The Influence of Molar Mass Distribution on the Complex Moduli of Polymer Melts

Analytical Rheology of Polymer Melts: State of the Art

“…Advances have been more forthcoming for polydisperse mixtures of LPs for three reasons, (i) there is a plethora of well-characterized experimental data [60,[206][207][208][209][210][211][212], (ii) rheological models have been built, tested, refined, and calibrated extensively [213], and (iii) it is possible to use approximate "double reptation-" type models [135,214], in lieu of the full tube model [142], which makes the mathematical model and its numerical solution more expedient.…”

“…The dependence of other linear and nonlinear material functions on molecular weight is also quite pronounced. This strong dependence can, in principle, be directly translated into analytical sensitivity and resolution, especially at higher molecular weights where competing analytical methods are particularly ill-suited [54,60,61].…”

Towards a rheological classification of flow induced crystallization experiments of polymer melts

“…(An estimate based on the observation that gelation occurs during early stages of the crystallization process (Schwittay et al 1995;Pogodina and Winter 1998) gives a larger magnitude of the HMW tail, but this is still a small quantity of the total MWD.) These small quantities are difficult to trace down in gel permeation chromatography measurements as well as in the linear and non-linear viscoelastic regime (Eder et al 1989;Eder and Janeschitz-Kriegl 1997;Graham et al 2001;Seki et al 2002;Hepperle 2002;van Meerveld 2004a , Eq. (7), may not be justified (Milner 1996;Watanabe 1999;McLeish 2002) and the magnitude of De rep is expected to be overestimated.…”

“…(This problem can be resolved by performing creep experiments; Kraft et al 1999;Gabriel and Mu¨ndstedt 2002. ) Second, the contribution of the HMW tail may be screened by the remaining part of the melt (Eder et al 1989;Suneel et al 2003;Hepperle 2002). It should be noted that magnitude of s rep of the chains in the HMW tail is reduced through the mechanism of tube dilation and fast Rouse relaxation modes in a complicated fashion depending of the MWD (Watanabe 1999;Pattamaprom et al 2000;Pattamaprom and Larson 2001).…”

Molecular weight distribution of regular asphalts from dynamic material functions

“…As an example, the zero shear rate viscosity of many polymeric materials depends approximately on molecular weight to the 3.4 power, and the first normal stress coefficient for monodisperse linear polymers has the power law dependence on molecular weight with exponent 6.8 [1]. The reported sensitivity of the rheological properties of polymers to the molecular weight distribution is very high [2][3][4]; it may be higher than the sensitivity of gel permeation chromatography (GPC).…”