Coupling of poly(lactic acid) with a polyurethane elastomer by reactive processing

•A segmented polyurethane elastomer was synthesized in poly(lactic acid) melt.•Reactive processing was compared with the conventional mixing of the components.•The successful synthesis of block copolymers was confirmed.•Isocyanate was found to react only with the hydroxyl end of poly(lactic acid).•Our results clearly show the benefits of reactive processing.