CHALLENGES IN POLYPROPYLENE BY CHEMICAL MODIFICATION

Radical reactions of i-PP are a well known technical process for the c hemical degradation to increase the flowability of the I-PP melt. By d ecreasing the temperature and increasing the life time of the PP-radic als, a process to synthesize long chain branched i-PP, was developed. The long chain branched-i-PP allows to introduce the i-PP in processin g technologies as blow moulding film technology or foaming technology. The mechanism will be discussed. The radical grafting of Polypropylen e (PP) becomes more important for the developing of PP-alloys with ext ended properties. Methylmethacrylate and styrene were polymerized and grafted in PP at low temperatures in solid state. Grafting and polymer izing in solid state means solving the monomers in the PP-powder dirce tly from the reactor without contacting with oxygen (air). The reactio n is started by the thermal decomposition of a peroxide. The reactivit y of the primary radicals from the peroxide and the transfer reactions of the polymer radical of the PMMA or PS influences the amount of the grafted polymer. The solubility of the monomers and the peroxide in t he amorphous i-PP-phase was measured. The grafting yield and the dispe rsity of the second polymer depends on the solubility and dispersity o f peroxide and monomers in the PP-powder particles.