{'fraction_non_alphanumeric': 0.02676864244741874, 'fraction_numerical': 0.0028680688336520078, 'mean_word_length': 5.0520231213872835, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
A Note on Rheology of Polymeric Systems.

Some of the "well-known" features in polymer rheology are inconsistent with recent data. (1) Complex modulus of non-entangled polymer solutions cannot be described with the Rouse-Zimm equation with any choice of parameters. An extra term with a single relaxation time removes the discrepancy and also accounts for shear thinning behavior in steady flow. (2) Values of the longest Rouse relaxation time, τR, derived from viscosity are much higher than those from dynamic modulus at high frequencies, which are consistent with retraction rate of extended chain estimated from stress overshoot. (3) Entanglement molecular weight, Me, evaluated from entanglement modulus for solutions in Θ solvent is equal to that in good solvent. Me values derived from viscosity-molecular weight relation vary with solvent quality. Parameters such as M e and τR from viscosity should be used with care; evaluation method is based on behavior of non-entangled systems, which may not represent behavior of entangled systems.