摘要：

A new family of composite rocket propellants with improved insensitive munitions (IM) characteristics has recently been developed. The propellants are based on cross-linked Hydroxy Terminated Polyether (HTPE) binders and are being used as alternatives to Hydroxy Terminated Polybutadiene (HTPB) compositions. HTPE propellants have similar mechanical properties to HTPB propellants, but their main advantage is that they give a less severe response in 'slow cook-off' tests for IM compliance. In this paper, we report a preliminary study aimed at understanding the behavior of HTPE propellants, during which we have synthesized and characterized an HTPE pre-polymer. The synthesis of a random copolymer of ethylene oxide (EO) and tetrahydrofuran (THF) was carried out through cationic bulk polymerization under sub-zero temperature conditions using ethylene glycol (EG) as a proton reservoir and tetra fluoroboric acid diethyl ether complex as a catalyst. Quantities of each reagent were changed over a series of experiments in order to obtain copolymers with different ratios of EO/THF groups and different molecular weights, and thus different chemical, physical, and mechanical properties. In order to characterize the HTPE copolymers, analyses were carried out to determine molecular weight, molecular structure, glass transition temperature (Tg), melting temperature (Tm), impurities, and density. These properties were determined by using a range of techniques including: Size Exclusion Chromatography (SEC), Nuclear Magnetic Resonance (NMR) Spectroscopy, Differential Scanning Calorimetry (DSC), Gas Chromatography-Mass Spectrometry (GC-MS), and Fourier Transform Infra-red (FTIR) Spectroscopy. Similar analyses were performed on a sample of an HTPB pre-polymer and the results were compared with those obtained for the HTPE copolymers.

展开