Self-Healing and Rheological Properties of Polyhydroxyurethane Elastomers Based on Glycerol Carbonate Capped Prepolymers

Polyhydroxyurethane were prepared from polyurethane prepolymers by end capping with glycerol carbonate (GC) and chain extension with an amine. The GC-based polyurethane (GPU) shows excellent mechanical properties together with superior self-healing properties compared with conventional polyurethane (CPU). The significant improvement in mechanical properties was driven by enhanced hydrogen bonding and the excellent self-healing was attributed to the exchange reaction of the -hydroxy unit of GPU. The self-healing efficiencies of GPU and CPU were approximately 92% and 42% at 110 degrees C, respectively. The characteristics of GPU were also studied by rheological measurements. GPU showed not only a negative normal stress difference (N-1) but also a crossover of storage (G) and loss (G) moduli. It is postulated that the exchange reactions of GPU in melts induce a negative N-1 as well as self-healing of the GPU, implying desirable melt processing stability with minimal die swell.