MECHANISMS OF REVERSIBLE AND IRREVERSIBLE LOSS OF MECHANICAL PROPERTIES OF ELASTOMERIC VULCANIZATES WHICH OCCUR AT ELEVATED TEMPERATURES
Abstract
Strength characteristics of five elastomeric gum vulcanizates were investigated over a wide range of conditions. Results from continuous and intermittent stress-relaxation evaluations made between 100 and 200 deg C showed that the thermal stabilities of the vulcanizates decrease in the following order: hydrofluorocarbon, resin-cured butyl, silicone, sulfur-cured butyl, and natural rubber. Tensile properties of each vulcanizate in the absence of thermal degradation were determined with an Instron tester at about 10 strain rates and 10 temperatures. Except for natural rubber, the ultimate tensile properties of each vulcanizate could be characterized by a time- and temperature-independent failure envelope which results from a plot of log sigma sub b 273/T vs. log epsilon sub b where sigma sub b is the tensile strength and epsilon sub b is the ultimate strains. No fundamental differences seem to exist in the strength characteristics of the various vulcanizates provided they are compared in corresponding temperature and physical states. Stress-strain curves for natural rubber were analyzed to separate time and finite- strain effects. Between -20 and 100 deg C, the stress-strain data were time independent although they are temperature dependent.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1962
- Accession Number
- AD0283324
Entities
People
- Thor L. Smith
Organizations
- SRI International