Reaction model and cure kinetics of fiber-reinforced phenolic system

Fiber-reinforced phenolic composite has become an ideal material for solid rocket motor’s (SRM) nozzle, because of its excellent high temperature resistance and ablation resistance. The physical and chemical properties of reinforcing fiber would significantly affect the cure reaction of phenolic (PF) resin, which results in the obvious difference between the cure characteristics of the fiber-reinforced phenolic system and neat resin. To clarify the difference in cure reaction between fiber-reinforced phenolic system and PF resin, meanwhile, to obtain the kinetics of high silica glass fiber/phenolic (GF-HSi/PF) prepreg and carbon fiber/phenolic (CF/PF) prepreg, the dynamic experiments of PF resin, GF-HSi/PF prepreg and CF/PF prepreg are carried out by differential scanning calorimetry (DSC). Iso-conversional kinetics is proposed, and the activation energy is determined as a function of cure degree. The reaction model f(α) is obtained by introducing the kinetics compensation effect, founding that the f(α) of PF resin is influenced significantly by reinforcing fiber. The kinetics of three materials are determined by the model-fitting method, founding that the kinetic models of PF resin, GF-HSi/PF prepreg and CF/PF prepreg are a one-step autocatalytic model, two-step model from autocatalytic reaction to N-order reaction and three-step model from autocatalytic reaction to N-order reaction respectively. [Figure not available: see fulltext.]