Coupling parameters of several polymers

Ngai and Plazek developed a relationship between the primitive relaxation times, To, and the measured relaxation times, T. Because To was dependent on both temperature and molecular weight, the relaxation times were related to the coupling parameter, n, where tOc is a coupling crossover frequency. 

In Ngai and Plazek s publications, they determined that numerous sets of data could be reconciled with the well known Williams-Landel-Ferry Equation. If the glass transition temperature (Tg) was utilized as the reference temperature, then  

The empirical parameters Ci and C2 were calculated to be 5.49 and 0.141 respectively and can be used to determine n. 

Many bulk polymer properties have been well defined in the recent literature. In addition, theories that offer reasoning for changes in these bulk properties with temperature, pressure, etc. have been developed. Focus has been shifted in the past decade to polymers in thin film geometries. These systems remain obscure to polymer scientists. 

Thin films have become ubiquitous in the polymer industry. Fueled by the microelectronics industry and its need for miniature parts, polymer applications have become more demanding. Polymers in these environments have been tested and modeled in laboratories around the world from universities to automobile companies, research surrounding thin films is quickly growing.  

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