Submicrometer thermoplastic vulcanizates obtained by reaction-induced phase separation of miscible poly(ε-caprolactone)/dimethacrylate systems

Reaction-induced phase separation of initially miscible mixtures of poly(e-caprolactone) (PCL) and elastomerprecursors based on difunctional methacrylate resins was applied to prepare thermoplastic vulcanizates (TPVs) withrubber particle sizes ranging from 80 to 900 nm. The radicals formed by the peroxide decomposition initiate theformation of a cross-linked rubber network with gel contents exceeding 90%, but also abstract hydrogen atoms from thealiphatic moieties in PCL. This leads to the formation of PCL-grafted rubber particles, which show a high nucleatingefficiency for crystallization of the PCL matrix. It is demonstrated that the tensile and elastic properties of these TPVs aredetermined by a complex interplay of the morphology, the type of elastomer precursor, the extent of PCL grafting, thecrystallinity, and the lamellar thickness. The materials showed a rheological behavior that is typical for TPVs, for whichthe melt changes from an elastic to a viscous behavior above a critical stress.