Improvement of β-TCP/PLLA biodegradable material by surface modification with stearic acid

Poly-L-lactide (PLLA) is a biodegradable polymer and used widely. Incorporation of beta tricalcium phosphate (beta-TCP) into PLLA can enhance its osteoinductive properties. But the interfacial layer between beta-TCP particles with PLLA matrix is easy to be destroyed due to inferior interfacial compatibility of the organic/inorganic material. In this work, a method of beta-TCP surface modification with stearic acid was investigated to improve the beta-TCP/PLLA biomaterial. The effects of surface modification on the beta-TCP were investigated by FTIR, XPS, TGA and CA. It was found that the stearic acid reacted with beta-TCP and oxhydryl was formed during the surface modification. Hydrophilicity of untreated or modified beta-TCP/PLLA composite was increased by the addition of 10 wt% beta-TCP, but it decreased as the addition amount increased from 10 wt.% to 20 wt.%. Two models were suggested to describe the effect of beta-TCP concentration on CA of the composites. Mechanical properties of beta-TCP/PLLA composites were tested by bending and tensile tests. Fractures of the composites after mechanical test were observed by SEM. It was found that surface modification with stearic acid improved bending and tensile strengths of the beta-TCP/PLLA composites obviously. The SEM results indicated that surface modification decreased the probability of interface debonding between fillers and matrix under load. (C) 2016 Elsevier B.V. All rights reserved.