Applied Mechanics and Materials Vols. 754-755

Abstract: A novel hybrid carbon nanotube-muscovite (CNT-muscovite) compound was synthesized via chemical vapour deposition (CVD) by directly grown CNT on muscovite particles. The synthesis of CNT using nickel catalyst and muscovite as a substrate material is rarely found. Morphological analysis using scanning electron microscope (SEM) and high resolution transmission electron microscope (HRTEM) showed that the CNT was successfully grown on muscovite flaky particles. The CNT-muscovite compound can be potentially used as a new class of filler in polymer composites technology.

Abstract: Blending of two or more polymer together can reduce the cost and better processing advantages of product. Waste rubber powders blending with polymeric materials provide an improvement to the rubber quality. In this work, the effects on tensile and morphology of ethylene propylene diene monomer blended with recycled nitrile gloves (EPDM/NBRr) were studied. Four different compositions of ethylene diene monomer (EPDM) and recycled acrylonitrile butadiene rubber (NBRr) with two different size of NBRr (S1: 250-500μm and S2: 3-10cm) were used. The compositions of EPDM/NBRr prepared were at 95/5, 15/85, 25/75 and 35/65 respectively. The properties of tensile and resilience of EPDM/NBRr blends were determined. Results indicated that the tensile strength and elongation at break (Eb) of EPDM/NBRr blends decrease as increase in NBRr for both S1 and S2. However, the tensile modulus (M100) shows an increment with increase NBRr. Results of resilience decreases and scanning electron microscopy study indicates that when more than 35 phr of NBRr content were used, NBRr exhibited a weak EPDM/NBRr matrix interaction, thus decreasing the mechanical properties of EPDM/NBRr blends. For overall results, 15 phr ratio of NBRr in EPDM/NBRr (S1) blend showed an optimum result respectively.

Abstract: The effect of carbonization temperature and heating rate on the characteristics of carbonized bamboo were investigated. Bamboo was carbonized at different temperature (250, 450 and 650°C) and heating rate (5 and 15°C/min). The results obtained shows that the char yield decreased with increasing temperature as well as heating rate. The carbon content is higher at higher temperature and heating rate. It also was observed from X-Ray Fluorescence (XRF) analysis that potassium and silica were the most predominant elements in carbonized bamboo. From Fourier Transform Infrared Spectroscopy (FTIR) spectra, it can be seen that most of the functional groups were diminished as the raw bamboo was carbonized and the intensity decreased with increasing carbonization temperature. Carbonization at 650°C with heating rate of 15°C/min was the best parameter for producing carbonized bamboo which content higher carbon.

Abstract: Most of the polymeric materials blending together with recycled waste rubber powder attributed to the economical and processing advantages for product specification. Therefore, the effect of curing characteristics, hardness and crosslink density of ethylene propylene diene monomer/recycled acrylonitrile butadiene rubber (EPDM/NBRr) blends were studied. The EPDM/NBRr blends were prepared at four different compositions (95/5, 85/15, 75/25 and 65/35) with two different sizes (S1: 250-500μm and S2: 3-10cm) of NBRr. Results indicated that the scorch time t₂, cure time t₉₀, and maximum torque (MH) for both EPDM/NBRr (S1) and EPDM/NBRr (S2) decreased, but the minimum torque (ML) increased.The increase of NBRr content in EPDM/NBRr leads to the increase in hardness and consequently decreases the crosslinking density of the blends. The incorporation of 15phr of S1 recycled NBRr appeared to better overall properties.

Abstract: The effects on curing characteristics and physical propertiesof recycled nitrile glove (NBRr) filled epoxidized natural rubbers (ENR25) were examined. Two different size ranges of NBRr particles, i.e., S₁ (250μm-500μm) and S₂ (2cm-5cm) were used in this study. The NBRr/ENR25 compounds with five different compositions of NBRr (5, 15, 25, 35 and 50 phr) were prepared using a two roll-mill at room temperature. The result of cure characterization show that scorch time, t₂ and cure time t₉₀ of the NBRr/ENR25decreased with the increased of NBRr content due to the existence of crosslinked precursors and unreacted curativein the recycled rubber.NBRr/ENR25 compounds with fine size, S₁ of NBRr particles exhibit lower minimum torque (M_L) compared with the coarse size, S₂ which resulted in more efficient processing. The maximum torque (M_H) of all NBRr/ENR25 compounds show the increasing trend with increased NBRr content probably due to the good interactions in NBRr/ENR25 compounds. For physical properties, NBRr/ENR25 compounds with fine size, S₁ of NBRr particles exhibited the higher hardness and crosslinking density at all compound ratios. The results overall indicated that the NBRr/ENR25 with fine size, S₁ of NBRr particles show better cure characteristics and physical properties (crosslink density and hardness test) compared to coarse size, S₂ of NBRr particles.

Abstract: The effects of mechanical properties (tensile properties and resilience test) and morphology of recycled nitrile glove (NBRr) filled epoxidized natural rubbers (ENR25) were examined. Two different size ranges of NBRr particles, i.e., S₁ (250μm-500μm) and S₂(2cm-5cm) were used in this study. The NBRr/ENR25 compounds with five different compositions of NBRr (5, 15, 25, 35 and 50 phr) were prepared using a two roll-mill at room temperature. The result indicated that the tensile properties such as tensile strength and elongation at break decreased as the ratio of NBRr increased. Meanwhile stress at 100% elongation show an increasing trend with the addition of recycled nitrile glove in ENR25. The resilience properties of NBRr/ENR25 compounds decreased when NBRr loading increased. The scanning electron microscopy studies showed that the fine size, S₁ of NBRr particles in NBRr/ENR25 compounds illustrated a better NBRr-ENR25 matrix interaction compared with coarse size, S₂ of NBRr particles. The results overall indicated that the NBRr/ENR25 with fine size, S₁ of NBRrparticles show better mechanical properties (tensile properties and resilience properties) and morphology compared to coarse size, S₂ of NBRr particles.

Abstract: This paper presents the multi-scale hybridization of carbon nanotube (CNT) with microparticles in polymers which offers new opportunity to develop high performance multifunctional composites. The hybrid carbon nanotube-alumina (CNT-Al₂O₃) compound was synthesized via chemical vapour deposition (CVD) by direct growth of CNT on alumina particles. This hybrid CNT-Al₂O₃ compound was incorporated into the epoxy matrix at various filler loadings (i.e., 1–5%) and compared to physically mixed CNT-Al₂O₃. The CNT-Al₂O₃ hybrid epoxy composites showed higher hardness compared to the CNT-Al₂O₃ physically mixed epoxy composites. This enhancement was associated with the homogenous dispersion of CNT-Al₂O₃ hybrid compound in the epoxy matrix.

Abstract: Studies on the thermoplastic elastomers (TPEs) had been extensively done. The incorporation of recycled materials into the TPEs formulation had been analysed, particularly involving recycled plastic due to its properties. The effects of partial replacement of virgin polyethylene (vPE) with recycled polyethylene (rPE) on the thermal properties and swelling behaviour of vPE/rPE/EPDM blends were studied. The discarded polyethylene used in the study was obtained from local wire insulation industry. The thermal properties and swelling behaviour of the blends were analyzed. Results show that increasing of sulfur loading had improved the thermal stability of the blends. The swelling percentage and swelling index of vPE/rPE/EPDM blends also decreased, inversely proportional to the increasing of sulfur loading. Thus, the increased incorporation of sulfur loading had improved the chemical and oil resistance of the blends.

Abstract: Geopolymers can be transforms into ceramics upon sintering. This paper reports the effect of temperature on the mechanical properties and microstructure of Na based kaolin geopolymer ceramic. The Na₂O.Al₂O₃.4SiO₂ was fabricated through powder metallurgy method. The geopolymers samples were exposed to temperature from 900 °C up to 1200 °C. The relative density, total porosity and flexural strength of sintered sample ranged approximately 84%-95%, 5.04%-15.73% and 20-70 MPa respectively. SEM analysis on as-sintered sample showed glassy phase while polished sample showed the pore structure and distribution. XRD results showed that nepheline appeared in all heated samples. Samples heated to 1200 °C achieved highest flexural strength and toughness of 70MPa due to the optimum density.

Abstract: Clay based geopolymer ceramic were produced through the geopolymerisation process by the alkali activation of kaolin with an activator solution which is mixture of sodium silicate and sodium hydroxide and undergoes heating at elevated temperature. The concentration of NaOH used in this study was in the range of 6 M-12 M. The ratio of kaolin to alkaline activator used is 1.0. Three different ratios of Na₂SiO₃/NaOH of 0.16, 0.24 and 0.32 were used to investigate the optimum flexural strength. The samples were cured at 80 °C for 24 hours and sintered at temperatures ranging from 900 °C-1200 °C. The optimum flexural strength of 86.833 MPa is obtained when the ratios of Na₂SiO₃/NaOH is 0.24 with the NaOH concentration of 12M at 1200 °C.