Burn Rate Modification with Carborane Polymers

Abstract

In the past, propellants containing boron clusters like n-hexyl carborane demonstrated an improved burn rate, decreased pressure exponent, and maintained a high energy output. However, the technology was hampered by expensive and hazardous synthesis as well as migration issues of the n-hexyl carborane plasticizer. A new, affordable synthesis procedure of decaborate salts was established at the University of Missouri-Columbia, which provides material for alkylation and subsequent synthesis to carboranylmethyl acrylate. In this paper, the investigation of the integration of covalently-bonded boron achieved through copolymerization in various binder polymers is presented. Since pure carboranylmethyl acrylate polymer is a solid crystalline material at room temperature, it was co-polymerized to produce a material suitable for formulations. The co-polymerization investigated was a combination of carboranylmethyl acrylate, butyl acrylate, and 2-hydroxyethyl acrylate. The boron-rich carborane was intended to serve as the high energy fuel portion of the polymer, the butyl acrylate provided a glass transition temperature below room temperature and low viscosity, and the hydroxylethyl acrylate contributed a cross-linkable moiety. The resulting polymer was used in a cast-cure formulation containing aluminum and ammonium perchlorate in order to test the effect of the carborane additive on the formulation burn rate when compared to a hydroxyl-terminated polybutadiene baseline. Strand burn rate testing demonstrated a distinctive increase in the burn rate for the carborane containing formulation. Synthesis and characterization of the carborane-based polymer are discussed along with the designed formulation. Further test data including sensitivity and thermal characterization are presented.

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Document Details

Document Type
Technical Report
Publication Date
Nov 01, 2017
Accession Number
AD1041543

Entities

People

  • Edward Cooke
  • Paul Anderson

Organizations

  • Picatinny Arsenal

Tags

Communities of Interest

  • Weapons Technologies

DTIC Thesaurus Topics

  • Additives (Chemicals)
  • Ammonium Perchlorate
  • Chemical Reactions
  • Glass
  • Glass Transition Temperature
  • High Energy
  • Hydrocarbons
  • Hydroxyl Terminated Polybutadiene
  • Low Temperature
  • Materials
  • Mechanical Properties
  • Polybutadiene
  • Polymerization
  • Propellants
  • Synthetic Rubber
  • Test Methods
  • Transition Temperature

Fields of Study

  • Chemistry

Readers

  • Organic Chemistry
  • Polymer Science and Engineering.
  • Rocket Propulsion.