Highly toughened polylactide (PLA) by reactive blending with novel polycaprolactone-based polyurethane (PCLU) blends

Polylactide (PLA)/polycaprolactone-based polyurethane (PCLU) blends were prepared by reactive blending of PLA with poly (caprolactone) triol (PCL-polyols) and isophorone diisocyanate (IPDI). The interfacial compatibility was markedly improved by the reaction of the terminal hydroxyl groups of PLA and the N = C = O groups of IPDI, as confirmed by Fourier transform infrared spectroscopy. Results of tensile testing and a notched impact test suggest that the elongation at break and impact strength of PLA/PCLU blends increased to more than 20 and 5 times those of neat PLA, respectively. Moreover, the tensile strength of PLA/PCLU blends slightly decreased. Excellent interfacial adhesion enabled the dispersed polyurethane elastomeric particles to act as effective stress concentration areas. The shearing yielding of PLA matrix triggered by internal cavitation was the main mechanical toughening mechanism.