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The process of shrink-wrapping is where items are wrapped tightly together in plastic so they cannot move around.
The purpose of this is so the items do not break, aren’t damaged in any way or fall apart.
Common shrink-wrapped items include bags of nuts, packets of crisps, cereal, bottled water and other various products. Most of these products are shrink wrapped to preserve freshness also.
Many people don’t give thought to how shrink wrap works or how it wraps a package in the first place.
Shrink wrap requires the manipulation of molecules; polymers are long molecules found in plastic where they are usually tangled and random. When those polymers are made into plastic film for the purpose of shrink wrapping, the molecules are stretched out so they are almost straight.
Both of these packaging materials hold items together in a compact air space in packaging applications.
These materials are both lightweight and puncture and tear resistant, thus making them the perfect cost alternative to container packages or boxes.
Shrink wrap
This material is typically a clear plastic or polymer-based film that ultimately shrinks when heated and will conform to the shape of the object it is encasing.
The benefit of shrink wrap is that it forms a very tight, tamper evident seal that protects the products inside the package from dirt, moisture, dust or any insects. It’s commonly used as a food bag and in other perishable applications and is available for utilisation in a selection of widths, designs and film gauge, all dependant on the application.
Stretch wrap
Stretch wrap is composed of polyethylene plastic, this responds to heat differently than shrink wrap, that when heated shrinks and secures the load, stretch wrap has an elastic memory that functions similarly to a rubber band.
Shrink wrap and stretch films should stick to certain standards so to ensure a proper design and functionality.
Standards such as ASTM D4649 are used during the selection and use of stretch wrap films.
ASTM D5416 and BS 2782-6 discuss the methods of testing abrasion resistance along with the shrinkage on heating, respectively.
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