Polycarbonyl functionalized non toxic polymeric binders synthesis characterisation and evaluation in explosives

Abstract

Polymer Bonded Explosives (PBX) are established to meet the newlinerequirements of insensitive munitions. PBX are used as warhead explosives, newlinedemolition explosives, and in destruct systems of launch vehicles. Explosive newlinecrystals are embedded in the polymeric binder matrix in PBX. The matrix thus newlinereduces the vulnerability of explosives to external stimuli towards the hazard of newlineunwanted explosions during handling and transportation. The polymeric binder newlineimparts structural integrity to the explosive charge. newlinePolyurethanes, formed by the crosslinking of hydroxyl terminated newlinepolymeric binders with isocyanate curing agents, are the widely used polymeric newlinematrix in PBX. Inert polymers like hydroxyl terminated polybutadiene (HTPB) or newlinepolyethers such as polycaprolactone diol (PCL diol), castor oil, polyethylene newlineglycol (PEG), polytetrahydrofuran (PTHF) etc. Energetic binders having newlineexplosophoric groups such as azido or nitrato in combination with explosive newlinefillers can result in superior performance at lower explosive loading. This newlineimproves the processing aspects of the PBX. The drawback of the commonly newlineused hydroxyl terminated binders is high affinity to moisture. The reaction of newlineisocyanate curing agents with moisture can lead to side reactions. This result in newlinedefective specimens and thereby result in catastrophic failures. Another problem newlineis that isocyanates are highly toxic. The development of energetic PBX newlineformulations with an isocyanate-free curing route is warranted to alleviate these newlineissues. newlineThe scope of the work is to develop new binder systems for PBX using a newlinepromising, non-toxic crosslinking methodology to impart functional properties. The work focuses on two new routes viz. Aza-Michael addition for a nontoxic, newlineisocyanate-free curing route for PBX and sigmatropic Claisen rearrangement for newlinethe self-healing applications of polyurethane-based PBX that can repair the newlinedefects at the interface. newline