Partition-function ratios temperature-extrapolations

Detailed analysis of the results published by Casper and Schulz 2) and measurements with the new chromatograph mentioned above 3) have shown that irrevesible thermodynamics, including two different kinetic effects, has to be applied to explain the resolution of the PDC-column 4 5 9) and to obtain the MWD of narrowly distributed polystyrene samples 6 8). In this way, not only the MWD is obtained, but also kinetic constants and thermodynamic functions of the polymer transfer between sol and gel, as well as hydrodynamic and kinetic spreading parameters of the system investigated, can be calculated from PDC-measurements performed at different constant column temperatures, with the same sample injected. The usual static quantities (such as the exponent of the partition function, ratio of the gel/sol volumes, etc.) proposed by Casper and Schulz can then be obtained by extrapolating the results to the theta temperature of the system. In addition, spreading phenomena alone can directly be... 

The Y method should be useful for the extrapolation of isotopic partition-function ratios over limited temperature ranges, especially in those cases where the h.t.a. fails. Such extrapolation would require an estimation of either 7or S(vir — V2i ) (cf,. Equation 5). Since the latter quantity can be expressed in terms of force constants and geometries (4, 7, 28), reasonably accurate estimations of it can be made (4,9), y is then calculated for a given temperature according to Equation 8 and a corresponding characteristic frequency 7 is evaluated. This 7 may then be used to predict the partition-function ratio at other temperatures of course, such a procedure implies the constancy of 7 over the temperature range considered. 

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