Molecular Polydispersity

Physical and Chemical Properties of Lignosulfonates. Even unmodified lignosulfonates have complex chemical and physical properties. Their molecular polydispersiti.es and stmctures are heterogeneous. They are soluble ia water at any pH but iasoluble ia most common organic solvents. 

Fig. 51. Increase of the coefficient C with molecular polydispersity for linear chains (left) and decrease of C with branching for regular star molecules (right)101 predicted by theory...

Molecular polydispersity has a large effect on the memory function m(/) and has... 

MOLECULAR POLYDISPERSITY AND STRUCTURE OF ORGANIC LIGANDS 4.1. Low molecular weight ligands... 

Chu and co-workers (IJO, 111) have studied the photon correlation function of light scattered by solutions of narrow molecular weight fractions of PS (Mn = 397,000) in cyclohexane near the critical demixing temperature Tc- Their data fit Equations 82 and 83 with y = 1.26 0.08, y = 0.77. The correlation lengths were in the range of 100-250A, and Vs = 0.62, vr = 0.58. For (T — Tc) < 0.1°, deviations from the critical exponent concept were discovered which may result from macro-molecular polydispersity or configurational fluctuations 111)-... 

The most important achievement of living /controlled polymerization methods and techniques is the synthesis of tailor-made block copolymers with specific macromolecular architecture, chemical composition/functionality, low molecular polydispersity, and corresponding minimized heterogeneity. 

Molecular polydispersity effect on a rheological function - assuming miscibility one may compute what effect incorporation of another polymer should have, compare with the experimental data, and draw conclusion. The following functions have been examined ... 

My,lM Molecular polydispersity index, MWD MWD Molecular weight distribution usually expressed as Nb Norbomyl... 

The shear effects, depending in a great measure by polymer molecular weight, are inevitably influenced by polymer molecular polydispersity. Figure 3.365, [997, 998]. 

Koppel, D.E. 1972 Analysis of macro molecular polydispersity in intensity correlation spectroscopy The method of cumulants, J. Chem. Phys. 57 4814—4820. 

Authors of work [141] believe that these eontradictions are related to molecular polydispersity of polymer, which leads to blurring of thermodynamic stability boundaries of polymer - oligomer mixtures, large-scale fluctuations appearing near these boundaries. We give several points to prove this assumption ... 

Further development of this theory was directed to consideration of molecular polydispersity of components and the influence of osmotic pressure. 

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