A New Technique for Using DSC Melting Endotherms to Study Isothermal Bulk Crystallization of Semicrystalline Polymers at Low Degrees of Undercooling: Syndiotactic Polypropylene^*

Abstract

In this manuscript, we present a new technique for using a differential scanning calorimeter (DSC) to study isothermal bulk crystallization and the kinetics of the process at “high” crystallization temperatures or “low” degrees of undercooling. It is based on measurements of the enthalpy of fusion from the subsequent melting endotherms after isothermal crystallization for various time intervals. Syndiotactic polypropylene (s–PP) was used as the model system. The benefits of the new technique, based on the results we present here, are threefold: (1) it allows an accurate determination of the induction time; (2) it offers a means to extend the use of DSC to obtain kinetics parameters for isothermal crystallization at temperatures at which the traditional technique is not applicable; and (3) it gives an insight into certain mechanistic aspects of the isothermal crystallization process as it occurs at different crystallization time intervals.

^*This manuscript is dedicated to the memory of Professor Donald C. Bogue.

Keywords:

• Avrami analysis
• Crystallization kinetics
• Crystallization and melting behavior
• DSC
• Syndiotactic polypropylene

ACKNOWLEDGMENT

We would like to thank Dr. Joseph Schardl of Fina Oil and Chemical Company, Dallas, Texas, for supplying the s-PP resin used in this study and Dr. Roger A. Phillips and his coworkers of Montell USA, Incorporated, Elkton, Maryland, for performing sample characterizations.

Notes

^*This manuscript is dedicated to the memory of Professor Donald C. Bogue.