Ishak Ahmad

Potential of using multiscale kenaf fibers as reinforcing filler in cassava starch-kenaf biocomposites.

Biodegradable materials made from cassava starch and kenaf fibers were prepared using a solution casting method. Kenaf fibers were treated with NaOH, bleached with sodium chlorite and acetic buffer solution, and subsequently acid hydrolyzed to obtain cellulose nanocrystals (CNCs). Biocomposites in the form of films were prepared by mixing starch and glycerol/sorbitol with various filler compositions (0-10 wt%). X-ray diffraction revealed that fiber crystallinity increased after each stage of treatment. Morphological observations and size reductions of the extracted cellulose and CNCs were studied using field emission scanning electron microscopy and transmission electron microscopy. The effects of different treatments and filler contents of the biocomposites were evaluated through mechanical tests. Results showed that the tensile strengths and moduli of the biocomposites increased after each treatment and the optimum filler content was 6%.

Effect of Fiber Content, Fiber Length and Alkali Treatment on Properties of Kenaf Fiber/UPR Composites Based on Recycled PET Wastes

Kenaf fibers were mixed with unsaturated polyester resin (UPR), which was prepared by recycling of polyethylene therephthalate (PET) waste bottles. Grinded PET waste bottles were subjected to recycle by glycolysis which was used to prepare unsaturated polyester resin. The resin was then mixed with kenaf fibers in two different lengths (2.5 and 5 mm) at different fiber loading (2.5 and 5 phr of kenaf in UPR resin). The effects of fiber content, fiber size and surface treatment on the mechanical properties, density and water absorption of the composite were studied. The SEM and FTIR analysis were used to analyse the influence of alkali treatment on fibers and interfacial interaction between fibers and matrix. The results show that the optimum values of the stiffness properties and impact strength is at 2.5 phr, whereas tensile strength decreases with increasing fiber content. The length of fiber played a significant role in some of the mechanical properties of the composites with 5 mm fiber length has higher mechanical properties than 2.5 mm length. The results also showed that alkali treatment causes a better adhesion between the fiber and UPR matrix and improves the mechanical properties of the composites. Furthermore, surface treatment reduced the water absorption of composites.

Effect of Extrusion Rate and Fiber Loading on Mechanical Properties of Twaron Fiber-thermoplastic Natural Rubber (TPNR) Composites

Mechanical behavior of short Twaron fiber thermoplastic natural rubber (TPNR) has been studied with respect to fiber loading and extrusion rates. The composites are prepared at two different compositions of NR/LLDPE matrixes i.e., 60/40 and 40/60. Twaron fibers are varied from 0 to 25% in the composites. The temperature profile for extrusion is 140, 145, 150, and 155°C for feeding zone, melting zone, mixing zone, and die respectively with the extrusion rate of 30, 50, 80, and 100 rpm. It has been found that the tensile strength, Young’s modulus, and impact strength increases with fiber loading, but the strain at break decreases. The optimum fiber loading in the system is found to be 20% in both blends. However, there is no effect of extrusion rate on the strength of composite observed.

Cassava starch biocomposites reinforced with cellulose nanocrystals from kenaf fibers

This study highlights the potential of cellulose nanocrystals (CNCs) from kenaf fibers as reinforcing fillers in starch-based biocomposites. By hydrolyzing kenaf fibers with 65 wt.% sulfuric acid, CNCs with diameters of 12 ± 3.4 nm were obtained. Cassava starch biocomposites were prepared using a solution casting method which includes 0–10 wt.% kenaf CNCs as fillers and glycerol/sorbitol (ratio of 50:50) as plasticizer. The composites were characterized by different techniques, including tensile tests, thermal stability tests, transmission electron microscopy, field emission scanning electron microscopy (FE-SEM), water uptake tests, and observation of the physical properties of the film cast. The CNCs appeared as white, shiny dots under FE-SEM with a good dispersion of the nanofillers within the starchy matrix. The tensile strength and modulus of the biocomposite films were significantly enhanced when compared to unfilled starch films. Transparent, thin, and flexible films were obtained from both the plain matrix and 6 wt.% CNC biocomposites, confirming that CNCs may be used as fillers without affecting the composite’s transparency. Furthermore, incorporation of CNCs in the plasticized matrix led to a decrease in water sensitivity.

Potential of using polyester reinforced coconut fiber composites derived from recycling polyethylene terephthalate (PET) waste

Unsaturated polyester resin synthesized from glycolyzed product of polyethylene terephthalate (PET) waste was used as a matrix to form coconut fiber/polyester composites. PET wastes were recycled through glycolysis and polyesterification reaction to produce a formulation for unsaturated polyester resin (UPR). FTIR spectra of glycolyzed product and prepared resin revealed that cross-links between unsaturated polyester chain and styrene monomer occurred at the saturated sites which resulted in the forming of cross linking network. To improve the adhesion between coconut fiber and polyester resin, various concentrations of alkali, silane and silane on alkalized fiber were applied and the optimum concentration of treatments was determined. The influence of water uptake on the sorption characteristics of composites was studied via immersion in distilled water at room temperature. Surface treatment of coconut fiber caused a significant increase in the tensile properties with the optimum treatment is 0.5 % silane on the 5 % alkalized coconut fiber/polyester composites. It was also observed that the treated fiber composites showed lower water absorption properties in comparison to those of untreated fiber composites. This observation was well supported by the SEM investigations of the fracture surfaces. From the study, it was concluded that polyester reinforced coconut fiber composites derived from recycling polyethylene terephthalate (PET) waste may have the potential application in the fields of construction and automotive interior substrates.

Effect of Chemical Treatment on Mechanical and Water-Sorption Properties Coconut Fiber-Unsaturated Polyester from Recycled PET

Coconut fibers were used as reinforcement for unsaturated polyester resin from recycled PET that has been prepared using glycolysis and polyesterification reaction. Various concentrations of alkali, silane, and silane on alkalized fiber were applied and the optimum concentration of treatments was determined. Morphological and mechanical properties of the composite have also been investigated to study the effect of fiber surface treatment. The influence of water uptake on the sorption characteristics of composites was studied via immersion in distilled water at room temperature. Surface treatment of coconut fiber caused a significant increase in the tensile properties with the optimum treatment of 0.5% silane on the 5% alkalized coconut fiber/polyester composites. For water absorption study, it was observed that the treated fiber composites showed lower water absorption properties in comparison to those of untreated fiber composites. SEM investigation showed that the surface modification of fiber has better fiber-matrix interaction. Thus, chemical treatments on the fiber improve fiber/matrix adhesion especially for silane on alkalized fiber treatment.

Hydrophobic kenaf nanocrystalline cellulose for the binding of curcumin

Nanocrystalline cellulose (NCC) extracted from lignocellulosic materials has been actively investigated as a drug delivery excipients due to its large surface area, high aspect ratio, and biodegradability. In this study, the hydrophobically modified NCC was used as a drug delivery excipient of hydrophobic drug curcumin. The modification of NCC with a cationic surfactant, cetyl trimethylammonium bromide (CTAB) was used to modulate the loading of hydrophobic drugs that would not normally bind to NCC. The FTIR, Elemental analysis, XRD, TGA, and TEM were used to confirm the modification of NCC with CTAB. The effect of concentration of CTAB on the binding efficiency of hydrophobic drug curcumin was investigated. The amounts of curcumin bound onto the CTAB-NCC nanoparticles were analyzed by UV-vis Spectrophotometric. The result showed that the modified CTAB-NCC bound a significant amount of curcumin, in a range from 80% to 96% curcumin added. Nevertheless, at higher concentration of CTAB resulted in lower binding efficiency.

Effect of PE-g-MA-Compatibilizer on the Morphology and Mechanical Properties of 70/30 HDPE/ENR Blends

The effects of PE-g-MA as a compatibilizer in binary blends of 70/30 high-density polyethylene/epoxidized natural rubber (HDPE/ENR) have been investigated by means of mechanical analysis and scanning electron microscopy. The special emphasis was given to the role of PE-g-MA in inducing interactions between HDPE and ENR. It has been observed that increasing the amount of PE-g-MA in the blend increases the tensile strength, elongation at break, and impact strength. It is believed that the degree of cross-link increased, which led to improve the interaction between the HDPE and ENR. The optimum stress values are shown in the blend containing 6% PE-g-MA. Scanning electron micrographs (SEM) of the samples also indicated that the addition of compatibilizer decreases the domain size of the dispersed phase. Well-dispersed plastic particles in a rubber matrix were strongly indicated in these samples. The results obtained reveal that the addition of PE-g-MA in HDPE/ENR blend led to an increase in the homogeneity of the blends.

Hydrophobic modification of cellulose isolated from Agave angustifolia fibre by graft copolymerisation using methyl methacrylate

Graft copolymerisation of methyl methacrylate (MMA) onto Agave angustifolia was conducted with ceric ammonium nitrate (CAN) as the redox initiator. The maximum grafting efficiency was observed at CAN and MMA concentrations of 0.91 × 10(-3) and 5.63 × 10(-2)M, respectively, at 45°C for 3h reaction time. Four characteristic peaks at 2995, 1738, 1440, and 845 cm(-1), attributed to PMMA, were found in the IR spectrum of grafted cellulose. The crystallinity index dropped from 0.74 to 0.46, while the thermal stability improved upon grafting. The water contact angle increased with grafting yield, indicating increased hydrophobicity of cellulose. SEM images showed the grafted cellulose to be enlarged and rougher. The changes in the physical nature of PMMA-grafted cellulose can be attributed to the PMMA grafting in the amorphous regions of cellulose, causing it to expand at the expense of the crystalline component.

Preparation of Unsaturated Polyester Liquid Natural Rubber Reinforced by Montmorillonite

The effect of liquid natural rubber (LNR) on the mechanical properties of unsaturated polyester (UP) has been studied in this article. Mechanical tests, such as impact and tensile test, have been conducted on the UP-LNR sample in order to determine the optimum LNR composition. The results showed that the tensile strength and impact energy increased with LNR and optimized at 10 phr. The optimum composition of LNR was used to prepare the composite with montmorillonite (MMT). X-ray diffraction of the composite showed the absence of peak in nanocomposites, which contain treated MMT. Scanning of electron microscopy also clearly showed that the agglomeration of clay occurs in the composite using untreated MMT, but is significantly reduced in size for the composite using treated MMT. On the other hand, the mechanical properties, such as tensile strength, tensile modulus, and impact energy, of the composites with modified MMT were also higher than the composite with unmodified MMT. The optimum composition of modified MMT in the composite was found at 4% filler loading.