2017 Volume 45 Issue 3 Pages 133-138
Dynamic viscoelastic properties of standard pullulan samples with different molecular weights and narrow molecular weight distributions in ionic liquids are measured in non-entangled region over a wide range of chain overlapping (1 ≤ C [η] ≤ 12.6) and compared with Rouse-Zimm (RZ) theory with and without introducing correction term called long time (LT) term, proposed by Osaki et al. (J. Polym. Sci., Part B, Polym. Phys. Ed., 39, 211-217, (2001)). When chains are overlapped (say 2.5 ≤ C [η]), loss modulus data (G") can be well expressed by the RZ theory with experimentally determined longest relaxation time τRZ while storage modulus (G') was larger than the calculation. However, addition of LT term made reasonable correction for calculation of G' similar to the results for standard polystyrenes. To apply the RZ fitting for Mw estimation of unknown sample (fitting G" by RZ theory), estimation error for τRZ and resulting Mw are examined. At high C [η], relative error of estimated Mw was about 15%, as long as τRZ can be determined with small error and coincidence of τRZ and the longest Rouse relaxation time calculated from estimated Mw is confirmed. At lower C [η], this method tend to underestimate Mw and the error become larger.
