Sunday, 7 April 2013

This a 250 grams chip packet. is it mad e of Polypropylene (PP) which  is a thermoplastic polymer commonly used in food packaging. Polypropylene has an intermediate level of crystallinity between low density polyethylene (LDPE) and high density polyethylene (HDPE) .
This material is less tough than HDPE and less flexible than LDPE. It also has excellent moisture barrier characteristics, good clarity, high gloss and good tensile stress. As PP has only average gas barrier properties, it is often used in combination with metallised film, PVDC coating or acrylic which provides additional barrier properties.
The chip packet is made from polypropylene laminated onto a metal foil. This material comprises polypropylene film which has been metallised on one surface by vacuum deposition of high purity aluminium. The appearance is of aluminium foil, but the film has the flexibility, strength and thickness of the base film which is the polypropylene.

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