Reactive blending toughened PLA by in situ formation of polyurethane crosslinked elastomer.

Polylactide (PLA)/polyurethane (PU) composites were prepared by reactive blending method with in-situ formation of PU particles via the reaction between polyester polyol (PPG) and toluene-2,4-diisocyanate (TDI). The interfacial compatibility and adhesion between the PLA and PU phases were greatly improved by the reaction of the terminal hydroxyl groups of PLA and N=C=O groups of TDI forming graft copolymer, as confirmed by FTIR spectroscopy. The elongation at break and notch impact strength of PLA/PU composites increased considerably with increasing PU content, and the tensile strength of PLA/PU composites decreased slightly compared with that of pure PLA. The excellent interfacial adhesion, dispersed PU elastomeric particles acting as stress concentration areas and the triggering of large matrix shearing yielding and many fibrils by internal cavitation were the main mechanical toughening mechanisms. [ABSTRACT FROM AUTHOR]