Equibiaxial elongational viscosity measurements of commercial polymer melts

Abstract

The equibiaxial elongational viscosity of six commercially available polymer melts is measured using a novel technique known as continuous lubricated squeezing flow. This technique is a modification of simple lubricated squeezing flow. The systems were chosen in order to investigate the dependence of equibiaxial elongational viscosity on molecular structure. Three of the melts are polyethylene with long chain branching, two are polyethylene with short chain branching, and one is polyisobutylene with linear chains. Each polymer was subjected to strain rates ranging from 0.003 to 0.1 s−1 and compared to the linear viscoelastic prediction so that the degree of strain hardening could be determined. For a modestly branched polymer, comparison of rheological behavior in both uniaxial and equibiaxial deformations was possible. POLYM. ENG. SCI., 55:1012–1017, 2015. © 2014 Society of Plastics Engineers

The influence of molecular weight distribution of industrial polystyrene on its melt extensional and ultimate properties

“…Apart from unique custom built equipment ulitilizing lubricated squeezing flow in a commercial scale true rheometers capable of controlling biaxial extension kinematics and measure the resulting stresses are practically unavailable. The situation is fortunately different for uniaxial extension which is qualitatively related to biaxial extension.…”