Identification of Materials from 60-mm Mortar Obturators
Abstract
Two plastic obturators for the 60-mm mortar were submitted for physical and chemical analysis. One of the obturators was from current U.S. Army stock while the other was from a contractor which had failed by misfire during field tests. The analysis revealed their composition to be polycarbonate and acetal polymer resins, respectively. This report discusses in detail the physical and chemical analysis. The polycarbonate resin obturator, tinted with a green dye, does not contain any inorganic filler material and thermally decomposes initially at about 500 C. The density is 1.213 at 25 C. The material is strong and tough. The white obturator is composed of acetal resin, poly(oxymethylene), polyether 1 which is a polymer of formaldehyde commonly known was Delrin. It is highly insoluble in practically all organic solvents and has a density of 1.520 at 25 C. It contains 20% inorganic filler. The material is hard and very brittle. Based upon the above results it is easy to understand why the white obturator failed by misfire in field tests. Keywords: Polycarbonates, Acetal resins, Thermal analysis; Formaldehyde resin; Infrared analysis; Plastics; Obturation(Ballistics).
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1988
- Accession Number
- ADA196040
Entities
People
- Alfred F. Tatyrek
Organizations
- United States Army Armament Research, Development and Engineering Center