Effect of entanglement upon branching on dispersibility, β-nucleating and mechanically strengthening ability of polystyrene in isotactic polypropylene

Polymers with benzene rings have the potential to act as macromolecular beta-nucleating agents and rigid organic particles for isotactic polypropylene (iPP). The dispersibility in iPP matrix is a key factor for their beta-nucleating efficiency and mechanically strengthening ability. In this paper, comb-like branched polystyrenes (cPSs) with different side chain lengths were introduced into iPP. The effect of entanglement upon branching on dispersibility, beta-nucleating and mechanically strengthening ability of PS in iPP was investigated in detail. Compared with the linear polystyrene with the same length of backbone, the incorporation of side chains intensifies the entanglement between cPS chains, not facilitating their dispersion in iPP matrix. However, short side chains (chain length lower than the critical chain entanglement molecular weight of PS) facilitate the interdiffusion between the cPS and iPP chains and ultimately lead to favorable dispersibility and high beta-nucleating efficiency, as well as prominent toughening and reinforcing effect on iPP.

Automated summary

The incorporation of comb-like branched polystyrenes with different side chain lengths into isotactic polypropylene was found to enhance their beta-nucleating efficiency and mechanical strengthening ability. Short side chains were shown to facilitate interdiffusion between the branched polystyrene and isotactic polypropylene chains, leading to improved dispersibility and beta-nucleating efficiency in the matrix.