Accession Number : AD0757885

Title :   The Ductile Brittle Transition of Low Density Polyethylene,

Corporate Author : STEVENS INST OF TECH HOBOKEN N J DEPT OF MECHANICAL ENGINEERING

Personal Author(s) : Weissmann,Dan

Report Date : OCT 1972

Pagination or Media Count : 106

Abstract : An extensive test program to determine the brittleness of low density, blown polyethylene film was undertaken as a result of failures of high altitude balloons constructed of this film. In this work, ductility and brittleness are defined by the ultimate elongations in uniaxial, constant strain rate tests. At each strain rate used it is shown that a critical temperature could be defined where the ultimate elongation changes significantly. It is suggested that this temperature be considered the cold brittleness temperature. Large deformations at break, referred to here as ductile behavior, are associated with yield and plastic flow. This phenomenon requires extensive freedom of motion of molecular chain segments, which can be determined from the dissipation (tan delta) CURVES. The tan delta curves demonstrate that the ductile behavior can be correlated with the strength of the beta transition and its domination of the relaxation spectrum. (Author, modified-PL)

Descriptors :   (*POLYETHYLENE PLASTICS, DUCTILE BRITTLE TRANSITION), (*FILMS, POLYETHYLENE PLASTICS), BALLOONS, HIGH ALTITUDE, BRITTLENESS, RUPTURE, MATHEMATICAL MODELS, COMPUTER PROGRAMS

Subject Categories : Lighter-than-air Aircraft
      Plastics

Distribution Statement : APPROVED FOR PUBLIC RELEASE