Characterization of poly(lactic acid)/hydroxyapatite prepared by a solvent-blending technique

Abstract

Poly(lactic acid) (PLA) was solvent blended in a chloroform solution using multiple weight fractions of hydroxyapatite (HAp) (5, 10, and 20 wt%). A miniature laboratory mixing extruder equipped with a ribbon die was used to produce thin ribbons of PLA/HAp biocomposites. The dynamic mechanical parameters (storage modulus (G′), loss modulus (G′′), complex viscosity (η*), and degree of crystallinity) increased with increasing HAp loading. In vitro hydrolytic degradation of the PLA biocomposites was conducted in a 0.01-M phosphate-buffered saline solution at 37°C. The presence of HAp tended to increase both the hydrolytic degradability of the PLA and the crystallinity, possibly resulting from the hydrophilicity of the HAp. The thermal stability of the PLA was slightly higher in the composites with HAp. Following hydrolytic degradation, several microholes and cracks appeared on the surface of these biocomposites, as observed by scanning electron microscopy. The Coats–Redfern method was used to evaluate the thermal degradation kinetics of the biocomposites with support from a chemical reaction model. From this evaluation, the activation energies of the biocomposites were found to exceed that of the neat PLA. These energies were observed to decrease after the hydrolytic degradation process.

Photo-Oxidative Degradation and Hydrolytic Degradation of Micro-Graphite Filled Poly(lactic acid) Composites

“…As shown in Figure 1 This phenomenon was also found when PLA was added by hydroxyapatite with more quantity (0-20% wt), as reported in our previous work (Kaavessina et al 2015). Tg can be concluded in constant value due to only shifting about 1-2 °C.…”

“…Again, this increase in crystallinity might be due to filler acting as a nucleating agent. A similar result was reported in our previous work on PLA/hydroxyapatite composite (Kaavessina et al 2015).…”

Preparation and Characterization of Bio-Based PLA/PBAT and Cinnamon Essential Oil Polymer Fibers and Life-Cycle Assessment from Hydrolytic Degradation

“…The weight loss of the fibers was below 5% during the period studied. Some authors have reported a weight loss of 27% after 16 weeks [4], 3% after 5 weeks [99], and 37% after 28 days (almost 4 weeks) [100] for in vitro hydrolytic degradation of PLA.…”

A Slow-Release Fertilizer of Urea Prepared via Melt Blending with Degradable Poly(lactic acid): Formulation and Release Mechanisms

“…This process involves the scission of PLA chains that are dominant in ester bonds concentrated in this phase to generate a lower M W PLA or monomer (lactic acid). Thus, the degradation occurs preferentially in the amorphous phase and then continues to the crystalline phase [ 29 , 30 , 31 ]. The rough surface and numerous micro-holes could be ascribed to PLA chain scission and removal in both phases.…”