Shrink wrapping

Nonfood packaging categories include dmgs and pharmaceuticals, textile goods, bags (merchandise, shipping, carry-out, T-shirt, and laundry), shrink wrap, stretch wrap, clear boxes, and many more. 

More than half of flexible packaging is used for food. Within foods, candy, bakery products, and snack-type foods, such as potato and com chips, use well over half of flexible packaging. Cheese, processed meat, shrink wraps, condiments, dry-drink mixes, fresh meats, and fresh produce represent smaller appHcations. 

Siace a large part of the beer market is take-home beer, brewers must provide retailers with packs that are easily handled and stored. Clear shrink wrappiag has become a dominant feature because it permits the content of the pack to be seen. Other packagiag methods are Shrink Wrapped 2 dozea Tray Pack, Cardboard Sleeve, Hi Coae 3 Pack, Hi Coae 6 Pack ia Tray, and Top CHp Bottle Pack (see Packaging materials). 

The market for PPVC film and sheet is only slightly less than for wire and cable insulation. Uses are as diverse as seepage barriers, factory doors, inflatables, baby pants, car trim, covering materials for book bindings and document cases and shower curtains. UPVC film has also been widely used for packaging of food, particularly for shrink-wrap purposes, but this market has been subject to some substitution by polypropylene. 

Example 4.3 A plastic shrink wrapping with a thickness of 0.05 mm is to be produced using an annular die with a die gap of 0.8 mm. Assuming that the inflation of the bubble dominates the orientation in the film, determine the blow-up ratio required to give uniform biaxial orientation. 

Chemists were greatly surprised when soccer-ball-shaped carbon molecules were first identified in 1985, particularly because they might be even more abundant than graphite and diamond The C60 molecule (10) is named buckminsterfullerene after the American architect R. Buckminster Fuller, whose geodesic domes it resembles. Within 2 years, scientists had succeeded in making crystals of buckminsterfullerene the solid samples are called fullerite (Fig. 14.32). The discovery of this molecule and others with similar structures, such as C70, opened up the prospect of a whole new field of chemistry. For instance, the interior of a C60 molecule is big enough to hold an atom of another element, and chemists are now busily preparing a whole new periodic table of these shrink-wrapped atoms. 

Like graphite, C60 can be transformed into diamond, but the process requires less stringent conditions. It has also been found that Cso becomes a superconductor at low temperature. Another interesting characteristic of Cso is that when it is prepared in the presence of certain metals, the Cso cage can enclose a metal atom. In some cases, other materials can be enclosed within the C60 cage in a "shrink wrapped" manner to form "complexes" that are described as endohedral. It has also been possible to prepare metal complexes of Cso that contain metal-carbon bonds. A compound of this type is (C6H5P)2PtC60. 

Figure 4. The various mechanisms for structural "shrink-wrapping" in bilayer GS inclusion compounds can be gleaned from these illustrative examples, here viewed down the channel direction, (a) quasihexagonal G2IH 2(CH3CN), (b) quasihexagonal G2V-1,4-diethynylbenzene, (c) shifted...

Films and sheets with high clarity, puncture resistance, impact strength, low heat-seal temperature used for shrink-wrap, heavy-duty shipping sacks, produce bags, bag-in-box food and technical packaging films... 

Shrink wrap is a film that is applied loosely around products, then sealed and shrunk by heating to take the shape of the contained products. It can be used to bind multiple packages, or to secure an entire pallet of packages, to bundle magazines and papers, to protect and display albums, CDs and so on. It is usually made of LLDPE, LDPE or polypropylene. 

LDPE/LLDPE Stretch wrap, shrink wrap Good clarity... 

PVC Some stretch and shrink wraps for industrial Excellent clarity... 

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