Natural fibers have become an important issue in the development of fiber reinforced polymer (FRP) composite to resolve the current ecological and environmental problems. Among the many types of natural fibers that are available, pineapple leaf fiber (PLF) was selected as the natural fiber used in this study due to comparatively better mechanical properties, ease of availability and low cost. In this work, the effects of pineapple leaf fiber (PLF) loading on the properties of PLF/polypropylene (PP) composites was studied. The sample of composites was fabricated with five different fiber loading of PLF (30, 40, 50, 60 and 70 wt.%). An alkaline treatment was conducted to enhance the PLF properties. The fabrication was made by compression molding technique with random orientation of PLF. From the experimental study, the results revealed that the voids percentage and interfacial bonding between the PLF and PP affected the mechanical properties of the PLF/PP composite. Based on the results of tensile stress, hardness and density, it can be concluded that the PLF/PP composite with the composition ratio of 30/70 wt.% has shown the best mechanical properties compared to other composition ratios (40/60, 50/50, 60/40 and 70/30 wt.%), which are 16.71 MPa, 62.83 Shore-D and 0.93 g/cm³ respectively.

The aim of this study is to determine the effect of different types of pore-forming agent and sintering temperature on the pore size of ceramics. The porous ceramic material was developed by mixing of alumina, zeolite and calcium oxide (CaO) as the main materials and ethylene glycol as the binder. Meanwhile, two types of pore-forming agent were used, i.e., yeast and a mixture of aluminium powder and expandable polymeric spheres (EPS). The content of pore-forming agent was at 10 wt% of the mixture and the samples were shaped by using plaster of paris mould. After being dried, the samples were sintered at temperature range of 1000 up to 1500 °C for two hours. Microstructural analysis and pores size measurement were performed to determine the effect of pore-forming agent and sintering temperature on the ceramic. The result showed that yeast yielded larger pore sizes in the porous ceramic upon being sintered at 1400 °C for two hours, which were up to 402 μm. Therefore, yeast has the potential to be utilized as pore-forming agent in development of filter and wall insulation material.

Corrosion process occurs naturally in which metals, such as steel, undergo degradation due to chemical or electrochemical reactions with their surroundings. This however can lead to serious malfunctions and costly damages to crucial steel uses. In marine activities, most metals and alloys used inevitably degrade since the sea is rich in corrosive electrolytes, in particular, chloride. This may lead to the occurrence of pitting corrosion, which is highly localised and can cause major catastrophes. Hence, it is important to understand the science of pitting corrosion which in turn can benefit corrosion control processes. This can be done through simulation of pitting activities. In this study, a three-dimensional model of a minute pit in steel, immersed in sodium chloride solution in water, is simulated using COMSOL Multiphysics version 5.6 with Chemical Reaction Engineering Module. The simulation is run to observe the shape of the polarization curve at the actively corroding pit. The initial pH of the immersing solution is at a slightly alkaline condition, namely at pH 8. The results show that the corrosion potential, Ecorr, of a point at the bottom of the corroding pit is -0.74 V. The model is also able to show a high concentration of ferrous ions, Fe2+, inside the pit geometry, reaching to a value of 2.5×103 mol m-3. These results indicates that metal dissolution occurs. The shape of the polarization curve obtained in this study exhibits a significant linkage to the propagation of pit, which in turn indicates the type of corrosion a pit can evolve into, in particular, pitting corrosion.

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