Influence of Temperature on Solid Phase Content in Polypropylene

Influence of Temperature on Solid Phase Content in Polypropylene

Stať ve sborníku v databázi WoS či Scopus

This work is a study of the relationship between properties of polypropylene, its copolymers and several types of polyethylene, and their structure. Structural parameters were characterized by means of molecular weight, molecular weight distribution and isotacticity index. Properties of polymers were examined by means of the pulsed 1H-NMR method in a temperature range from 0 to 80C, and the dynamic mechanical analysis method (DMA) in a temperature range from -80 to 140C. Absolute values of the solid phase content and its temperature dependence were evaluated accurately by the pulsed 1H-NMR method. The measurement was performed over a broad variety of materials, especially in form of injection molded specimens (commercial PP homopolymers, random and sequential copolymers P/E, HDPE, LDPE, LLDPE, and others specially prepared materials), in form of pellets, strings from melt indexer, and hot pressed films. Reproducible results of thermal dependency of a solid phase content were obtained, and a good correlation with mechanical-physical properties of polypropylene was found. Thermal dependencies of mechanical properties (modulus of elasticity, mechanical loss factor) were determined using the DMA method. The solid phase content was determined accurately in the whole series of materials evaluated at temperatures above the glass transition temperature. Besides Tg, liquid-liquid phase transitions were detected on some materials.

This work is a study of the relationship between properties of polypropylene, its copolymers and several types of polyethylene, and their structure. Structural parameters were characterized by means of molecular weight, molecular weight distribution and isotacticity index. Properties of polymers were examined by means of the pulsed 1H-NMR method in a temperature range from 0 to 80C, and the dynamic mechanical analysis method (DMA) in a temperature range from -80 to 140C. Absolute values of the solid phase content and its temperature dependence were evaluated accurately by the pulsed 1H-NMR method. The measurement was performed over a broad variety of materials, especially in form of injection molded specimens (commercial PP homopolymers, random and sequential copolymers P/E, HDPE, LDPE, LLDPE, and others specially prepared materials), in form of pellets, strings from melt indexer, and hot pressed films. Reproducible results of thermal dependency of a solid phase content were obtained, and a good correlation with mechanical-physical properties of polypropylene was found. Thermal dependencies of mechanical properties (modulus of elasticity, mechanical loss factor) were determined using the DMA method. The solid phase content was determined accurately in the whole series of materials evaluated at temperatures above the glass transition temperature. Besides Tg, liquid-liquid phase transitions were detected on some materials.

polypropylene, pulsed 1H-NMR, crystallinity

polypropylene, pulsed 1H-NMR, crystallinity

VILČ, L.; KRATOCHVÍLA, J.

29.09.2004

Halle

3-928466-68-2