The role of adhesion and binder stiffness in the impact sensitivity of cast composite energetic materials

Abstract

The drop weight impact or drop hammer test has been a staple of energetic material small-scale sensitivity testing for over 100 years, but the link between material properties and sensitivity has proven difficult to evaluate, especially for composite materials. In this study, the work of adhesion and elastic modulus of the binder were varied to assess their impact on the sensitivity of a family of plastic bonded explosive composite energetic materials. Drop weight impact tests performed using the German Bundesanstalt für Materialprufung impact test demonstrated significant decreases in sensitivity as the elastic modulus and the work of adhesion decrease. It was determined that the elastic modulus of the binder was the most significant contributor to the corresponding changes in sensitivity.

Sources of Variation in Drop-Weight Impact Sensitivity Testing of the Explosive Pentaerythritol Tetranitrate

“…Although drop-weight impact tests have documented limitations, they are the most common method for measuring explosive sensitivity, and there exists a large collection of impact test results for various explosive materials. Researchers have recently begun collecting and analyzing impact test results in more detail, to better understand the benefits and limitations of impact tests for evaluating material sensitivity. − It is imperative to understand the limitations of drop-weight impact tests when drawing conclusions regarding molecular properties of explosive materials from impact tests, as many recent papers do. − …”

Thermo-chemo-mechanically coupled cavity dynamics and the emergence of multi-phase bursts

“…Energetic materials are a class of materials that can release high amounts of stored chemical energy through an exothermic chemical reaction beyond that necessary to self-sustain the reaction; they find applications in propellants, explosives and pyrotechnics [20,21], and are often used in the form of energetic crystals that are embedded in a polymer binder. Recent experiments demonstrate that the mechanical properties of the confining inert binder material can significantly affect the explosion behaviour and can thus impact their sensitivity to premature explosions [11,22]. Models that can explain the explosion behaviour and its sensitivity to external stimuli are thus crucial to determine standards for safe handling and transportation of energetic materials.…”