Improved adhesive properties and bonding performance of HTPB-based polyurethane elastomer by using aziridine-type bond promoter

Abstract

Theeffect of two aziridine-type bond promoters on adhesive and mechanical properties of a hydroxyl terminated polybutadiene-based elastomeric liner used in solid propellant rockets was investigated by varying the concentration to determine the optimum value. The performance of butyleneiminetrimesoylaziridine (BITA) was compared with that of tris[1-2-methylaziridinyl]phosphine oxide (MAPO) in the elastomeric liner of otherwise the same composition. The adhesive performance of the elastomer to the composite was determined by using metal-elastomer-composite tensile and peel tests. The adhesive performance of the elastomer to the metal was also determined, this time by using peel and shear tests. The mechanical characterization of the elastomer was done by tensile and hardness tests. A significant enhancement in the bonding performance of the elastomeric liner toward composite propellant and metal case was achieved by optimizing the concentration of bond promoter in the elastomeric composition. All the elastomer compositions with bond promoters BITA and MAPO loadings of 1.0, 1.5, and 2.0 wt % were found to be sufficient for the rocket motor operations because the interfacial adhesive strength of these compositions is higher than the cohesive strength of the composite. Compositions with bond promoter quantities of 1.0, 1.5, 2.0, and 2.5 wt % have better strength values than the others. Liner compositions with the bond promoter BITA give better bonding performance between the composite–metal system and better mechanical properties when compared with the elastomers with the bond promoter MAPO. The best results are obtained in terms of bonding performance and adhesive properties by using the bond promoter BITA in optimized quantities of 1.0 and 1.5 wt % loadings in the elastomer compositions. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 806–814, 2001