THE DEFORMATION MECHANISMS IN BRANCHED POLYETHYLENE MELTS
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)
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 31, 1962
- Accession Number
- AD0293405
Entities
People
- Bryce Maxwell
- James C. Galt
Organizations
- Princeton University