Production and evaluation of hydroxyapatite reinforced polysulfone for tissue replacement

A variety of bioactive composites have been developed for tissue replacemen t over the last two decades. In this investigation, a new material consisti ng of hydroxyapatite (HA) and polysulfone (PSU) was produced and evaluated for potential medical applications. The HA/PSU composite containing up to 2 0 vol % of HA was studied at the initial stage. It was manufactured via a s tandardized procedure which included drying, blending, compounding and inje ction/compression molding. Defect-free composite samples (rectangular bars, discs and dumbbell specimens) could be obtained by injection molding. Thic k composite plates could be made by compression molding. Both compounded ma terials and molded parts were assessed using a variety of techniques. It wa s found through scanning electron microscopy (SEM) that HA particles were w ell dispersed in the PSU matrix. Thermogravimetric analysis (TGA) verified the amount of HA in the composite. Differential scanning calorimetry (DSC) results indicated that the glass transition temperature (T-g) of the polyme r matrix was not affected by the incorporation of HA. Rheological analysis revealed that PSU and the composite exhibited pseudoplastic behavior. For u nfilled PSU, its viscosity decreased with an increase in temperature. The v iscosity of HA/PSU composite increased with an increase in the HA volume fr action. It was shown through dynamic mechanical analysis (DMA) that the sto rage modulus of the composite was increased with an increase in HA volume p ercentage below T-g of the polymer, while tan delta was maintained at nearl y the same level. It was established that water uptake reached an equilibri um after 7 days' immersion in distilled water for PSU and HA/PSU composite. After 7 days' immersion in distilled water, the storage modulus of the com posite was decreased less than that of PSU. (C) 2001 Kluwer Academic Publis hers.