| Step shear rate experiments in the range of 0.1 < gamma < 30s(-1) (0.14 < Wi < 42) were performed with a PS 158K melt at 190 degreesC. A cone (gap angle = 0.148 rad) and partitioned plate tool was used to measure the time dependent first (N-1) and second (N-2) normal stress difference. N-1 and N-2 were extracted from a series of measurements with different ratios of R/R-Stem, R being the sample radius, R-Stem the radius of the central part of the plate connected to the transducer. A very good reproducibility was found for the measured torque. Edge fracture was observed for strains greater than or equal to 18, independent of shear rate. For larger samples, the onset of edge fracture as seen by the transducer was delayed to larger strains. This is due to damping of the disturbances by the melt between the rim of the sample and the stem. The steady state value of the ratio -N-2/N-1 decreases from 0.24 at 0.1 s(-1) shear rate to 0.05 at 30 s(-1). For gamma > 10s(-1) the steady state value of -N-2/N-1 becomes larger if smaller cone angles are used. Data for sigma = 0.148 rad showed a better coincidence with the linear visco-elastic predictions of viscosity eta and first normal stress coefficient psi(1) = N-1/gamma(2) compared to smaller cones.
for LaTeX users @article{TSchweizer2002-41,
author = {T. Schweizer},
title = {Measurement of the first and second normal stress differences in a polystyrene melt with a cone and partitioned plate tool},
journal = {Rheol. Acta},
volume = {41},
pages = {337-344},
year = {2002}
}
\bibitem{TSchweizer2002-41} T. Schweizer,
Measurement of the first and second normal stress differences in a polystyrene melt with a cone and partitioned plate tool,
Rheol. Acta {\bf 41} (2002) 337-344.TSchweizer2002-41
T. Schweizer
Measurement of the first and second normal stress differences in a polystyrene melt with a cone and partitioned plate tool
Rheol. Acta,41,2002,337-344 |
mk@mat.ethz.ch
1 out of 816 entries requested
[H-factor to-date: > 0]
