Resumo

SUAREZ, N; ALDANA, M; COSTANZO-ALVAREZ, V  e  SEQUERA, M. Dielectric study of plasticization and antiplasticization effects in Cretaceous samples from Eastern and Western Venezuela. Rev. mex. fis. [online]. 2006, vol.52, suppl.3, pp.81-84. ISSN 0035-001X.

In this work we have studied plasticization and antiplasticization effects using the thermal stimulated depolarization current (TSDC) technique in rocks samples from Cretaceous strata located in North-Eastern (group A) and South-Western (group B) Venezuela . Drying and rehydration treatments show that the dielectric relaxation peaks of both groups are associated with the physisorbed moisture trapped at different sites in the material. In the samples from group A, drying treatments shift the peaks to higher temperatures. Rehydration treatments move the peaks towards lower temperatures and increase the intensity of the peaks. This could be explained in terms of water molecules acting as a plasticizer, that hint the molecular reorientation by increasing the free volume. Concerning the temperature shifting of the peaks the opposite behavior is observed in samples from group B. This antiplasticization effect could be explained in terms of dynamic interactions and restrictions between the sorbed water molecules and the complex polarizable entities of the material.

Palavras-chave : Structural relaxation; TSDC; plasticization; antiplasticization.

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