Environmental Effects on the Deformation of Polymers at Low Temperatures.
Abstract
The mechanical properties of every linear polymer are affected by liquid and gaseous nitrogen, Argon, and oxygen if the temperature is less than about 70 degrees above the boiling point. The tensile strength decreases and the creep rate increases with respect to an increase in the surface concentration of the gas. The surface concentration is related to the pressure and temperature by the parameter peQ/RT where Q was about equal to the heat of vaporization of the gas. The usual effect of the gas was to produce crazes. About 12 gases were tested and the only two gases that had no effect were helium and hydrogen because they have low heats of vaporization. The range of the experiments were from 78K to the glass transition temperature. The mechanical behavior was also found to depend on the size and shape of the specimen as measured by area per unit volume because crazes usually nucleate at the surface. It was found that the macroscopic mechanical behavior could be quantitatively derived from the measurable microscopic parameters of the crazes. The pressure range of 0-1 atmospheres was investigated. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 15, 1977
- Accession Number
- ADA045726
Entities
People
- Norman Brown
Organizations
- University of Pennsylvania