Plastics categories

It is interesting to note that the articles dealing mainly with substances considered to be toxic contained within plastics (category 7 in Figure 1.3) like phthalate or BPA represent only 4% of the total number of articles, while the impact of plastics upon the environment or health is the main subject for 1% of the articles. 

Plastic materials included in the thermosetting plastic category and discussed separately in the following sections of this book include alkyds, diallyl phthlate, epoxies, melamines, phenolics, polyesters, silicones, and ureas. A list of typical tradenames and suppliers of the more common plastics is given in Table IN.l. 

Flammability was determined by the flame method UL-94 according to PN-EN 60695-11 -10 2002/A 1 2005 B method - vertical burning test, which shows in the laboratory conditions, how the sample behaves after the removal of the flame source. This method is based on a double fire set for 10 s vertically suspended plastic specimen. The burning phenomena observation was conducted, such as glow and dripping. The trial was done to a set of five pieces of specimens. The results can be compared with the criteria specified in the norm, and on that basis the flammability of plastic category can be determined. The materials should be classified as follows V-0, V-1, or V-2 (V indicate the vertical way of combustion), according to the norms. 

There are two categories of white oils technical white oils and medicinal white oils. The technical white oils, which are already highly dearomatized, are used for specialized lubricants, particularly in the textile industry, and also as components in cosmetics, as plasticizers in the rubber or plastics industries, or as emulsion bases for certain pulverized agriculture products. The medicinal white oils, whose dearomatization is pushed further still, are used in pharmaceuticals, or in the food industry, wherever residual oils might be in contact with food. 

Substances in this category include Krypton, sodium chloride, and diamond, as examples, and it is not surprising that differences in detail as to frictional behavior do occur. The softer solids tend to obey Amontons law with /i values in the normal range of 0.5-1.0, provided they are not too near their melting points. Ionic crystals, such as sodium chloride, tend to show irreversible surface damage, in the form of cracks, owing to their brittleness, but still tend to obey Amontons law. This suggests that the area of contact is mainly determined by plastic flow rather than by elastic deformation. 

Adhesive Transfer Processes. Many polymers, whether dehberately or accidentally, are adhesives, so that much of the adhesive industry can be regarded as a part of the mbber and plastics industry. However, there are several important material-transfer appHcations involving polymer products that are so critically dependent on controlled adhesion that they merit specific mention in that category. They include hot stamping foils, release coatings for pressure-sensitive adhesive products, photocopier materials, transfer coatings, and transfer printing of textiles. 

Clays used in plastics and mbber have historically been divided into two categories fillers that extend a polymer or fillers that reinforce a polymer. 

Plating on nonconductors comprises two technologically very different categories plating of plastics and priated circuit productioa. 

Although the first two materials discussed in this chapter, the polyphenylenes and poly-p-xylylenes, have remained in the exotic category, most of the other materials have become important engineering materials. In many cases the basic patents have recently expired, leading to several manufacturers now producing a polymer where a few years ago there was only one supplier. Whilst such competition has led in some cases to overcapacity, it has also led to the introduction of new improved variants and materials more able to compete with older established plastics materials. 

The primary non-woven applications for hot melts are in disposable articles such as diapers and sanitary napkins (see Fig. 22). These articles are made by high speed processes and are immediately packaged in sealed plastic bags, thus they are prime candidates for hot melt use. The applications are broken down into three categories, requiring three different types of adhesives construction, elastic attachment, and garment attachment. 

In the following sections most of the common plastics will be described briefly to give an idea of their range of properties and applications. However, before going on to this it is worthwhile considering briefly several of the special categories into which plastics are divided. 

Acrylonitrile-butadiene-styrene (ABS). ABS materials have superior strength, stiffness and toughness properties to many plastics and so they are often considered in the category of engineering plastics. They compare favourably with nylon and acetal in many applications and are generally less expensive. However, they are susceptible to chemical attack by chlorinated solvents, esters, ketones, acids and alkalis. 

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