Accession Number : AD0685617

Title :   MECHANICAL BEHAVIOR OF POLYTETRAFLUOROETHYLENE AROUND THE ROOM TEMPERATURE FIRST ORDER TRANSITION.

Descriptive Note : Technical rept.,

Corporate Author : STEVENS INST OF TECH HOBOKEN N J DEPT OF CHEMISTRY AND CHEMICAL ENGINEERING

Personal Author(s) : Andrews,Rodney D. ; Koo,George P.

Report Date : 06 MAR 1969

Pagination or Media Count : 42

Abstract : The effect of the room temperature first order transition on the plastic yield behavior of polytetrafluoroethylene (PTFE) has been investigated. Stress-strain curves were measured at different strain rates and temperatures. Tensile creep under constant dead load was also measured as a function of temperature and stress level. The effect of degree of crystallinity was investigated by using both a rapidly quenched and slow cooled polymer. The curve of yield stress vs temperature in the temperature range from -50 to +68C was found to be almost identical with the curve of elastic modulus vs temperature: the yield stress shows a marked local decrease at the first order transition. The experimental observations suggest a model of the solid-state structure of PTFE which could be described as an 'elastic-plastic network', in which crystalline domains are connected by elastic amorphous regions, and in which the crystalline domains can flow plastically at sufficiently high stress or temperature. (Author)

Descriptors :   (*HALOCARBON PLASTICS, TRANSITION TEMPERATURE), (*STRAIN HARDENING, HALOCARBON PLASTICS), MECHANICAL PROPERTIES, POLYMERS, STRESSES, FLUORINE COMPOUNDS, CREEP

Subject Categories : Physical Chemistry
      Plastics

Distribution Statement : APPROVED FOR PUBLIC RELEASE