Materials Science Forum Vol. 840

Abstract: In this research, the effect of stirring and aging time on the formation of β-tricalcium phosphate (β-TCP) powder was studied. β-TCP powder was synthesized using calcium nitrate tetrahydrate (Ca(NO₃)₂.4H₂O) (0.6M) and diammonium hydrogen phosphate (NH₄)₂HPO₄) (0.4M) via wet precipitation method. The mixture was stirred with different duration (1, 3, 5 and 7 hours) then centrifuged before washed with distilled water (twice) and ethanol followed by drying in oven (80°C, 24 hours). The cake was ground to form powder. The as prepared powder was analyzed using thermo-gravimetric (TGA) to determine the suitable calcinations temperature. TGA results show that the proper calcinations temperature was 800°C. The formation of β-TCP was characterized using X-ray Diffraction (XRD) analysis. Sample with optimum formation of β-TCP phase will choose for further study on the effect of aging time (0.5, 1, 20 and 24 hours). XRD analysis confirmed that sample stirred for 7 hours and aging for 24 hours produced β-TCP as major phase. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) proved that β-TCP powder form as agglomerated particles

Abstract: Anodic oxidation is an electrochemical method for the production of ceramic films on a metallic substrate. It is a simple and low cost method to produce bioactive material. This work describes the effect of ultrasonic amplitude on the surface properties of anodised titanium. Specifically, high purity titanium foils were anodised in mixture of 0.04 M β-glycerophosphate disodium salt pentahydrate (β-GP) and 0.4 M calcium acetate monohydrate (CA) at 350 V and 70 mA.cm^-2 for 10 minutes. The ultrasonic amplitude was varied from 20-60 μm. Next, field emission scanning electron microscopy (FESEM) glancing angle X-ray diffractometer (GAXRD) and atomic force microscopy (AFM) were used to characterise the anodised titanium. The results showed that application of sonication is able to remove the entrapped bubbles on the anode surface and enhance the oxidation process. The pores size and surface roughness were increased as increasing of ultrasonic amplitude. At ultrasonic amplitude ≥ 50 μm, rutile TiO₂ was formed on the surface of oxide layer. It was found that the sonication is a simple method to improve the surface properties of anodised titanium for implant applications.

Abstract: Gelatin extractedfrom fish skin is an alternativeresource instead of mammalian animals. Theextraction process of gelatin from black tilapia skin was carried out throughthe use of hydrochloric acid (HCl) with different concentration (0.05 M – 1.0 M)and followed by a final extraction with water at 50°C for 4 hours and endedwith drying. Characterization of gel strength was done in accordance with BSI:1975while moisture content and percentage yield on wet basis with AOAC 1999. Theeffects of acid concentration used during pre-treatment process on yield andphysical properties of fish gelatin were measured. The yield of gelatin for0.05 M and 1.0 M were 10.45% to 22.25% respectively. The gel strength ofgelatin at 0.05 M is the highest (833 g) due to longer storage time. Gelatin whichtreated with high acid concentration gives lower in gel strength that suitableas an edible gelatin.

Abstract: Anodic oxidation is an effective method to modify the smooth surface (bioinert) of titanium to rough or porous surface (bioactive) to be able the titanium to be used as artificial implant in biomedical. In this study, the effect of ultraviolet (UV) light treatment on anodised titanium in various UV light treatment conditions is evaluated. Anodised titanium was prepared using traditional anodic oxidation method in 0.3 M of sulphuric acid (H₂SO₄). The anodised titanium was modified by using 100 V of applied voltage with constant 75 mA.cm^-2 current density for 10 min of oxidation process at room temperature. After anodic oxidation, the anodised titanium undergoes UV light treatment under different wavelength and soaking duration in distilled water. The anodised titanium films were characterised using X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM). Contact angle goniometer was used to determine the wettability properties of UV light treated anodised titanium. From this study, the UV light treatment affect the wettability properties of the anodised titanium without changing it physical properties. The UV-C (365 nm) of UV light wavelength with 4 hours soaking duration produced better hydrophilic properties. This will leads better apatite formation ability when soak in simulated body fluid for bioactivity test.

Abstract: Anodic oxidation is an electrochemical method to deposit ceramic coatings on the metals substrate to improve the bioactivity. This study aims to investigate the effect of bath temperature on the surface properties of anodised titanium. High-purity titanium foil was modified by anodising in mixture of β-glycerophosphate disodium salt pentahydrate (β-GP) and calcium acetate monohydrate (CA). The experiments were carried out at 350 V, 30 mA.cm^-2 for 10 minutes at different bath temperature (4-100 °C). Field emission scanning electron microscopy (FESEM), glancing angle X-ray diffractometer (GAXRD) and goniometer were used to characterise the surface morphology, mineralogy and wettability of anodised titanium, respectively. The results showed that porosity and crystallinity of surface decreased as increasing of bath temperature. Interestedly, the α-tricalcium phosphate (α-TCP) was deposited on the samples which anodisation at higher bath temperature (≥ 60 °C) and resulted high hydrophilicity behaviour even the surface was found relatively smooth.

Abstract: Microdialysis, being a well-established sampling technique, still suffers from mass transfer limitations. Arguably, the biggest contributor to mass transfer limitation in this case is the membrane layer. To reduce limitations to mass transfer, and at the same time, increasing the performance of microdialysis probes, a concise mass transfer analysis must be done. For microdialysis probes, being relatively small in size and operating under possibly stringent biological conditions, an experimental route of analysis is less preferred compared to a computational route. This paper looks at the needs of computational mass transfer studies, and provides an idea why a comprehensive physical characterization effort is imperative for computational mass transfer studies.

Abstract: The porous scaffold has a weakness in terms of compressive strength. This is due to the porosity that is inversely proportional to the strength of the porous scaffold. Greater the percentage of porosity will decreasing the compressive strength. However, this compressive strength can be improve by controlling several factors (i.e., number of PU pores, composition ratio of slurry, percentage of binder and number of coating process). In general, fabrication porous alumina by conventional process was takes a longer time and consuming high cost. In addition, the conventional process could not explain the interaction relationship between all factors. Therefore, experimental design using Minitab 16 is applied to investigate the factors’ interaction. From the analysis, a combination of composition ratio and number of coating were found to have a significant impact to increase the compressive strength (> 2MPa) while others are less significant.

Abstract: The purpose of this study is to investigate the effect of nitrile butadiene rubber (NBR) particles and ceramic fillers on the density of PMMA denture base materials. The denture base was prepared based on the mixture of PMMA powder and MMA liquid. The density of the denture base has been modified by adding three different ratios of nitrile rubber (5, 7.5 and 10 wt %), three types of ceramic fillers (Al₂O₃, YSZ and SiO_2, respectively) fixed at 5 wt %, 0.5% of benzoyl peroxide (PBO) and ethylene glycol dimethacryate (10 wt% EGDMA). The powder/liquid (P/L) was mixed by 2.5:1 g ratio. At 10 wt% of NBR the denture base density has reduced to 50%. Furthermore, the addition of ceramic fillers together with NBR particles has also reduced the denture base density. The density data was statistically analysed by on-way (ANOVA) and the values were significantly effect when addition of rubber particles in PMMA denture base composite (p < 0.05).Therefore, the density issue can be easily adjusted in retention and stability of denture base in the patient mouth.

Abstract: Cobalt Chromium Molybdenum (CoCrMo) is a metal that are widely used in the biomedical field of orthopedic applications. CoCrMo foam was developed in the form of a porous structure where it has a high porosity on the surface with the different pore sizes and shapes. This research is intended to produce CoCrMo foam by using slurry method and to study the effect of composition and sintering temperature on the metal foams. The slurry of CoCrMo was prepared by mixing the binder materials of Methylcellulose (CMC), Polyethylene Glycol (PEG) and distilled water for an hour. Followed by mixing and stirring the CoCrMo powder for another 1 hour until it becomes slurries. Polyurethane (PU) foam was then impregnated into the slurry and dried for a day in the oven with 60 °C. Sintering process is carried out at temperature of 1000 °C, 1100 °C and 1200 °C using a tube furnace. Then sample of CoCrMo foam was going through a shrinkage measurement, microstructure analysis by using Scanning Electron Microscope (SEM), analysis of element by using Energy Diffraction X-ray (EDX) and also the density and porosity test by using Archimedes method. The sample with the composition of 65wt% was the best result in this experiment. While sintering temperature of 1200 °C produced the highest number of porosities. The shrinkage percentage is from 2.67% to 14.13%. The density obtained is in between 1.538 g/cm3 and 2.706 g/cm3 while the percentage of porosity is from 50.284% to 78.934%. The average pore size is in the range of 249.63μm to 445.38μm. The best sintering temperature and composition to produced high porosity were on 1200 °C and 65wt%.

Abstract: Slurry dipping is a simple and popular method of producing porous and interconnected foams using a metallic slurry. The advantage of the network-like metal foams is it exhibits a natural bone-like structure which enables ingrowth of bone cells and blood vessels. The aim of the present study was to investigate the effect of using difference composition and scaffold to produce Cobalt Chromium Molybdenum (CoCrMo) foams. The CoCrMo slurry was prepared by using different composition of CoCrMo powder which was 60wt%, 65wt% and 70wt%. Also two different types of scaffold were used in this study. The CoCrMo slurry was produced by mixing CoCrMo powder with Polyethylene Glycol (PEG), Carboxyl Methyl Cellulose (CMC) and distilled water. Then, polyurathane foam template was dipped in CoCrMo slurry and dried at room temperature. Sintering process was running by vacuum furnace at high temperature, 1200°C. The CoCrMo foam was characterized by using a Scanning Electron Microscopy (SEM) analysis. The physical properties of CoCrMo foam was analyzed by porosity and bulk density test that was Archimedes method. From the study it was expected that the composition of metallic slurry play important roles to produce a CoCrMo foam. In order to orthopaedics application to apply in cancellous bone, highest value of porosity from PU foams type (a) was most suitable result to use. This is due to the value of porosity that generate that was 65.2%.