Molecular weight ratio, critical

Fig. 4.2. Reduced steady-state sheaf compliance JeR as a function of the ratio of molecular weight to critical molecular weight MjM, according to eq. (4.10) (theoretical curve)...

The values of C and D are evaluated at the critical point and normal boiling point. U. is the vertical molecule-cation interaction energy and U isJthe corresponding molecule-anion term. U and w are calculated as the sums of all the appropriate dielectric and Lennard-Jones potentials. The actual calculation of an x/m isotherm is the superposition of several solution models. The principal one corresponds to the partial filling by molecules on the cation sites. The value of x/m is a constant times Xg, summed over all sites, where the constant is the molecular weight ratio. 

Figure 7. Location of critical molecular weight ratio as a function of S, protection mode, and light absorption decrement ratios...

Under 0 conditions occurring near room temperature, [r ] = 0.83 dl g for a polystyrene sample of molecular weight 10. f Use this information to evaluate tg and for polystyrene under these conditions. For polystyrene in ethylcyclohexane, 0 = 70°C and the corresponding calculation shows that (tQ /M) = 0.071 nm. Based on these two calculated results, criticize or defend the following proposition The discrepancy in calculated (rQ /M) values must arise from the uncertainty in T>, since this ratio should be a constant for polystyrene, independent of the nature of the solvent. 

This could occur if the separation ratio of another solute pair, although larger, was very close to that of the critical pair but contained solutes, for example, of widely different molecular weight (and, consequently, very different diffusivities). Fortunately, the possibility of this situation arising is remote in practice, and will not be considered in this discussion. It follows that the efficiency required to separate the critical pair, numerically defined, is the first performance criterion. 

Thus, fracture occurs by first straining the chains to a critical draw ratio X and storing mechanical energy G (X — 1). The chains relax by Rouse retraction and disentangle if the energy released is sufficient to relax them to the critically connected state corresponding to the percolation threshold. Since Xc (M/Mc) /, we expect the molecular weight dependence of fracture to behave approximately as... 

Physical and Chemical Properties - Physical State at 15 X and 1 atm. Liquid Molecular Weight S5.W -, Boiling Point at 1 atm. Decomposes-, Freezing PoirU -5.8, -21,252 Critical Temperature Not pertinent Critical Pressure Not pertinent Specific Gravity 0.925 at 25 °C (liquid) Vapor (Gas) Density Not pertinent Ratio of Specific Heats of Vapor (Gas) 1.074 Latent Heat of Vaporization No... 

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