PHYSICAL, MECHANICAL AND MORPHOLOGICAL CHARACTERISTICS OF CHAIN MODIFIED GAP AND GAP-HTPB BINDER MATRICES

摘要

Glycidyl azide polymer (GAP) is one of the most promising high-energy propellant binders for use in advanced composite solid propellant formulations. GAP is a unique binder of high density with positive heat of formation and is compatible with advanced oxidizer like ADN and can give improved performance in terms of specific impulse and chlorine-free exhaust. This paper details the physical, mechanical and morphological characteristics of chain modified GAP and GAP-HTPB binder matrices. The effect of GAP functionality, NCO/OH equivalent ratio, concentration of cross-linker and curing conditions on the mechanical properties of the cured GAP and GAP-HTPB blends were evaluated. GAP being bifunctional needs a minimum cross-linker concentration of 3% for an NCO/OH ratio of unity to achieve satisfactory mechanical strength for the cured network. The suitability of GAP for using as an energetic additive with HTPB binder was also investigated using GAP-HTPB blends of varying proportions ranging from 0 to 100 %. GAP-HTPB blends of 50:50 to 30:70 ratios show superior mechanical properties over the virgin networks of GAP and HTPB, due to the synergetic effect of interlocking of the two networks. The morphology of GAP-HTPB networks shows higher degree of topological entanglements of both networks at GAP-HTPB ratio between 50:50 and 30:70.