Modification of cross-linked rubber particles by free radical polymerization

The synthesis of polystyrene chains covalently bound to the surface of
cross-linked rubber particles from recycled tires (ground tire rubber, GTR) was
investigated via free radical polymerization in situ by using azobisisobutyronitrile
(AIBN) and dibenzoyl peroxide (BPO) as initiators. Indeed, the graft polymerization
provides a significant route to modify the physical and chemical properties of these
particles allowing to improve their compatibility with other polymers. Polymerization
reactions were carried out in bulk by changing the styrene/GTR ratio as well as the
amount of free radical initiator. Appreciable amounts of polystyrene (PS) were grafted
on GTR when BPO was used as confirmed by particle characterizations