Investigation on crystallization kinetics and solidification behavior of isotactic polypropylene (iPP) using an enthalpy transformation method

ABSTRACT

The enthalpy transformation method, a widely accepted way to solve the phase transition related problems, was utilized to investigate the relationship between solidification behavior and crystallization kinetics of isotactic polypropylene (iPP). Our findings suggest that the cooling medium temperature is more effective in controlling the average cooling rate than the melt temperature. A generalized equation, which was obtained by plotting the cooling curves in a double-logarithmic scale, could be adopted to estimate the minimum cooling time (MCT) of the crystalline polymer to optimize the design of an injection molding (IM) cycle. Moreover, the quantitative description of the position dependence of the crystallization rate was also established. The present study will be of practical use to further exploration of the correlation between cooling parameters and the structural evolution of crystalline polymers as well as a better understanding of microstructural formation mechanisms.

KEYWORDS:

• Crystallization
• solidification
• phase transition
• injection molding
• enthalpy transformation method

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors are indebted to the financial support to this work by the National Key R&D Program of China (2017YFB0406204), the National Natural Science Foundation of China (51973002), the University Collaborative Innovation Project of Anhui Province (GXXT-2019-001) as well as “211 Project” of Anhui University.