The materials used in food packaging are very common polymers. Their permeability to gases and vapors is at the origin of their barrier properties and capacity for protection of the food.
Polymers or plastic packaging materials have increasingly replaced traditional materials such as metal, glass or paper in many food packaging applications because of their light weight and superior functionality.
Polymers properties affecting permeability, such as free volume, crystallinity, tacticity, cross-linking, orientation and thickness.
Polymers for food packaging may be in the from films and other flexible items, or in the form of rigid containers, such as clear drinks bottles or opaque cartons for dairy products.
Polymer will usually require good barrier properties, both to prevent loss of moisture from the food, and to prevent ingress of undesirable, possible odorous contamination from outside.
There are few examples of the most commonly used plastic polymers:
*Polyethylene
*Polypropylene
*Polystyrene
*Polyvinyl chloride
In general, food diffuses into plastic packaging, which enhances migration of unreacted monomers and potentially mobile additives form the plastic into the food.
Probably the two most important barrier polymers for food packaging are polyvinyllidene and ethylene vinyl alcohol, although other materials find important niches.
Polymers for food packaging
