Study the Effect of Functionality of Aromatic Epoxies on the Curing Kinetics of Polybutadiene Acrylonitrile Acrylic Acid (PBAN) Terpolymer Using FT-IR

Polybutadiene acrylic acid acrylonitrile (PBAN) is binder for composite solid propellants used in spacecraft systems, curing kinetics of which is very important. In this research, the effect of functionality of epoxy curative on the curing kinetics of PBAN is researched. Equivalent stoichiometric ratios of PBAN and di-functional (DER 331) and tri-functional (LY 5052) epoxy curatives was cured at 80ºC. During curing reaction, 16 in-situ FT-IR spectra were obtained from the samples to monitor the progress of ester group formation (curing progress). Curing reaction of PBAN with both curatives consists of two separated steps with dissimilar kinetics. Transition from first step to second step of curing reaction, for difunctional curative is occurred after 7 days while, for tri-functional curative after 3 days. The rate of curing reaction using di-functional epoxy curative, is approximately half of tri-functional epoxy curative. These results are important in the aspect of production process and mechanical properties of final product.