Investigation of the Effect of Chain Extender and Fillers on the Tensile and Bonding Strength of Liner Based on HTPB

Solid propellant systems are basically two types: case bonded and cartridge. Liner, as a polymeric glue, is responsible for bonding propellant to casing in case bonded ones, therefore, it must have sufficient mechanical and adhesive strength. The type and amount of each component of polymeric composition plays an important role in liner strength. In this research, effect of chain extender content (4-6 percent) and fillers (9-17 percent) on tensile strength of liner based on HTPB and bonding strength of liner-propellant was investigated. The result showed that with increase in amount of chain extender, bonding strength between liner and propellant, tensile strength and elongation at break liner was increased. In addition, it was found that increase in fillers content up to 15 percent improve tensile strength and elongation at break, whiles increase in fillers, decrease bonding strength through decrease in permeability of liner into propellant surface.