Development of Grubbs' Catalyzed Compositions for Net-Shape Manufacturing Of Nitramine-based Energetic Systems

摘要

A novel process is developed to achieve net-shape manufacturing of energetic products with perfect local and global "stoichiometric" composition uniformity without the need of deploying high stress laminar mixing. The "kernel" elements of the novel approach consist of creating and using free-flowing coated particles, in primary or cluster form which are used to fill the vessel containers of the particular energetic products to obtain the desirable level of uniform particulate packing densities. These steps are followed by infusing a surface compatible and curable binder system into the unoccupied volume. The elimination of the laminar mixing of low viscosity polymeric / pre-polymeric fluids highly loaded with energetic particulates makes this net-shape manufacturing process a safer, cleaner and more efficient alternative than the currently used melt pour counterpart.Ambient curable liquid compositions have been formulated based on the Grubb's chemistry. Ethylidene-norbornene (ENB) is used as the co-monomer at various concentrations in order to lower the melting point of dicyclopentadiene (DCPD), and improve the curing kinetics of the Grubb's catalyst compositions. When compared to two-part curable systems such as epoxy or urethane based compositions, the modified Grubb's catalyzed compositions are much lower in viscosity, which greatly reduce the overall production cycle time. Furthermore, since the principal polymerization and curing reactions are ring-opening metathesis in nature, the overall heat of reaction is also noticeably lower than that of the two-part curable systems.Experimentation has demonstrated that when pre-coated particles with the Grubb's catalyst via a simple spray coating operation are packed in a 120mm burster tube, the infused DCPD/ENB binder can be quickly polymerized, cured and solidified into a very strong binder phase free of any voids or air bubbles. This technique is free of complex liquid mixing processes and precise metering steps required in the two-part binder counterpart process, resulting in a much simpler, faster and cleaner operation. In addition to describing this net-shape manufacturing process and providing evidence of packing density uniformity, this paper reports on selected curing kinetics results of the modified Grubb's catalyzed compositions by Different Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FTIR), as well as other process parameters that affect the packing and infusion steps.