Key Engineering Materials Vol. 904

Abstract: In this paper, the effects of different sample clamping modes, curing time of the adhesive during sample preparation, gauge length of the sample and tensile rate on the tensile properties of continuous alumina fiber bundles are briefly introduced. These parameters can accurately affect the tensile properties of alumina fiber bundles.

Abstract: The tensile properties of quartz fiber fabric-reinforced resin composites at high temperature were studied. The effects of specimen type and dimension, temperature loading procedure, holding time and loading rate on the tensile properties of the composites at high temperatures were analyzed through series of comparative experiments, the tensile test parameters were determined. Chinese national standard for high-temperature tensile property testing of the composites was compiled based on the data collected. According to the established standard, the tensile testing at 500°C was carried out. Compared with the tensile properties at room temperature, the tensile strength and tensile modulus of the composite at high temperature decreases significantly, with the tensile strength decreasing by about 42.32% and the tensile modulus decreasing by about 24.18%. This is mainly due to the high temperature which causes part of the resin matrix to pyrolyze and detach from around the fiber, thus losing the integrity of the material. In addition, this national standard for high-temperature tensile properties has some general applicability to different types of fiber-reinforced resin composites.

Abstract: The aim of the article is to highlight the effect of the environment on the properties of a polycarbonate (PC). It consists in aging this material under Ultra-violet (UV) combined with temperature for different periods of time, and to reveal the physicochemical and mechanical changes caused by aging. PC is a highly valued technical material for its various important characteristics and low cost. It finds its application in various fields but mainly in those whose requirements are the transparency and the impact resistance. The physicochemical and mechanicals characterizations of the marketed polycarbonate are necessary in order to highlight its intrinsic properties and to develop strategies that can improve its lifespan. In this work, we highlight the physicochemical and mechanical characteristics of virgin and aged polycarbonate. For this, analytical techniques and mechanical tests were used. A comparison of the characteristics revealed the combined effects of temperature and ultraviolet rays.

Abstract: The thermal degradation process of epoxy resin/intumescent flame retardant/flake graphite/hexagonal boron nitride (EP/IFR/FGP/h-BN) was analyzed by thermogravimetry. The effects of binary nano flake graphite/hexagonal boron nitride as synergistic flame retardant on the thermal stability. Flynn wall Ozawa method was used to calculate the activation energy of thermal degradation kinetics of EP/IFR/FGP/h-BN. The mechanism functions of the EP/IFR/FGP/h-BN in different reaction stages were determined according to Malek method, and the thermal degradation mechanism of EP/IFR/FGP/h-BN was obtained. The binary nanoFGP/h-BN is helpful to improve the thermal stability of EP.

Abstract: In this paper, the composites between polylactic acid (PLA) and eggshell powder (ESP) from the chicken shell were prepared by melt blending method in the internal mixer and then injection molded to produce the bio-composite specimen. The effect of the ESP concentration in the composites was investigated on the mechanical and thermal behaviors. The results indicated that the tensile strength and elongation decreased with increased ESP loading. Furthermore, the impact strength was not altered for PLA filled system with 10-30% of ESP. At the 10%wt of ESP in the PLA-composites was not significantly different of the onset (T_onset) and maximum degradation temperature (T_d) from neat PLA but at higher ESP loading, T_onset and T_d tend to decrease, therefore ESP could be able to accelerate degradation in the composites. The cold crystallization (T_cc) showed decreasing when the ESP was incorporate about 10-30 %wt. Otherwise, the incorporation of ESP affected on the declination of crystallinity in the PLA composites. The morphology, size and elements were examined using a scanning electron microscope (SEM) coupled with an energy dispersive X-ray system (EDX). It was indicated that agglomeration of ESP in the PLA matrix.

Abstract: Metal matrix composite has been increasingly appreciated by many engineering applications due it its tailored properties for specific uses. Powder injection moulding is one of the most effective composite processing essentially for small and complex parts. Moulding of feedstock is the key step determining green and sintered properties. This research investigated effects of moulding parameters which are % solid loading and moulding speed on microstructure and properties of aluminium composite. Commercial aluminium alloy powder and SiC particulate at 15 vol.% addition were formulated at 55 % and 60 % solid loading. Injection moulding were operated using a horizontal screw driven typed machine at 1600-1800 rpm speed and 280 - 300 °C moulding temperature. After sintering at 655 °C, property assessment via microstructure, density, % shrinkage, distortion and hardness were carried out. It was found that feedstock of 55 % solid loading occasionally led to flash problem while that of higher solid loading experienced higher viscosity to fulfill four-cavity mould. Moulding speed investigated did not significantly affect mould filling and overall properties. Sintered microstructures generally showed well-distributed SiC particulate in the aluminium matrix. The optimum injection moulding condition was the feedstock prepared at 60% solid loading, moulding at 1800 rpm speed, which offered theoretical density of greater than 98.5 % and micro Vickers hardness of 125.2 H_v.

Abstract: Thermoplastic starches and a nonwoven pineapple leaf sheet (NPALF) were prepared. Two types of flours were used to prepare thermoplastic starches (TPSs) which were Rice flour thermoplastic starch (RTPS) and Glutinous rice flour thermoplastic starch (GTPS). Two layers of thermoplastic starches and NPALF layer were sandwiched and pressed by a hot pressing machine at 150°C with 1500 psi for 15 min. All composites were investigated their densities and tensile properties. The density of all composite types had a lower density than each neat TPSs and types of rice flours did not affect their densities. The tensile property results confirmed NPALF could be used as a reinforcing agent both in GTPS and RTPS composites but their tensile improvement effectiveness in both systems are different. NPALF composite with RTPS did not affect the tensile strength but provided a slight improvement in modulus. Remarkably, NPALF composite using GTPS explored the great improvement performance both in strength and modulus which were increased up to 174% and 308% comparing with neat GTPS. SEM micrograph evidence clearly showed good wetting between GTPS and the reinforcement layer in the composite. This is resulting in the NPALF-GTPS composite showed a strong improvement in tensile properties.

Abstract: Modified reduced graphene oxide (rtgo) was prepared by using γ - isocyanate propyl triethoxysilane (IPTS) as modifier. Graphene / polyurethane nanocomposites were prepared by in-situ polymerization. Graphene / polyurethane composites were characterized by scanning electron microscopy, TGA, DIN abrasion and electronic universal testing machine. The effects of different reaction formulations and graphene addition on the wear resistance and mechanical properties of the composites were studied. The results show that the wear resistance and tear resistance of the composite can be greatly improved after the functional graphene is compounded with polyurethane.

Abstract: Banana fiber (BF) was utilized as a reinforcing filler for natural rubber (NR). BF/NR composites containing banana fiber contents of 5, 10, and 15 parts per hundred parts of rubber (phr) were mixed on a two-roll mill machine. The hardness, tensile properties of BF/NR composites were studied. It was found that the hardness and moduli of BF/NR composites are higher than that of NR. Despite tensile strength and strain at break of BF/NR composite lower than NR. Moreover, hardness and moduli of BF/NR composites increased, while tensile strength and strain at break decreased with the increase in banana fiber content. Thus, banana fiber exhibited improvement in the stiffness significantly of NR composites

Abstract: The adhesion between the carbon fibre reinforced copper matrix composite material and the coating is of particular importance for the mechanical and functional properties of the resulting system, and also for its handling and for the lifetime of the final product. To have a better understanding of the microstructure at the interface region, three different coating processes, i.e. electroplated Nickel coating, alkyd resin coating and polyolefin coating have been carried out and compared using SEM/EDX techniques. The experimental results indicate that the electroplated Nickel coating gives the best adhesion strength at the interface, suggesting this method the most promising approach and can be further investigated for electrical and electronic engineering applications in power industry.