A Study On The Biodegradable β-TCP/PLLA Nanocomposites By Self-modification

β-Tricalcium phosphate (β-TCP), is widely used in the biomedical fields because of its osteoconductivity and biocompatibility to human tissue. Combiningβ-TCP particles with PLLA could make composites with greater bioactivity and overcome inflammatory response problems during degradation.Using wet process method to synthesis of nano-β-TCP. In order to make a good kind of bone repairing composites with favorable interface compatibility, mechanical properties and dispersibility, the surface of nano-β-TCP particles have been modified for improving the phase compatibility between theβ-TCP and PLLA matrix.β-TCP/PLLA composites were prepared by solution blending method.1. Using Ca(NO₃)₂·4H₂O and (NH₄)₂HPO₄ to prepare high purity of nano-β-TCP which size is about 200 nm. The first modification method was modifying low molecular weight ploy(L-lactide) onto theβ-TCP particles through ionic interaction. FT-IR spectra confirmed that at LMW PLLA was directly connected onto theβ-TCP surface where a new broad peak appeared at 1622 cm-1. The second modification method by surface grafting reaction of L-lactic acid oligomer with activatedβ-TCP particles was developed. FT-IR showed that the modifiedβ-TCP in the 1759 cm-1 appeared new carbonyl functional group. The modified particles'contact angle and grafting rate is 85°and 14.4 %, respectively.2. With L-lactic acid as law material, stannous octoate as catalyst, ethyl acetate as purifying solvent, a process which consist of dehydration- oligomerization- depolymerization stages had been used to prepare high-purity L-lactide which was up to 99.82 %. The pre-dried L-lactide could be used to polymerize high molecular weight of PLLA chould up to 41 w.3. It is using solution blending method to prepare composites, SEM and EDS showed that the modified particles had an effective approach to prepare homogeneous composites and had a better compatibility with matrix. Tensile tests showed that mechanical properties and elongation at break was improved, the highest is up to 59.5 MPa and 8.12 %. The tensile strength and elongation at break ofβ-TCP/PLLA decreased with filler content...