Comparison of the elongational behavior of various polyolefins in uniaxial and equibiaxial flows

摘要: For processing operations with a pronounced elongational component, it was found that the uniformity of extruded items is improved by presence strain hardening usually measured in uniaxial elongation. Many such as foaming, film blowing, and blow molding are dominated biaxial deformations, however, therefore, question arises how deformation compares. Besides linear long-chain branched PP, one classical LDPE, an HDPE pipe extrusion grade bimodal MMD, LCB-mPE were also characterized. measurements elongation Munstedt tensile rheometer (MTR) ARES-EVF used, while lubricated flow method applied for equibiaxial deformation. It more pronounced. The dependence on rate qualitatively same both modes. In range rates, chosen LDPE PP exhibit hardening, which approximately independent rates applied, whereas becomes smaller increasing rate.