Shrink wrap forming

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. 

Compound words made from combining verb forms are frequently hyphenated The psychiatrist insisted his birthday presents be shrink-wrapped. 

Polyethylene, as LDPE, LLDPE or a mixture or blend involving combinations of LDPE, MDPE, HDPE, EVA, etc., finds a wide usage in bags, sacks, sachets, overwraps, shrink wraps, stretch wraps, etc. Most deep freeze packs, for example, use LDPE or an LDPE mixture which is produced from a reel on a form fill seal type machine. However, as many of these packs are up to 100% printed, even ink of 2-5 Pm could be considered as a separate layer which modifies some of the physical and chemical properties. As all polyolefins need a surface (oxidative) treatment to ensure a good print key, this or any other surface treatment process may further modify the film properties. 

This may involve the collation of packages of similar or variable shapes. The most popular form uses either a direct shrink wrap (e.g. multi-packs) or a shallow tray which is usually made from corrugated board or solid board. Thermoformed plastic trays with a formed base (and/or a lid/cover) are also widely employed (e.g. bottles and aerosols). These systems offer restriction to pilferage and due to the see-through nature of the film may avoid the need for external labels. (Internal labels may be necessary if stock is controlled via a bar code.) Although LDPE has the major use, PVC may occasionally be used for its higher clarity. Gauges of 25 to 100 m are usually employed. 

The blowing agent is usually chemically stable, volatile, and so its introduction into the molten polymer reduces the foam product density, by forming a myriad of closed cells. The foam is then trimmed to desired shape. The Foam Boards are packed into shrink-wrapped bundles on the pallets. And then these pallets are stored for curing during a certain period, until shipment. ... 

The price given will be based on the assumption that the material is purchased in 1 ton/tonne lots a tonne is 1,000 kg. If purchased in this way then the plastics material will probably be supplied in 25 kg/55.11b sacks, with 40 sacks shrink wrapped onto a pallet. When supplied in 501b/22.6kg sacks, then the material is often supplied in 20 sack (1,0001b) loads. Supplying the material in sacks, or bags, is not the only way that the material can be supplied considerable discounts may be obtained if the plastics material is purchased in bulk and, supplied in, for example, bulk containers. With some materials, this form of supply may not be acceptable as, for example, excessive water absorption may occur. 

Fig. 24a Automatic shrink-wrapping lines for forming palletless unit loads composed of stacked sacks konterpac process...

Besides forming strong and conveniently storable and stackable unit loads, palletless shrink-wrapping has the advantage that the cement can be packed in ordinary two-ply paper sacks, whereas otherwise cement intended for shipment overseas usually has to be packed in five- or six-ply sacks. 

The vibrational changes that occur on orientation and crystallization have been used to research the origin of the residual orientation frequently found in blown or extruded film. These materials frequently show quite well developed orientation, and hence are useful as shrink wrapping. As the flowing melts from which they are formed are optically dichroic, it seems reasonable to propose a model involving flow-orientation-crystallization and solidfication in an oriented manner. It has been shown, however, that the orientation of a flowing polyethylene melt (as measured by infrared, Raman diffraction and X-ray diffraction) is very small [38]. 

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