ANALYSIS OF POLYMER FLOW NEAR GLASS TRANSITION TEMPERATURE

摘要

In many polymer manufacturing operations, the material is processed near the glass transition or melting temperature. Examples are plastic welding, thermoforming, blow molding, film blowing, forging, and de-airing in safety glass lamination. In these processes, some of the solid-like behavior like strain hardening and yield stress may play important roles. They make material flow (or deformation) substantially different from that of a polymer melt. In order to understand the flow behavior near the glass transition temperature, polyvinyl butyral (PVB), a polymer used in safety glass lamination, was studied in this work. The material properties of the polymer were characterized by using the Rheometrics Mechanical Spectrometer (RMS) and the Rheometrics Solids Analyzer (RSA). The measured flow properties were modeled by a viscoplastic model. A finite element code, DEFORM, was applied to compare the simulation results with a compression molding experiment.