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Polymer-Oxygen Compatibility Testing: Effect of Oxygen Aging on Ignition and Combustion PropertiesThe oxygen compatibility of six polymers used in oxygen service was evaluated after exposure for 48 hours to oxygen pressures ranging from 350 to 6200 kPa (50 to 900 psia), and temperatures ranging from 50 to 250 C (122 to 302 F). Three elastomers were tested: CR rubber (C873-70), FKM fluorocarbon rubber (Viton A), and MPQ silicone rubber (MIL-ZZ-765, Class 2); and three thermoplastics were tested: polyhexamethylene adipamide (Zytel 42), polytetrafluoroethylene (Teflon TFE), and polychlorotrifluoroethylene (Neoflon CTFE M400H). Post-aging changes in mass, dimensions, tensile strength, elongation at break, and durometer hardness were determined. Also, the compression set was determined for the three elastomers. Results show that the properties under investigation were more sensitive to oxygen pressure at low to moderate temperatures, and more sensitive to temperature at low to moderate oxygen pressures. Inspection of the results also suggested that both chain scissioning and cross-linking processes were operative, consistent with heterogeneous oxidation. Attempts are underway to verify conclusively the occurrence of heterogeneous oxidation using a simple modulus profiling technique. Finally, the effect of aging at 620 kpa (90 psia) and 121 C (250 F) on ignition and combustion resistance was determined. As expected, aged polymers were less ignitable and combustible (had higher AlTs and lower heats of combustion). Special attention was given to Neoflon CTFE. More specifically, the effect of process history (compression versus extrusion molding) and percent crystallinity (quick- versus slow-quenched) on the AIT, heat of combustion, and impact sensitivity of Neoflon CTFE was investigated. Results show the AIT, heat of combustion, and impact sensitivity to be essentially independent of Neoflon CTFE process history and structure.
Document ID
20000102418
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Waller, Jess M.
(Allied-Signal Technical Services Corp. Las Cruces, NM United States)
Haas, Jon P.
(White Sands Test Facility Las Cruces, NM United States)
Wilson, D. Bruce
(Wilson (D. Bruce) Mesilla Park, NM United States)
Fries, Joseph
Date Acquired
August 19, 2013
Publication Date
January 1, 2000
Subject Category
Nonmetallic Materials
Meeting Information
Meeting: 9th International Symposium on Flammability and Sensitivity of Materials
Location: Paris,
Country: France
Start Date: September 28, 2000
End Date: September 29, 2000
Sponsors: American Standard for Testing and Materials
Funding Number(s)
CONTRACT_GRANT: NAS9-95682
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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