Types of Plastics Packaging

Computer chips for various types of electronic appliances are very susceptible to damage from static electricity. Special plastic wraps or bags provide a conductive path to dissipate the static charges, thus protecting the chips from damage during parts distribution. 

Production of flexible packaging begins with extrusion of plastic resin to yield sheet or film. For film, two main processes are used. In the cast-film process, the resin is extruded through a slit-shaped die onto a water-cooled chrome roUer, where it is solidified. After the edges are trimmed off, the film is wound onto a roll. The film may be oriented by stretching it in the machine direction (uniaxi-ally oriented) or in both the machine and cross directions (biaxially oriented) to improve mechanical and barrier properties. This process is also used to produce plastic sheet for thermoforming or other applications. 

In the blown-film process, the resin is extruded through an annular die and internal air pressure used to expand the bubble. After the resin solidifies, the bubble is collapsed and may be wound as a tube or slit and wound as rolls of flat film. Since the film is stretched by the take-off rollers as well as by the bubble expansion, it has biaxial orientation. 

Injection blow molding is used primarily for plastic resins that lack sufficient melt strength for extrusion blow molding. Injection blow molding is also used for 

Coextrusion blow molding is often used to produce multilayer plastic containers. A multilayer parison is produced, and subsequent operations are identical to ordinary blow molding. Reuse of flash is more difficult since it will be multilayer. In many cases, the flash is used in an inner layer in the container, either alone or combined with other recycled plastic. High-density polyethylene (HDPE) laundry product bottles, for example, routinely are made with a three-layer structure in which the inner layer contains flash blended with postconsumer recycled HDPE. 

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For small samples, it is recommended that polypropylene [e.g. Nalgene ] bottles be used with a cap insert inside the neck. This type of plastic packaging is extremely resilient to compression and damage. Glass bottles should be avoided where possible. All very small quantities should be shipped as a combination package - an inner package in a UN approved box containng a suitable fabric adsorbent... 

Phenylmercuric salts are absorbed by rubber stoppers and some types of plastic packaging components uptake is usually greatest to natural rubbers and polyethylene and least to polypropylene. ... 

The packaging industry has been responsible for rapid growth in all types of plastics packages. Plastic films and containers have established new concepts in packaging and developed new markets not previously open to plastic. This growth trend will continue in the 60 s at an even faster rate. 

There are different types of plastics packaging used in different applications. 

In this chapter, we will examine the types of plastics packaging, their fabrication methods, their occurrence in municipal solid waste, environmental impacts (both positive and negative) associated with their use and disposal, and packaging changes that can reduce those environmental impacts. First, we will examine... 

Fig. 4. Exterior view line drawings showing other types of plastic packages. From Ref. 7, with permission.

The PSA formulator can also take advantage of plasticizers. For example, polyether-based plasticizers have both good low-temperature flexibility and good hydrophilicity. Using these properties, acrylic PSAs have been formulated with these types of plasticizers to obtain high adhesion to food packages stored under refrigerated conditions [102]. Similarly, polyether plasticized acrylics have been used to make repulpable PSAs [103]. 

It is instructive to consider the sources of plastics waste. Table 11.1 shows the types of plastics and their use in packaging, whilst Table 11.2 shows the proportion of waste classified by end use. This shows how significant packaging is in generating waste, and causing environmental problems. Applications such as furniture and electrical appliances show more acceptable use of polymers, because discard rates are low and lifetimes of the products are generally long. 

Products composed of one type of plastic only. Examples are monolayer foils used, e.g., in packaging for bakery or in the form of bags for household application. It is worth noting that a mono-material film, consisting, e.g., of polypropylene, may contain more than one component. If the film is coloured, this is obtained by mixing a polypropylene matrix with a colourant carried by another polypropylene, normally of lower molecular weight. 

Semisolid plastic shortenings are usually packaged in 0.5-kg and 1.5-kg (1-lb and 3-lb) cans, cubes, 50-kg (110-lb) cartons, and in dmms containing about 175 kg (3801b). This type of plastic shortening is also available in chubs, prints, and sheets ready for direct end-use application. 

Liquid oral preparations are usually contained in PET or PETG containers. PETG has a different polymeric composition than PET as discussed under Types of Packaging Materials. Physical characteristics are listed in the USP and 21 C.F.R. specifies their composition. Identification of PET and PETG shows that these plastics are distinct and distinguishable from one another by IR spectrum, but the two compounds are similar as evaluated by thermal analysis.f " This type of plastic should be tested for colorant extraction as previously discussed. " ... 

Type of inner packaging Glass, porcelain or stoneware packaging Plastic packaging Metal packaging... 

Besides consumer products, another important field of application for PSAs is that of plastic adhesive labels. The PSAs must adhere very efficiently to the plastic carrying material and at the same time adhere well to a wide variety of plastic packaging types (e.g., bottles, containers for chemicals). 

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