Synthesis of branched polypropylene by a reactive extrusion process

Polypropylenes with long chain branches were obtained using reactive extrusion in the presence of peroxide, a polyfunctional acrylate monomer and a co-reactant: a sulfide compound such as thiuram disulfide. By thermal decomposition, the thiuram disulfide gives two dithiocarbamate radicals. These radicals can be reacted with the macroradical PP, and this reaction is reversible. They induce a decrease in the instantaneous concentration of free radicals, favor the branching, and thus limit the effect of the beta-scission. The long chain branches structure was confirmed by dynamic viscoelastic measurements and thermal analysis.