Shear creep recovery behavior of IUPAC low-density polyethylenes

Shear creep and creep recovery measurements were carried out on three low-density polyethylenes that were the object of extended investigations of the International Union of Pure and Applied Chemistry Working Party on the Structure and Properties of Commerical Polymers. The measurements were carried out in torsion at 130° and 153°C using a frictionless apparatus with a magnetic levitation bearing. The three samples were found to be experimentally the same at short deformation times and a high shear rates. Larger nonlinear recoverable compliances were exhibited by one of the samples, which is suspected of containing a high molecular weight tail, possibly microgel, at long times and low creep stresses.