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On the drying of glassy polystyrene
Author(s) -
Laria J. C.,
Aleman J. V.
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.760211211
Subject(s) - polystyrene , materials science , tray , glass transition , relative humidity , extrusion , polymer , composite material , molding (decorative) , diffusion , humidity , expanded polystyrene , volumetric flow rate , polymer chemistry , chemical engineering , thermodynamics , mechanical engineering , physics , engineering
Many commercial polymers contain water which must be reduced to a lower level for application. The drying behavior of polystyrene (PS), molecular weight 12,000, and flow characteristics suitable for extrusion and injection molding, have been studied. A laboratory tray dryer was used at temperatures below the glass transition temperature of PS ( T g ∼ 373 K). Effects of air flow rate (from 0.5 to 3.5 liters/s), temperature (from 323 to 373K) and relative humidity (from 0.5 to 25 percent) on retained water in PS were measured, and from those effects the effective diffusion coefficients (D) have been deduced as:\documentclass{article}\pagestyle{empty}\begin{document}$$ D\left(T \right) = D_0 \cdot e^{{{ - \Delta E} \mathord{\left/ {\vphantom {{ - \Delta E} {RT}}} \right. \kern-\nulldelimiterspace} {RT}}} = 3.6 \times 10^{ - 5} \cdot e^{{{ - 294} \mathord{\left/{\vphantom {{ - 294} T}} \right. \kern-\nulldelimiterspace} T}} \ln D\left({X\%} \right) = \ln D_{X\%= 0} + aX\%= - 19.30 + 4.0\left({X\%} \right) $$\end{document} .