Abstract
Spherical aggregates of hydroxylapatite (HAp) were prepared by the reactions with colloidal calcium carbonate (CaCO3) and were surface-modified with a silane coupling agent, sorbic acid and liquid carboxylic polybutadiene (LB). HAp and surface-modified HAp particles were kneaded with three kinds of styrene-based thermoplastic elastomeric (TPS) and the mechanical properties of HAp/TPS composites were investigated by comparisons to those of CaCO3/TPS and silica/TPS composites. The tensile strengths of styrene-isoprene-styrene block copolymer (SIS) composites filled with HAp in low elongation region increased comparing to those of CaCO3/SIS and silica/SIS composites, but the tension set (TS) decreased. Due to filling of the modified HAp, the modulus at 300% strain (M300) and the tensile strength at break (TB) of composites increased furthermore and TS decreased. LB was effective as a modifier for surface modification of HAp. HAp particles abbreviated as IS-HAp were prepared by the reactions with CaCO3 slurry containing potassium salt of LB and phosphoric acid. IS-HAp was composed of hybrid particles with LB and HAp. IS-HAp showed not only an excellent reinforcing effect but also an improved effect of heat-resistance for unsaturated TPS.
