Investigation of polypropylene degradation during reactive extrusion process

Polymer degradation is an important aspect of polymer science and engineering. Degradation during extrusion is very common and can be of various types. It depends ontemperature, heating time, concentration of peroxide as initiator and the radicals generated from the thermal decomposition of peroxide. The first step is the thermal decomposition of peroxide to form primary radicals (RO·). The following step is the abstraction of a hydrogen atomfrom PP backbone by a RO· leading to formation of a macroradical. The macroradicals can further undergo ß-scission or react with PP and multifunctional monomer. Due to the high instability of tertiary macroradicals, the degradation process is extremely fast at high temperatures(T > Tm), which will result in the reduction of the melt strength of PP. Co-agent is used as a coreactant to stabilize macroradicals and could control the chain cleavage In this paper the effects of the initiator and co-agent on degradation are discussed. Two concentration of peroxide(0.03, 0.06 wt %) and two different concentration of co-agent (0.09, 0.14 wt %) are studied