Search

Raman spectroscopy is a widely used technique for chemical and physical analyses of materials, which allows for the study of composition and the structure of the samples. Particularly in recent years, it has been used to identify the normal modes of vibration in the chemical structure and in the functional groups of monomers and polymers. This dispersive technique is employed in the study of the epoxy/amine system, where the normal modes of vibration in the system composed of the epoxy oligomer Diglycidyl ether of bisphenol-A (DGEBA) and trimethylene glycol di-p-aminobenzoate (TMAB) are identified. The principal normal modes of vibration were determined for amine groups of TMAB around 1626, 3333 y 3436 cm-1 and for epoxy rings of DGEBA around 736, 915, 933, 1131, 1249-1252, 1407, 2713, 2760 and 3006 cm-1. The peaks associated with nitrogen-hydrogen symmetric and antisymmetric bonds of the amine (1626 y 1687 cm-1) and the symmetric vibration of the CH2 groups of the epoxy group (3006 cm-1) are indicative of the progress of crosslinking reaction. [ABSTRACT FROM AUTHOR]

This work includes the study of the hydrolytic biodegradation of coatings based on polylactic acid, polyglycolic acid and hydroxyapatite. These coatings were obtained by cathodic electrodeposition over piezoelectric quartz crystals, using an electrolyte with different polymer/ceramic ratios but with a fixed time, voltage and volume of solvent. The films obtained were immersed into a simulated body fluid (SBF) during 1, 3, 5, 7 and 10 days at constant temperature and pH. The coatings were analyzed by EIS and QCM to find a correlation between frequency changes and the total transferred mass. [ABSTRACT FROM AUTHOR]