Study of the thermal degradation of bioactive sol-gel coatings for the optimization of its curing process Articles uri icon

publication date

  • February 2012

start page

  • 499

end page

  • 508

issue

  • 2

volume

  • 107

International Standard Serial Number (ISSN)

  • 1388-6150

Electronic International Standard Serial Number (EISSN)

  • 1588-2926

abstract

  • A set of materials has been prepared by sol&-gel process containing different quantities of hydroxyapatite (0, 2.5 and 5% HAp w/w) using as silica precursors glycidyloxypropyltrimethoxysilane (GPTMS) and triethoxyvinylsilane (VTES). In order to optimize the curing process to obtain sintherized systems (inorganic network) or hybrid systems (organic&-inorganic) a TG and FTIR studies have been developed and degradation kinetic triplet parameters were obtained (the activation energy, pre-exponential factor, and function of degree of conversion). The kinetic study was analyzed by means of an integral isoconversional non-isothermal procedure (model free), and the kinetic model was determined by the Coats&-Redfern method and through the compensation effect (IKR). All the systems followed the n = 6 kinetic model. The addition of HAp increases the thermal stability of the systems. The isothermal degradation was simulated from non-isothermal data, and the curing process could be defined to obtain the two types of materials. Temperature under 250 °C allows the formation of hybrids networks.

keywords

  • sol gel; hap; vtes; gptms; kinetics