Optimization of Curing Agents for Linear Difunctional Glycidyl Azide Polymer (GAP), with and without Isocyanate, for Binder Applications

Abstract

Glycidyl Azide Polymer (GAP) is one of the most potential energetic binders for rocket propellants and gas generator compositions. In the present paper GAP of molecular weight (Mn) ~2000 was cured with a mixture of di-and tri-isocyanates without a cross linker. The curing profile and time of curing was recorded using a rheometer. The minimum curing time was observed for samples cured with Desmodour N-100 alone, whereas the maximum curing time was observed for samples cured with a mixture of Desmodour N-100 and Isophorone Diisocyanate (IPDI) (1:1 w/w). It was observed that all of the samples cured well and were void or bubble free. The mechanical properties data showed that the tensile strength (TS) of GAP cured with Desmodour N-100 alone was 1.19 kgf/cm 2 , which is a minimum, while the maximum TS (3.66 kgf/cm 2 ) was achieved with a mixture of N-100 and 4,4'methylenebis(phenylisocynate) (MDI). The percent elongation for a sample cured with Desmodour N-100 was 160, and was reduced to 64.27 when a mixture of MDI and N-100 was used. In order to study the curing of GAP without an isocyanate, GAP diol was cured with hexanediol di-acrylate. GAP was also cured with an alkyne-based curing agent i.e. bis-propargyl succinate (BPS), which showed improved curing. Comparative thermal studies of GAP cured with isocyanate and acrylate was carried out. Differential Scanning Calorimetry (DSC) and Simultaneous Thermal Analysis (STA) curves for all of the cured samples were recorded in order to study and compare the thermal decomposition behaviour of the cured GAP. Isocyanate cured GAP exhibited a single stage decomposition, with larger heat output. Acrylate cured GAP exhibited a two stage decomposition. Finally, a mixture of IPDI and Desmodour N-100 was selected for curing of GAP. Accordingly, curing was carried out and was tested in a small ballistic evaluation motor (BEM) to observe the combustion behaviour and burn rate. From the pressure-time profile it was Central European Journal of Energetic Materials

Glycidyl Azide Polymer and its Derivatives-Versatile Binders for Explosives and Pyrotechnics: Tutorial Review of Recent Progress

“…Another approach to curing GAP was adopted by Agawane et al [30], who employed multiple curing agents: mixtures of di-(CI1, CI3) and tri-functional (CI2) isocyanates, an alkyne curing agent (CA6) and, most interestingly, an acrylate-based (CV1) curing agent (Figure 6). Although the authors, similarly to Hagen [28], achieved the best mechanical properties when using a mixture of isocyanate curing agents, they did not attempt sequential curing, which may have resulted in even better properties.…”

Effect of components on the curing of glycidyl azide polymer spherical propellant through rheological method

“…Glycidyl azide polymer (GAP) is a binder which is widely used in propellant [1][2][3][4][5][6]. GAP spherical propellant prepared by an internal solution method is one of the most popular components of composite modified double-base (CMDB) propellant [7,8].…”