Isocyanate-free energetic polymer binders

Abstract. There are numerous classes of energetic materials, including them polymer-bonded explosives (PBX). They are used in the defense industry, generally in metal containers such as shells. These energetic composites have two main constituents, the energetic charge and an inert binder. Usually, the binder is a polymer matrix, the purpose of which is to give the material mechanical strength and to phlegmatise it. As they do not comply with REACH regulations and are incompatible with recently developed energetic charges, the isocyanate functions limit the use of polybutadiene-based polymer matrices which is are commonly used in PBX systems. There is therefore a desire to find substituents polymers that does not contain isocyanates. The latter must meet certain criteria, such as not having a phase transition over its range of use [-47 to 70°C]. Two types of matrices are therefore distinguished, so-called ‘low Tg’ matrices, which have a glass transition below -47°C, and ‘high Tg’ matrices, which have a glass transition above 70°C.Thermomechanical tests were carried out on matrices synthesized on a laboratory scale, with and without mimetics fillers of the energetic charges. « Low Tg » polymers exhibit elastomeric behaviors at the temperature of use, characterized by a low elastic modulus and high elongations at break, with a high capacity to absorb stresses such as shocks. Silicones and certain acrylic polymers are promising ‘low Tg’ matrices. Composites based on silicones and acrylics with non-reactive mimetic fillers have been successfully synthesized and thermo-mechanically tested. The ‘high Tg’ materials obtained have very different mechanical properties to those of elastomers, they have a much higher elastic modulus but a much lower elongations at break. This class of material could meet other needs in the polymer-bonded explosives domain. Epoxy polymers and certain other acrylic polymers are potentially interesting ‘high Tg’ matrices for this application.