Accession Number : AD0293405

Title :   THE DEFORMATION MECHANISMS IN BRANCHED POLYETHYLENE MELTS

Corporate Author : PRINCETON UNIV N J PLASTICS LAB

Personal Author(s) : GALT,JAMES C. ; MAXWELL,BRYCE

Report Date : 31 AUG 1962

Pagination or Media Count : 1

Abstract : A program was undertaken to determine point to point response to stress of a high polymer above its crystalline melting point. From these observations, the actual velocity profiles for branched polyethylene melts in a capillary were obtained. Explanation for the unique character of the velocity profiles must be based on considerations of the molecular structure of each polymer. Velocity within the capillary depends not only on the location of the point of interest but also on which representative infinitesimal element of the melt is under consideration. A boundary annulus is next to the wall. It contains the stick-slip at the wall, zero velocities away from the wall, and pure translation (no rotation). The cause of the highly elastic, discontinuous flow of polymer in this region may be attributed to long-chain branching. A plug of elastically-strained structure is found at the centerline of the capillary. The plug flows at a uniform time-average velocity. The shear annulus is the region between the plug and the boundary annulus. Flow in this region is viscous or viscoelastic but shows structural breakdown and the thixotropic nature of polymer melts. (Author)

Descriptors :   *DEFORMATION, *ETHYLENES, *MELTING, *PLASTICS, *POLYMERS, ELASTIC PROPERTIES, MOLECULAR STRUCTURE, MOLECULAR WEIGHT, SHEAR STRESSES, STRESSES, THEORY, VELOCITY, VISCOSITY

Distribution Statement : APPROVED FOR PUBLIC RELEASE