Fabrication and mechanical properties of PLA/HA composites: A study of in vitro degradation

Abstract

The adverse effects of stress shielding from the use of high-modulus metallic alloy bio-implant materials has led to increased research into developing polymer-ceramic composite materials that match the elastic modulus of human bone. Of particular interest are poly-l-lactic acid- hydroxyapatite (PLA/HA)-based composites which are fully resorbable in vivo. However, their bioresorbability has a deleterious effect on the mechanical properties of the implant. The purpose of this study is to investigate, from a micromechanistic perspective, the in vitro degradation behavior of such composites manufactured using a simple hot-pressing route for two different hydroxyapatite particles: a fine-grained (average particle size ∼5 μm) commercial powder or coarser whiskers (∼25-30 μm long, ∼5 μm in diameter). We observed that composites with ceramic contents ranging between 70 and 85 wt.% have mechanical properties that match reasonably those of human cortical bone. However, the properties deteriorate with immersion in Hanks' Balanced Salt Solution due to the degradation of the polymer phase. The degradation is more pronounced in samples with larger ceramic content due to the dissolution of the smaller amount of polymer between the ceramic particles.

Biocomposites and hybrid biomaterials based on calcium orthophosphates

“…One can also prepare these biocomposites by mixing HA particles with L-lactide prior to the polymerization 380 or by a combination of a slip-casting technique and hot pressing. 389 Addition of a surfactant (surface active agent) might be useful to keep the suspension homogenous. 390 Furthermore, HA/PLA 314,315 and HA/PLGA 316 microspheres might be prepared by a microemulsion technique.…”

Calcium orthophosphate-based biocomposites and hybrid biomaterials

“…The resulting solid composites might be shaped using different processing techniques. One can also prepare these biocomposites by mixing HA particles with L-lactide prior the polymerization [312] or by a combination of slip-casting technique and hot-pressing [321]. A surfactant might be useful to keep the suspension homogeneity [322].…”

Biomimetic Materials by Freeze Casting

“…[19][20][21][22] Figure 1e shows a schematic of this process. A variety of different polymer infiltration techniques includes polymer melt immersion, 23 polymersolvent evaporation, [24][25][26][27][28] in situ polymerization, [19][20][21][29][30][31][32] particle centrifugation, 33 and chemical vapor deposition. [34][35][36] In situ polymerization is the most popular method used to impregnate porous scaffolds with polymers.…”