Relationship between Peroxide Initiators and Properties of Styrene Grafted Polypropylene via Reactive Extrusion

Abstract

ABSTRACTTo understand the relationship between the initiators and the properties of grafted polypropylene (PP), and provide guidance for designing polymers with different performance through selecting appropriate initiators, a series of styrene (St) grafted PP was prepared by modifying commercial linear PP via reactive extrusion using two different peroxide initiators, dicumyl peroxide (DCP) and benzoyl peroxide (BPO). Fourier transform infrared spectra indicated that the use of DCP led to a higher St grafting degree compared to the system using BPO. The melt flow index and rheological characteristics suggested the existence of short chain branching (SCB) structures in the St grafted PP using DCP, and long chain branching (LCB) structures in the St grafted PP using BPO. Differential scanning calorimetry and polarized optical microscopy results showed that the degradation of the PP chains and the introduction of SCB structures hindered the crystallization process of the St grafted PP using DCP, and the existence of the LCB structures accelerated the crystallization process of the St grafted PP using BPO. We suggest this research can contribute to the understanding of methods to prepare grafted PP with special properties via reactive extrusion by using proper initiators.