Gradient density grafted polymers on ground tire rubber particles by atom transfer radical polymerization

The graft polymerization of styrene and (meth) acrylic monomers via ATRP from cross-linked rubber particles, produced by recycled tires ('ground tire rubber', GTR), is repoted. GTR particles, obtained by cryogenic grinding process, still contain C = C unsaturations on the surface, which were first oxidized to hydroxyl groups and then modified by reaction with 2-bromoisobutyryl bromide to serve as ATRP macroinitiators. Graft polymerizations were carried out using CuBr/CuBr2/N,N,N'N',N' -pentamethyldiethylenetriamine as catalystic system in bulk or in anisole at high temperature. The grafted particles were analyzed by ATR-IR (spectra were recorded on particles surface and cross-sectional slices), TGA, SEM and X-ray microanalysis.