Influence of Polymer Molecular Weight, Temperature, and Strain Rate on the Mechanical Properties of PBX 9501

Abstract

Compression and tensile measurements were conducted on newly formulated (baseline) and lower molecular weight (virtually‐aged) plastic‐bonded explosive PBX 9501. The PBX 9501 binder system is composed of nitroplasticized Estane 5703,™ a polyester polyurethane copolymer. The molecular weight of polyester urethanes can degrade with time as a function of hydrolysis, affecting the mechanical behavior of the polymer or a polymer composite material of high explosives, i.e. PBXs. The molecular weight of Estane 5703™ was degraded by exposure to high temperature and humidity for different periods of time, and then formulated to produce “virtually‐aged” PBX 9501 specimens. Quasi‐static and dynamic compression tests were conducted on the baseline and virtually‐aged PBX 9501 as a function of temperature and strain rate. Quasi‐static tensile tests were also conducted as a function of temperature and test rate. Rate and temperature dependence was exhibited during both compression and tensile loading. Results also show significant differences between the baseline and virtually‐aged specimens for the dynamic compression tests at −15°C, and for the quasi‐static compression tests at −15°C, 22°C, and 50°C.