Studies on structure property correlation of cross‐linked glycidyl azide polymer

Abstract

Glycidyl azide polymer (GAP) has been evaluated for use as binder for solid propellants. The effects of various parameters like cross-linking conditions, concentration of crosslinker, and the ratio of isocyanate to hydroxyl functional groups (NCO/OH ratio) on the mechanical properties were studied in detail. It was observed that the type of curing agent and the NCO/OH ratio have a strong influence on the gum-stock properties. Similar impact was seen for cross-linker concentration also. The swelling characteristics of the cross-linked binder prepared with different NCO/OH ratios were evaluated with toluene and tetrahydrofuran (THF). The polarity and the solubility parameter of the solvents were found to influence the swelling of GAP. The NCO/OH ratio and cross-linker concentration of the polymer were also found to affect the swelling characteristics. The sol fraction determined for the polymer was found to follow a similar pattern. The cross-link density and average molecular weight between crosslinks (Mc) were determined from the swelling studies and also from the stress-strain relationship. The Mc values were found to be influenced by the NCO/ OH ratio. Finally, the Mc values determined from the swelling data were correlated to the gum-stock properties, and the model parameters were estimated.

Thermal Behavior and Decomposition Kinetics of RDX and RDX/HTPB Composition Using Various Techniques and Methods

“…The curing agent, HMDI, was then added at 55 °C and the ingredients were mixed for another 30 min. The binder system was then cast and cured at 60 ± 2 °C for seven days under vacuum [31]. The cured HTPB binder system was prepared with an NCO/OH ratio of 0.83.…”

Improvement of mechanical characteristics of glycidyl azide polymer binder system by addition of flexible polyether

“…Among these ingredients, the binder acts as a matrix to hold the solid fillers together and gives the desired shape and structural integrity to the propellant . Glycidyl azide polymer (GAP) is a unique binder of high density with a positive heat of formation of +117.2 kJ/mol, and it is greatly insensitive to impact and at the same time provides high burning rates. For its positive effect on the energetic performance and burning rate, the GAP binder has attracted the attention of researchers for the past two decades …”

Energetic interpenetrating polymer network based on orthogonal azido–alkyne click and polyurethane for potential solid propellant

“…15 Recent advances in the field of propellant for high energetic properties, GAP is one of the promising binders for propellant industry and many researchers have reported its synthesis, performances and different applications. [16][17][18][19][20] Although GAP has numerous advantageous like high positive heat of formation, higher density and good compatibility with advanced oxidizers like hydrazinium nitroformate (HNF) and ammonium dinitramide, GAP does not show excellent mechanical properties especially low temperature properties due to its poor polymer backbone flexibility. 20 The critical temperature of GAP is 6 o C where the polymeric binder starts to quickly lose its elastomeric properties.…”

“…[16][17][18][19][20] Although GAP has numerous advantageous like high positive heat of formation, higher density and good compatibility with advanced oxidizers like hydrazinium nitroformate (HNF) and ammonium dinitramide, GAP does not show excellent mechanical properties especially low temperature properties due to its poor polymer backbone flexibility. 20 The critical temperature of GAP is 6 o C where the polymeric binder starts to quickly lose its elastomeric properties. Glass transition temperature of GAP are much greater than those of inert binder HTPB and this significantly limits its application in composite solid propellants.…”