Z. A. Mohd Ishak

The effect of lignin as a compatibilizer on the physical properties of coconut fiber-polypropylene composites

Lignin has been employed as a compatibilizer in the coconut fiber-polypropylene. The effect of lignin as a compatibilizer on mechanical properties has been studied. The study demonstrates that composites with lignin as a compatibilizer possess higher flexural properties as compared to the control composites. The results also show that tensile properties do not improve as lignin is incorporated. Scanning electron microcopy results (SEM) display some proof of an enhanced compatibility at the interfacial region. In addition to that, the results also exhibit evidence that size irregularities and fiber distribution may play a dominant role on the properties, which may surpass the effect of improved compatibility. Lignin is shown to reduce the water absorption and thickness swelling of the composites. Overall, composites with maleic anhydride-modified polypropylene (Epolene E-43) as a compatibilizer display greater mechanical properties than those with lignin.

Polypropylene–oil palm empty fruit bunch–glass fibre hybrid composites: a preliminary study on the flexural and tensile properties

Polypropylene (PP) hybrid composites were made using oil palm empty fruit bunch (EFB) and glass fibres (GF) as reinforcing agents in PP matrix. The incorporation of both fibres into PP matrix has resulted in the reduction of flexural and tensile strengths. Both flexural and tensile modulus have been improved with the increasing level of overall fibre content loading. Three types of coupling agents, i.e. maleic-anhydride-modified PP (commercial name Epolene, E-43), polymethylenepolyphenyl isocyanate (PMPPIC) and 3-(trimethoxysilyl)-propylmethacrylate (TPM), were attempted. Overall, E-43 and TPM had imparted considerable improvements in the flexural and tensile properties. However, only slight improvements in some cases were shown for those composites treated with PMPPIC.

Mechanical properties and enzymic degradation of thermoplastic and granular sago starch filled poly(ε-caprolactone)

The mechanical, morphological and biodegradation properties of two types of poly(e-caprolactone)/sago starch (PCL/sago) composites were investigated i.e. dried granulated sago starch and undried thermoplastic sago starch (TPSS). Thermoplastic starch was extruded with a twin screw extruder model Haake Rheomix (TW100 attached to a Haake Rheometer (Haake Rheodrive 5000). The composites were compounded with a Haake internal mixer (Haake Rheomix 3000) attached to the Haake Rheometer. Tensile properties were determined with the Monsanto Tensometer T10. A Shimadzu UV-160A visible UV spectrophotometer was used to monitor the liberation of carbohydrate as a consequence of starch hydrolysis by α-glucoamylase. Determining the weight loss of composites as well as the acid liberated from PCL also monitored biodegradation. The results indicate that dried granulated sago starch function better as fillers in terms of mechanical properties and the ease of biodegradation. However, TPSS imparted better yield strength to the composites. Poor wetting of starch accounts for the decreased mechanical properties at higher starch concentration as agglomeration occurs. While the rigid granular starch retained their shape in the composites, thermoplastic starch that is surrounded by microvoids is easily deformed due to plasticization.

Effect of silane‐based coupling agents and acrylic acid based compatibilizers on mechanical properties of oil palm empty fruit bunch filled high‐density polyethylene composites

The mechanical properties of composites consisting of high-density polyethylene (HDPE) and oil palm fibrous wastes—that is, empty fruit bunch (EFB)—have been investigated. Tensile modulus showed an increase, whereas tensile strength, elongation at break, and impact strength decreased with increasing filler loading. The strong tendency of EFB to exist in the form of fiber bundles and the poor filler–matrix interaction is believed to be responsible for the poor strength displayed by the composites. Attempts to improve these properties using two types of coupling agents, that is, 3-aminopropyltrimethoxysilane (3-APM) and 3-aminopropyltriethoxysilane (3-APE) and two types of compatibilizers, poly(propylene–acrylic acid) (PPAA) and poly(propylene–ethylene–acrylic acid), (PPEAA), are described. While almost all chemical treatments increased the stiffness of the composites, limited improvement has been observed in the case of tensile strength. This have been attributed to the presence of fiber bundles that remain intact even after several types of chemical treatment have been carried out. Thus, the role of EFB as reinforcing agent is not fully realized. Scanning electron microscopy (SEM) micrographs revealed that the main energy-absorbing mechanisms contributing towards toughness enhancement is through the fiber bundle pull-out process.

Oil palm wood flour reinforced epoxidized natural rubber composites : The effect of filler content and size

Abstract The effect of filler content and size on curing characteristics and mechanical properties of oil palm wood flour (OPWF) reinforced epoxidized natural rubber (ENR) composites has been studied. The cure (t90) and scorch times of all filler size decrease with increasing OPWF content. At any filler content, larger OPWF particle size show shorter t90 and scorch time. The torque values increase with an increase in fibre content and OPWF with smallest particle size shows the highest torque. Increasing OPWF content in ENR compound resulted in reduction of tensile strength and elongation at break but increased tensile modulus, tear strength and hardness. Again, the composites filled with smaller OPWF size showed higher tensile strength, tensile modulus and tear strength.

Effects of hygrothermal aging and a silane coupling agent on the tensile properties of injection molded short glass fiber reinforced poly(butylene terephthalate) composites

Abstract The hygrothermal and mechanical properties of injection molded poly(butylene terephthalate) (PBT) composites containing 10, 20 and 30 wt.% short glass fiber (SGF) has been investigated. The kinetics of moisture absorption was investigated by immersion of PBT and SGF–PBT specimens in water at three different temperatures, i.e. 60°C, 80°C and 100°C. A single free-phase model of diffusion, which assumed Fickian diffusion and utilized Ficks second law of diffusion was used in analysing the data. A good agreement was observed between the experimental and theoretical values. The equilibrium moisture content, Mm and the apparent diffusivity, D, were found to be dependent on the volume fraction of the fibers. DSC measurements revealed that the thermal behavior, viz. the melting point and the degree of crystallinity of PBT and SGF–PBT composites were affected by hygrothermal aging process. This was attributed to the changes in the microstructure of PBT due to its interactions with water molecules. Hygrothermal aging reduced the tensile properties of PBT, the effect of which is strongly dependant on factors such as water immersion temperatures, volume fractions of fibers and also the chemical treatment of SGF. The presence of 3-aminopropyltriethoxysilane (3-APE) coupling agent has improved the retention of tensile properties of SGF–PBT composites, especially under adverse hygrothermal condition. Failure modes of both the matrix and the composites, assessed by fractographic studies in a scanning electron microscope (SEM) are discussed.

Rubberwood–high-density polyethylene composites: Effect of filler size and coupling agents on mechanical properties

Composites were made from rubberwood in the form of fibers (RWF) and powder (RWP) and high-density polyethylene (HDPE). The RWP–HDPE composites showed higher tensile strength than those of the fibers. The inferior properties of the RWF-filled composites were believed to be attributed to the agglomeration of the fibers. Two types of coupling agents, that is, 3-(trimethoxysilyl)propyl methacrylate (TPM) and 3-aminopropyltriethoxysilane (APE), were employed in an attempt to improve the mechanical properties of the composites. The former was able to significantly improve the modulus of elasticity (MOE) and impact strength of the RWF-filled composites. Treatment with TPM resulted in the reduction of the tensile modulus and increase in the elongation at break (EB) for both RWF and RWP-filled composites. APE produced RWP-filled composites with a higher tensile strength and modulus.

Flexural and impact properties of oil palm empty fruit bunch (EFB)-polypropylene composites-the effect of maleic anhydride chemical modification of EFB

Abstract This study focused on the effect of chemical modification of oil palm empty fruit bunch (EFB) filler on the flexural and impact properties of EFB-filled polypropylene (PP) composites. EFB filler has been chemically modified with maleic anhydride (MAH). The modification involved the reaction of EFB and MAH (dissolved in dimethylformamide) at 90°C. The composites with MAH-treated EFB showed higher flexural and impact strength than those with untreated EFB. The modification had significantly improved the flexural modulus and toughness of the composites. This may be attributed to the enhanced adhesion between the MAH-treated EFB and PP matrix, as shown in the scanning electron microscopy (SEM) study. Fourier Transform Infra-Red analysis (FTIR) showed evidence of C=C and C=O groups from MAH at 1630cm−1 and 1730cm−1, respectively. The analysis also showed a reduction of absorption at 1630cm−1 for MAH modified EFB–PP composites which indicated the reaction of C=C from MAH with PP.

The effect of coupling agents on the mechanical and physical properties of oil palm empty fruit bunch-polypropylene composites

Oil palm empty fruit bunch–polypropylene (EFB-PP) composites have been produced using a twin-screw extruder as the compounding equipment. Two levels of EFB were employed, 40 % and 60 % of the total weight of the sample. Three types of coupling agent, maleic anhydride-modified polypropylene (commercial name Epolene E-43), polymethylene(polyphenyl isocyanate) (PMPPIC) and 3-(trimethoxysilyl)-propylmethacrylate (TPM), were used. Overall, all coupling agents imparted considerable improvements in the flexural properties, E-43 showing the highest enhancement. However, only E-43 was observed to improve impact strength and tensile properties of the composites. All composites with coupling agents showed lower water absorption and thickness swelling. The absorption and swelling decreased as the loading of the coupling agents was increased. © 2000 Society of Chemical Industry

Degradation studies and moisture uptake of sago-starch-filled linear low-density polyethylene composites

The degradation and moisture uptake of sago-starch-filled linear low-density polyethylene (LLDPE) composites have been studied. Enzymatic hydrolysis of the composites apparently involves surface starch granules; embedded granules are not easily accessible because of the poor moisture absorption or transmission property of the matrix. Exposure of the composites to weathering resulted in massive deterioration typified by turbidity, discoloration, embrittleness and dimensional changes. Soil burial led to a drop in the pH of the soil and the presence of holes on the samples, probably due to microbial activity. Furthermore, the drop in mechanical properties of the composites increased with time of burial for the first four months and decreased gradually thereafter. Moisture uptake increased with increased starch content and immersion time. The time taken for the composites to equilibrate was about three months even when they were immersed completely in water. The mechanical properties of the composite also dropped with increasing moisture uptake.