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Injection molded vetiver-polypropylene (PP) composites at various ratios of vetiver content and vetiver length were prepared. When compared to PP, vetiver-PP composites exhibited higher tensile strength and Young's modulus but lower elongation at break and impact strength. An increase in vetiver content led to an increase in viscosity, heat distortion temperature, crystallization temperature, and Young's modulus of the composites. On the other hand, the decomposition temperature, tensile strength, elongation at break, and impact strength decreased with increasing vetiver content. The chemical treatment of the vetiver grass improved the mechanical properties of the composites.

This study was a preliminary observation for a potential use of the bovine bone-based hydroxyapatite (b-HA)/poly(lactic acid) (PLA) composite as a biomaterial. SEM micrographs, XRD pattern, and FTIR spectrum of calcined bovine bone revealed that the obtained powder was in a form of crystalline carbonated HA, and highly agglomerated. The surface of HA powder was modified with either 3-aminopropyltriethoxysilane (APES) or 3-methacryloxypropyltrimethoxysilane (MPTS) in order to enhance the compatibility between b-HA and PLA matrix. TGA and GPC results revealed that the incorporation of silane-treated HA into the PLA matrix significantly increased thermal stability of the composites and decreased the thermal degradation of PLA chains. SEM micrographs revealed that modification of HA with APES or MPTS eased dispersion of HA in PLA matrix and enhanced interfacial adhesion between both phases. Therefore, the mechanical properties of silane treated HA/PLA composites were improved as compared with those of b-HA/PLA composites. In addition, in vitro cytotoxicity tests indicated that the extracts from all HA/PLA composites had no toxicity to human osteoblast cell.

The effect of natural fibers (vetiver grass and rossells) on quiescent crystallization of polypropylene (PP) composites was analyzed in this study. Also, equilibrium melting temperature (T 0 m ) of the composites was elucidated. Natural fiber-PP composites showed lower T 0 m when compared to neat PP. Thermal analysis was performed via differential scanning calorimeter to study the crystallization kinetics. Natural fiber-PP composites exhibited higher rate of crystallization than that of neat PP. Furthermore, spherulitic growth rate and transcrystallinity of the composites were investigated under a polarized light optical microscope. It was found that the growth rates of the composites were lower than that of neat PP. The spherulitic growth rates combined with the crystallization rates were used to calculate number of effective nuclei. It was shown that the number of effective nuclei of the composites was higher than that of neat PP. This suggested that natural fibers could act as a nucleating agent in the composite.

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Tuned spherical vaterite calcium carbonate polymorphs have been precipitated from discarded eggshells and loaded with silver nanoparticles by in situ synthesis.