Preparation of Thermoplastic Polyurethane Composites Based on Reclaimed Polyurethane Foam and Ground Fluoroelastomer: Effect of Pretreatment of Fluoroelastomer through Solid-State Mechanochemical Milling

Abstract

Thermoplastic polyurethane composites were made from ground fluoroelastomer (FKM) and reclaimed polyurethane (PU) foam which derived from shoe making industry through melt-mixing. Pan-mill type mechanochemical reactor made in our lab was applied to realise the devulcanisation and ultrafine pulverisation of FKM, thereby to enhance mechanical properties of the composites. Fluorescence microscopy studies indicated that the dispersion of devulcanised FKM in PU matrix was much better than ground FKM. Glass transition temperature of devulcanised FKM filled-PU composites was higher than that of pristine PU, as confirmed by differential scanning calorimetry and dynamic mechanical analysis. The mechanochemical devulcanisation of FKM significantly enhanced the mechanical properties of FKM/PU composites. When the content of FKM was 20%, the tensile strength of the composites was enhanced from 13.2 MPa to 23.2 MPa through devulcanisation, by about 80.2%; and the elongation at break was increased from 380.2% to 500.2%, by about 30.2%. Furthermore, the onset degradation temperature increased from 252.8°C to 273.3°C with the addition of 100 phr devulcanised FKM powder.