Water-Soluble Polymer

This sliver of film is a water-soluble polymer made from polyvinyl alcohol (PVA). The water solubility of the material can be controlled by tweaking the structure of the polymer. If the polymer chain is acetate-heavy, the material will be very soluble and will dissolve even in cold water, whereas if alcohol groups replace those acetate groups, the material will only dissolve in hot water. 

The purpose of plastic film is generally to protect goods from water, but this seemingly impractical water-soluble plastic is beginning to finding new uses. For example, hospitals use them for containing contaminated sheets and gowns so that laundry workers don’t have to come into contact with them, and can put the sealed water-soluble PVA bag straight into the washing machine. PVA is also sometimes used as a ‘sacrificial’ material for making cores for the injection moulding process. Since PVA is non-toxic and easily dissolved, these films have started to appear in consumer goods packaging, for example as the casing in detergent-filled ‘liqui-tabs’.