Application of phase dispersion-crosslinking synergism on recycling commingled plastic wastes

A tetra-component blend, consisting of low-density polyethylene (LDPE), pol yvinyl chloride (PVC), polypropylene (PP), and polystyrene (PS), was studie d as a model system of commingled plastic wastes (LDPE/PVC/PP/PS, mass rati o: 70/10/10/10). Effects of chlorinated polyethylene (CPE), ethylene-propyl ene-diene monomer (EPDM), styrene-butadiene-styrene (SBS), and their mixtur e (CPE/EPDWSBS, mass ratio: 2/2/2) on the mechanical properties and morphol ogy of the system were investigated. With addition of several elastomers an d their mixture, the tensile strength of the blends decreased slightly, alt hough both the elongation at break and the impact strength increased. Among these elastomers, EPDM exhibited the most significant impact modification effect for the tetra-component blends. SBS and the mixture have a good phas e-dispersion effect for the tetra-component blend. By adding a crosslinking agent [dicumyl peroxide (DCP)], the mechanical properties of the tetra-com ponent blends also increased. When either SBS or the mixture was added to t he blend together with DCP, the probability that the crosslinking agent (DC P) would be at the interface improved because of the phase-dispersion effec t of SBS. Therefore, more co-crosslinked products will form between LDPE an d other components. Accordingly, remarkable improvement of the interfacial adhesion and hence the mechanical properties of the tetra-component blends occurred. (C) 2001 John Wiley & Sons, Inc.