Thermal, structural and morphological assessment of PVP/HA composites

• Published in: Journal of thermal analysis and calorimetry 2010-09, Vol.101 (3), p.899-905
• Main Authors: Mendes, L. C., Rodrigues, R. C., Silva, E. P.
• Format: Article
• Language: English
• Subjects: Analysis; Analytical Chemistry; Applied sciences; Assessments; Calorimetry; Chemistry; Chemistry and Materials Science; Combustion; Composite materials industry; Composites; Degradation; Differential scanning calorimetry; Exact sciences and technology; Forms of application and semi-finished materials; Hydrogen; Hydroxides; Hydroxyapatite; Hydroxyl groups; Infrared spectroscopy; Inorganic Chemistry; Measurement Science and Instrumentation; Physical Chemistry; Polymer industry, paints, wood; Polymer Sciences; Technology of polymers; Thermogravimetry
• ISSN: 1388-6150; 1588-2926; 1572-8943
• DOI: 10.1007/s10973-010-0835-4

Composites of poly(vinyl pyrrolidone)/hydroxyapatite (PVP/HA), at variable proportions (100/0; 80/20; 50/50; 20/80 wt%) were prepared and characterized by Fourier transformer-infrared spectroscopy (FT-IR), wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and thermogravimetry/differential thermogravimetry (TG/DTG). PVP carbonyl stretching was slightly shifted to lower frequency in composites indicating the formation of hydrogen bonding with HA hydroxyl groups. At the first cycle of heating, the calorimetric curves revealed a broad peak the intensity of which was reduced insofar as the amount of PVP decreased in the composites. This peak was attributed to the PVP enthalpy relaxation. According to the TG/DTG curves, PVP degraded into two steps sharply perceivable in the composites. The first decay was ascribed to the release of the pyrrolidone pendant groups and the following one concerned the burning of the hydrocarbon chains. The HA molecules seem to exert a catalytic action on the PVP degradation.