Thermal stability and pyrolysis kinetics of lignin-phenol-formaldehyde resins

A thermal stability and kinetic study from non-isothermal experiments of a commercial and a lignin-novolac resin mixed with two amounts of curing agent has been done employing thermogravimetric analysis technique. Three kinetic models have been tested: a single heating rate method, such as Coats-Redfern, employing several mechanistic functions and contrasted with Van Krevelenit is the first time that this method has been employed in polymer degradation. Finally, the Ozawa method allowed the obtaining of the activation energy by the multiple-heating-rate without knowing the mechanism. Results show that commercial mixtures of resins lose less weight than lignin-novolac resins. The calculated kinetic parameters showed that Coats-Redfern gives similar results to Van Krevelen, which means that these methods are adequate for novolac pyrolysis, and Ozawa shows activation energies in accordance with the last mentioned models. (c) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012