Viscoelastic behavior of carboxyl-terminated (butadiene-co-acrylonitrile)-based composite propellant binder containing polyglycidyl-type bonding agent

Abstract

The influence of tris(2,3-epoxypropyl) isocyanurate as bonding agent on the physico-chemical, viscoelastic and uniaxial tensile mechanical properties of carboxyl-terminated (butadiene-co-acrylonitrile) cured with the polyglycidyl ether of glycerol and epichlorhydrin was investigated. Cross-link density values were estimated by swelling measurement. Temperature and frequency dependencies of rheological behaviour parameters (storage modulus, loss modulus, loss factor and glass-rubber transition temperature) were also analyzed. Based on the frequency dependencies of storage modulus, put in the range of temperature from -50 ?C to 20 ?C by the experiment, master curves (logG' vs log ?) were generated, reaching broader frequency interval in comparison to that used in the measurements. By choosing the glass-rubber transition temperature to be the reference one, Williams-Landel-Ferry equation constants were determined. Further, material constants, fractional free volume at the glass-rubber transition temperature and thermal coefficient of free volume expansion were calculated. Although small quantity of tris(2,3-epoxypropyl) affects the network density, the dynamic mechanical analysis showed that the bonding agent content did not affect the glass-rubber transition temperature of the tested materials.