Papers by Author: Sujan Debnath

Abstract: In recent decades, polymer composites have gained significant interests within the research community due to its high strength-to-weight ratio. Its properties, such as low cost, lightweight, corrosion resistance, and impact resistance, make it desirable for both household and industrial applications. However, the reliability of the composite model with density influence is still challenging. In this study, experiments were carried out using epoxy systems of varying densities to fabricate oil palm empty fruit bunch (OPEFB) carbon nanoparticle composites to investigate the influence of matrix density on its Weibull modulus. It is found that the increase in matrix density increases the nanocomposite reliability. A Weibull modulus of 9.5, 82.2 and 183.4 were obtained for low, medium and high matrix density nanocomposites, respectively. Such findings would facilitate the development of particle-reinforced composites.

Abstract: Numerous literatures have suggested that the use of natural fiber as filler can improve the mechanical properties of a polymer composite. Oil palm empty fruit bunch fibers (OPEFB) are no exception and have shown to exhibit good mechanical properties, with the potential to produce environmentally friendlier composites. In this study, the tensile strengths and morphologies of micro OPEFB filled composites with varying loadings (0.3125 wt% to 10 wt%) were investigated. It was found that increasing content of OPEFB reduces the translucency of the composite almost linearly. It was also revealed that the addition of 0.3125 wt% to 2.5 wt% has a reinforcing effect, observing improvement up to 17.4% compared to its neat condition. Such findings would facilitate the development of an effective OPEFB reinforced polymeric nanocomposite.

Abstract: Ionogel is an emerging hybrid material where the ionic liquid is immobilized within polymer matrix. Interesting combination of properties has permitted wide applications of ionogel. In this study, a well-known method, sol-gel is used to synthesize ionogel. However, it is intended to identify the optimum concentration of ionic liquid within ionogel which endows the ionogel with the best electrochemical performance. By varying the concentration of ionic liquid, the appearance of ionogel is compared. FTIR is performed to understand the structural changes that occur in ionogel. Linear Sweep Voltammetry is performed to study the electrochemical stability of ionogel.

Abstract: During the composite’s fabrication process, one of the most common defect occurs is void. Numerous literatures have suggested that the presence of void negatively affect its mechanical properties and effective degassing process is one the solutions for such issue. In this study, experiments were carried out using neat E132 epoxy to investigate the effects of different degassing process (hot water, ultrasonic bath, and vacuum) on its tensile strength. The duration of its process was carried out from 5 – 9 minutes for hot water and ultrasonic bath where vacuum process was extended until 10 minutes to observed limiting behavior. It is found that the vacuum degassing method is the most effective. Vacuum degassing process displayed the least formation of bubble and micro voids even for 10 minutes. It is also revealed that vacuum degassing process resulted the highest average tensile strength at 48.8MPa. Such findings would facilitate the well bonded effective nanocomposite fabrication process.

Abstract: In recent years, studies regarding natural fiber reinforced composites have been increased as they are biodegradable with good mechanical performance therefore can help to overcome the environmental issue. As the natural fibers are easy to obtain, many industries have started to make use of natural fiber composites which are light in weight and possess good mechanical properties. However, the natural fiber composites also possess certain limitations most importantly their high moisture absorption ability which makes them incompatible at degradable environment. The fiber constituents of natural fiber composite may have different type of interactions at different environmental conditions. In addition, the involvement of nanoparticles in the composite may be the solution to overcome the deficiencies. In this research, the degradation behaviour of Oil palm empty fruit bunch (OPEFB) fibers reinforced epoxy composites upon exposure to degradable environmental conditions and the effect of adding nanoparticles have been studied. The tensile tests were conducted before and after the exposure to different environmental conditions including plain water, moist soil, brine solution, and cooking oil. Results shows that the addition of 10wt% of OPEFB fiber to the epoxy composites had improved the mechanical tensile strength up to 15.97% and composites exposed to brine solution have the most prominent sign of degradation in mechanical properties in both composites with and without nanosilica. Nevertheless, the composites with nanosilica have shown up to 24.28% improvement in tensile strength after exposure to different environmental conditions. The improvement were attributed due to filling the voids of the composites with nanosilica and good interfacial adhesion between the nanofiller, fiber, and matrix.

Abstract: Surface treatment is one of the method used to enhance the mechanical performance of natural fiber composite by improving the compatibility of fiber and matrix. Nevertheless, no proof can be shown on which surface treatment is the absolute solution in improving the mechanical properties of natural fiber composite. Different surface treatments might have needed for different kinds of natural fiber composites. In this research work, water, alkaline, permanganate, bleaching and acetylation treatment on bagasse fiber are evaluated and the effect of soaking temperature as well as the effect of fiber loading are investigated. The mechanical performance of bagasse fiber-epoxy composite was studied by carrying out three-point bending test and optical microscopy test. Among 0w/w% and 5w/w% fiber loading, composite with 1w/w% and 2w/w% fiber loading possessed the highest flexural strength and modulus respectively. However, poor wettability between fiber and matrix was observed at higher fiber loading. Water, bleaching, permanganate and acetylation treatment have minor positive effect on the mechanical performance of the composite, yet a great increment in flexural properties of alkali treated fiber composite was noticed such that 21.48% and 23.95% of improvement was made on flexural strength and flexural modulus respectively. Optical microscopy test indicated that alkali treatment is responsible for roughening the fiber surface, and improving the fiber wettability and dispersion. Depend on the surface treatment, effect of soaking temperature may vary. In some treatments, hotter soaking temperature led to faster rate of reaction, which resulted in greater surface roughening and greater cleansing effect. Despite of that, over reaction can be happened in some cases, which will result in lower flexural properties due to over damaged fiber. Hence, it was concluded that the alkaline treatment at room temperature could be the most effective surface treatment to enhance the mechanical performance of bagasse fiber-epoxy composite.

Abstract: Bamboo fibers as a natural fiber offer numerous advantages such as high specific strength over synthetic fiber when used as reinforcing fiber for polymer composites. Yet the hydrophilic nature of bamboo fibers with high moisture absorption results in incompatibility in between bamboo fibers and unsaturated polyester resin. An experimental study was carried out to investigate the effects of alkali treatment of bamboo fiber on the mechanical properties and water sorption properties of polyester composite. The result revealed that, the bamboo fiber polyester composite with 5% Alkali treated bamboo fiber possesses the highest mechanical properties. Besides, Alkali treated fibers composite showed a significant reduction in moisture uptake compared to untreated fibers, where composite with 7% Alkali treated showed the lowest moisture uptake.

Abstract: Electro discharge machining (EDM) as a die sinking process has taken off in 1943. Since then it was known as a non-conventional machining process and its application was limited for processing only electrically conductive materials. Later on, due to the widespread applications, this EDM process is considered conventional as usual. However, in the recent years EDM has gone through considerable changes especially with dielectric fluids, simple to complex geometry, meso to micro sized structures, nanometric surface finish, and so on. In addition, the application of EDM has also been extended for processing electrically semi-conductive and non-conductive materials like ceramics and composites. This paper discussed micro electro discharge machining of non-conductive ceramic materials. It includes detail process development, modelling of material removal rate and surface finish which include the effect of multi spark and random spalling conditions.

Abstract: The aim of this paper is to investigate the effect of chemical treatment on the flexural properties of the composite. Oil Palm Empty Fruit Bunch Fibers (OPEFB) reinforced Vinylester composite were prepared in this study. Soxhlet extraction together with sodium hypochlorite bleaching methods was used for chemical treatment. The diameter of fibers was reduced from a range of 250-350 μm to 10-15 μm by treatment. Shape and texture of the fibers transformed from solid brown colored strings into a white gel. Thermogravimetric Analysis (TGA) test was carried to investigate the effect of treatment on the thermal properties of natural fibers. Vinylester composites were fabricated using untreated and bleached OPEFB fibers. The bending test results showed the bleached fibers displayed greater flexural properties compared to untreated fibers, where the time of bleaching was an important factor in the treatment process.

Abstract: The effect of alkali treatment and nanoclay addition on the mechanical properties and water absorption behavior of rice husk particle (RHP) reinforced unsaturated polyester (UP) composites was investigated. Thermogravimetric analysis (TGA) indicated that the alkali treatment removed most of the hemicellulose and impurities from the RHP with the tensile strength, tensile modulus, flexural strength and flexural modulus of the resulting composites being improved by alkali treatment. The results indicated that the 5% sodium hydroxide concentration had the optimum performance on mechanical strength and water absorption resistance. Furthermore, the influence of nanoclay addition (1, 3 and 5 wt%) on the properties of optimum alkali treated RHP-UP composites was investigated with the lowest content (1 wt%) of nanoclay showing the highest mechanical performance. However, further addition of nanoclay improved the moisture absorption resistance of the composites. Good interface bonding between the filler and matrix was observed from scanning electron micrographs for the optimum RHP alkali treated and nanoclay dispersed RHP-UP composites.