Grafting of methyl methacrylate to polypropylene and polyethylene

Abstract

In a study of chemical modification of hydrocarbon polymers an investigation was made of the grafting of methyl methacrylate onto polypropylene and polyethylene. The grafting process was carried out both through preliminary polymer hydroperoxide formation and through chain transfer reactions. Polymer hydroperoxide‐induced grafting proceeds via direct free radical initiation of side chain growth and via hydrogen atom transfer from the hydrocarbon polymer to the polymethyl methacrylate radical. Here the contributions to the chain transfer from the initiator and the methyl methacrylate radical were determined for the separate polymers. Since the grafting was carried out in swollen polymers the effect of viscosity of the medium on the course of the grafting of methyl methacrylate was examined. During the grafting of methyl methacrylate to polyethylene and polypropylene the possibility of crosslinking of these polymers arises. Of particular interest is crosslinking of polypropylene, in view of the fact that the direct reaction induced by ionizing radiation or by hydroperoxide decomposition is connected with certain complications brought about by degradation of the polymer backbone. In the case in question, the formation of a crosslinked structure is due to recombination of the growing methyl methacrylate chains. The crosslinking of the graft polymer is hindered by the chain transfer reaction and by disproportionation during chain termination. In the case of methyl methacrylate, the ratio between recombination and disproportionation is favorable to crosslinkage of the graft polymers, a fact which has been confirmed experimentally. Based on the data concerning the chain transfer reactions and the conditions of formation and decomposition of polymer hydroperoxides a discussion has been presented of the most favorable procedures for grafting methyl methacrylate onto polypropylene and polyethylene and for the formation of crosslinked graft polymers.

Hot melt adhesives prepared by grafting of acrylic and crotonic acids onto metallocene ethylene–octene copolymers

“…Then, due to the autocatalytic peroxide decomposition, the prolonged RXP oxidation leads to a reduced peroxide concentration accompanied by significant polymer molecule scission. 12…”

“…More favorable conditions for higher grafting efficiency (the portion of monomer in batch grafted to modified polymer) were reported for polypropylene that contains hydrogen on tertiary carbons, which is more reactive in transfer reactions. 12,13…”

“…The most important solvent-free reaction benefit is the substantial increase in grafting efficiency when the reaction is performed in a heterogeneous system, in particular for modifying film and fiber surfaces. 12,14,15…”

Grafting of iPP powder with methacrylate monomers in water medium

“…The search for effective methods for grafting isotactic polypropylene (iPP) evolved over the past fifty years 1, 2. The aim of this effort is, in most cases, to suppress the nonpolar character of iPP by attaching to it polar functional groups or chains.…”

Application of ultraviolet photografting technology to acrylamide/polyethylene to improve the interfacial adhesion of polyethylene/unsaturated polyester resin composites

“…Related developments and applications formed by the chemical grafting method for improving surface qualities have been reported successively. For instance, in 1961, Lazar et al13 used the chemical modification of hydrocarbon polymers to make a graft of methyl methacrylate onto polypropylene (PP) and PE. Hitoshi et al14 used scanning electron microscopy (SEM) to discuss the surface morphology of a polyolefin grafting plate.…”