Crystallization of polymers at constant and high cooling rates: A new hot-stage microscopy set-up
Résumé
A prototype hot-stage termed "Polymer High Cooling - Optics" was especially designed to follow on-line the nucleation and growth of crystallizing entities at constant cooling rates. The optically transparent hot-stage receives a gaseous flow at a constant temperature, which passes over the sample. Quiescent crystallization is monitored in real-time at relatively moderate (from 30 to 500 degrees C/min) and even at high (from 500 to 2000 degrees C/min) constant cooling rates. As a first application of this new set-up, two relevant parameters of the cc-modification of isotactic polypropylene, i.e., the crystallization temperature and the spherulite growth rate, were successfully captured for different constant cooling rates in a reproducible way. The superposition of these newly-collected growth rate data with those compiled by Janeschitz-Kriegl (2006) demonstrates the reliability of our experimental determination.