Studies on Biodegradable Polymeric Nanocomposites Based on Sheet Molding Compound for Orthopedic Applications

Biodegradable polymeric bone plates suffer from warping, hollowing or substantial erosion inherent with the process of degradation. In order to solve the problem of warping and insufficient mechanical strength, forging of curable sheet molding polyester compound has been attempted. Polymeric nanocomposite was prepared by forging using compression molding with a sheet molding compound (SMC) consisting inorganically modified hydroxy terminated poly (propylene fumarate) (HT-PPF). Hydroxyapatite nanopowder (100-250nm sintered) and polyol modified-polymeric diphenyl methane diisocyanate (Empeyonate PM-35, NCO Content 27%) were used for modification of HT-PPF to get the SMC. The DTA studies on SMC mixed with methyl methacrylate reveal exothermic peak at 94.9oC for the curing of SMC though crosslinking of HT-PPF with methyl methacrylate. SEM microphotographs (fractography) of as-prepared compression molded polymeric nanocomposite reveal serrated structure reflecting higher mechanical strength and good dispersion of hydroxyapatite in the polymer matrix and good interfacial bonding between the polymer and hydroxyapatite nanocrystals.The surface studies revealed the hydrophilicity of the composite. The in-vitro degradation of the nanocomposite was found to be more in Ringer solution than PBS which is due to the slow degradation by the buffering effect of the PBS and hydroxyapatite. The nanocomposite is nonhemolytic, noncytotoxic and blood compatible.