THERMOPLASTIC POLYURETHANE FOAMING THROUGH EXTRUSION USING A BLOWING AGENT

摘要

This study investigated a process of making thermoplastic polyurethane (TPU) foam using Expancel~R as blowing agent during an extrusion process. For this purpose, different let down ratios (LDRs) of blowing agent were implemented in TPU. The study employs X- ray micro computed tomography (μCT) in order to see effect of the changing LDR on expansion ratio and cellular structure of the foamed TPU. The results reveal that LDRs and pressure significantly influence both the expansion ratio and the morphology of the phases present in the foamed TPU. Also the viscosity of TPU at different LDRs was measured using a custom-made in-situ capillary rheometer, which was mounted to an extruder.