TGA and TPD MS study of silica-gelatin materials
Gelatin-based films with silica-to-gelatin weight ratio 1:5 or 8:5, containing either hydrophilic or hydrophilic-hydrophobic silica, have been prepared and studied by means of thermogravimetric analysis and temperature-programmed desorption mass spectrometry. It has been shown that silica presence has no effect on the mechanism of thermal decomposition of gelatin; however, it affects the kinetics of gelatin thermolysis both in vacuum and in air, including an increase in the activation energy of the volatile products formation at hydrophilic silica content about 17 wt. %. Hydrophobization of silica surface as well as an increase in hydrophilic silica concentration in the film from 17 to 62 wt. % decreases the activation energy of the volatile products formation during gelatin thermolysis. This effect is explained by reduced binding of gelatin with silica owing to either substitution of some surface silanol groups upon partial hydrophobization of silica, or their involving into interparticle rather than in silica-gelatin interactions at higher silica content.