Linear and Nonlinear Viscoelasticity of Polypropylene Containing Cross‐Linked Gels

Abstract The dynamic viscoelastic and elongational flow behaviors of polypropylene (PP) with increased loading of micron‐sized gelled particles have been investigated. The results reveal that incorporating gel particles can significantly enhance the PP melt storage and loss modulus, complex viscosity, and degree of strain hardening. The gel particle, acting as a soft, deformable filler, exhibits a core–corona structure. The core is made of cross‐linked PP, with the corona region consisting of chain loops, dangling chains, and strongly constrained PP matrix chains. The matrix chains bridge globally between the adjacent gel particles once the interparticle distance is shorter than the PP random coil size. This, in turn, results in a gel‐like behavior of the entire PP matrix. The present findings serve to advance fundamental understanding on the rheological behavior of polymeric systems containing self‐similar soft particles for improving melt strength.