CHANGES OF RHEOLOGICAL PARAMETERS OF POLYPROPYLENE AND POLYETHYLENE AFTER EXPOSURE IN ALIPHATIC n-HEXANE

Rheological properties of thermoplastic polymer materials before and after exposure to a chemical solution were evaluated using the frequency sweep test, which monitors changes in viscoelastic properties of polymers with respect to their molecular structure and their behavior in thermoplastic processing. As experimental material thermoplastic polyethylene and polypropylene samples were used and subjected to influence of n hexane solution for period of 3 and 6 months. Measurements were performed using oscillating rheometer Physica Rheometer MCR301 and carried out at the temperatures of 160 °C and 80 °C. Degradation process resulted in changes of complex dynamic viscosity, storage and loss modulus, changes in molar mass and its distribution which sufficiently prove the rheological changes.