Plasticizers nonpolar elastomers

This group of high volume nonpolar elastomers is typically plasticized with soybean and rapeseed oil factices and the full range of hydrocarbon process oils. Only when a special lubricating effect is wanted is a synthetic plasticizer used. To illustrate, the following two examples (a) 10 phr DOA added to an EPDM Arctic CB radio coil cord where it acted as an extreme low temp (LT) flexibilizer (b) a typical LT glycol ester (TEG-2EH) used at 8 phr in BR to achieve both processing and LT enhancements. In both examples, the incompatible plasticizer acted as a lubricant. 

Nonpolar molecules such as heptane and PE are attracted to each other by weak London or dispersion forces that result from induced dipole-dipole interactions. The temporary or transient dipoles are due to instantaneous fluctuations in the electron cloud density. The energy range of these forces is fairly constant and about 8 kJ/mol. This force is independent of temperature and is the major force between chains in largely nonpolar polymers, for example, those in classical elastomers and soft plastics such as PE. 

Poly(vinyl chloride) (PVC) homopolymer is a stiff, rather brittle plastic with a glass temperature of about 80°C. While somewhat more ductile than polystyrene homopolymer, it is still important to blend PVC with elastomer systems to improve toughness. For example, methyl methacrylate-butadiene-styrene (MBS) elastomers can impart impact resistance and also optical clarity (see Section 3.3). ABS resins (see Section 3.1.2) are also frequently employed for this purpose. Another of the more important mechanical blends of elastomeric with plastic resins is based on poly(vinyl chloride) as the plastic component, and random copolymers of butadiene and acrylonitrile (AN) as the elastomer (Matsuo, 1968). On incorporation of this elastomeric phase, PVC, which is ordinarily a stiff, brittle plastic, can be toughened greatly. A nonpolar homopolymer rubber such as polybutadiene (PB) is incompatible with the polar PVC. Indeed, electron microscopy shows... 

Because nitrile rubbers are polar elastomers, their vulcanizates are very resistant to swelling in hot oil, gasoline, grease, and other nonpolar substances. The resistance to swelling in nonpolar oils, solvents, and so on, is improved greatly with increasing nitrile content. Here we see the need for compromises increasing nitrile content improves oil resistance but reduces elasticity and set resistance and most severely reduces low-temperature flexibility. Plasticizers are very necessary to surmount this problem. 

TPOs (olefinic blends) comprise a lower-performance, lower-cost class of TPEs (Fig. 4.39). Their performance and properties are generally inferior to those of thermoset rubbers. Yef they are suitable for uses where (1) the maximum service temperature is modest (below 80°C), (2) nonpolar flnid resistance is not needed, and (3) a high level of creep and set can be tolerated. Thns, TPOs are marketed more on the basis of cost rather than performance, competing directly with the lower-cost general-purpose rubbers (NR, SBR, and the hke). TPOs are associated with the traditional practice of rnbber componnd-ing and mixing. They can be prepared by the same techniques and equipment as for thermoset mbber however, they need to be processed at temperatures above the of the thermoplastic hard phase. The amounts of elastomer, rigid thermoplastic, plasticizer, and other ingredients can be varied to achieve specific properties in much the same manner as with rnbber componnds. 

The plastics that have been discussed above have the common characteristic that they may be considered somewhat structural if fabricated in a relatively thick cross section, or relatively nonstructural and even flexible if fabricated in thinner sections. Other types of plastics are given the general term elastomer and have the quality of being stretchy and easily deformed at the surface. They also often contained plasticizing additives and may range from nonpolar materials like natural rubber to significantly polar materials like nitrile rubber. Thermal or... 

In the rubber Industry, DOP is needed for use as a plasticizer in compounds based on polar elastomers such as nitrile rubber or polychloroprene. Since DOP is a polar plasticizer, it is compatible with polar elastomers. If a nonpolar plasticizer such as... 

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