Thermo-physical Properties of Thermoplastics: Relationships with Degree of Crystallinity


Noor S. Zaki*, Tawfeeq W. Mohammed


Mustansiriyah University, College of Engineering, Iraq

Corresponding Author Email: ebma023@uomustansiriyah.edu.iq.

This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

The purpose of this study is to determine the direct relationship between the crystallinity of thermoplastic polymers and their corresponding thermo-physical properties that influence the performance of plastics in many thermal applications. These properties are glass-transition temperature, melting point and specific heat capacity. The materials used are POM, HDPE, LDPE, PP, PA, and PET which have different values of degree of crystallinity. The study includes theoretical and experimental works. The analytical work has used mathematical functions extracted from reliable empirical relationships. The experimental work included manufacturing the specimens; specifying the cooling procedure to get the required degree of crystallinity; measuring thermo-physical properties and finally analyze the data and introduce the experiences obtained from the investigation. Theoretical values, as well as experimental data, were both behave similarly concerning the physical property. The results show that by increasing the degree of crystallinity the melting point has increased, while glass-transition temperature and specific heat capacity have decreased. It is noticed experimentally that the change in the value of glass-transition temperature between high and low crystalline specimens was in the range of 10-30 oC (5-15%), while the change in the value of melting point for the same specimens was 3-6 oC (5-10%).