Topological effect, glass transition temperature

In this approach, connectivity indices were used as the principle descriptor of the topology of the repeat unit of a polymer. The connectivity indices of various polymers were first correlated directly with the experimental data for six different physical properties. The six properties were Van der Waals volume (Vw), molar volume (V), heat capacity (Cp), solubility parameter (5), glass transition temperature Tfj, and cohesive energies ( coh) for the 45 different polymers. Available data were used to establish the dependence of these properties on the topological indices. All the experimental data for these properties were trained simultaneously in the proposed neural network model in order to develop an overall cause-effect relationship for all six properties. 

On samples previously drawn at different temperatures, de Candia et al. found similar behavior [36]. The analysis of the dynamic-mechanical behavior showed two effects an appreciable increase in the elastic modulus on drawing and a relevant increase in the glass transition temperature. The modulus hardening can be considered as a further indication of the morphological and topological reorganization induced by drawing. 

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