Dynamic Mechanical Analysis during polyurethane foaming: Relationship between modulus build-up and reaction kinetics

The modulus build-up and relative density evolution during the reactive foaming of four standard polyurethane formulations was monitored in-situ by Dynamic Mechanical Analysis (DMA) with a customised set-up in parallel plate geometry. increased from 0.01 MPa first minutes to over 1.2 within 20 min. also enabled recording vitrification followed curing times. These typically occur 3 min each other. results DMA are corroborated measurements reaction kinetics Infrared Spectroscopy. This goes show that remains nearly unchanged stage swiftest isocyanate conversion, while point gel conversion is accompanied their increase.