RELAXATION PROCESSES

Author: MICHELENA GONZÁLEZ OLATZ.
Year: 2005.
University: PAÍS VASCO [www.ehu.es].
Place of defense: FACULTAD DE CIENCIAS QUÍMICAS.
Place of preparation: FACULTAD DE CIENCIAS QUÍMICAS.

Summary: In order to help clarify the microscopic origin of the secondary relaxation of polycarbonate, and thus the search for the relationship between molecular structure and mechanical properties of this type of polymer engineering and high performance, in this paper we have studied their dielectric relaxation processes. The molecular analysis of the movements involved in the relaxation technique using dielectric spectroscopy (SD) has enabled cover a wide range of frequencies measured with high sensitivity, being one of the macroscopic most powerful technique for studying the molecular dynamics. On the one hand, has studied the effect on the dielectric relaxation of small changes in the molecular structure of the polymer unit repetitive as has been used extensively by other spectroscopic techniques such as molecular dynamics. On the one hand, has studied the effect on the dielectric relaxation of small changes in the molecular structure. On the one hand, has studied the effect on the dielectric relaxation of small changes in the molecular structure of the polymer unit repetitive as has been used extensively by other techniques, including spectroscopy dinámica-mecánica (DMS). On the other hand, has used a completely original approach to studying the problems effect on the dielectric relaxation of the chemical modification did not allow substantial progress in understanding the molecular mechanisms responsible for the dielectric relaxation of polycarbonate, the results of the second approach combined with those obtained previously by other members of the group through neutron scattering, have achieved its goal. Moreover, the molecular interpretation obtained, has allowed explain the influence of different chemical change in the characteristics of dielectric relaxation identified in the first part of the work.