Plastic wrap
Plastic wrap, cling film (UK), cling wrap or food wrap, is a thin plastic film typically used for sealing food items in containers to keep them fresh over a longer period of time. Plastic wrap, typically sold on rolls in boxes with a cutting edge, clings to many smooth surfaces and can thus remain tight over the opening of a container without adhesive or other devices. Common plastic wrap is roughly 0.5 thou, or 12.5 µm, thick.[1][2] Although as technology advances the trend has been to produce thinner thicknesses, particularly for household use (as not too much stretch is needed), so now majority of brands on shelves around the world have reduced to 8, 9 or 10 microns.
Materials used
Plastic wrap was first created from polyvinyl chloride (PVC), which remains the most common material. Non-PVC competitive producers, for example low density polyethylene (LDPE), promote this type of Plastic Film, but have huge difficulty against PVC's high performance. There have also been concerns about the transfer of plasticizers from PVC into food, but this is a myth, because modern legislations in food contact materials are so stringent that all plasticisers used are non-toxic and totally harmless to human health.
In two countries, namely the USA and Japan, there is a production of plastic wrap using polyvinylidene chloride (PVdC), but it seems to be declining also.
A common alternative to PVC is low density polyethylene (LDPE), which is less adhesive than PVC. However, newer production processes are closing the adhesive gap between PVC and LDPE. Linear low density polyethylene (LLDPE) is sometimes added to the material, as it increases the adhesive qualities and the tensile strength of the film.[3]
The main difference, and this is the reason why PVC still dominates the market compared to LDPE films, is that PVC allows for permeability to water vapour and oxygen transmission.[4] This is important in allowing fruit and produce to breathe naturally and in keeping meat products in a fresh and appetising manner. This type permeability or air transmission in a package does not happen in LDPE packed foods, therefore the shelf-life, or freshness kept over time, is longer with PVC films.
However, LDPE is substantially cheaper and easier to make.
Medical use
- Wrapping premature babies in plastic wrap immediately after birth helps prevent low temperature before arrival to the neonatal intensive care unit.[5]
- Containing external organs of babies with rare medical conditions before surgery.[6]
See also
- Stretch wrap, plastic wrap used in large-scale industrial/commercial packaging
- Overwrap
- Wax paper
- Aluminium foil
References
- ^ http://www.matweb.com/search/datasheet.aspx?matguid=57c29e222a7749d58267c18e9e18b637
- ^ http://www.glad.com/faqs/plasticwrap.php
- ^ Cling Wrap Explained
- ^ Coultate, Tom (2015-08-17). Food: The Chemistry of its Components: 6th Edition. Royal Society of Chemistry. ISBN 9781849738804.
- ^ McCall, EM; Alderdice, F; Halliday, HL; Jenkins, JG; Vohra, S (Mar 17, 2010). "Interventions to prevent hypothermia at birth in preterm and/or low birthweight infants". The Cochrane database of systematic reviews (3): CD004210. doi:10.1002/14651858.CD004210.pub4. PMID 20238329.
- ^ "Baby girl born with her intestines on the outside of her body was saved when doctors wrapped her in CLING FILM". www.thesun.co.uk. Retrieved 2016-03-31.
External links
