New Reclaiming Process of Thermoset Polyurethane Foam and Blending with Polyamide-12 and Thermoplastic Polyurethane

A new method to reclaim thermoset polyurethane (PU) foam by thermo-mechanical degradation using a batch Drais mixer was investigated, and the performance of reclaimed PU in blends with polyamide-12 (PA-12) or thermoplastic polyurethane (TPU) was studied. The reclamation method used disrupts the crosslinked structure of PU, decreasing its degree of crosslinking, which was confirmed through the determination of gel content, and by DSC, TGA and FTIR analyses. Under severe reclaiming conditions, the reclaimed PU was found to retain about half of its initial gel content. The blends of original PU and reclaimed PU (PU-r) with PA-12 and with TPU were prepared using a twin-screw extruder and were characterized with respect to their mechanical properties. For the PA-12/PU 75/25 blend, the addition of PU was observed to toughen the PA-12 matrix whereas for TPU/PU blends, the rubber-like behavior of TPU was not significantly affected by the presence of PU. The remarkable mechanical behavior of the blends attests to the high compatibility of PU-r with both PA-12 and TPU. This may be due to the physical interactions between the blend components, leading to high interfacial adhesion. The reclamation of PU-r before its melt processing with PA-12 or TPU was found to improve the processability during the injection molding of the PA-12/PU-r and TPU/PU-r blends.