Materials Science Forum Vol. 1030

Abstract: The effect of doping small amounts of Magnesium Oxide ranging between 0 to 1 vol% on Zirconia Toughened Alumina (ZTA) composites which is one of main biomaterial used for production of total hip arthroplasty were investigated. The samples were produced via conventional two-stage sintering with T₁ varies between 1450°C and 1550°C with heating rate of 20°C/min. The samples were then rapid cooled to T₂ set at 1400°C with holding time of 12 hours. The microstructural and mechanical properties of the two-stage sintered ZTA are then investigated to determine the feasibility of MgO addition. Combination of two-stage sintering at T₁ above 1500 and also small amount of MgO up to 0.5 vol% were shown to have positive effect on ZTA which exhibited improvement on its grain size, mechanical properties such as Vickers hardness, Young’s modulus and fracture toughness compared to undoped ZTA composites. The sample with 0.5 vol% MgO addition sintered at T₁ of 1500°C and T₂ 1400°C was able to achieve Vickers hardness of 19.6 GPa, Young’s modulus of 408 GPa and fracture toughness of 6.8 MPam^1/2 without significant grain growth compared to undoped ZTA composites.

Abstract: The microstructure and mechanical properties of Zirconia Toughened Alumina (ZTA) produced via two-stage sintering at various sintering temperature of T₁ and T₂ in addition to effect of various holding time were investigated. T₁ temperature was set between the range of 1400°C to 1500°C with a heating rate of 20°C/min. The samples were then sintered at T₂ ranging from 1350°C to 1400°C followed by various holding time between 2 hours to 12 hours. The sintered samples’ microstructural properties, bulk density, hardness (Vickers hardness), elastic modulus (Young’s modulus) and fracture toughness (K_1C) were then determined. Compared to standard holding time of two-stage sintering which is 12 hours, results show that ZTA produced via two-stage sintering with shorter holding time of 4 hours with T₁ set at 1500°C and T₂ of 1450°C are capable of achieving full densification. In addition, the same sample were also able to achieve hardness up to 19 GPa, Young’s modulus of 390 GPa and fracture toughness of 6.1 MPam^1/2. The improvement in mechanical properties can be mainly attributed to the absent of surface diffusion at T₂ above 1400°C and also presence of Y-TZP which contributed to lower grain growth due to the pinning effect.

Abstract: In-vitro drug release is used to measure the release of the silver sulfadiazine (SSD) from thermo-responsive cellulose hydrogel using a vertical diffusion cell (VDC). However, selected VDC set-up used by researchers are random, and the studies are lacking in information on the challenging sink conditions during in-vitro drug release study. The objective of this study is to examine the influence of VDC set-up on the in-vitro SSD drug release from thermo-responsive cellulose hydrogel. VDC set-up including receptor medium composition, membrane type, and stirring speed were studied. The results depicted that SSD release rate increased with increasing ammonia percentage in phosphate buffer solution. On the other hand, membrane type do not influence SSD release rate. While, increasing stirring speed results in forming vortex or air bubble entrapment underneath the membrane. 0.25 v/v% ammonia receptor medium, cellulose membrane or polysulfone membrane, and 600 rpm stirring speed are the optimum VDC set-up, confirming sink condition and discriminating ability of this optimum VDC set-up. This work has successfully studied the influence of VDC set-up on in-vitro SSD drug release from thermo-responsive cellulose hydrogel, and the optimum VDC set-up was selected.

Abstract: Hydroxyapatite (HA)-Zirconia (ZrO2) composite with varying zirconia composition ranging from 1 to 10 wt% was investigated for biomedical applications in order to produce high compressive strength. Precipitation method was used to prepare both hydroxyapatite and zirconia powders. To find the ideal composition, mixture-containing 1, 3, 5 and 10 wt% ZrO2 powder was added. Each mixture was sintered for 4 hours at 750^oC, 1050^oC and 1250^oC. Hardness and compressive strength test were used for evaluation. It was found that with 1 wt% of ZrO2 sintered at 1250^oC showed the greatest structural strength as its volume fraction porosity is the lowest. The hardness and compressive strength of this sample were found to be 2.75 GPa and 72.0 MPa respectively. This can be useful for biomedical applications especially in promoting osteo-integration.

Abstract: Aloe Vera and sea cucumber are the natural material which has been used widely in bio-medical field in Malaysia, especially for wound healing purposes due to its therapeutic effects. Recently, thin films which can absorb acceptable amount of fluid has been gaining attentions in biomaterial wound dressing applications. Hence, the incorporation of these natural materials in the fabrication of the thin films were investigated regarding the fluid intake capacity under the condition of being in contact with deionized water and pseudo-wound exudate. Three types of films made of different compositions of Aloe Vera and sea cucumber were prepared and evaluated. The morphology of the films was analysed using the Scanning Electron Microscopy (SEM) evaluation and the fluid intake capacity through the Free Swell Absorptive Capacity test. Results showed the variety of fluid intake capacity of different type of the film after being immersed in both solutions. The morphological structure of each film also varied from one another. The result also indicated that the Aloe Vera film held the adequate fluid intake capacity without any degradation behaviour.

Abstract: Pineapple leave fiber (PALF) can be considered as one of the green materials to the industries, which is the potential to replace the non-renewable synthetic fiber. However, the high disparity in the mechanical properties of PALF becomes an issue in structural composite design. Hence, improved Weibull distribution is utilised to quantify the tensile strength variation of PALF in various gauge lengths. The single fiber tensile test was performed after the fiber surface treatment and fiber diameter scanning. The predicted PALF strength by applying the improved Weibull distribution incorporating with conical frustum model is well compromised with experimental data compared to the traditional Weibull model.

Abstract: The world as we probably are aware of is confronting a major problem known as environmental pollution, therefore, leading to global warming. Researchers from around the world have been focusing on green composites to improve the general effect of polymer pollution leading to environmental pollution. This need has constrained numerous researchers to concentrate on making composites utilizing natural fibers and biodegradable polymers. Moreover, natural fibers are cheaper to purchase, have great mechanical properties, biodegradability and demand lower amount of production energy. This paper focuses on one of the natural fibers known as Luffa Cylindrica (LC). Chemical surface treatments are necessary in order to get the best adhesion possible between the polymer and fiber which leads to better mechanical properties. Therefore, in this paper sodium hydroxide, silane and acetylation chemical surface treatments were performed. Furthermore, with the help of Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA) and Derivative Thermogravimetry (DTG) it was predicted that all the chemical surface treatments were successful. With the help of the results it was predicted that these specific chemical surface treatments showed removal of hemicellulose and lignin. Furthermore, with the help of thermal analysis it was predicted that silane treated samples showed highest amount of thermal resistance whereas, acetylated samples predicted lowest.

Abstract: Natural fibers have advantages over that of synthetic fibers such as biodegradability, low densities, and low cost of production. Optimum interfacial bonding is crucial since it determines the mechanical properties of a polymer-based composite materials. Surface treatment needs to be performed prior to the composites fabrication in order to improve the interfacial bonding. Coating application is an environmentally friendly alternative to the conventional methods of fiber treatments. In this research, the mechanical properties such as tensile (37.1 per cent increase), flexural strengths (61.7 per cent increase) and hardness (31.4 per cent less prone to surface indentation) of rice straw reinforced Polylactic acid composite at 10 wt% fiber and 90 wt% polymer after fiber treatments are analyzed through fabrication and testing. The fiber treatments involved are alkali treatment, heating treatment and coating. The results showed observable increase in tensile, flexural strengths and hardness for alkali treatment, heat treatment. However, from coating process, there is only slight increase in all the mechanical tests. These results have inferred that heat treatment has the highest improvement in mechanical properties, followed by alkalization and then comes coating.

Abstract: The Disposal of Scrap Tires has Resulted in Major Environmental Problems Worldwide. Therefore, Utilizing Scrap Tires as Crumb Rubber is being Used in Brick Production to Improve the Properties of the Bricks as well as to Provide Feasible Waste Management of Scrap Tires. this Study Presents the Literature Research on Utilizing Crumb Rubber in Bricks Manufacturing. the Review Summarized the Manufacturing Process of Producing Crumb Rubber and then Documented the Application of Crumb Rubber in Masonry. the Results Show that the Compressive Strength of Masonry Bricks Decreases with the Increased Percentage Substitution of Crumb Rubber as a Replacement of Fine Aggregate while the Water Absorption Increased. Moreover, the Addition of Crumb Rubber in Masonry Applications Reduce the Density which Produce Lightweight Masonry Products. Generally, the Findings Confirmed that the Masonry Bricks Incorporated Crumb Rubber Exhibit Good Physical and Mechanical Properties. the Usage of Crumb Rubber in Bricks Making Helps to Solve Problems Associated with Scrap Tire Management all over the World.