Viscometry molecular weight averages

Polymethyl Methacrylate. Table 4 shows the results obtained for three commercially available polyraethyl methacrylate samples. Again the molecular weight averages obtained with SEC/Viscometry are in good agreement with the nominal values and the K and o values are self-consistent and in excellent agreement with the literature values.(40)... 

Equation (5) is an important practical molecular weight average derived from viscometry. In order to calculate this average, the exponent a of the Mark-Houwink relationship relating intrinsic viscosity [p] to molecular weight must be known ... 

Which of the following techniques yields a number-average molecular weight (a) viscometry,... 

Membrane Osmometry and Viscometry. Number-average molecular weights of PMMA were determined with a Mechrolab model 501 highspeed membrane osmometer in toluene at 60 °C except for samples 122-4 and 122-6 which were determined at 40°C. 

Viscometry The specific viscosity of each polymer from the bulk polymerization was measured in acetone at 30°C using an Ubbelohde dilution viscometer. Five concentrations in the range of 1.120 to 0.242 g/d poly(vinyl acetate) and polyvinyl trideuteroacetate) and 0.385 to 0.084 g/dl (poly(trideu-terovinyl acetate)) were run. Intrinsic viscosity was calculated by extrapolation of the Tlsp/c versus c plot to zero concentration. Number average molecular weights were calculated using the equation(20) [q] =1,0 x 10 1 [Mn] 0 72 which is in the mid range of the equations listed. 

J. Lesec, Problems encountered in the determination of average molecular weights by GPC viscometry, in Liquid Chromatography of Polymers and Related Materials II (J. Cazes and X. Delamare, eds.), Chromatographic Science Series, Vol. 13, Marcel Dekker, Inc., New York, 1980, pp. 1-17. 

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