Thermoplastic elastomers classification

The classification given in Table 1 is based on the process, ie, thermosetting or thermoplastic, by which polymers in general are formed into usehil articles and on the mechanical properties, ie, rigid, flexible, or mbbery, of the final product. AH commercial polymers used for molding, extmsion, etc, fit into one of these six classifications the thermoplastic elastomers are the newest. 

Chapters 10 to 29 consisted of reviews of plastics materials available according to a chemical classification, whilst Chapter 30 rather more loosely looked at plastics derived from natural sources. It will have been obvious to the reader that for a given application plastics materials from quite different chemical classes may be in competition and attempts have been made to show this in the text. There have, however, been developments in three, quite unrelated, areas where the author has considered it more useful to review the different polymers together, namely thermoplastic elastomers, biodegradable plastics and electrically conductive polymers. 

As shown in Fig. 1, plastics are classified as thermoplastics, elastomers, and duroplastics. In practice, classification is made in accordance with a number of different aspects. In Fig. 1, thermoplastics are categorized in physical terms (according to stmcture), elastomers in chemical terms (double bond), and duroplas-tics according to process pressure. 

Fig. 6 Classification of thermoplastic elastomers (based on Osen and Sckuhr [5])...

Synonyms Polystyrene-block-poly (ethylene-ran-butylene)-block-polysty-rene S-EB-S SEBS copolymer Classification Thermoplastic elastomer... 

Classification Thermoplastic elastomer Properties Dens. 1.15-1.22 kg/l m.p. 165-210 C tens. str. 40-50 MPa elong. break 500-850% good elastic, abrasion, and solv. resist. 

Classification Thermoplastic elastomer Definition Polymer of isoprene major component of natural rubber, also made synthetically avail, in range of std., oil-extended and carbon bik.-filled grades props, vary with catalysts used in mfg. (lithium, titanium)... 

Classification Thermoplastic elastomer Definition Polymer consistg. of hard segments embedded in a soft, elastomeric polyol phase exc. abrasion/impact resist. high str. wide working temp, range good hydrolytic stability two types polyether- or polyester-based Properties Solid... 

Classification Thermoplastic elastomer Definition Produced by coupling styrene-isoprene diblock copolymers into S-l-S triblock with typical styrene content of 14%... 

ASTM D4474-00 Standard Classification System for Styrenic Thermoplastic Elastomer Injection Molding and Extrusion Materials (TES)... 

The macroscopic behavior of the polymer materials caused by the polymer architecture is the basis of the classification of polymers in thermoplastics, elastomers and thermosets. 

Fig. 17.15. Classification of i-PP samples prepared with different catalysts, as stiff-plastic materials, fiexible-plastic materials, and thermoplastic elastomers depending on concentration of rr defects of stereoregulaiity and Young s modulus (E)...

The most common way of classifying polymers is outlined in Fig. 1.2 where they are first separated into three groups thermoplastics, elastomers and thermosets. Thermoplastics are then further separated into those which are crystalline and those which are amorphous (i.e. non-crystalline). This method of classification has an advantage in comparison to others since it is based essentially upon the underlying molecular structure of the polymers. 

Another means of classification is to organize materials based on their flexibility. We often have specific uses for materials that are stiff and rigid, and other uses for materials that are flexible and elastic. While this kind of classification is often helpful on a general level, in reality it often becomes cumbersome, since many materials can be formulated in a variety of stiffnesses. It is mostly used to describe a general category of bigbly flexible materials, known as thermoplastics elastomers. These will be discussed in greater detail in the next chapter. 

The broadest classification for plastics is the old thermoplastic and thermosetting . Examples of the former group are polyethylene, polystyrene, and poly-(methyl methacrylate) examples of the latter are urea-formaldehyde condensation polymers, powder coatings based on polyesters, epoxy resins, and vulcanized synthetic elastomers. 

Polymers can be classified in many ways, such as by source, method of synthesis, structural shape, thermal processing behavior, and end use of polymers. Some of these classifications have already been considered in earlier sections. Thus, polymers have been classified as natural and synthetic according to source, as condensation and addition (or step and chain) according to the method of synthesis or polymerization mechanism, and as linear, branched, and network according to the structural shape of polymer molecules. According to the thermal processing behavior, polymers are classified as thermoplastics and thermosets, while according to the end use it is convenient to classify polymers as plastics, fibers, and elastomers (Rudin, 1982). 

Further classification of polymers in the groups of additional polymers and condensation polymers has been on monomer composition, because this provides an orderly approach, whereas classification based on polymer uses, such as plastics, elastomers, fibers, coatings, etc. would result in too much overlap. For example, polyamides are used not only as synthetic fibers but also as thermoplastics molding compounds and polypropylene, which is used as a thermoplastic molding compound has also found uses as a fiber-forming material. 

It is not possible to discuss here the special properties of all the different types of plastic materials that can occur within these three groups. The plastics industry today, by employing copolymerization or chemical modification, is capable of producing an extraordinary number of combinations of properties, making the identification of corresponding plastics more complicated. Its physical appearance and its classification as a thermoplastic, thermoset, or elastomer therefore permit us to draw conclusions about the chemical nature of the plastic only in simple cases. But they often provide a useful additional way of characterizing the material. 

Figure 5 shows the structural model for elastomers. Table 3 presents the classification and applications of elastomers. TPE are two-phase or multiphase plastics (block copolymers) with elastic properties similar to those of elastomers, but with a melting temperature that allows for processing as with thermoplastics. Figure 6 illustrates the classification of TPE. 

Synonyms Butanoic acid, 3,3-bis ((1,1-dimethylethyl) dioxy)-, ethyl ester Ethyl 3,3-bis (t-butylperoxy) butyrate Ethyl-3,3-di-(t-butylperoxy) butyrate Classification Org. peroxide Empirical C14H28O6 Properties M.w. 292.36 NFPA Health 2, Flammability 2, Reactivity 2 Uses Polymerization initiator initiator for curing elastomers and for polymer modification thermoplastic crosslinking agent Trade Name Synonyms Aztec EBU-40-G t[Aztec Peroxides] Aztec EBU-40-IC f[Aztec Peroxides]... 

Classification Phosphite Empirical C27H47O3P Properties Wh. solid sol. in THF, toluene, cyclohexane, xylene m.w. 450 m.p. 90 C Uses Antioxidant for polyolefins, styrenics, engineering thermoplastics, PVC, elastomers, adhesives, food-grade polymers Regulatory FDA 21CFR 178.2010 Trade Name Synonyms Ultranox 641 t[GE Spec, http //www.ge. com/specialtychemicals]... 

Although there are numerous minor classification schemes for polymers, depending on how one wishes to categorize them, nearly all polymers can be placed in one of two major classifications—thermosetting materials (or thermosets) and thermoplastic materials. Likewise, foams, adhesives, embedding resins, elastomers, and so on, can be subdivided into thermoplastic and thermosetting classifications. 

A classification of thermoplastic products (not including elastomers and thermosetting resins) is shown in Figure 1.6. 

The SAE J200/ASTM D2000 classification only covers crosslinked elastomers. Hytrel, Alcryn and the other thermoplastics are included for comparison. 

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