Effect of pressure on the crystallization kinetics of polymers and its consequences for pvT measurements

Description

The influence of both pressure and temperature on the crystallization of an industrial polypropylene was analyzed. The main focus was directed on the spherulitic growth-rate under different pressures and temperatures. In addition also the influence on the nucleation density and on the half-value time of crystallization was investigated. The crystallization experiments were performed using a self-made pressure-dilatometer under pressures between 0.9 and 66.9 MPa and temperatures between 130 – 150 °C ± 0.5 °C. The spherulitic growth-rates as well as the numbers of nuclei were obtained through images from a polarizing light microscope of 5 µm thin-sections of the products from the pressure-dilatometer. The numbers of nuclei rise disproportional at the highest pressure (66.9 MPa). This may be explained by the fact that a mixture of monoclinic and triclinic crystals exist in Polypropylene above a formation pressure of 50 MPa. The half-value time of crystallization was obtained through shrinkage curves from the pressure-dilatometer. These were fitted with an Avrami-fit function where the Avrami-exponent n was set as three, caused by a supposed three-dimensional growth. In addition to temperature as determining

Period	28 Sept 2017
Event title	5th International Conference on Polymer Processing and Characterization
Event type	Conference
Location	PolandShow on map