The objective of this research is to propose a new way to fabricate a composite material for future bone replacement development via growing apatite crystal on silk fibroin fiber. Apatite crystallization on silk fibroin fiber was prepared by precipitation reaction between Ca(NO3)2 solution and (NH4)2HPO4 solution adjusted pH by NH4OH solution. In this work Effect of solution concentration and initial pH values was investigated on apatite crystals. Chicken eggshells were used as calcium source by heating sufficiently powdered eggshells at 1300 °C for 4 h to acquire CaO powders made Ca(NO3)2 solution by dissolving in 65% HNO3 solution. Prepared Ca(NO3)2 solutions were adjusted concentration as 3 levels and were adjusted different pH values of 7 8 and 9 respectively. For processing of apatite crystallization silk fibroin fibers were immersed in Ca(NO3)2 solutions for 30 min. After that (NH4)2HPO4 solutions were added in silk fibroin fibers immersed in Ca(NO3)2 solutions. Reaction time was fixed about 1 min before cleaning to remove impurity precipitates on surface of silk fibroin fiber. Finally apatite crystallization on silk fibroin fibers occurred. The obtained result can conclude morphologies of apatite crystals on silk fibroin fibers was sheets sphere and flower. Solution concentrations and initial pH values directly influenced on Ca/P ratio of obtained apatite crystals by Ca/P ratio increases as increased solution concentrations or increased pH values. Finally research silk fibroin fibers were woven as two patterns of plain weave and twill weave and they were investigated Young’s modulus and tensile strength. The result indicates that Young’s modulus of silk fibroin fiber sheets woven as twill weave and as plain weave were about 616 MPa and 425 Mpa and tensile strengths of them weave were about 40 Mpa and 72 Mpa respectively. The optimum condition of growing apatite crystals on silk fibroin fibers was sample of CP19. Design of silk fibroin fiber with plain weave was an optimum pattern for future biomedical applicaions.

This research work was to study the chemical release of wood/polyvinylchloride composites (WPVC) affecting the physical and chemical properties of water. WPVC specimens in ratio of PVC and wood (100:100 by weight) were prepared by using twin screw extruder. The water conditions for specimen immersion testing were varied for temperatures of 30-70 oC and specimen immersion time of 0-120 h. The water quality was estimated by measuring pH electrical conductivity turbidity and color of water after immersion of WPVC specimen as comparing with case of PVC specimen. The result suggested that pH values of water slightly decreased with increasing specimen immersion time whereas the change of temperature of water did not affect the pH value. The electrical conductivity remained unchanged with increasing specimen immersion time or temperature except for immersion of WPVC specimens at 70 oC. This might be attributed the weak interfacial bonds between PVC and wood and this led to more easily release the metal ions from additives of PVC. The turbidity and color of water for case of WPVC increased with increasing specimen immersion time whereas those for case of PVC did not change. From the results of water quality testing it indicated that WPVC applications which contact with water are safety. This was because water quality after immersion of WPVC specimen is within the effluent standards of pollution control department.