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A biaxial extensiometer for molten plastics
Author(s) -
RhiSausi J.,
Dealy J. M.
Publication year - 1981
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760210409
Subject(s) - materials science , polystyrene , viscoelasticity , viscosity , composite material , polymer , polyethylene , range (aeronautics)
While biaxial stretching plays a central role in several polymer processes, there has been no technique suitable for laboratory study of controlled biaxial stretching of molten thermoplastics at typical melt processing temperatures. The sheet inflation technique, which has been used previously to study rubbers and very high viscosity melts, has been adapted for use with molten thermoplastics by the use of oil as an inflation medium. Problems encountered in the use of the first prototype were eliminated in a second model, which is thought to produce reliable results. Stress growth data are presented for a low density polyethylene and for a polystyrene. A basic limitation of the technique is that the maximum achievable strain is in the range of 1.3 to 1.7, and this is often insufficient to bring out the nonlinear viscoelastic behavior of the melt.