Which material EVA or PS, would be expected to be a better barrier material against water? Why?
What will be an ideal response?
Water is a polar molecule so it would be excluded best by a non-polar polymer. EVA has many polar atoms in the pendent group and would allow water to
permeate easily. Polystyrene is nonpolar and would exclude polar molecules like water. The size of the side chain for EVA is large, as is the pendent group for polystyrene. Both plastics would have about the same openness so size would not be a factor in determining the permeation differences between these two plastics. Therefore, polystyrene is a better barrier material for mater than is EVA.
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