Effect of external electron donors on microstructure and final properties of PP/EPR in-reactor blends

In this paper the effect of external electron donor on microstructure and mechanical properties of polypropylene/(ethylene-co-propylene) in-reactor blends were investigated. It was found that the type of external donor profoundly affects the microstructure of copolymer. Considering two electron donors phenyltriethoxysilane (donor A) and cyclohexyldimethoxymethylsilane (donor C), it was found that using the mixture of donors has synergistic effect on molecular weight (viscosity) and impact properties of blends, so that the blends synthesized using pure donors had lower molecular weight and impact properties. In addition, it was found that the amount of block copolymers was higher in the blend based on 25% donor C and 75% donor A. This fact may be the reason for significant higher impact strength of this blend

Keywords:

PP/EPR , In-reactor blending , Ziegler-Natta , Mixed electron donors , microstructure