Ibrahim Abdullah

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 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.

Liquid Natural Rubber: Preparation and Application

Liquid natural rubber (LNR) is a modified form of natural rubber (NR) with a shorter polymeric chain. The preparation of LNR can either be done via mechano-oxidation or redox reaction or photosensitized oxidation. Mechanooxidation, being the earliest method to be developed, is still widely used with some modifications. Pilot plant scale has already been tested on two redox reaction methods using phenylhydrazine-air and sodium nitrite/chlorite - hydrogen peroxide as oxydo-reducing couples. Photosensitized oxidation of NR is made possible by using a photosensitizer which is active in visible light and able to induce degradative oxidation. Research in the field is quite active but so far no method has developed into a commercial scale. The short nature of the LNR polymeric chain allows many chemical modifications possible and thereby enlarging the field of applications of NR. The potential applications of LNR are in the preparation of thermoplastic NR, adhesives, binders, bitumen, low hardness vulcanizates, paints and varnishes.

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.

Electrically Conductive Polystyrene/Polypyrrole Nanocomposites Prepared via Emulsion Polymerization

Polypyrrole (PPy) nanoparticles in polystyrene (PS) matrix were synthesized by emulsion polymerization using ferric sulfate, sodium dodecyl sulfate, and n-amyl alcohol as an oxidant, emulsifier and dopant, and co-emulsifier, respectively. The content of PPy nanoparticles in the composites varied from 14.11 to 34.63 wt%, as calculated from elemental analysis. Field Emission Scanning Electron Microscopy images showed spherical nanopartciles of PPy with diameters of 30–74 nm were well dispersed in PS matrix. It was found that the thermal stability and electrical conductivity of PS/PPy composites increased with increasing content of PPy nanoparticles.

The physical and chemical natures of cellulose extracted from torch ginger stems

Cellulose was extracted from torch ginger stems through alkali and bleaching treatments. The material obtained after each stage of the treatments was carefully characterised and its chemical composition was determined. Structural analysis was carried out by Fourier transform infrared (FTIR) spectroscopy. The results indicated that the progressive removal of hemicellulose and lignin from the extracted cellulose. The α-cellulose content was increased extensively with successive treatments. The morphology observation with scanning electron microscope (SEM) showed that the average diameter of the extracted cellulose was reduced from 300 µm to 12 µm. X-ray diffraction (XRD) analysis revealed that the crystallinity increased after each treatment with an increased of the fibre crystallinity from 45% to 67%. The thermal stability of the fibre was found to increase at various purification stages when compared to the raw material.

Structural Characterisation of Cellulose and Nanocellulose Extracted from Mengkuang Leaves

Nanocellulose was isolated from mengkuang leaves (Pandanus tectorius) by using concentrated sulphuric acid. The structural analysis of the leaves at different stages of treatments was performed by fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Transmission electron microscope (TEM) was used to investigate the dimensions of the isolated nanocellulose. The FTIR and XRD results indicated that the hemicelluloses and lignin were removed extensively in the extracted cellulose and nanocellulose, and the crystallinity were increased after removing these components. The TEM image showed that the diameter of isolated nanocellulose between 5-25 nm. The isolated nanocellulose may have applications in the fields of nanocomposites.

Mechanical properties of bio-composite natural rubber/high density polyethylene/ mengkuang fiber (NR/HDPE/MK)

The use of mengkuang fiber (MK) as a filler in NR/HDPE/MK bio-composite was investigated. The suitability of MK as reinforcing filler was studied in terms of the mechanical properties and phase morphology formed. Melt-blending was performed using an internal mixer (Haake Rheomix 600). The processing parameters identified were 135 °C temperature, 45 rpm rotor speed and 12 min processing time. The optimum MK loading in 40/60 of NR/HDPE blend was obtained at 20 wt.% with the tensile strength, tensile modulus, and impact strength of 12.4 MPa, 377 MPa and 17.2 kJ/m2, respectively. These results showed an enhancement in tensile strength of 10.7% compared to the unfilled NR/HDPE blend. The maximum impact strength obtained at 5% fiber loading was 23.5 kJ/m2, which was 7.8% higher compared to unfilled NR/HDPE blend. The FESEM micrographs showed good adhesion between MK fiber and matrix. These mechanical properties enhancements proved the suitability of mengkuang fiber as potential reinforcing filler in NR/HDPE blend.

Gas permeability of ENR/PVC membrane with the addition of inorganic fillers

Epoxidized natural rubber (ENR) was blended with polyvinyl chloride to form a flexible and porous membrane. SiO2 and MgO were added into the membrane for pore formation and the effects of the addition was investigated by means of FTIR, TGA, SEM, EDX and gas permeability towards CO2 and N2 gases. FTIR result showed the presence of Si–O–Si asymmetric stretching at the absorption peak of 467 cm−1 for ENR/PVC/SiO2 membrane and MgO signature peak at 3700 cm−1 for ENR/PVC/MgO membrane. Thermal analysis showed that the thermal stability of ENR/PVC membrane increased with the addition of fillers. Morphological studies prove that subsequently, the pores in the membranes increased showing that some of the added fillers were drawn towards the water leaving empty spaces and tracks. The remaining fillers are homogenously distributed on the surface of the membranes. CO2 and N2 gas permeability increased with increasing filler content and the permeability of ENR/PVC/SiO2 membranes towards CO2 and N2 gasses was higher th...

Celluloses filled ENR/PVC membranes for palm oil mill effluent (POME) treatment

Membranes from composite materials have been used especially in water treatment applications. In this paper the composite membranes of celluloses filled ENR/PVC were successfully prepared for POME treatment application. The preparation of the membrane involves solution blending, casting, phase inversion and drying methods. Two types of fillers, cellulose (Cell) and cellulose grafting polymethyl methacrylate (Cell-g-PMMA) were added into ENR/PVC matrix in various compositions (1, 5, 10, 15 and 20 wt%) to determine the effect of the filler to the performance of the membrane. The membranes were characterized by using FTIR and SEM. Membrane properties in terms of porosity and water flux were examined using mathematical calculation. FTIR spectrum shows the existence of stretching vibration from the functional group of ester carbonyl, –C=O at peak 1725 cm−1 that belongs to Cell-g-PMMA filler in ENR/PVC/Cell-g-PMMA membrane which makes the membranes slightly hydrophobic. SEM micrographs exhibit that pores were f...