R. Mat Taib

Effects of PE-g-MA on Tensile Properties, Morphology and Water Absorption of LDPE/Thermoplastic Sago Starch Blends

Effects of polyethylene-grafted maleic anhydride (PE-g-MA) on tensile properties, morphology and water absorption of LDPE/ Thermoplastic sago starch (TPSS) blends were studied. TPSS was prepared by mixing starch (65 wt. %) and glycerol (35 wt. %) and stored overnight at room temperature. The mixture then was melt-compounded using a heated 2 roll-mills at 150°C for 10 minutes. LDPE/TPSS blends with different TPSS loadings, with and without the addition of PE-g-MA were prepared by using a Haake Rheomix mixer at 150°C. All mixing were carried out for 10 minutes at a rotor speed of 50 rpm. Tensile test specimens were cut out from the compression molded sheets. Results indicated that the mixing torque of LDPE/TPSS blends reduced with increasing TPSS loading. The tensile strength and elongation at break of LDPE/TPSS/PE-g-MA blends were greater than LDPE/TPSS blends particularly at higher TPSS loadings. The interfacial properties between LDPE and TPSS were improved after PE-g-MA addition as evident from the tensile fracture surface morphology using a scanning electron microscopy. Chemical functional groups formed after the addition PE-g-MA were studied with FTIR. Equilibrium water uptakes for LDPE/TPSS/PE-g-MA blends were higher than those of LDPE/TPSS blends.

Mechanical, Thermal and Water Absorption Properties of Kenaf-Fiber-Based Polypropylene and Poly(Butylene Succinate) Composites

The use of composites made from non-biodegradable conventional plastic materials (e.g., polypropylene, PP) is creating global environmental concern. Biodegradable plastics such as poly(butylene succinate) (PBS) are sought after to reduce plastic waste accumulation. Unfortunately, these types of plastics are very costly; therefore, natural lignocellulosic fibers are incorporated to reduce the cost. Kenaf fibers are also incorporated into PP and PBS for reinforcing purposes and they have low densities, high specific properties and renewable sourcing. However without good compatibilization, the interfacial adhesion between the matrix and the fibers is poor due to differences in polarity between the two materials. Maleic anhydride-grafted compatibilizers may be introduced into the system to improve the matrix-fiber interactions. The overall mechanical, thermal and water absorption properties of PP and PBS composites prepared with 30 vol.% short kenaf fibers (KFs) using a twin-screw extruder were being investigated in this study. The flexural properties for both types of composites were enhanced by the addition of compatibilizer, with improvements of 56 and 16xa0% in flexural strength for the PP/KF and PBS/KF composites, respectively. Good matrix-fiber adhesion was also observed by scanning electron microscopy. However, the thermal stability of the PBS/KF composites was lower than that of the PP/KF composites. This result was confirmed by both DSC and TGA thermal analysis tests. The water absorption at equilibrium of a PBS composite filled with KFs is inherently lower than of a PP/KF composite because the water molecules more readily penetrate the PP composites through existing voids between the fibers and the matrix. Based on this research, it can be concluded that PBS/KF composites are good candidates for replacing PP/KF composites in applications whereby biodegradability is essential and no extreme thermal and moisture exposures are required.

Mechanical and Morphological Properties of Polylactic Acid/Kenaf Bast Fiber Composites Toughened with an Impact Modifier

Polylactic acid (PLA)/kenaf bast fiber (KF) composites were prepared with different amounts (0 to 40 wt%) of ethylene acrylate copolymer impact modifier (IM). With increasing IM content, the impact strength and elongation at break of the composites improved but an opposite trend was observed for the tensile strength and modulus. Addition of IM resulted in the formation of ductile or flexible interface between the PLA matrix and KF as confirmed by scanning electron microscopy examination on the composite fractured surfaces. Deformability of the PLA matrix was also improved. Mechanisms for the morphology-property relationships of the composites were discussed.

The Effects of Natural Weathering on the Properties of Linear Density Polyethylene (LDPE)/Thermoplastic Sago Starch (TPSS) Blends

Linear density polyethylene (LDPE)/thermoplastic sago starch (TPSS) blends with and without the addition of compatibilizer (Polyethylene-grafted-Maleic Anhydride, PE-g-MA), with different TPSS loadings (10, 20, 30, 40 and 50 wt.%) were prepared. These blends were subjected to a natural weathering condition which was tropical climate in Penang, Malaysia, for 3 and 6 months. Results of mechanical tests showed that with an increase of weathering time, the tensile strength and elongation at break decreased for both uncompatibilized and compatibilized blends. But the Young modulus increased during 3 months and 6 months of exposure. With the increase of TPSS loading, tensile strength and elongation at break were also decreased. The Young modulus however increased with the increase in TPSS loading. Scanning electron microscopy (SEM) on blends surfaces after weathering showed that the degradability increased with the increase of TPSS loading as well as exposure time. This explained the reduction in tensile strength and elongation at break after weathering. Fourier transform infrared spectroscopy results on the blends after exposure to natural weathering indicated the presence of carbonyl, vinyl, and hydroxyl groups, which formed from various chemical reactions taking place during weathering.

Effect of Immersion Time in Water on the Tensile Properties of Acetylated Steam-exploded Acacia mangium Fibers-Filled Polyethylene Composites

Composites of high-density polyethylene and acetylated steam-exploded Acacia mangium fibers are immersed in water at room temperature for 30 days and tested for tensile properties after 2, 4, and 6 days of immersion. All composites absorb water but the water uptake decreases with increasing weight percent gain (WPG) of the acetylated fibers (AAEF). Immersion time has negative effect on the tensile properties and the impact is lesser for composites filled with AAEF of higher WPG. Tensile modulus decreases linearly (R 2=0.80) with water uptake. Acetylation does not improve fiber—matrix interaction but reduces the amount of water absorbed by the composite systems.

Mechanical, Water Absorption and Dimensional Stability Studies of Kenaf Bast Fibre-Filled Poly(butylene succinate) Composites

The effects of fibre loadings (10−40 wt.%) on mechanical properties, water absorption and dimensional stability of poly(butylene succinate)-filled kenaf bast fibre composites were investigated. The flexural strength and modulus of the composites increased with increasing fibre loading, while the impact strength of the composites decreased with increasing fibre loading. The higher the KBF loading was the higher absorption rate, equilibrium moisture content and the poorer dimensional stability of the composites. The poor retention and recovery of the composites from effect of water absorption were reflected by the poor flexural properties of the wet and re-dried composites after exposed to 90 days water immersion.

Effect of Moisture Absorption on the Tensile Properties of Steam-exploded Acacia mangium Fiber–Polypropylene osites

Polypropylene-filled alkali-extracted steam-exploded Acacia mangium fiber (AEF–PP) composites are immersed in water at room temperature for three months. All composites, including those with maleated polypropylene (MAPP) are found to absorb water considerably. The results of tensile properties indicate that the properties deteriorate following water absorption. The addition of MAPP to the composite systems (AEF–PP–MAPP) does not help in retaining the tensile properties. Scanning electron microscopy (SEM) examinations of the fracture surfaces of AEF–PP–MAPP composites reveal degradation of interfacial interaction. The composites, however, recover more than 90% of the tensile properties after oven treatment probably due to recovery of interfacial interaction as evident in scanning electron micrographs. The tensile properties recoveries for AEF–PP composites are fewer than for those with MAPP. Permanent damages in composite structures due to water absorption might account for this result.

Effect of Acetylation and MAPE on the Properties of Steam-Exploded Acacia mangium Fiber—HDPE Composites

Composites of high-density polyethylene (HDPE) and alkali-extracted steam-exploded Acacia mangium fiber (AEF) were prepared using 2-roll mill and compression molding. AEF was acetylated (AAEF) to three different wt% gains (WPG) and maleic anhydride grafted polyethylene (MAPE) was used as compatibilizer. Acetylation of AEF (AAEF) did not improve the tensile properties, particularly tensile strength of the composites. Addition of maleic anhydride-grafted polyethylene (MAPE) to either HDPE—AEF or HDPE—AAEF composites improved the composite strength. The effectiveness of MAPE, however, was limited by the weight percent gain (WPG) of AAEF resulting in a decrease in composite strength and stiffness. Sorption kinetics and characteristics of water absorption of the composites immersed in distilled water at room temperature for 30 days were determined and compared. All composites were found to exhibit Fickian diffusion process. Results showed that acetylation and MAPE reduced equilibrium water uptake as well as rate of water absorption (diffusion coefficient) of the composites. A synergistic effect, however, was only observed for the equilibrium water uptake when both were considered in a composite formulation.

Effect of Heat Treatment on Properties of Kenaf Fiber Mat/Unsaturated Polyester Composite Produced by Resin Transfer Molding

This study investigated the effect of heatingtime during heat treatment on mechanical and physical properties of the kenaf fiber and its composites. Kenafbast fibers were modified by heat treatmentat 140°C for2.5, 5, 7.5, 10 and 12.5 hours. Composites were fabricated by resin transfer molding process with unsaturated polyester as matrices and needle-punched kenaf fiber mat as reinforces. The fiberswerecharacterized by Fourier Transform-Infra Red (FT-IR) and X-Ray Diffraction (XRD). FT-IR resultsshowedthe changesin intensity ofhemicelluloce wavelength (1736 cm-1). Besides XRD observation also confirmed the increase of cellulose content in kenafthat described to the increase of crystallinity index ofkenaf fiber with heat treatment. The single fiber strength investigation stated that the highest strength and modulus was obtained bykenaf fiber heated for10hours indrying oven. SEM observation showed the decreasing numbers of impuritieson thefibers surface with fiber treatment compared to untreated kenaf fibers. The flexural properties of composites showed a similar trend to fiber strength, but the fracture toughnesshas showedcontrary results.

Processing parameters optimisation of nonwoven kenaf reinforced acrylic based polyester composites

The present work studies the dependence of mechanical properties of kenaf fibre (KF) reinforced acrylic based polyester composites on the processing parameters. Prior to moulding, non-woven kenaf fibre (NWKF) with areal density of 1200u2005g/m2 was impregnated by acrylic based polyester resin using an impregnation line followed by a post-drying step. The flexural properties of the composites were investigated with respect to changes in impregnation and moulding conditions based on Design of Experiment (DOE) of Response Surface Methodology (RSM). RSM through Central Composite Design (CCD) was applied to develop a model of flexural properties with respect to the combination of processing variables. The mathematical regression models of the flexural properties were derived from the analysis of variance (ANOVA) to determine the model significance. All processing variables in linear terms exhibit significant effect on the flexural strength of the composites. Optimisation of the independent variables to maximise the flexural properties was estimated and verified.The present work studies the dependence of mechanical properties of kenaf fibre (KF) reinforced acrylic based polyester composites on the processing parameters. Prior to moulding, non-woven kenaf fibre (NWKF) with areal density of 1200u2005g/m2 was impregnated by acrylic based polyester resin using an impregnation line followed by a post-drying step. The flexural properties of the composites were investigated with respect to changes in impregnation and moulding conditions based on Design of Experiment (DOE) of Response Surface Methodology (RSM). RSM through Central Composite Design (CCD) was applied to develop a model of flexural properties with respect to the combination of processing variables. The mathematical regression models of the flexural properties were derived from the analysis of variance (ANOVA) to determine the model significance. All processing variables in linear terms exhibit significant effect on the flexural strength of the composites. Optimisation of the independent variables to maximise th...