Viscosity average molecular mass

Viscosity-Average Molecular Mass Molecular mass determined on the basis of viscosity measurements coupled with an empirical equation such as the Staudinger—Mark—Houwink equation. 

In the above equation the R group designates the particular acrylate. Ethyl, iso-propyl, and / -butyl acrylates were produced yielding the polymers poly(ethyl acrylate)-di (PEA-di), poly(wo-propyl acrylate)-di (PIPA-di) and poly(n-butyl acrylate)-di. For PIPA the viscosity average molecular mass was measured to be 98,000 daltons.(5) The molecular masses of the other polymers were not estimated directly because their Mark-Houwink coefficients were not known, but they had similar intrinsic viscosities. At these molecular weights, we expect the relaxation times to be independent of molecular mass.(i)... 

Viscosity average molecular mass correlates with the ability of the polymer solution to flow because "a" is a crude measure of hydrodynamic volume of the polymer molecules in the solution and this volume controls solution viscosity. When the capacity of the polymer solution to scatter light is measured, it will not depend on... 

The Mark-Houwink equation defines the viscosity average molecular mass as ... 

More recently Weidmann and Doll [27] have shown that the craze dimensions decrease markedly in PMMA at low molecular masses. In a study of the molecular mass dependence of fracture surfaces in the same pol3mier, Kusy and Turner [28] could observe no interference colours for a viscosity average molecular mass of less than 90 000 daltons, concluding that there was a dramatic decrease in the size... 

Figure 12.10 Dependence of fracture surface energy on reciprocal molecular mass) A/, is viscosity average molecular mass). (Reproduced with permission from Berry, J. Polym. Sci., A2, 4069 (1964))...

Polyisobutylene and Butyl Rubber. Polyisobutylenes are polymers of low polarity and low Tg and are available in a wide range of molecular masses. For pressure-sensitive adhesives, polymers with a viscosity average molecular mass My of at least 10 are used in combination with low molecular mass types. 

For PMMA, Berry showed that the surface energy was strongly dependent on polymer molecular mass [25], His results (Figure 13.10) fitted an approximately linear dependence of the fracture surface energy on reciprocal molecular mass, such that y = A — B /Mv, where My is the viscosity average molecular mass. Many years previously, Flory [26] had proposed that the brittle strength is related to the number average molecular mass. 

Find the viscosity-average molecular mass of the polyvinyl alcohol sample of Problem 28.41. 

Hydroxypropylmethyl cellulose, HPMC, (trade name Methocel K4M CR, methoxyl content 22.7%, hydroxypropyl content 8.9%) was obtained from Colorcon Ltd., England. Viscosity average molecular mass was Mv=91,500 g/mol, determined at 20 °C. Critical overlap concentration of HPMC was c =0.1269%. Sodium carboxymethyl cellulose, NaCMC, degree of substitution DS=0.77, purity >96%, was obtained from Milan Blagojevic , Serbia. Viscosity average molecular mass of NaCMC was Mv=121,000 g/mol, determined at 25 °C, and critical overlap concentration c =0.1927%. Sodium dodecylsulfate, SDS, purity >99%, was obtained from Merck, Germany. Critical micelle concentration was... 

The standard Huggins extrapolation procedure was employed to determine intrinsic viscosity. The viscosity-average molecular mass was calculated from the Mark-Houwink equation ... 

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