Rheologische Methoden zur Bestimmung der Molmasse und Molmassenverteilung / Rheological Methods for Determining Molecular Weight and Molecular Weight Distribution

Rheological investigations of linear and hyperbranched polyethersulfone towards their as-spun phase inversion membranes' differences

“…The wider MMD could be attributed to the interactions of polymer side chains or branches in HPES macromolecules. The quantitative data for materials' molecular weight (M w ) and polydispersity index (PDI) obtained via sophisticated molar mass distribution (MMD) method [26][27][28] are tabulated in Table 2 and are in consistent with our qualitative interpretations. It should be noted that usually the rheo-MMD conversion is based on the rheological theory for linear chain polymers only.…”

Solution-free methods for the determination of the molecular mass distribution of polymers

“…is relaxation time of the chain conformation. The J 0 value characterises that part of the temperature dependence of the modulus of elasticity (compliance) which is unaffected by the MM and MMD of the polymer and serves as a basis for the calculations of the function j(T ) [see Eqn (7)]. Schematically, the procedure for the determination of j(T ) using the temperature dependence of deformation (compliance) of a linear polymer is shown in Fig.…”

Correlations of single‐point parameters of linear rheology and molecular weight distribution of polypropylene homo‐ and copolymers

“…The rheological behavior of thermoplastic polymers, which is critical both in polymerization and conversion, results from a combination of chain structure (chemistry and stereostructure), chain topology (branching degree and branch length), and molecular weight distribution (MWD). [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Although modeling efforts have been made for all of these aspects and different rheological approaches, the highest number of papers deals with establishing models for interrelating the linear viscoelastic behavior and MWD of linear (non-branched) polymers. [3][4][5][6][7]9,10 Over time, various factors have renewed the interest in this interrelation; ranging from fundamental understanding of polymer molecules behaviors 9,10,19 through the design of target MWD for specific processes 8,13,17,20 and applications, to the use in advanced flow modeling and production simulation.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Although modeling efforts have been made for all of these aspects and different rheological approaches, the highest number of papers deals with establishing models for interrelating the linear viscoelastic behavior and MWD of linear (non-branched) polymers. [3][4][5][6][7]9,10 Over time, various factors have renewed the interest in this interrelation; ranging from fundamental understanding of polymer molecules behaviors 9,10,19 through the design of target MWD for specific processes 8,13,17,20 and applications, to the use in advanced flow modeling and production simulation. 15 A specific aspect in the industrially very relevant area of polyolefins has been the use of dynamic rheology instead of high temperature size exclusion chromatography for determining MWD or MWD-related parameters to be used in polymer design and production control.…”

“…This results in a typically "soft" form of the corresponding storage and loss modulus, G 0 and G 00 , as a function of frequency, ω, of which only a limited frequency range is easily accessible. Using timetemperature superposition 19 for expanding said range is also of limited value because the respective shift factors are rather small due to the large distance between the usual measuring range of 180-240 C and the glass transition of $0 C. Full MWD calculations from dynamic moduli, as performed in the group of Friedrich 4,6,7 for polystyrene (PS) are consequently difficult for PP, and deviations found can mostly be linked to said narrow frequency range. 7,37 Morshedian et al investigated the rheology and associated MWD of five commercial isotactic PP grades, employing a rheological material function to predict the MWD data.…”