Modified Brittle Poly(lactic acid) by Biodegradable Hyperbranched Poly(ester amide)

Melt blending of poly(lactic acid) (PLA) and biodegradable hyperbranched poly(ester amide) (HBP) has been performed in order to toughen PLA without compromising its biodegradability and biocompatibility. The FTIR spectra, thermal properties, disperse phase morphology, and mechanical properties of the blends with different HBP contents were investigated. A reasonable toughening mechanism is also given. The presence of intermolecular hydrogen bonds between PLA and HBP is confirmed by FTIR spectroscopy technique. Addition of HBP not only reduced the crystallinity of PLA from 30.99% to 18.58%, but also has toughened it as well. By an increase in HBP content from 2.5% to 10%, the blend showed a slight increase in tensile strength but a significant increase in elongation-at-break values. Meanwhile the scanning electron micrographs showed an evenly dispersed HBP in PLA. The hydrogen bond interactions and the energy-dissipation process led to a tough biodegradable polymer blend.