Food packaging materials include: PVDC (polyvinylidene chloride), PE (polyethylene), PA (nylon), EVOH (ethylene/vinyl alcohol copolymer), aluminized film (aluminum + PE), etc.
Different materials have different properties and different uses. General food packaging bags are not a single material, but are generally multi-layer composites.
The red sausage casing is a single material PVDC.
However, the packaging bag is not a single material. Generally, the inner layer is PE, the outer layer is PA, and the middle may be EVOH or PVDC.
Some use aluminum film.
Reason : PE's heat sealability is better, it is easy to seal
The printability of the PA is better. It is used on the outer layer to print a beautiful picture.
PVDC and EVOH have better barrier properties and prevent oxidation. The aluminized film has good light-tightness and is suitable for products that are hard to see.