Hydroxyapatite (HA)-reinforced high density polyethylene (HDPE) was developed as a bone replacement material. In order to enhance the interfacial bonding between HA and polyethylene and improve the mechanical properties of HDPE/HA composites, the surface of the micron-sized HA particles was modified by in situ polymerization of butyl acrylate (BA) and in situ copolymerization of vinyl triethoxyl silane (VTES) and BA, then the modified HA particles were compounded with HDPE. The effects of the surface modification of HA on morphology and mechanical properties of HDPE/HA composites were investigated. The experimental results show that the presence of HA particles does not inhibit the polymerization of BA. The poly(butyl acrylate) (PBA) segments on the HA surface enhance the compatibility between HA and HDPE, improve the dispersion of HA particles in HDPE matrix, and enhance the interfacial adhesion between HA and matrix. Surface modifications, especially by in situ copolymerization of VTES and BA, significantly increase notch impact strengths and marginal stiffness and tensile strengths of HDPE/HA composites. And it is found that there is a critical thickness of PBA coating on HA particles for optimum mechanical properties of HDPE/HA composites.
The surfaces of the micron-sized HA particles were modified by in situ copolymerization of vinyl triethoxyl silane (VTES) and styrene (St). Then, the modified HA particles were compounded with HIPS. The results showed that the polystyrene (PS) macromolecules were grafted on the surfaces of HA particles during in situ copolymerization of VTES and St. Thereby, PS chains grafted on the HA surface enhance the compatibility between HA and HIPS, improve the dispersion of HA particles in HIPS matrix, and enhance the interfacial adhesion between HA and matrix. The stiffness, tensile strength and notch impact strength of HIPS/HA composites are improved at the same time. And there is a critical coating thickness of PS to the HA surface for the optimum mechanical properties of HIPS/HA composites.
Nano-sized silica particles were modified with methacryloxy-propyltrimethoxysilane(MPS) followed by in situ copolymerization of methyl methacrylate(MMA) and butyl acrylate(BA).These modified nanoparticles were compounded with polypropylene(PP) to prepare PP/silica nanocomposites.PMMA grafted on nano-silica enhances the dispersion of the nanoparticles and interfacial adhesion,decreases the size of PP spherulites in nanocomposites and leads to increasing the Young's modulus and toughness of PP/silica nanoc...
