Self-reinforcement and hydrolytic degradation of amorphous lactic acid based poly(ester-amide), and of its composite with sol-gel derived fibers

The self-reinforcing and hydrolytic degradation of an amorphous poly(ester-amide) (PEA) based on lactic acid have been studied and compared with those of poly-L-lactide (PLLA). The studied PEA-rods were self-reinforced (SR) by solid-state die drawing resulting double shear strength. The hydrolytic degradation of PEA was studied during exposure to phosphate buffered saline at pH 7.4 and at 37 °C for 18 weeks. The degradation and mechanical properties of PEA were also followed in a self-reinforced composite structure consisting of PEA and sol-gel derived SiO 2 -fibers (SGF, 8 wt %). The hydrolytic degradation of the SR-PEA-rods with and without SG-fibers was significantly faster than that of SR-PLLA-rods. The weight average molecular weight ( M w ) of PEA decreased by 90% from the initial M w during the first 6 weeks in hydrolysis, when the M w of the PLLA decreased by 10%.