On the thermal expansion hysteresis of a UK PBX

Abstract

The linear coefficient of thermal expansion of a UK PBX has been measured over the temperature range -40 to +80 °C: (5.55 ± 0.05) ×10 -5 K -1. A subtle but measurable hysteresis in length as a function of temperature was observed. This is attributed to a mismatch between the thermal expansion coefficients of its solid-fill and binder constituents. On heating or cooling this induces mechanical stresses within the binder system, which being viscous it can flow to relieve. A change in sample temperature results in an asymptotic relaxation to a mechanical equilibrium length. This is analogous to the type of stress relaxation and creep behaviour normally associated with the bulk response of viscoelastic materials when more conventional stresses are applied. © 2012 American Institute of Physics.