Glass transition in the lower homologues of polyethyleneoxide |
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Authors: | Valery P Privalko Alla P Lobodina |
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Institution: | Institute of Macromolecular Chemistry, Academy of Sciences of the Ukrainian SSR, 252160, Kiev 160, Kharkovskoye Chaussee 48, U.S.S.R. |
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Abstract: | Experimental measurements of Tg for two series of lower homologues of polyethyleneoxide. differing in their end-groups, are discussed in terms of existing theories. Simple free-volume considerations predicting linear dependence of Tg on (molecular weight)?1 are inadequate in systems with end-groups capable of specific interactions (hydrogen bonding). Thermodynamic arguments show that the true Tg of infinitely long PEO chain is 220 ± 5°K. Suitable modification of parameters of the Gibbs-DiMarzio equations to account for the dependence of the free volume fraction on the concentration of end-groups results in good fit of the experimental data for hydroxyl-terminated samples and correctly predicts Tg(∞). Analysis of the data for chlorine-substituted oligomers suggests the existence of specific intermolecular interactions in the latter, involving chlorine atoms. |
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