Role of Chain Dynamics in the Melt Memory Effect of Crystallization

Le résumé fourni par la source

Self-nucleation (SN) methods, stress relaxation, interrupted shear flow experiments, and a one-dimensional diffusion model were used to reveal the kinetic origin of the melt memory effects of polycaprolactone (PCL), which can be regulated by changing chain dynamics with the introduction of a miscible dynamically asymmetric component, poly(styrene- co -acrylonitrile) (SAN). SAN plays a pivotal role in strengthening the melt memory effect and increasing the nucleation efficiency of the PCL in the blend. The lifetime of the melt memory effect in PCL/SAN blends is much longer than the relaxation time of segmental orientation and the mutual diffusion time, while the re-entanglement kinetics almost matches the survival of the melt memory effect. The lifetime and the re-entanglement time possess similar temperature dependence with activation energy much higher than that of the viscous flow. Such quantitative agreements provide solid evidence that the kinetic origin of the melt memory effect in PCL/SAN blends far above the melting point is chain re-entanglements.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.