Reactive extrusion of poly(vinyl chloride) compounds with polyethylene and with ethylene‐vinyl acetate copolymers

The mechanical properties of poly(vinyl chloride)/polyethylene blends can be improved by a reactive extrusion process in the presence of an organic peroxide and a coupling agent. With a judicious loading of dibenzoyl peroxide and triallyl isocyanurate coupling agent, such blends generally exhibit significantly greater ultimate tensile strengths and dynamic moduli. The nature of the sample posttreatment after compression molding is shown to have a major impact upon the relative magnitude of these differences. Evidence is also presented to suggest that such improvements result from a superior physical interlocking between blend components, rather than through the formation of co‐crosslinked graft segments (which would, presumably, impart a compatibilization effect). Similar extrusion trials with a poly(vinyl chloride)/poly(ethylene‐ stat ‐vinyl acetate) mixture revealed a general worsening of material properties with increasing dibenzoyl peroxide levels. These observations can be rationalized by examination of the degradation reactions that likely occur in these reacting systems.