Poly skeletal frequencies

Comparison of Amide and Skeletal Frequencies of a-Poly(i.-alanine) and a-Poly(L-glutamic Acid)... 

Improvements beyond the empirical, direct additivity of heat capacities is needed at low temperatures, where skeletal vibrations govern the heat capacities. With only few measured points it is possible to establish the functional relationship of the 0, and 3 temperatures with concentration for the inter- and intramolecular vibrations (see Sect. 2.3). The group-vibration frequencies are strictiy additive, so that heat capacities of complete copolymer systems can be calculated using the ATHAS, as discussed in Sect. 2.3.7. hi Fig. 2.70 the glass transition changes with concentration, to reach 373 K for the pure polystyrene, as for the previously discussed copolymer systems with polystyrene. Below T, the solid Cp of both components needs to be added for the heat capacity of the copolymer, above, the liquid Cp must be used. The glass transition retains the same shape and width as seen in Fig. 7.68 on the example of brominated poly(oxy-2,6-dimethyl-l,4-phenylene) [29]. 

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