Reactive Blend of Thermosetting Polyurethane and Thermoplastic Polypropylene Using a Twin Screw Extruder for Recycling

摘要

A reactive blending method of a thermosetting polyurethane and a thermoplastic polypropylene was developed using a twin screw extruder for recycling. The most innovative aspect of this method is breakage of the network structure of the thermosetting polyurethane by hydrolysis of its crosslinking points. The hydrolysis of the thermosetting polyurethane was performed in the polypropylene matrix melt in the twin screw extruder. The hydrolyzed thermosetting polyurethane was ground and dispersed in the polypropylene matrix as very small particles (sub-micron size) due to shear distoftion by the screw extruder. The reactive blended material thus obtained shows excellent mechanical properties, higher elongation at breakage, and higher impact strength comparing with the material obtained by simple blend without hydrolysis. Further study was carried out to improve the reactive blended material. In the final stage of the reactive blending, a small amount of diisocyanate was added into the melt blend to polymerize polyurethane oligomer which was generated by the hydrolysis. This procedure was found to be very effective to reduce volatile components from the reactive blended material.