Development of an Extrusion-Rheometry-Based Setup for the Characterization of the Flow Behavior of Diluted Polymer Melts

Description

Lubricants are often crucial additives in polymer processing as they reduce shear viscosity and processing energy. Diluents with ultra-low molecular weight may induce a similar effect in polymers. The determination of the rheological properties of diluted polymers has been studied extensively, at least for high-molecular-weight dilutions. However, characterizing low-molecular-weight dilutions is still a challenge, since the high melt temperature of polymers causes the diluents to evaporate while testing in standard experimental configurations (e.g., oscillatory rheometers with parallel plate setup), resulting in an ongoing loss of diluent concentration in the mixture. Moreover, the available commercial instruments proved to be inadequate for oscillatory experiments at elevated pressures, at least for the specific materials used in this study. Therefore, this work presents a novel high-pressure-increases-evaporation-temperature-of-diluents approach to minimize diluent evaporation during rheological characterization. Consequently, we developed an experimental setup based on extrusion rheology, employing a high-pressure dual-piston pump for injecting liquids into the polymer melt. This setup successfully prevented the diluent from evaporating during testing and showed a good reproducibility. This new methodology now enables a thorough analysis of the viscosity dilution phenomenon in dependance of diluent concentration, shear rate, and temperature, respectively.

Period	02 Oct 2024
Event title	PPS2024
Event type	Conference
Location	SpainShow on map