Advanced Materials Research Vol. 748

Abstract: The effect of bio-polymer as compounding material in mechanical properties of HDPE is described in this study. 10% of bio-polymer was added to the HDPE and then mixed by using Brabender Plastograph machine using mixer and roller screw and then test specimens were prepared by injection moulding. The origin bio-polymer (VOP), HDPE and the compounding bio-polymer/ HDPE (CDM) were compared by using tensile test and the microstructure was investigated through scanning electron microscopy (SEM) for the fractured surface of the samples. The tensile strength of CDM was found to increase that is 17.47 MPa compared to pure VOP that only 5.69 MPa while pure HDPE has the highest tensile strength that is 20.98 MPa. By adding 10% bio-polymer to the HDPE was increased up the strength at about 207.16% while pure HDPE produced 268.91% increment with VOP as the precursor. SEM of the VOP produced brittle fracture surface while CDM have brittle and ductile surface and HDPE has totally ductile surface with highest plastic deformation properties of all.

Abstract: This study aims to evaluate the influence of solvent acids and glycerol as plasticizer on the antimicrobial and physical properties of chitosan films. Three types of acids were used in the same concentration, e.g. 1% acetic acid, 1% citric acid and 1% lactic acid whereas glycerol was fixed on 10% (w/w). In terms of barrier properties, chitosan film obtained by citric acid as solvent showed the lowest water vapour transmission rate (WVTR) followed by chitosan film prepared with lactic acid and acetic acid. Concerning mechanical properties, chitosan film prepared with acetic acid exhibited the highest tensile strength and the lowest percentage elongation. The expected result was obtained where plasticized chitosan films had higher percentage elongation than the unplasticized one. In this study, disc and well diffusion method were used against bacteria, yeast and fungi to characterize antimicrobial activity of the obtained films. When the disc diffusion method was used, all of chitosan films showed an inhibition activity against E. coli, B. cereus and S. aureus whereas no inhibition against Penicillium sp. and Candida sp except chitosan film prepared with acetic acid that showed inhibition against Candida sp. The same result was observed by using well diffusion method with the exception of chitosan solutions prepared with acetic acid solution where they also showed inhibition activity against Penicillium sp. and Candida sp.

Abstract: Bamboo is known as economically and environmental friendly plant. The most common application of bamboos is furniture and traditional handcrafts. Many studies on mechanical and physical properties of bamboo have been conducted. However the thermal insulation property of these abundance species has never been recognized and commercially utilized which results in the reason why thermal properties of bamboo have never been studied. In this experiment, two species of bamboo which are Akar bamboo (Dendracalamus pendulus) and Semantan bamboo (Gigantochloa scortechinii) has been tested to determine their thermal conductivity. The test samples were prepared to conduct this experiment in parallel and perpendicular grain direction towards the heat source. Wood adhesive was used as the binder for cylindrical laminated bamboo. The result shows that thermal conductivity of bamboo is low in perpendicular direction towards the heat source compared to the parallel direction. Different species of bamboo also give significant result on thermal conductivity hence improved the insulation properties of the bamboo.

Abstract: This study reports on the effect of UV-light on the mechanical properties of bio polymer thin films (BPF) doped with 10 % Titanium Dioxide (TiO₂). Bio monomer was mixed with 4, 4-methylenebis (phenylisocyanate) (MDI) to produce neat BPF and TiO₂ was added to form BPF doped with 10 % TiO₂. The film samples were irradiated in UV Accelerated Weatherometer at 50 °C with different exposure time. Universal Testing Machine was used to measure the tensile strength and the fracture surfaces of the tensile specimens were observed by Scanning Electron Microscopy (SEM). The maximum tensile strength of UV irradiated neat BPF is lower than BPF doped with 10 % TiO2 of 3.5 MPa and 4.2 MPa respectively. Stress of neat BPF was decreased from 3.7 MPa to 3.2 MPa after 144 hours of UV exposure at 50 ^°C while BPF doped with 10 % TiO₂ decrease from 4.7 to 3.6 MPa. The Modulus Young of neat BPF is lower than BPF doped with 10 % TiO₂ which are 0.32 GPa and 0.33 GPa respectively. The cumulative strain percentage irradiated neat BPF is lower than BPF doped with 10 % TiO₂ with 98.7 % and 113.7 % respectively. Unexposed UV light of neat BPF and BPF doped with 10 % TiO₂ were observed by SEM shows smooth fracture and brittle fracture respectively. Neat BPF and BPF doped with 10 % TiO₂ exposed to UV light show higher ductility property as compared to unexposed BPF. The higher the exposure time of BPF to UV light, revealed systematic increment of tensile strength due to increased crosslink between isocyanate and hydroxyl group.

Abstract: Majority of engineered wood product such as glulam, laminated veneer lumber and parallel strand lumber relies greatly on wood adhesive bonding and adhesive penetration. Determination of bonding strength and adhesive penetration of adhesive-wood could enhance effective utilization of wood as construction material. Kapur (Dryobalanops aromatica) and Kelat (Syzygium spp.) were two commercial Malaysian medium hardwoods were used in the study. Since pressure is essential during wood bonding, the purpose of the study is to determine the effect of different pressure on bonding strength and adhesive penetration. Kapur and Kelat samples were bonded using Phenol resorcinol formaldehyde (PRF) and press at three different pressures (100 psi, 200 psi and 300 psi). Shear stress of bond line and Adhesive penetration were measured. The result shows that Kapur has lower bonding strength compares to Kelat and both samples pressed with 200 psi pressure shows higher shear strength then 100 psi and 300 psi. The result of adhesive penetration shows that higher pressure applied during bonding assembly resulting in the higher adhesive penetration into the wood porous structure.

Abstract: Various types of metals and alloys are used for medical implants due to their excellent mechanical properties and corrosion resistance; however, their lacks of osteoinductive properties bring about the introduction of biomaterials which can help enhancing the bioactivity between the bones and the implants. Hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂, or HA) which is one of the calcium phosphates that has similar mineral constituents of human bone, has been used as coating material to the metals/alloys substrate. Coating HA usually involves high-temperature such as the plasma spraying coating, which can alter the crystal structure of the HA partially become amorphous. The amorphous nature of HA lessen the benefits of coating with the biomaterial HA. Electrostatic spray deposition (ESD) was used in this research due to the fact that this process is simple, economical, and room-temperature operated. The preliminary results showed a promising thickness layer of about 40 μm; however, the adhesion of the coated layer to the stainless steel 316L was improved by mixing the HA powder with phosphate bioglass and cured in the vacuum furnace at 700oC. Taguchi experimental design technique was used for screening several ESD process parameters: powder feed rate, voltage, current, air volume, distances, time, and nozzle types to significant factors to the coated thickness of the ESD process. The results showed that feed rate, air volume, and time were the significant factors and then Full factorial analysis and response surface method was used for obtaining optimal conditions for the coating, as well as the predicted equation for determine the thickness coated layer with significant factors.

Abstract: Current trend has demonstrated the implementation of natural polymers as alternative materials in various engineering applications including biomaterials and biomedical applications. This paper reviews the potential of Cellulose Phosphate derived from Oil Palm Empty Fruit Bunch (OPEFB-CP) as a biomedical material. OPEFB-CP will act as reinforcement to glass materials in fabricating good and flexible scaffold composite materials. A 3-dimensional scaffold composite material comprised of the cellulose phosphate and glass material was produced by using a sol-gel technique. The composite biomaterial is expected to have degraded together as one material.

Abstract: Titanium and titanium alloys are widely used in aeronautical, marine, chemical and biomedical applications and so on, owing to their specific properties such as good corrosion resistance, low densities, high specific strength and modulus, and high-temperature resistance. However titanium and titanium alloys also have many disadvantages, such as low hardness, low wear-resistance and the low corrosion-resistance in some cases, which limit their wider application. Recent years, the corrosion resistance of titanium and titanium alloys is required to elevate in some fields. Proper surface modification can solve the problems effectively. This paper reviews the recent investigations of laser surface modification to improve the corrosion resistant of titanium and its alloys. The microstructures, the corrosion resistance properties, and the influence factors of the coatings were discussed systematically. And the future prospect of the further researches and uses is presented.

Abstract: Titanium and titanium alloys possess some attractive properties, such as excellent corrosion and erosion resistance, low densities, high specific strength and modulus, enabling them extensively used in aeronautical, marine, chemical and biomedical applications and so on. Nevertheless, Recent years, the corrosion resistance of titanium and titanium alloys is required to elevate in some fields, proper surface modification such as surface oxidation can solve the problems effectively. In this paper, the recent investigations of thermal oxidation and micro-arc oxidation to improve the corrosion resistant of titanium and its alloys are reviewed. The structures, properties and their influence factors of the coatings are analysed systematically. And the existing problems and the future prospect of the further researches is mentioned.

Abstract: Laser cladding, as an effective method of metal surface modification, is to fuse an alloy coating of enhanced mechanical and chemical properties on the surface of a substrate. Therefore, laser cladding has been attracting continuous and extensive research for years. In this paper, the research progress in laser clad cobalt-based alloys is summarized. The preparing processes, microstructures, properties and influence factors of laser clad cobalt-based alloys coatings and their ceramic particles strengthened composites coatings are analyzed systematically. And the existing problems, some solving measures, the development tendencies and industral uses are presented.