Homogeneous membranes were prepared by blending poly (acrylic acid) with poly (vinyl alcohol). These blend membranes were evaluated for the selective separation of alcohols from toluene by pervaporation. The flux and selectivity of the membranes were determined both as a function of the blend composition and of the feed mixture composition. The results showed that a polymer blending method could be very useful to develop new membranes with improved permselectivity. The pervaporation properties could be optimized by adjusting the blend composition. All the blend membranes tested showed a decrease in flux with increasing poly (vinyl alcohol ) content for both methanol-toluene and ethanol-toluene liquid mixtures. The alcohols permeated preferentially through all tested blend membranes, and the selectivity values increased with increasing poly(viny1 alcohol) content. The pervaporation characteristics of the blend membranes were also strongly influenced by the feed mixture composition. The fluxes increased exponentially with increasing alcohol concentration in the feed mixtures, whereas the selectivities decreased for both liquid mixtures.
The overall and preferential sorption of alcohol−toluene mixtures in homogeneous blends of
poly(acrylic acid) and poly(vinyl alcohol) were determined. Both the overall solubility and the
equilibrium sorption selectivity were strongly dependent on the composition of the blend and of
the liquid feed mixture. The swelling of the blends increased with increasing poly(acrylic acid)
content and with increasing alcohol content in the liquid mixtures. Alcohols were sorbed
preferentially over toluene in all cases tested. The equilibrium sorption selectivity increased
with increasing poly(vinyl alcohol) content in the blends and with decreasing alcohol content in
the liquid mixtures. The equilibrium sorption selectivity was predicted by a model which was
derived from Flory−Huggins thermodynamics. The agreement between the predicted and the
experimental results was very good. In addition, the equilibrium sorption results were compared
with the pervaporation results, and this clearly shows that preferential sorption dominates the
pervaporation selectivity in the systems studied.
Four different coating formulations have been formulated with different amounts of photoinitiator and cured under different atmospheres (21, 5, 1 and 0% of oxygen). Surface cure and through cure were assessed for each combination. It was observed that the cure process for all formulations was strongly affected by the atmospheric conditions, and that the formulations required substantially less photoinitiator if cured under 5% of oxygen if compared to curing under air. Calculations show that the lower price of the formulation due to the decreased photoinitiator level may outweigh the additional equipment and running costs in specific cases. Therefore, UV‐inertisation is not only attractive from a product quality point‐of‐view, but can also offer economic advantages.
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