0892705715569822.full

Article

Green compositesfrom kapok husk andrecycled polypropylene:Processing torque,tensile, thermal, andmorphological properties

Koay Seong Chun, Salmah Husseinsyah andChan Ming Yeng

AbstractThe present work was developed to utilize kapok husk (KH) as filler in recycled poly-propylene (rPP) green composites. Stearic acid (SA) was used as surface modifier in rPP/KH composites. It was found that the modified KH with SA was reduced the stabilizationtorque of composites. The addition of KH in rPP decreased the tensile strength andelongation at break but increased tensile modulus of composites. The modified KH withSA improved the tensile strength, tensile modulus, crystallinity, and thermal stability ofcomposites. The scanning electron microscopic micrograph provd that the interfacialinteraction and adhesion was improved by SA modification.

KeywordsKapok husk, recycled polypropylene, composites, stearic acid, surface modifier

Introduction

In recent years, green composites have garnered interest among researchers and indus-

tries due to todays environmental issues and economic factor as well as the accumu-

lation of agricultural waste and by-product. Many agricultural waste and by-product such

as coconut shell,14 palm oil empty fruit bunch,5 groundnut shell,6 palm kernel shell,7

Division of Polymer Engineering, School of Materials Engineering, Jejawi, Perlis, Malaysia

Corresponding author:

Salmah Husseinsyah, Division of Polymer Engineering, School of Materials Engineering, Universiti Malaysia

Perlis, 02600 Jejawi, Perlis, Malaysia.

Email: [email protected]

Journal of Thermoplastic Composite

Materials

119

The Author(s) 2015Reprints and permissions:

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DOI: 10.1177/0892705715569822

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1

pineapple leaf,8 cocoa pod husk,9,10 and corn cob1113 have utilized as filler in com-

posite materials. Kapok (Ceiba pentandra) tree is heavily cultivated in Malaysiacountry purposely to obtain the kapok cotton and seed.14 In the kapok industry, kapok

cotton is used to fill pillows and mattress as well as the kapok seeds are processed to

obtain seed oil, which has similar properties to cotton seeds oil.14,15 However, kapok

husk (KH) became one of the by-products in kapok cotton industry.14 During har-

vesting of kapok pod (as shown in Figure 1), the KH become waste after removing the

kapok cotton and seeds. Commonly, the KH is readily abundant and do not have any

economic value. Therefore, KH has a potential use as inexpensive filler in thermo-

plastic materials. The utilization of KH in thermoplastic can also reduce the waste of

kapok industry.

Nowadays, various combinations of agricultural waste and thermoplastic material

have been successfully made into commercial products. In Malaysia, a series eco-

tableware was made from rice husk-filled thermoplastic eco-composites by Melsom

Biodegradable Enterprise, Malaysia.4 In our previous research, coconut shell powder or

corn cob was incorporated with polylactic acid to produce eco-packaging product3 and

eco-tableware.11 However, the incompatibility between natural filler and thermoplastic

material was a major issue in processing of natural filler-filled thermoplastic composites.

The interface incompatibility between hydrophilic nature of the natural filler and

hydrophobic nature of thermoplastic was hardly to produce good properties of compo-

sites. Usually, unmodified natural filler has poor dispersion, wettability, and adhesion

with thermoplastic material. In general, the good performance composites can be

achieved by filler modification via alkaline treatment,1618 esterification,1,3,9,13,1921

silane treatment,2,22,23 use of maleated polymer,10,2427 and other chemical.4,11 Besides,

fatty acid and its derivative can be also used as green coupling agent in natural filler

treatment as it acts asa coupling effect on the natural filler-based composites. Some

studies claimed that the use of stearic acid (SA) as coupling agent was able to improve

the properties of sisal fiber28,29 or coconut coil-30 reinforced composites.

In this research, the KH was combined with recycled polypropylene (rPP) to produce

green composites. The SA was used to modify KH in order to promote the dispersion as

well as enhance the properties of rPP/KH eco-composites. The effect of SA modification

on tensile, thermal and morphology properties of rPP/KH composites have been

investigated.

Methodology

Materials

The KH was obtained from Kapok Plantation, Perlis, Malaysia. The KH was dried in

oven at 80C for 24 h. Then, KH was crushed and ground into fine powder. The averageparticle size of KH was 28 mm, which is analyzed by Malvem Particle Size AnalyzerInstrument (Malaysia). The density of KH was 1.148 g cm3. The rPP was supplied byToray Plastics Sdn. Bhd (Malaysia). The SA and ethanol were supplied by Sigma

Aldrich (Penang, Malaysia).

2 Journal of Thermoplastic Composite Materials

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Filler modification

The SA was dissolved in ethanol with amount of 3% (w/v). The KH powder was added inSA solution and stirred with mechanical stirrer for 1 h and soaked it for overnight. The

modified KH was filtered and dried in oven at 80C for 24 h.

Preparation of composites samples

The rPP/KH composites were prepared by using Brabender1 Plastrograph (Germany)

internal mixer with counterrotating mode at 180C and 50 r min1 of rotor speed. TherPP/KH composites were mixed according to formulation in Table 1. Firstly, the rPP

was transferred into mixing chamber for 2 min until it fully melted. After that, KH

was added to melted rPP and mixed for 6 min. The total mixing time was 8 min. All

formulated rPP/KH composites were molded into sheet form with 1 mm thickness

using compression molding model GT 7014A at 180C. The compression sequencesinvolved preheat compound for 4 min, compression under pressure at 9.81 MPa for 1

min, and cooling under same pressure for 5 min. The rPP/KH composites sheet was

cut into tensile bar by using dumbbell cutter. Figure 2(a) and (b) shows the rPP/CPH

composites in form of sheet and tensile bar. The dimension of the tensile bar was

referring to ASTM D638 type IV.31

Table 1. Formulation of unmodified and modified rPP/KH composites.

Materials Unmodified rPP/KH Modified rPP/KH

rPP (wt%) 100, 90, 80, 70, 60 100, 90, 80, 70, 60KH (wt%) 0, 10, 20, 30, 40 0, 10, 20, 30, 40

rPP: recycled polypropylene; KH: kapok husk.

Figure 1. Dried kapok pod.

Chun et al. 3

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Processing torque measurement

The processing torque was measured during the compounding of composites using

Brabender Plastrograph internal mixer. The torque changes of compound with the time

were recorded and torques versus time curves were plotted by computer. The torque

values at the end of processing time were taken as stabilization torque.

Tensile testing

Tensile testing was performed using an Instron machine model 5566 (USA) according to

ASTM D638 standard.31 The test was carried out at 23+ 2C. A crosshead speed of 30mm min1 was used and the loading was 50 kN.

Morphology analysis

The tensile fracture surface of rPP/KH composites was analyzed using a scanning

electron microscope (model JEOL JSM-6460 LA, Japan). The samples were coated with

a thin layer of palladium for conductive purpose before analyzed.

FTIR spectroscopy

Fourier transform infrared (FTIR) analysis was conducted using FTIR spectroscopy,

Perkin Elmer, Waltham, Massachusetts, USA, model Paragon 1000, which equipped

with an attenuated total reflectance (ATF) device. FTIR was used to determine the

functional chemical groups of unmodified and modified KH. The samples were recorded

with 16 scans in the wavelength range 6004000 cm1 with resolution of 4 cm1.

Figure 2. rPP/KH composites in (a) sheet form and (b) tensile bar.rPP: recycled polypropylene; KH: kapok husk.


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DSC analysis

Differential scanning calorimetry (DSC) analysis was carried out using DSC Q10,

Research Instrument (USA). The sample was cut into small pieces and placed into closed

aluminum pan with sample weight in range 7 + 2 mg. The specimen was heated from30C to 200C with a heating rate of 10C min1 under nitrogen atmosphere. Thenitrogen gas flow rate was 50 ml min1. The degree of crystallinity of composite (Xc) canbe evaluated from DSC data by using equation (1).

Xc HfH0f

100; 1

where Hf is the heat fusion of the rPP composites, and H0f is the heat fusion for 100%

crystalline PP H0f 209 J g1

.4

The crystallinity of PP matrix (XrPP) was calculated using following equation (2),

where Wf rPP is the weight fraction of rPP matrix.

XrPP XcWf rPP

2

Thermogravimetric analysis

Thermogravimetric analysis (TGA) was evaluated using TGA Pyris Diamond Perki-

nElmer apparatus. The sample was about 7 + 2 mg in weight and was placed intoplatinum crucible. Then, the sample was heated from 30C to 700C at a heating rate of10C min1 under nitrogen atmosphere with the nitrogen flow rate of 50 ml min1.

Results and discussion

Processing torque

Figure 3 shows the processing torque versus times curves for the unmodified and

modified rPP/KH composites with different filler content. The first processing torque

increased rapidly due to the shearing action from the solid rPP pellets. The processing

torque was followed by a gradual reduced indicates the decrease of viscosity as rPP

pellets molten by the high temperature and continuous shear. The second torque

development can be found at time after 2 min. This caused by the addition of the KH into

molten rPP. The processing torque decreased gradually and the stabilization torque

achieved after the rPP/CH in homogenized mixture. The similar trend on processing

torque was also found in previous study.9,10 From Figure 4, the stabilization torque was

increased with the increasing of KH content. This due to the fact of the presence of

dispersive resistance from KH particles increased the viscosity of rPP especially at high

filler content. However, the stabilization torque of modified rPP/KH composites lowers

as compared to unmodified rPP/KH composites. This is because the modified KH shows

lower dispersive resistance due to the SA attached on the filler surface separated each

KH particles from agglomeration and promoted the organophilic behavior to KH

Chun et al. 5

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particles (as shown in Figure 5). The unmodified KH was easily to agglomerate to each

other through the hydrogen bonding and contributed high dispersive resistance. There-

fore, modified KH was well dispersed in molten rPP, resulting in modified rPP/KH

composites with lower viscosity than unmodified rPP/KH composites.

Figure 3. Processing torque versus time curves of unmodified and modified rPP/KH compositeswith different filler content.rPP: recycled polypropylene; KH: kapok husk.

Figure 4. Stabilization torque of unmodified and modified rPP/KH composites with different fillercontent.rPP: recycled polypropylene; KH: kapok husk.


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Tensile properties

The effect of filler content on tensile strength of unmodified and modified rPP/KH

composites is shown in Figure 6. The incorporation of KH decreased the tensile strength

of both composites. A similar trend was found in our previous work.4 Besides, the poor

wettability between hydrophilic filler and matrix was usually contributed to poor dis-

persion and weak fillermatrix adhesion. This due to hydrophobic rPP was hardly to wet

Figure 5. The reduction of KH agglomeration after filler modification with SA.KH: kapok husk; SA: stearic acid.

Figure 6. Effect of filler content on tensile strength of unmodified and modified rPP/KH composites.rPP: recycled polypropylene; KH: kapok husk.

Chun et al. 7

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the unmodified KH during the compounding by penetrating crevices on KH surface,

which lead to weak interfacial bonding and interfacial voids (as shown in Figure 7(a)).

Therefore, the efficiency of stress transfer was reduced in the presence of weak inter-

facial bonding and voids. As a result, the tensile strength of composites decreased. On

the other hand, modified KH had long alkyl chains (from SA) covalent bonded on its

surface, leading to increase the wettability with rPP matrix and it enhanced the interfacial

bonding with greater surface interlocking as illustrated in Figure 7(b). At 40 wt% of fillercontent, the tensile strength of modified rPP/KH composites with SA (17.95 MPa) was

slightly higher than modified rPP/coconut shell powder (CSP) composite with sodium

dodecyl sulfate (SDS, 17.02 MPa) as found in previous study.4

Figure 8 shows the elongation at break of unmodified and modified rPP/KH com-

posites. It can be seen that the elongation at break decreased when the KH was added.

The presence of KH reduced the polymer chain flexibility induced to more rigid and

brittle composites. This was a commons trend that also found in our previous work and

other researchers.14,7,22,25 Nevertheless, filler modification had decreased the elonga-

tion at break of rPP/KH composites. As discussed before, the modified KH had better

interfacial bonding with rPP matrix, resulting in the ductility of rPP/KH composites was

decreased by the strong interfacial bonding. Modified rPP composites with KH or CSP4

exhibited lower elongation at break compared to unmodified rPP composites.

However, the increasing of KH content increased the tensile modulus of unmodified

and modified rPP/KH composites was displayed in Figure 9. This is attributed by the

friction between KH particles and rPP matrix generated a rigid interface, which inhibited

the polymer chain mobility. Chun et al.9 also report that the increased of the filler content

increased the tensile modulus of polypropylene/cocoa pod husk eco-composites. As the

Figure 7. (a) Unmodified rPP/KH eco-composites with poor wettability due to rPP matrix unableto penetrate the asperities on KH surface and (b) modified rPP/KH composites with good inter-facial interlocking.rPP: recycled polypropylene; KH: kapok husk.


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friction area increased with increases of filler content, the stiffness of eco-composites

also increased. Moreover, the stiffness of modified rPP/KH composites is higher than

unmodified rPP/KH composites. This might be due to the improvement of fillermatrix

interaction with SA modification. At similar filler content, the modified rPP/KH

Figure 8. Effect of filler content on elongation at break of unmodified and modified rPP/KH com-posites.rPP: recycled polypropylene; KH: kapok husk.

Figure 9. Effect of filler content on tensile modulus of unmodified and modified rPP/KH composites.rPP: recycled polypropylene; KH: kapok husk.

Chun et al. 9

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composites with SA has 20% lower tensile modulus compared with modified rPP/CSPcomposites with SDS as reported in previous study.4

The relationship between filler modification and interfacial adhesion can be

expressed quantitatively by using Pukanszkys model.32 The model (equation (3))

included the three important factors affecting the tensile strength of composites as fol-

lowing: (i) n is the change of specimen dimensions during the deformation and the raiseof tensile strength due to strain hardening; (ii) 1 = 1 2:5 is the effect ofreducing load bearing cross section of matrix due to addition of filler; and (iii) exp (B)represented the interfacial adhesion.32,33

T T0n 1 1 2:5 exp B ; 3

where T and T0 represent the true strength of the composite and the polymer matrix,respectively (T , where is the measured engineering tensile strength), is relativeelongation ( L/L0, where L0 is the original length and L is length at the failure point), nis related to strain hardening exponent of polymer matrix, is the volume fraction of filler,and B is a parameter expresses the load-bearing capacity of filler, which is related to the

effect of interfacial adhesion. Equation (4) can be rewritten and expressed in linear form:

ln Tred lnTn

1 2:51 ln T0 B 4

The graph of ln-reduced tensile strength (Tred) versus filler content will give astraight line with a slope of parameter B. The plot of ln Tred as function of filler contentof unmodified and modified rPP/KH composites is displayed in Figure 10. The results

show a two straight linear correction line. This means that the parameter B related to

interfacial adhesion and stress transfer can be measured with more accuracy. The slope

of line represent unmodified and modified rPP/KH composites was different, where the

parameter B of modified rPP/KH composites (2.85) was higher compared to unmodified

rPP/KH composites (2.29). This indicates the adhesion between KH and rPP matrix was

improved due to the filler modification using SA. Thus, the stress transfer at the inter-

facial region was enhanced, which result in a significant increase of the tensile strength.

Morphological properties

Figure 11(a) and (b) shows the scanning electron microscopic (SEM) micrograph of

tensile fracture surface of unmodified rPP/KH composites with 20 wt% and 40 wt% offiller content. Regarding the SEM micrograph, there are discontinuouss phase presence

between KH particles and rPP matrix. This indicates the poor wetting between

hydrophilic filler and hydrophobic matrix. There were numerous voids caused by filler

pull-out from matrix. This proves that the poor interfacial adhesion occurred in

unmodified rPP/KH composites. The SEM micrograph of modified rPP/KH compo-

sites in Figure 12(a) and (b) exhibited better wettability and adhesion between KH

filler and rPP matrix.


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FTIR analysis

The FTIR spectra of unmodified and modified KH are shown in Figure 13. The

characteristic peaks of unmodified and modified KH were summarized in Table 2. The

broad peak at 30003800 cm1 was attributed by the hydroxyl groups (OH) of KH.According to Table 3, the peak intensity of the OH groups absorption band was

significantly reduced after KH modified with SA. This means that the hydrophilicity of

KH was reduced while the OH groups react with SA. The peak intensity at 2920 cm1

Figure 10. Reduced tensile strength of unmodified and modified rPP/KH composites plottedagainst filler content.rPP: recycled polypropylene; KH: kapok husk.

Figure 11. SEM micrographs of unmodified rPP/KH composites with (a) 20 wt%, and (b) 40 wt%filler content.SEM: scanning electron microscopic; rPP: recycled polypropylene; KH: kapok husk.

Chun et al. 11

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and 2850 cm1 were also increased after the KH modified with SA. The change of peakintensity at 28002950 cm1 was assigned to the CH groups of long alkyl chain from SA,which chemically bonded on KH surface. Furthermore, the increase of peak intensity at

1724 cm1 indicated the presence of ester bonding (CO) occur between SA and KH. Theproposed schematic reaction between SA and KH is illustrated in Figure 14.

Figure 12. SEM micrographs of modified rPP/KH composites with (a) 20 wt%, and (b) 40 wt%filler content.SEM: scanning electron microscopic; rPP: recycled polypropylene; KH: kapok husk.

Figure 13. FTIR curves of unmodified and modified rPP/KH composites.FTIR: Fourier transform infrared; rPP: recycled polypropylene; KH: kapok husk.


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Thermogravimetric analysis

The derivative TG and TGA curves of neat rPP, unmodified, and modified rPP/KH

composites are illustrated in Figures 15 and 16, respectively. The TGA data of samples

was summarized in Table 4. Figure 12 shows that the neat rPP was decomposed in single

step at temperature 250500C. The unmodified and modified rPP/KH compositesdecomposed in the following three steps: (i) loss of moisture at temperature 30150C,

Table 2. The functional groups of kapok husk.

Wave Number (cm1) Compounds

30003800 Hydroxyl (OH) groups from cellulose, hemicellulose, and lignin34

2921, 2850 CH streching34

1724 Carboxyl group (CO) steching in acetyl group in hemicelluloseor ester linkage of carboxylic group35

1609 CC stretching from hemicellulose41420 CH2 groups deformation from cellulose or CH deformation in lignin

36

13801320 CH groups deformation in cellulose and hemicellulose37

1252 CO groups from acetyl group in lignin13

1161 COC groups of cellulose and hemicellulose9,10

10001150 COC and CO groups from main carbohydrates of celluloseand lignin38

700900 CH vibration in lignin13

Table 3. The major spectra of modified KH with SA.

Frequency (cm1) Type of bonding Intensity (%)

3328 OH bonding Decreased (4.9)2920 CH streching Increased (2.2)2850 CH streching Increased (2.3)1724 CO ester bonding Increased (3.4)

KH: kapok husk; SA: stearic acid.

Figure 14. Proposed schematic reaction between KH and SA.KH: kapok husk; SA: stearic acid.

Chun et al. 13

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(ii) decompose of hemicellulose at temperature 200350C, and (iii) decompose oflignocellulose at temperature 350400C and along with decompose of rPP matrix. Theweight loss of rPP/KH eco-composites at 100C was increased with the increase of KHcontent. This is assigned to the increase of moisture content as KH content increased.

However, the moisture content of composites was decreased with the SA modification.

Figure 15. DTG curves of unmodified and modified rPP/KH composites.DTG: derivative thermogravimetric; rPP: recycled polypropylene; KH: kapok husk.

Figure 16. TGA curves of unmodified and modified rPP/KH composites.TGA: thermogravimetric analysis; rPP: recycled polypropylene; KH: kapok husk.


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An early thermal decomposition of unmodified and modified of rPP/KH composites can

be found around temperature 300C. This weight loss at temperature 300C was refer-ring to the weight loss of decomposed hemicellulose. Therefore, the weight loss at 300Cincreased at more KH content. The decomposition temperature at maximum rate (Tdmax)

of neat rPP was found to be at 412C. The Tdmax was shifted to higher temperature withincreased residue at 700C as the content of KH increased. This indicated that theaddition of KH increased the thermal stability of rPP matrix at higher temperature. It can

also be explained by the presence of high thermal stability pyrolysis product from early

thermal decomposition, given rPP matrix a thermal protecting layer and delay the

thermal decomposition. This statement was agreed by other researchers.13 In addition,

the modified rPP/KH composites showed better thermal stability than unmodified rPP/

KH composites. It can be observed that from the decrease of weight loss at 300C, Tdmaxand residual at 700C increases. This might be due to the improvement of filler dis-persion and fillermatrix interaction. According to Koay et al.,4 the modified CSP with

SDS has improved the thermal stability of rPP composites.

Differential scanning calorimetry

The DSC curves of unmodified and modified rPP/KH composites are shown in

Figure 17. The DSC data of both composites are summarized in Table 5. The increase

of KH content decreased the crystallinity (Xc) of rPP/KH composites. However, the

XrPP of composites was slightly increased at 20 wt% of KH content. This is because ofnucleating effect of natural filler. Similar results are also reported by other research-

ers.9,10 At 40 wt% of filler content, an endothermic peak 50120C can be observeddue to the evaporation of the moisture in KH. The presence of moisture probably forms

hydrogen bonding among the KH particles and it influences adhesion with rPP matrix.

As mentioned early, the KH tends to form agglomeration at higher filler content. Thus,

the results show the addition of more KH hindered the crystallization of the rPP matrix,

especially at 40 wt% of KH content. The decrease of XrPP is probably due to the poorfiller dispersion and poor adhesion between unmodified KH and rPP matrix. Most of

the literatures reported that the crystallinity of composites usually affected by filler

Table 4. TGA data of unmodified and modified rPP/KH composites.

SampleWeight lossat 100C (%)

Weight lossat 300C (%) Tdmax (

oC)Residue at700C (%)

Neat rPP 0.03 6.89 412 0.22rPP/KH: 80/20 (unmodified) 1.72 8.52 422 3.11rPP/KH: 60/40 (unmodified) 3.65 13.76 444 8.09rPP/KH: 80/20 (modified) 0.91 7.62 433 4.64rPP/KH: 60/40 (modified) 2.06 12.75 447 10.23

TGA: thermogravimetric analysis; rPP: recycled polypropylene; KH: kapok husk; Tdmax: maximum

decomposition temperature.

Chun et al. 15

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content, filler dispersion, and fillermatrix interaction.1,4,7,2123 However, the modi-

fied rPP/KH composites exhibited higher crystallinity than unmodified rPP/KH

composites (Table 5). The hydrophilicity of KH has reduced after the modification

with SA, which improves the filler dispersion and adhesion at interface between KH

and rPP matrix. The improvement of interfacial adhesion enhanced the migration and

diffusion of rPP chain to form crystalline structure. Moreover, a better filler dispersion

provided more nucleating site for initiation of spherulites growth. Thus, modified KH

showed nucleating effect on the rPP/KH composites. The results show the melting

temperature (Tm) of rPP/KH composites remains unchanged with the increasing of KH

content or filler modification. In general, the Tm of semi-crystallinity polymer

increased with increase of crystallinity due to the larger spherulites size.39 The addition

of particulate filler often increases crystallinity of semi-crystalline polymer by

Figure 17. DSC curves of unmodified and modified rPP/KH composites.DSC: differential scanning calorimetry; rPP: recycled polypropylene; KH: kapok husk.

Table 5. DSC data of unmodified and modified rPP/KH composites.

Sample Tm (oC) Xc (%) XrPP (%)

Neat rPP 163 43 43.0rPP/KH: 80/20 (unmodified) 163 38 47.5rPP/KH: 60/40 (unmodified) 163 16 26.7rPP/KH: 80/20 (modified) 163 43 53.8rPP/KH: 60/40 (modified) 162 25 41.7

DSC: differential scanning calorimetry; rPP: recycled polypropylene; KH: kapok husk; Tdmax: maximum

decomposition temperature; Tm: melting temperature; Xc: degree of crystallinity; XrPP: crystallinity of

polypropylene matrix.


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increasing the number of spherulites, but the size of spherulites is smaller.40,41 As a

result the Tm of composites might not significantly change by filler content or filler

modification.42,43

Conclusion

The addition of KH in rPP composites showed higher stabilization torque. However,

filler modification with SA reduced the dispersive resistance of KH particles resulting in

lower stabilization torque compared to unmodified rPP/KH composites. The increase of

KH content decreased the tensile strength and elongation at break, but it increased the

tensile modulus rPP/KH composites. The modified rPP/KH composites have higher

tensile strength and modulus compared with unmodified rPP/KH composites. The

modified rPP/KH shows higher tensile strength but lowers tensile modulus compared to

modified rPP/CSP composites. The thermal stability of rPP/KH composites improved

with presence of KH as the Tdmax and residual at 700C increase. The thermal stability of

rPP/KH composites was further enhanced by SA treatment. The crystallinity of rPP/KH

composites decreased with increasing of the KH content. The filler modification wit SA

improved the nucleating effect of KH and increased the crystallinity of rPP/KH com-

posites. The improvement of tensile and thermal properties due to the enhanced inter-

facial bonding between KH and rPP matrix is proved by SEM micrograph. The

development of such green composites in this study can be used as a material in pro-

ducing injection-molded furniture.

Funding

This research received no specific grant from any funding agency in the public, commer-

cial, or not-for-profit sectors.

References

1. Chun KS, Husseinsyah S and Osman H. Mechanical and thermal properties of coconut shell

powder filled polylactic acid biocomposites: effect of the filler content and silane coupling

agent. J Polym Res 2012; 19: 18.

2. Salmah H, Koay SC and Hakimah O. Surface modification of coconut shell powder filled

polylactic acid biocomposites. J Thermoplast Compos Mater 2013; 26: 809819.

3. Chun KS, Husseinsyah S and Osman H. Properties of coconut shell powder-filled polylactic

acid ecocomposites: effect of maleic acid. Polym Eng Sci 2013; 53: 11091116.

4. Chun KS, Husseinsyah S and Azizi FN. Characterization and properties of recycled polypro-

pylene/coconut shell powder composites: effect of sodium dodecyl sulphate modification.

Polym Plast Technol Eng 2013; 52: 287294.

5. Ibrahim NA, Hashim N, Rahman MZA, et al. Mechanical properties and morphology of oil

palm empty fruit bunch-polypropylene composites: effect of adding ENGAGETM7467.

J Thermoplast Compos Mater 2011; 24: 713732.

6. Ishidi EY, Adamu IK, Kolawale EG, et al. Flammability and thermal characteristic of alkaline

aqueous solution treated groundnut shell-HDPE composites. J Thermoplast Compos Mater

2011; 24: 875888.

Chun et al. 17

17

7. Hussiensyah S, Chun KS, Hadi A, et al. Effect of filler loading and coconut oil coupling agent

on properties of low-density polyethylene and palm kernel shell eco-composites. J Vinyl Addit

Technol. Epub ahead of print 29 July 2014. DOI: 10.1002/vnl.21423.

8. Smitthipong W, Tantatherdtam R and Chollakup R. Effect of pineapple leaf fiber-reinforced

thermoplastic starch/poly(lactic acid) green composite: mechanical, viscosity, and water resis-

tance properties. J Thermoplast Compos Mater. Epub ahead of print 18 June 2013. DOI: 10.

1177/0892705713489701.

9. Chun KS, Husseinsyah S and Osman H. Modified cocoa pod husk-filled polypropylene com-

posites by using methacrylic acid. BioResources 2013; 8: 32603275.

10. Koay SC, Salmah H and Hakimah H. Ultilization of cocoa pod husk as filler in polypropylene

biocomposites: effect of maleated polypropylene. J Thermoplast Compos Mater. Epub ahead

of print 26 November 2013. DOI: 10.1177/0892705713513291.

11. Chun KS and Husseinsyah S. Polylactic acid/corn cob eco-composites: effect of new organic

coupling agent. J Thermoplast Compos Mater. 2014; 27: 16671678.

12. Yeng CM, Husseinsyah S and Ting SS. Chitosan/corn cob biocomposite films by cross-linking

with glutaraldehyde. BioResources 2013; 2: 29102923.

13. Yeng CM, Husseinsyah S and Ting SS. Modified corn cob filled chitosan biocomposite films.

Polym Plast Technol Eng 2013; 52: 14961502.

14. Husseinsyah S, Yeng CM, Kassim AR, et al. Kapok husk-reinforced soy protein isolate bio-

films: tensile properties and enzymatic hydrolysis. BioResources 2014; 9: 56365651.

15. Broad N. Modern technology of oils, fats & its derivatives. Delhi: Asia Pacific Business Press,

2002.

16. Jacob M, Jospeh S, Prothan LA, et al. A study of advances in charaterization of interfaces and

fiber surfaces in lignocellulosic fiber-reinforced composites. Compos Interfaces 2005; 112:

95124.

17. Pothan LA, George J and Thomas S. Effect of fiber surface treatments on the fiber-matrix

interaction in banana fiber reinforced polyester composites. Compos Interfaces 2002; 9:

335352.

18. Gwon JG, Lee S, Chun SJ, et al. Effect of chemical treatment of hybrid fillers on the physical

and thermal properties of wood plastic composites. Compos A 2010; 42: 14911497.

19. Zhang Y, Xue Y, Toghiani H, et al. Modification of wood flour surfaces by esterification with

acid chlorides: use in HDPE/wood flour composites. Compos Interfaces 2009; 16: 671686.

20. Ismail SH and Abu Bakar A. The effect of chemical modification of paper sludge filled poly-

propylene (PP)/ethylene propylene diene terpolymer (EPDM) composites. J Reinforc Plast

Compos 2006; 25: 4358.

21. Salmah H, Faisal A and Kamarudin H. The mechanical and thermal properties of chitosan

filled polypropylene composites: the effect of acrylic acid. J Vinyl Addit Technol 2011; 17:

125131.

22. Ismail SH and Abu Bakar A. Properties of paper sludge filled polypropylene (PP)/ethylene

propylene diene terpolymer (EPDM) composites: the effect of silane-based coupling agent.

Int J Polym Mater 2006; 55: 643662.

23. Salmah H, Faisal A and Kamaruddin H. Chemical modification of chitosan filled polypropy-

lene composites: the effect 3-aminopropyltriethoxysilane on mechanical and thermal proper-

ties. Int J Polym Mater 2011; 60: 429440.

24. Sameni JK, Ahmad SH and Zakaria S. Performance of rubberwood fiber-thermoplastic natural

rubber composites. Polym Plast Technol Eng 2003; 42: 139152.

25. Vineta S, Gordana BG, Maurizio A, et al. Utilization of recycled polypropylene for production

of eco-composites. Polym Plast Technol Eng 2009; 48: 11131120.


18

26. Salmah H and Ismail H. The effect of filler loading and maleated polypropylene on properties

of rubber wood filled polypropylene/natural rubber composites. J Reinforc Plast Compos

2008; 27: 18671876.

27. Husseinsyah S, Azmin AN and Ismail H. Effect of maleic anhydride-grafted-polyethylene

(MAPE) and silane on properties of recycled polyethylene/chitosan biocomposites. Polym

Plast Technol Eng 2013; 52: 168174.

28. Kalaprasad G, Francis B, Thomas S, et al. Effect of fibre length and chemical modification on

the tensile properties of intimately mixed short sisal/glass hybrid fibre reinforced low density

polyethylene composites. Polym Int 2004; 53: 16241638.

29. Torres FG and Ubillas ML. Study of the interfacial properties of natural fibre reinforced

polyethylene. Polym Test 2005; 24: 694698.

30. Enriquez JKEDV, Santiago PJM, Ong TF, et al. Frabication and charaterization of high-

density polyethylene-coconut coir composites with stearic acid as compatibilizer. J Thermo-

plast Compos Mater 2010; 23: 361373.

31. ASTM Standard D638. Standard test method for tensile properties of plastics. West Consho-

hocken: ASTM International, 2010. DOI: 10.1520/D0638-10.

32. Pukanszky B. Influence of interface interaction on the ultimate tensile properties of polymer

composites. Composites 1990; 21: 255262.

33. Danyadi L, Renner K, Moczo J, et al. Wood flour filled polypropylene composites: interfacial

adhesion and micromechanical deformations. Polym Eng Sci 2007; 47: 12461255.

34. Khalil HPSA, Ismail H, Rozman HD, et al. The effect of acetylation on interfacial shear

strength between plant fiber and various matrices. Eur Polym J 2001; 37: 10371045.

35. Alemdar A and Sain M. Isolation and characterization of nanofibers from agricultural

residues-wheat straw and soy hulls. Biores Technol 2008; 99: 16641671.

36. Sgriccia MC, Hawley MC and Misra M. Characterization of natural fiber surfaces and natural

fiber composites. Compos A 2008; 39: 16321637.

37. Troedec ML, Sedan D, Peyratout C, et al. Influence of various chemical treatments on the

composition and structure of hemp fibres. Compos A 2008; 39: 514522.

38. Nacos MK, Katapodis P, Pappas C, et al. Kenaf xylan a source of biologically active acidic

oligosaccharides. Carbohyd Polym 2006; 66: 126134.

39. Daniels CA. Polymers: structure and properties. Lancaster: CRC Press, 1989.

40. Ning N, Fu S, Zhang W, et al. Realizing the enhancement of interfacial interaction in semi-

crystalline polymer/filler composites via interfacial crystallization. Prog Polym Sci 2012;

37: 14251455.

41. Ning N, Yin Q, Luo F, et al. Crystallization behavior and mechanical properties of polypro-

pylene/halloysite composites. Polymer 2007; 48: 73747384.

42. Mattos BD, Misso AL, Cadematartori PHG, et al. Properties of polypropylene composites

filled with a mixture of household waste of mate-tea and wood particles. Constr Build Mater

2014; 61: 6068.

43. Parparita E, Darie RN, Popescu CM, et al. Structuremorphologymechanical properties rela-

tionship of some polypylene/lignocellulosic composites. Mater Des 2014; 56: 763772.

Chun et al. 19

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