SANS and Contrast Variation Measurement of the Different Contributions to the Total Surface Area in PBX 9501 as a Function of Pressing Intensity

Abstract

We have used small‐angle neutron scattering (SANS) in conjunction with the method of contrast variation to measure the surface area (SHB, SHV, and SBV) associated with the three interfaces (HMX‐binder (HB), HMX‐voids (HV) and binder‐voids (BV)) in pressed pellets of PBX 9501 (95% HMX and 5% binder, by weight). These interfaces are of interest as they may influence the transmission of microstresses and hot spot formation under shock conditions. Because of the difficulty in making measurements, little is known about the microstructure of pressed PBX 9501 parts and thus how it is affected by processing. Here, we explore the effect of varying the pressing intensity on the PBX 9501 microstructure and in particular, how the three interfaces (HB, HV and BV) are affected. Disk‐shaped samples of PBX 9501 were die‐pressed with applied pressures ranging between 5,000 and 29,000 psi. SANS measurements were performed on 4–5 pellets at each pressure. Analysis of the SANS data indicates systematic changes in SHB, SHV, a...