Aqueous hydrogen peroxide-induced degradation of polyolefins: AÂ greener process for controlled-rheology polypropylene

In this work we demonstrate that aqueous hydrogen peroxide is an effective reagent for chain scissioning or vis-breaking of polypropylene during melt-processing to produce a controlled rheology product. The novel process involves the direct injection of aqueous hydrogen peroxide into the polypropylene melt under pressure. The polypropylene produced has reduced molar mass, narrowed molar mass distribution, and is indistinguishable in terms of melt flow rate, molar mass distribution, crystallinity and melt rheology from conventionally vis-broken polypropylene produced using an organic peroxide (2,5-dimethyl-2,5-di-tert-butylperoxyhexane (DHBP)). However, the polypropylene produced in the current process is notably free of the initiator-derived organic volatiles that are formed as by-products in the case where organic peroxides such as DHBP are used.