Flame retardance and thermal degradation of new epoxy containing silicon and phosphorous hybrid ceramers prepared by the sol-gel method

An epoxy containing silicon and phosphorous hybrid (modified epoxy hybrid) was prepared and compared with pure epoxy. Four methods have been used to study the degradation of the hybrid during thermal analysis. These investigated methods are Van Krevelen, Horowitz-Metzger, Coats-Redfern, and MacCallum-Tanner. The activation energies (E-a) were obtained from these methods and compared. It is found that the value of E-a for modified epoxy hybrid is smaller than that of pure epoxy. The low activation energy is probably due to the presence of phosphorous-carbon (P-C) bonds which are susceptible to chain scission during thermal degradation and which act as a weak link. The thermal stability of modified epoxy hybrid ceramer is not superior to that of the pure epoxy, however the char yield of modified epoxy hybrid is higher than that of the pure epoxy at 800 degreesC. The limiting oxygen indices (LOI) of pure epoxy and modified epoxy hybrid are 24 and 32, respectively. This indicates that modified epoxy hybrid possesses better flame retardance. (C) 2002 Elsevier Science Ltd. All rights reserved.