Estimation from molecular weight change

Equations 4a,b provide means for evaluating the kinetic parameters by combined measurements of the rate and the number average molecular weight. Conversely, if the kinetic parameters have been determined, for example, by measurements of the initial rate as a function of molecular weight, the molecular weight change may be estimated from the more readily measured rate of volatilization. It must be noted in this connection that the coefficients e and a are only approximately constant and independent of C, since they are both functions of the radical concentration R. For the case corresponding to Equation 4a we find (21,26) ... 

A cross-linked polymer has a density of 0.94 g cm" at 25°C and a molecular weight between crosslinks of 28,000. The conformation of one bond in the middle of the molecule changes from trans to gauche, and the molecule opens up by 120°. In w-butane, the trans to gauche transformation requires about 3.3 kJ mol". Estimate a value for AH of stretching based on this model, and use the law of cosines to estimate the magnitude of the opening up that results. 

It is possible to estimate the influence of temperature on A2 from the change in the state of the polymer. The value of A2 depends on the Molecular weight and also on the Molecular... 

The fact that the thickness of the interphase estimated here stays unchanged at 34A in the molecular weight range of 30,000-100,000, while the mass fraction and thickness of amorphous phase change remarkably, is particularly meaningful. Flory et al. [6,7] anticipated in 1984 based on their lattice theory that the methylene chains that emerge from the basal plane of lamellar crys-... 

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