| Abstract | Phosphate-based glasses (PGs) and their composites are of interest as bone repair and tissue engineering scaffolds due to the totally degradable nature of the materials. This study investigated the effect of Si and Fe on the properties of PG particulate-filled polycaprolactone (PCL) matrix composites. Two glass compositions were investigated (in mol%): 50 P₂O₅, 40 CaO and 10 SiO₂ or Fe₂O₃ (Si₁₀ and Fe₁₀ respectively). All composites contained 40 vol% particulate filler, either of Si₁₀, Fe₁₀, or a blend (40Si₁₀/0Fe₁₀, 30Si₁₀/10Fe₁₀, 20Si₁₀/20Fe₁₀, 10Si₁₀/30Fe₁₀, 0Si₁₀/40Fe₁₀). Ion release, weight loss and composite mechanical properties were charaterized as a function of time in deionised water (DW) and phosphate buffered saline (PBS), respectively. The potential for calcium phosphate deposition was assessed in simulated body fluid (SBF). Calcium and phosphate ions release in DW increased in tandem with the rate of composite weight loss, which increased with Si₁₀ content. A Si₁₀ content rate of pH reduction was observed in DW. At day 56, PG in 40Si₁₀/0Fe₁₀ composite completely dissolved, whereas 67% of the 0Si₁₀/40Fe₁₀ remained. The initial flexural strenght of 40Si₁₀/0Fe₁₀ composites was significantly lower when compared to the other materials. An increase in Si₁₀ content led to an increase in Young's modulus and a concomitant decrease in flexural strain. It was found that the PCL molecular weight (Mw) was significantly decreased with an increase in Si₁₀ content. FTIR analysis showed that Si incorporation into PG led to their reaction with the PCL ester bonds resulting in a reduction in PCL Mw when processed at elevated temperatures. Changes in mechanical properites with time in PBS were glass blend dependent and a more rapid rate of reduction was observed in Si₁₀ dominant composites. At day 28 in SBF, surface deposited brushite was formed in 20Si₁₀/20Fe₁₀ PG containing composites. Therefore the properties of PCL-PG composites could be tailored by controlling the phosphate glass blend composition. |
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