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Young Brunette Girl Foil-wrapped In A Plastic Film
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Glad Press'n Seal has its surface covered by shaped dimples, which hold the adhesive away from the surface. While being handled, the wrap is unsticky, but when pressure is applied the dimples are flattened and the adhesive pushed against the contacting surface, sticking them together. The adhesive used is a special edible type similar to chewing gum.
PVdC has better barrier properties than the more-permeable LDPE, making the foods wrapped in it less subject to freezer burn. However, LDPE is substantially cheaper and easier to make.
Natural polymers of LDPE and PVdC are insufficiently clingy on their own, and they do not adhere to themselves. To achieve the desired clinginess, certain polymers with lower molecular weight have to be added; the most common two are polyisobutene (PIB), and polyethylene-vinylacetate (EVA) copolymer. Their chains readily interact with each other and their lower molecular weight makes them more mobile within the host polymer matrix.
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