Polydopamine Modified PBX 9501 Evaluation via Brazilian Disk Compression with Digital Image Correlation

Plastic-bonded explosives (PBXs) are composite materials containing explosive crystals and plastic binder. PBX 9501 been studied extensively for the past 20 years. The primary location of mechanical failure in PBX 9501 is at the crystal-binder interface, where a crack is more likely to propagate. Polydopamine (PDA) has been used across fields such as micro- electronics to improve composite properties at interfaces. It has been proposed that PDA bonded to HMX when formulated into PBX 9501 could increase the ultimate stress of the explosive by increasing strength at the crystal-binder interface. Nominal PBX 9501 and PDA modified PBX 9501 were die-pressed into 1-in. diameter by ¼ -in. thick disks at an average density of 1.812 g/cc, approximately 98.47% theoretical maximum density. This study compares the differences in mechanical response via Brazilian disk compression in the quasi-static regime at three different temperatures: -15°C, 23°C, and 50°C. A three-dimensional displacement field of the disk surface is estimated using Digital Image Correlation (DIC) software in a stereo camera setup. Shear Modulus, Young's Modulus, and Poisson's ratio are derived from this displacement field. Differences in the deformation fields and mechanical response are discussed. The Correlation Coefficient parameter, C, is used to monitor macro-crack initiation and propagation, which is used in this study to describe how the fracture behavior of each explosive differs.