Inhibited Plastic Containers

Inhibited structural plastics are manufactured by the extrusion of blends of structural polymers and Cl. 

Injection and blow molded products based on inhibited PE and PP produced by the Northern Instruments Corp. (USA) have become world standard for anticorrosion plastic containers. Similar plastic products modified by VCI are manufactured by the German companies Rose Plastic and Brangs and Meinrich [20]. Another original sort of inner packages for small diameter metal tubes is a tube strip. Tube strips are extruded PE tubings inserted into metal tubes to protect their interior surfaces from corrosion [21]. 

Laminated plastics are a convenient material for the production of inhibited containers as they allow the distribution of the functions of the master container and inner package between different layers of the plastic. 

The most applicable representatives of this class of materials are the Zerust Ferrous Chipboard and Fibreboard. They are produced by applying extruded VCI-modified PE coatings about 1.5 mm thick on either chipboard sheets or Kraft paper. One kind of the fibreboard is made as a three-ply material with a paper-coating-paper structure. Therefore the fiberboard can be used as a conventional cardboard or a lining for layer-wise packing of products for preservation. 

Dunnage trays and bins are used to speed up and reduce the necessity for care during the handling of parts on assembly lines. Thermoformed 

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This zone of inhibition test shows only that the plastic contains an antibacterial agent that is able to migrate from the product being examined. 

Alternatively, the container may contain an opacifying agent, e.g., titanium dioxide. The use of multilayered bags was demonstrated to inhibit photochemical decomposition of vitamin E in TPN fat emulsions (Allwood and Martin, 2000). PVC films discolor on irradiative exposure due to photochemical degradation of the polymer (Hollande and Laurent, 1997). Plastic containers for parenteral use may contain several additives, e.g., antioxidants, stabilizers, plasticizers, lubricants, impact modifiers, and coloring matter when justified and authorized. In an appendix, the European Pharmacopoeia presents a list of plastic additives that may be used (European Pharmacopoeia, 2002). The additives should not be extracted by the contents in such quantities as to alter efficacy or stability of the product or to present any risk of toxicity (European Pharmacopoeia, 2002). However, organic additives extracted in concentrations below the detection limits of the analytical methods authorized by the European Pharmacopoeia may be sufficient to initiate photosensitized reactions in the formulation. 

Inhibited plastics are composite materials (CM) consisting of inhomogeneous components (phases) separated by interfaces. They contain thermoplastics... 

Furthermore, an idea of obtaining inhibited plastics by filling polymer binders with solid inhibitor particles has apparently been realized. A wide range of structural plastics, films and coatings containing powder inhibitors is produced by the major companies of the world at the present time. The... 

This class of inhibited plastics includes multilayered films containing particles of a powder inhibitor between its polymer layers. 

In contrast to film materials, express estimates of the protective ability of inhibited structural plastics have been insufficiently elaborated so far. For example, the effect of inhibited plastics on the wear rate of metal samples has been studied by the authors of [100] using a pendulum tribometer containing a plastic-metal friction pair. Corrosion tests of systems such as inhibited structural plastic-metal counterparts are usually conducted in real operation regimes [44]. 

Parts of friction joints and seals are often made from inhibited structural plastics (see Chap. 4). Their main role in metal-polymer friction joints is to abate Mechano-chemical wearing of metal counterbodies. Application of inhibited antifrictional materials is considered to be a promising trend for extending the life of friction joints operating in hostile media. The structural polymers or their blends most often contain plasticizers. Cl, fillers and modifiers as additional components. The inhibited plastics are employed in plain bearings, sealing elements and other members of oil-extracting equipment and vehicles. 

Plastic containers (pallets, boxes, cases, etc.) are commonly made of structural inhibited plastics based on chiefly recycled materials. 

Inhibited foam plastic is a structural material preliminary foamed by Cl vapors or based on foamed inhibited plastics and is used for plastic-based containers. The inhibited vapor phase can be introduced into the polymer base by one of the following methods. 

A typical representative of the inhibited foam plastics used in plastic containers is an isocyanate-derived polymer whose cells contain inhibitor vapors of the cyclohexilylamine chromate, cyclohexylamine M-mononitro benzoate, dicyclohexylamine chromate and dicyclohexylamine nitrite series [23]. 

The effectiveness of plastic protection means containing volatile Cl depends much on the liberation kinetics of Cl from the polymer matrix. We have already analyzed (see Sect. 1.5) the problem of binding inhibitors within the plastic structure. The delivery velocity of the required amount of Cl to the metal part surface turned out to be a reliable criterion for estimating the efficiency of inhibited plastics. Some plastic grades do not need to take account of the Cl delivery factor if the inhibiting component is located in the most probable place of corrosion. 

Neutralizing removes the large amount of hexavalent chromium from the surface of the part. Hexavalent chromium shortens the life of the catalyst, and trace amounts completely inhibit electroless nickel deposition. The neutralizer is usually a mildly acidic or basic reducing agent, but other types of neutralizers are available, especially for substrates that are difficult to plate. The neutralizer may also contain surfactants (qv) or other compounds that increase catalyst absorption absorption promoters are often needed for non-ABS plastics. 

Although inhibitors are deliberately added to the silicone formulation to control cure rate, unwanted cure inhibition can be caused by other species that react to form strong complexes with the platinum catalyst. Most notable of these undesired inhibitors include organotin and other organometallic compounds, sulfur, polysulfides, polysulfones or other sulfur-containing materials, amines, urethanes or amine-containing materials, unsaturated hydrocarbons in plasticizers, and some solder flux residues. 

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