Key Engineering Materials Vols. 471-472

Abstract: The comparison of binder system between PP/ palm stearin and PE/ palm stearin both mixed with palm stearin were studied based on the rheological properties to (MIM) process. The microstructure of distribution and dispersion studied using scanning electron microscope (SEM) to observe the pattern of the attached binder with stainless steel powder. The types of binder system used were palm stearin with Polypropylene (PP) and Polyethylene (PE). The powder loading for stainless steel 316L with average size of 20µm used was determined at 66 vol %. The palm stearin was the main significant factor for both viscosity and sensitivity of the feedstock behavior. Less content of palm stearin reduce the viscosity of the feedstock in the range of 100-10000 Pa.s and less influence on changing towards temperature and pressure. As the percentage of addition of palm stearin increase, the feedstock becomes less viscous with high sensitivity. PP and PE feedstock shows dilatant and pseudoplastic flow behavior respectively. PE homogenously coated each of stainless during morphology observation. Meanwhile poor distribution of PP can be observed from SEM observation at 1000x magnification.

Abstract: Epoxy resin is one of the most applied thermoset polymers as a matrix for Glass Fiber Reinforced Pipes (GFRP). Curing process of epoxy resin is important for the integrity of the GFRP. The present work has been conducted to determine the proper pre-curing and post-curing temperatures and duration to develop epoxy-clay nanocomposite. During this study a differential scanning calorimeter (DSC) was used to determine the glass transition temperature and hence the degree of curing. Several samples of epoxy were prepared at different pre-curing and post-curing temperatures and durations. Pre-curing temperatures ranging from 80 to 150°C and post-curing temperatures ranging from 150 to 200°C were studied. The results show that the optimum pre-curing and post-curing temperatures are 100 and 170°C, respectively. Regarding the effect of curing duration, several specimens were prepared at the same pre-curing and post-curing temperatures with different curing durations of 1, 2, and 3 hours. It was observed that beyond one hour curing, the changes in the Tg and the degree of crosslinking were negligible. Using these optimum conditions samples of epoxy-clay nanocomposites were prepared using ultrasonication. The results showed that the addition of nonoclay to epoxy resulted in a reduction of the Tg.

Abstract: In the present study the effect of Mg addition on the characteristics of Al/SiC nanocomposite powder particles produced via a relatively new method called in situ powder metallurgy (IPM) is investigated. Commercially pure Al and Al-Mg alloy melts containing different amounts of Mg were used as the matrix alloy. Nano-sized SiC particles with the average size of 60 nm were used as the reinforcing material. The effect of Mg content on the fluidity of the melt as an influencing factor affecting both the process yield and wettability of SiC with molten metal was investigated. The size distribution of produced powders was characterized using a laser particle size analyzer. Scanning electron microscopy was utilized to investigate the possibility of embedding of SiC nanoparticles within the metallic matrix. Results of microhardness measurements together with SEM micrographs and EDS analysis showed that nano-sized SiC particles could be embedded in the relatively coarse Al-Mg powders containing at least 1 wt.% Mg.

Abstract: In the current paper, a new semi-energy finite strip method is developed based on the concept of first order shear deformation theory (FSDT) in order to attempt the post-buckling solution for relatively thick composite plates subjected to uniform end-shortening. The main advantage of the semi-energy finite strip method (FSM) is that it is based on the closed form solution of von Karman’s compatibility equation in order to derive the analytical shape functions for the in-plane displacements fields. The developed finite strip method is applied to analyze the post buckling behavior of a relatively thick anti-symmetric cross-ply composite plate with clamped out-of-plane boundary conditions at its loaded ends. The results are discussed in detail and compared with those obtained from finite element method (FEM) of analysis. The study of the results has provided confidence in the validity and capability of the developed finite strip in handling post-buckling problem of relatively thick laminated plates.

Abstract: In this paper, the application of previously the semi energy finite strip method (FSM) for the non-linear post-buckling analysis of rectangular anti-symmetric laminates is extended to include the effects of normal pressure loading in addition to the progressive end-shortening. One of the main advantages of the semi-energy FSM is that it is based on the closed form solution of von Kármán’s compatibility equation. The developed finite strip method is applied to analyze the large deflection behavior of anti-symmetric angle ply composite laminated plates with simply supported boundary conditions at its loaded ends. To validate the results, they are compared with those obtained from finite element method (FEM) of analysis.

Abstract: Lignocelluloses based natural fibers composites are very prone to water absorption due to OH functional group within cellulose and hemicelluloses of natural fibers. In this work, the water retention in the kenaf/polypropylene (kenaf /PP) composite due to repeated immersion and drying are studied. The composites (40%, 50%, 60% and 70% fiber loading) are immersed in the water and then dried in room condition (24°C and 48 % humidity) for 4 cycles (1 cycle is 10 days of immersion and drying). The parameters are 8\2 (imply 8 days immersion\ 2 days drying), 6\4, 4\6 and 2\8 per cycle. Continuous immersion (100% immersion) is used as a reference of water absorption behavior of the composite. The results for 70% fiber loading under minimum drying days of 8\2, shows that the water retention reduced to 36% from the water absorbed and further drying only reduced to 31%. When the experiment are repeated for several cycles, 70% fiber loading composites shows a decreasing pattern in water retention at the second cycle whereas 40% fiber loading composite showing an increasing pattern. Duration of immersion\drying does play an important role in the amount of water retention in the composite. The water retention of the composites either show an increasing or decreasing pattern depending on kenaf fiber loading and repetition of the immersion\drying for several cycles.

Abstract: Polymer composites using natural fibers as the reinforcing agents have found their use in many applications. The initial development of polymer composite based on high density polyethylene (HDPE) with banana pseudostem fiber was studied based on the effect of non-aging and aging treatments. Tensile, flexural and impact tests were performed to investigate the mechanical properties of banana pseudostem fiber reinforced composite. Flexural and impact test results show that the specimen strength improved after aging treatment was applied. However, the tensile test results gave a reverse effect on the strength of the composite after aging. The specimen became more brittle when the composite was exposed to the aging temperature.

Abstract: Due to urbanisation and rapid development in Malaysia, the waste generated from the construction has increased tremendously. Such waste accumulation has been a major issue not only in Malaysia but also worldwide. In line with this, recycling construction as coarse aggregate can be introduced to solve two environmental aspects namely waste disposal crisis while protecting from depleted natural resources. In this study, three types of construction waste namely floor tiles, clay bricks and crushed concrete aggregate were used to replace coarse aggregate in concrete production. The effect of coarse aggregate replacement on the workability, compressive strength, and flexural strength Grade 30 concrete were investigated and discussed. The concrete specimens that made of crushed floor tiles, crushed bricks, and crushed concrete aggregate were termed as tile concrete (TC), brick concrete (BC) and crushed aggregate concrete (CAC). The result for all specimens has shown good workability with slump ranging from 51-85 mm. BC showed optimum brick replacement of 17% with the 28-day compressive strength of 36 N/mm2. TC and CAC on the other hand showed optimum result at 20% and 16% replacement with 28-day compressive strength of 31.43 N/mm2 and 31.25 N/mm2 respectively. It can be concluded that optimum result for BC, TC and CAC have achieve concrete G30. The flexural strength of BC, TC and CAC ranges from 3.03-4.49 N/mm2, 3.62-4.60 N/mm2, and 4.05-5.43 N/mm2.

Abstract: This research was conducted to evaluate the potential of sugar palm residue as a raw material to produce the new green composites. The physical properties of sugar palm fibre reinforced unsaturated polyester composites from different part which are sugar palm frond (SPF/PE), sugar palm bunch (SPB/PE), sugar palm trunk (SPT/PE) and black sugar palm fibre (ijuk/PE) were studied. Samples were submerged in distilled water for 24 hours. The water absorption and thickness swelling were investigated in order to determine the dimensional stability of the composites. It is found that SPF/PE showed the higher value of water absorption and thickness swelling which are 1.57%, and 1.56% followed by SPB/PE (1.35%, 1.11%), ijuk/PE (0.65%, 0.76%) and SPT/PE (0.39%, 0.50%). Generally, this investigation is valuable for researchers in order to evaluate the potential and some possible application of sugar palm residues as a new natural composites product.

Abstract: Low-velocity impact test on sandwich panels composed of aluminum face sheets and thermoplastic honeycomb cores have been performed to characterize the impact performance as a function of core thickness and drop heights. Impact parameters like maximum impact force, impact energy and impact damage area were evaluated and compared. Consequent damages were inspected visually on the impact surface as well as the rear surface. The experimental results found that panels with thicker core exhibited higher impact force than thinner core counterparts, allowing the panel to absorbed more energy. Higher degree of impact damage can be observed at elevated drop heights as most of the damage took the form of local core crushing, face sheet buckling and debonding between the face sheet and core,. Resulting damage area were different according to the core thickness as thicker core prone to absorbed more energy that lead to more damage propagation.