A Study of the Effect of Liner Aging on Adhesion with Propellant Materials
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Abstract
Solid rocket motors are widely used in military and defense applications due to their simplicity and high reliability. These motors typically consist of a motor case, thermal insulation, liner, and solid propellant grain. The strength of adhesion for each material in the solid rocket motor depends on processing, storage duration, and environmental changes. The quality of adhesion, especially between the liner and the propellant, play a role in ensuring proper motor performance. Poor bonding may lead to structural failure from design and performance. In a production line after curing liner already, there are a long period of times for waiting of propellant casting. The objective of this paper is to investigate the effect of liner aging on adhesion with propellant casting on the interfacial adhesion between the liner and the propellant in composite solid rocket motors.
The research considers various functional group ratios (Rt) in polyurethane formulations, Physical properties including density, tensile strength, and elongation rate are analyzed. Liner samples with Rt values ranging from 1.10 to 1.50 are produced and tested. Adhesion is evaluated using bonded rectangular specimens. The liner samples are stored for 3, 7, 10, and 15 days before propellant casting. The liner-propellant rectangular in each specimen is accelerated aging equivalent to 3 years of storage life. Experimental results show that liners with Rt at least 1.20 exhibited optimal mechanical properties. The bond strength of liner-propellant ranged from 0.76 to 1.06 MPa, which significantly exceed the design requirement of 0.50 MPa. This result indicates that storing the liner for up to 15 days prior to casting does not degrade adhesion quality. This research supports more flexible production timelines and enhances quality assurance in manufacturing of solid rocket motors.
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