In order to get PE -g- PS, polyethylene was used as the backbone polymer for grafting styrene using dicumyl peroxide(DCP). DCP, due to its high radical reactivity, is known to promote hydrogen abstraction and the grafting sites occur onto polyethylene. Significant levels of grafting could be achieved and grafting depends upon the relative concentrations of monomer and backbone polymer.
Analytic expressions for conversion, grafting efficiency and degree of grafting during copolymerization of PE -g- PS were derived. The use of a kinetic model allowed the evaluation of relative rate coefficients between graft site initiation and homopolymer initiation. The model also provided successful interpretations of the grafting data and its dependence upon the concentrations of monomer, initiator and backbone polymer. The complete kinetic model is capable of predicting reaction rate, graft efficiency and degree of grafting.
The simultaneous generation of both homopolymer and graft copolymer in graft copolymerization is due to the competitive reactions of homopolymeric radical and backbone polymeric radical toward monomer molecules.
When graft site is promoted by only primary radical attack to the polyethylene, graft efficiency was shown to be insensitive to the concentration of initiator, while it was significantly dependent upon the monomer concentration. Thus instantaneous graft efficiency should increase with conversion level during polymerization.
And it was not very temperature sensitive, i.e., the activation energies for $K_i1$ and $K_i2$ was reasonably close in value
Compatibilization of low density polyethylene(LDPE) / PS / PE-g-PS blends was investigated in terms of morphology, rheological, and tensile properties.