Dialectric spectroscopy of poly (ethil acrylate) linear exposed to p-xylene atmosphere

Abstract

Consulta en la Biblioteca ETSI Industriales (8825)

[EN] Scientific research on the structure and properties of hydrogels is of great importance in material science. Hydrogels have been proposed for many biomedical applications because of their good biocompatibility and the possibility of synthesizing materials with a broad spectrum of micromorphologies and specific properties. Therefore, they are extensively used in numerous technological and medical fields. One of these fields is Biomechanics. This final project, includes the preparation and testing of poly(ethyl acrylate) swollen in p-xylene atmosphere at different percents. The main objective was to obtain a general view of the influence of a non-polar solvent on the properties of this material. The Technical Methods used for this purpose, include mass measurements, amount of pxylene absorbed as well as Differential Scanning Calorimetry (DSC), and Dielectric Spectroscopy techniques. Particulary, Thermally Stimulated Depolarization Currents (TSDC) and Dielectric Relaxation Spectroscopy (DRS) techniques. The measurements showed that by increasing the amount of p-xylene up to 20 percent, a plasticization of the ¿-relaxation of PEA is found. Between 20 and 30 percent an additional peak appears in DSC and TSDC, probably a second ¿ relaxation, which it is called T¿¿. Likewise in DRS measurements, close to 20 percent is where the relaxation time of the ¿-relaxation is changing in a strange way. Above 30 percent, the system measured, by the three different techniques, goes back to higher temperatures, showing a behaviour similar to that of a sample with around 10 percent of p-xylene. It is concluded that an amount of non-freezable p-xylene was found which was ascribed to the increasing viscosity of the swollen matrix as the system reaches temperatures close to the glass transition, as it was shown in previous studies of benzene (12,13).