Melt Rheology of Block Copolymers in Relation to Melt Structure

摘要

It is well known that block copolymers composed of incompatible polymers have multiphase structure, each component polymer being separated into its own phase, and their multiphase structure leads to unusual physical properties. In particular, block copolymers composed of a soft polymer as the major component and a hard polymer as the minor component can have elastomeric properties since the hard polymer blocks from different molecules segregate into hard domains dispersed in the soft matrix of the soft polymer blocks and the hard domains serve as crosslinking and reinforcement. Some block copolymers of this nature are now successfully used as thermoplastic elastomers. Block copolymers also exhibit unusual melt rheological properties notably very high viscosity and elasticity in comparison to the component homopolymers of equal molecular weight. The unusual melt rheological properties have been attributed to the remnants of the multiphase structure which persist far above the glass transition or melting points of the component polymers.