Hobbies And Interests
Materials
Over time, plastic wrap has been made out of a variety of materials including polyethylene, PVC or PVDC. PVC and PVDC are made from vinyl chloride and vinylidene chloride -- two materials that are used less frequently because of the presence of chloride, which is harmful to the environment.
Beginning Process
Most plastic wrap materials come from the burning of hydrocarbons such as oil and natural gas. The gas is burned away and vapors rise through a fractionating column. As the vapors rise, different chemicals become liquid at different chambers and move out of the column. The polymers to make plastics, including plastic wrap, remain as gases and move to the top of the chamber, where they are siphoned off and allowed to cool, creating granules of plastic.
Creating Sheets
The plastic granules are chunky and must be heated until they make a liquid plastic, which is then passed through a die. As the plastic moves through the die, air is introduced, which creates bubbles in the plastic and, in effect, stretches it. The bubbles are then smoothed out between metal rollers. This process continues until the plastic reaches the desired thickness. The plastic is then rolled onto large rollers that hold vast quantities of the wrap.
Roll It Up
The plastic wrap is unrolled from the large roll and cut into various sizes for packaging, then rerolled onto a cardboard roller on which the product is shipped. The process of rolling, unrolling and re-rolling the plastic gives it a slight negative static-electric charge. This charge is one of the properties that helps the plastic cling to various surfaces.