Toughening mechanism of heterogeneous aliphatic polyurethanes

Highly cross-linked polyurethanes have a high elastic modulus and creep resistance, but they undergo a brittle fracture below the glass transition temperature. The lack of substantial toughness in these polymers limits their use in practical engineering applications. One method that has shown promise in recent years is the creation of local regions of reduced modulus that absorb strain energy and act to toughen the polymer. For instance, rubbers...