chitosan biocomposites samples of approximate

dimensions 25mm x 20mm x 1mm were used for themeasurement of water absorption according to ASTM D570. The samples were oven-dried at 80!C for 24 h, andimmersed in distilled water at room temperature until aconstant weight was reached. A Mettler balance type wasused, with precision of $ 1mg. The percentage of waterabsorption, (Mt), was calculated according to the followingformula:

My ¼ WN & Wd

Wd' 100

where Wd ¼ Original dry weight and WN ¼ Weight afterimmersed.

Morphology StudyStudies of the morphology of tensile fractured surfaces

for RPE=chitosan biocomposites were carried out by usinga scanning electron microscopy (SEM) model JOELJSM-6460LA. SEM was used to examine qualitatively thedispersion of chitosan in RPE matrix. The fracture endsof specimens were mounted on aluminium stubs and sput-ter coated with a thin layer of palladium to avoid electro-static charging during examination.

Differential Scanning Calorimetric (DSC)Thermal analysis measurements of selected systems were

performed using a Perkin Elmer DSC-7 analyzer. Samplesof about 10–25mg were heated from 20 to 250!C using a

nitrogen air flow of 50ml=min and the heating rate of20!C=min. The melting and crystallization behavior ofselected biocomposites were also performed using a PerkinElmer DSC-7 (USA). The crystallinity (Xcom) of biocom-posites was determined using the following relationship:

Xcomð%crystallinityÞ ¼ DHf=DH!f ' 100%

where DHf and DH!f are enthalpy of fusion of the system

and enthalpy of fusion of perfectly (100%) crystalline PE,respectively. For DH!

f (PE) a value of 285 J=g was usedfor 100% crystalline PE homopolymer.

RESULTS AND DISCUSSIONEffect Filler Loading on Mechanical PropertiesTensile Properties

Figure 1 shows the effect of filler loading on tensilestrength of RPE=chitosan biocomposites with and withoutMAPE and silane. The results indicates that the tensilestrength for both biocomposites increase with increasingof filler loading. The increasing of tensile strength showsthe effectiveness of compatibilizer and coupling agentand, in turn, improving stress transfer between filler andmatrix. Biocomposites incorporated with MAPE and silaneimproved the strength of biocomposites because they cre-ated more filler-matrix contact with the presence of compa-tibilizer and coupling agent and therefore increased thepotential for bonding. It was clear that, to improve reinfor-cing effect of filler, the presence of silane as coupling agentwas important. The application of coupling agent and com-patibilizer in RPE=chitosan biocomposites was used toovercome the dispersion problem and to enhance theproperties of biocomposites by improving adhesionbetween filler and matrix.

Figure 2 shows the effect of filler loading on elongationat break of RPE=chitosan biocomposites with and without

FIG. 1. The effect of filler loading on tensile strength of RPE=chitosanbiocomposites with and without MAPE and silane.


MAPE and silane. The result shows the drastic decrease ofelongation at break with increasing of filler loading. Atsimilar filler loading, compatibilized and treated biocom-posites exhibitedlower elongation at break than uncompa-tibilized and untreated biocomposites. This indicates thatcompatibilizer and coupling agent imparts a greater stiffen-ing effect to biocomposites.

Figure 3 shows the effect of filler loading on Young’smodulus of RPE=chitosan biocomposites with and withoutMAPE and silane. The increase in Young’s modulus wasattributed to the increased stiffness and brittleness of bio-composites due to addition of chitosan. The biocompositeswith MAPE and silane exhibit higher Young’s moduluscompared to biocomposites without MAPE and silane.Significant improvement was more for high chitosan load-ing. Thus, the biocomposites with MAPE and silane give

better properties than biocomposites without MAPE andsilane. The presence of MAPE and silane give betterfiller-matrix adhesion and stress transfer at the interface.MAPE and silane have modified the inherent poor com-patibility between thermoplastic and filler. It is suggestedthat the higher efficiency of maleated polyethylene wasdue to more available anhydride group for reaction withhydroxyl group of treated chitosan with silane, andwithlonger hydrocarbon chain that entangle more effectivelywith RPE matrix.

Water AbsorptionFigure 4 indicates the curves of the percentage of water

absorption versus time of RPE=chitosan biocompositeswith and without MAPE and silane at 0, 20 and 40 php.Figure 5 shows the equilibrium water absorption ofRPE=chitosan biocomposites with and without MAPEand silane at different filler loading. The percentage ofwater absorption increases with increasing of filler loading.At similar filler loading, the presence of MAPE and silanereduced the amount of water absorption. The reduction inwater absorption with MAPE and silane treatment wasattributed to improve interfacial adhesion which reducedwater from entering the biocomposites.

Morphological StudiesFigure 6 shows the scanning electron micrograph of

chitosan that indicates the irregular shape of chitosan suchas particulate, fiber and flake morphology. SEM micro-graphs of tensile fracture surface of RPE=chitosan biocom-posites with and without MAPE and silane for 20 and 40php are shown in Figures 7–10, respectively. SEM micro-graphs of tensile fracture surface of RPE=chitosan biocom-posites without MAPE and silane at 20 and 40 phpchitosan are shown in Figures 7 and 8. The biocompositeswith 20 php of chitosan show ductile morphology.

FIG. 2. The effect of filler loading on elongation at break of RPE=chitosan biocomposites with and without MAPE and silane.

FIG. 3. The effect of filler loading on Young’s Modulus of RPE=chitosan biocomposites with and without MAPE and silane.

FIG. 4. The percentage of water absorption versus time of RPE=chitosan biocompositeswith andwithoutMAPEand silane at 0, 20 and 40 php.


FIG. 5. The equilibrium of water absorption versus time of RPE=chitosan biocomposites with and without MAPE and silane.

FIG. 6. Scanning electron micrograph of chitosan at magnification1000X.

FIG. 7. The SEMmicrograph of tensile fracture surface of RPE=chitosanbiocomposites without MAPE and silane at 20 php at magnification 200X.

FIG. 8. The SEM micrograph of tensile fracture surface of RPE=chitosanbiocomposites without MAPE and silane at 40 php at magnification 200X.

FIG. 10. The SEMmicrograph of tensile fracture surface of RPE=chitosanbiocomposites with MAPE and silane at 40 php at magnification 200X.

FIG. 9. The SEM micrograph of tensile fracture surface of RPE=chitosanbiocomposites with MAPE and silane at 20 php at magnification 200X.


In Figure 7 chitosan is not well dispersed in matrix. Pooradhesion can causes cracks and voids between matrix andfiller. The morphology of biocomposite at 40 php exhibitsrough surface with the presence of less voids and cavities.This indicates that the chitosan have better dispersion inRPE matrix. SEM micrograph of tensile fracture surfaceof RPE=chitosan biocomposites with MAPE and silaneat 20 and 40 php at magnification 200X are illustrated inFigures 9 and 10. The SEM micrograph of biocompositeswith MAPE and silane clearly show the less pulled-outtraces from the matrix. This result clearly demonstratedthe treatment of biocomposites provides strong interfacialadhesion and good wetting, which consequently resultedin better adhesion between filler and matrix.

Thermal PropertiesFigure 11 shows the curves of RPE=chitosan biocompo-

sites with and without MAPE and silane at 20 php ofchitosan. The thermal parameter of DSC for biocompositeswith and withoutMAPE and silane at different filler loadingis shown in Table 5. It can be seen in Table 5 that the value ofDHf(com) and percent crystallinity increase with increasing offiller loading. The results show that the biocomposites withMAPE and silane exhibit higher value of enthalpy and crys-tallinity. This may be due to the silane treated of filler whichare display strong molecular interactions with the compati-bilizer in matrix. The slight increase in crystallinity wasprobably due to covalent adhesion between filler and matrixwith presence of MAPE and silane.

CONCLUSIONBiocomposites from chitosan and recycled polyethylene

were prepared. The presence of MAPE and silane in RPE=chitosan biocomposites enhanced the tensile strength,Young’s modulus and cystallinity but reduced the elonga-tion at break and water absorption of biocomposites.SEM micrograph study proved that biocomposites withMAPE and silane improved the adhesion between chitosanand RPE matrix.

ACKNOWLEDGMENTThis research was supported by Ministry of Higher

Educational (MOHE) for providing FundamentalResearch Grant Schemes (FRGS).

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TABLE 5DSC analysis of RPE=chitosan biocomposites with andwithout MAPE and silane at different filler loading

Sample Tm (!C)DHf(com)

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(% crystallinity)

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124 113.3 39.8

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124 144.3 50.6


123 164.7 57.8


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