Exploring Alternative Methods for Determining the Recoverable Creep Compliance of Polymer Melts

The limiting, steady‐state, recoverable compliance is the basic measure of the elasticity of polymer melts. Although normally measured using a creep experiment, there are alternative viscoelastic measurements that might be more convenient or even less prone to error. The purpose of this work was to examine these alternatives for practicality and error, using polymer melts. While melts are often studied because of their commercial importance, melts are chosen here for simplicity: no concerns about solvent loss, phase separation or safety issues. The major test polymer used was a linear low‐density polyethylene (LLDPE) with a trade name of LDPE‐6201 (Union Carbide). As extrapolation is required for all methods, one expects discrepancies and such were found. At least with a stress‐controlled rheometer, the traditional method (creep) appears to be optimal, although some long times are required to reduce extrapolation error. A dynamic method was found to be simple to run and quite reproducible, but the found value of was higher by ~7%. This discrepancy will be examined in future work.