Thermomechanical and Morphological Characteristics of Cross-Linked GAP and GAP-HTPB Networks with Different Diisocyanates

• Published in: Propellants, explosives, pyrotechnics explosives, pyrotechnics, 2008-04, Vol.33 (2), p.146-152
• Main Authors: Mathew, Suresh, Manu, S. K., Varghese, T. L.
• Format: Article
• Language: English
• Subjects: Cross-Linking; GAP; Gum-Stock; Kinetics
• ISSN: 0721-3115; 1521-4087
• DOI: 10.1002/prep.200800213

This paper describes the mechanical and thermal characterisation of cross‐linked glycidyl azide polymer (GAP) and GAP–hydroxyl terminated polybutadiene (HTPB) networks. Cross‐linked GAP and GAP–HTPB networks were prepared by reacting GAP diol and GAP–HTPB diol mixture with different diisocyanates. The physical and mechanical characteristics were found to be influenced by the type of isocyanate curing agents, [NCO]/[OH] equivalent ratios and concentration of GAP. For all the three types of curing agents, GAP–HTPB blends of 50 : 50 to 30 : 70 ratios show higher mechanical strength over the virgin networks of GAP or HTPB. Thermal decomposition of cross‐linked GAP–HTPB networks was evaluated by thermogravimetric analysis (TGA). The kinetic parameters for the decomposition of GAP–HTPB blends were found to be dependant on the concentration of GAP and HTPB in the blend. The cross‐linked GAP–HTPB blends were subjected to dynamic mechanical analysis (DMA). The glass transition characteristics of the blends were evaluated by DMA and it was found that blends prepared with GAP content up to 30% showed single transition in the loss tangent trace indicating no phase separation in the cured network.