Applied Mechanics and Materials Vols. 754-755

Abstract: Natural rubber (SMR L grade), epoxidized natural rubber (ENR) 25 and 50 were loaded with hybrid tackifiers consisting of a mixture of coumarone-indene and gum rosin. The coumarone-indene was fixed at 40 parts per hundred of rubber (phr) while the concentration of gum rosin was varied from 20 to 80 phr. The viscosity, peel and shear strength of the adhesives prepared from the elastomers was studied. Results show that peel strength exhibits a maximum value at 60 phr gum rosin for SMR L-based adhesive while for ENR 25 and ENR 50 based adhesives a maximum value is observed at 40 phr gum rosin which was attributed to the occurrence of optimum wettability and compatibility at this tackifier loading. Meanwhile, viscosity and shear strength decreases with increasing gum rosin concentration. SMR L-based adhesive consistently exhibits higher viscosity and shear strength whereas ENR 25-based adhesive steadily shows higher value for all modes of peel tests.

Abstract: The main purpose of incorporating Nypa Fruticans (NF) into Polylactic Acid (PLA)/Recycled Low Density Polyethylene (rLDPE) biocomposites is to decrease costs and change the properties. Polyethylene–co–acrylic acid (PEAA) was used as a compatibilizer. The effect of NF content and PEAA on the mechanical properties and morphology of the biocomposites were investigated. Results show that the effect of NF content increased Young’s modulus but decreased the tensile strength and elngation at break of PLA/rLDPE/NF biocomposites. It was found that incorporation of compatibilizer (PEAA) increased the tensile strength and Young’s modulus but decreased the elongation at break of compatibilized biocomposites. Scanning electron microscopy (SEM) study of the tensile fracture surface of the biocomposites indicated that the presence of PEAA improved the interfacial interaction between Nypa Fruticans and LDPE matrix.

Abstract: Generally, the composite pipes are fabricated using glass fiber and polyester resin matrix by hand lay-up and also by 2-axis filament winding machine. In this work, a filament winding machine was used for the fabrication of geopolymer composites pipes. In this study, raw material based geopolymer resin composites reinforced by continuous glass fiber were used for fabrication and synthesized by different types of raw materials which is fly ash, silica sand, white clay, kaolin and pozzolanic. The effects of different types of raw materials on the product were investigated. The morphological properties, density and burnout of the resulting composite were determined on an optical microscope for morphology and densimeter for bulk density. The results shows fly ash has the higher density compare to the others and kaolin has the highest reduction of weight percentage.

Abstract: Nowadays bioplastics is the most recent study materials as the substitute for conventional plastics. The interest in bioplastics has lead to the production of polylactic acid (PLA) biocomposite films. In this study the PLA/Corn husk (CH) biocomposite films were prepared by using solvent casting method and the effect of CH content on the tensile properties were studied. The result found that increasing of CH content decreased the tensile strength and elongation at break of the biocomposites film. While, the modulus of elasticity increased with the increasing of CH content in the PLA matrix.

Abstract: In this work, UHMWPE reinforced composites containing hybrid zinc oxide (ZnO) and chitosan particles were prepared via the hot compression technique. The effect of ZnO contents (10, 20, 30 wt.%) and chitosan contents (1, 2, 3 wt.%) on the thermal properties of UHMWPE/ZnO and UHMWPE/Chitosan-ZnO reinforced composites were successfully investigated using DSC and TGA analysis, respectively. Based on DSC results, both UHMWPE/ZnO and hybrid composites did not record significant changes in the melting temperatures (T_m). The heat fusion enthalpy (Hm) and degree of crystallinity (X_c) of hybrid composites were found to be higher than UHMWPE/ZnO composites. As the TGA results shown, hybrid composites were also found to have higher thermal stability than UHMWPE/ZnO composites at 10 % and 50 % weight loss level. Overall, the UHMWPE/ZnO + 3 wt.% Chitosan hybrid reinforced composite recorded comparable mechanical properties and better thermal properties than neat UHMWPE.

Abstract: In this study, LLDPE/RH composites were tested under various strain rate loadings (0.001/s, 0.01/s and 0.1/s) using the universal testing machine. Static compression properties of LLDPE/RH composites with different filler contents of 5 wt%, 10 wt%, 15 wt%,20 wt% and, 30 wt% RH were investigated. Results show that the yield stress, ultimate compressive strength and the rigidity properties of LLDPE/RH composites were strongly affected by both filler contents and strain rate loadings. Apart from that, the rate of sensitivity of LLDPE/RH show great dependency towards applied strain rate, where it was increased with increasing strain rates. Unfortunately, the thermal activation values show contrary trend. Visually, from the post damage analysis, the results show that applied strain rates affected the deformation behavior of tested LLDPE/RH composites.

Abstract: An experimental approach based on the conventional universal testing machine (UTM) was employed to perform low strain rate loading (0.001/s, 0.01/s and 0.1/s) in this research, to examine the reliance of natural filler contents towards HDPE/sawdust composites. By following to the low strain rate loading, static compression properties of HDPE/sawdust composites with varies filler contents of 5 wt% SD, 10 wt% SD, 15 wt% SD, 20 wt% SD and 30 wt: % SD were successfully studied. The results show that the yields stress, ultimate compression strength and the rigidity properties of HDPE/sawdust composites were sturdily affected by both filler contents and strain rate loadings. Moreover, for the post damage analysis, the results clearly show that different static loading employed to the specimens gives significant effects towards deformation behavior of HDPE/sawdust composites. The increasing of static loading employed caused the specimens to experience severe deformation.

Abstract: The objective of the study was to characterize and to evaluate physical and mechanical properties of experimental particleboard panels made from rubberwood (Hevea brasiliensis) using modified starch-urea formaldehyde as binder. Panels were manufactured using 13% corn starch modified with glutardialdehyde with addition of 2 % urea formaldehyde resin and tested for their physical and mechanical properties. All of the particleboards satisfied the Japanese Industrial Standard which required 2000 N/mm², 8.0 N/mm² and 0.15 N/mm² for modulus of elasticity, modulus of rupture and internal bonding strength, respectively. The mechanical properties were comparable to those made using 15 % urea formaldehyde resin with reduction of formaldehyde fume was over 50 %.

Abstract: Graft copolymers of natural rubber with itaconic anhydride (IA) were prepared in toluene using benzoyl peroxide (BPO) as an initiator. The effects of reaction temperature, reaction time, monomer concentration and initiator concentration on natural rubber grafting were investigated. Graft copolymers (NR-g-IA) were characterized by Fourier transform infrared spectroscopy (FTIR). The grafting content of IA onto NR was estimated by means of FTIR using the absorbance peak ratio for 1783 cm^-1 and 835 cm^-1, corresponding to the symmetric C=O stretching and the =C-H out of plane bending in natural rubber, respectively. Titration was also used to determine the amount of IA grafted onto natural rubber. The optimal grafting conditions for preparation of NR-g-IA were found at 10 phr IA, 2.5 phr BPO, 85°C temperature, and 2.5 hr reaction time.

Abstract: This paper focuses on the study of the effect of chemical treatments of fibres by alkalization on the flexural and impact properties of epoxy matrix composites reinforced by kenaf fibre (KF) produced via resin transfer moulding (RTM) technique. The reinforcement consists of KF nonwoven fiber mat fabricated using needle punching method. Prior to punching process, KF are subjected to alkali treatments with Sodium hydroxide (NaOH) at 3, 6 and 9% for a period of 3h at room temperature. The composites were reinforced with kenaf nonwoven mat at 40% by volume. Effect of alkaline treatment concentration to wettability of KF towards epoxy resins are measured by means of contact angle and surface energy analysis. Influences of alkaline treatment on the flexural properties are studied to determine the optimum conditions of alkaline treatment. As concentration of NaOH in alkaline treatment increased, the experimental results show that the flexural properties of composites increases. For 6% NaOH treatment, the flexural strength and flexural modulus improved by 7.88 MPa to 81.38 Mpa and from 4.79 GPa to 5.41GPa compared to untreated fibre composites. However, as the concentration of NaOH increase to 9%, the bending properties reduced significantly.