Irradiation of blends of post-consumer plastics

Tensile properties of immiscible polymer blends generally are inferior to those of the individual components. Two variables which might increase compatibility are crosslinking and the addition of a reinforcing filler. Of the crosslinking techniques, gamma radiation has the advantage of not introducing high levels of obnoxious odors. In actual production, a high-voltage electron beam would probably be more practical than gamma radiation. A particular polymer blend of interest in the recycling industry is low density polyethylene (LDPE) with poly(vinyl chloride) (PVC). These two often are mixed in insulation recovered from wire and cable which has been treated to reclaim the copper conductor. In preliminary work, virgin LDPE and PVC are combined with carbon black and exposed to 5 Mrad of gamma radiation while held at 175 degrees C over a period of 22 hours (e. 0.22 Mrad/hr). Radiation crosslinking, of course, decreases room temperature elongation greatly. However, it has no consistent effect on yield stress