Rubbers Natural rubber Styrene-butadiene

Rubbers differ in their resistance to ozone. All the highly unsaturated rubbers (natural rubber, styrene-butadiene rubber, butyl rubber, nitrile rubber) are readily cracked while the deactivated double carbon-carbon bonds rubber (such as polychloroprene rubber) shows moderate ozone resistance. 

Most rubbers used in adhesives are not resistant to oxidation. Because the degree of unsaturation present in the polymer backbone of natural rubber, styrene-butadiene rubber, nitrile rubber and polychloroprene rubber, they can easily react with oxygen. Butyl rubber, however, possesses small degree of unsaturation and is quite resistant to oxidation. The effects of oxidation in rubber base adhesives after some years of service life can be assessed using FTIR spectroscopy. The ratio of the intensities of the absorption bands at 1740 cm" (carbonyl group) and at 2900 cm" (carbon-hydrogen bonds) significantly increases when the elastomer has been oxidized [50]. 

AA Natural rubber, styrene butadiene, butyl, ethylene propylene, polybutadiene, Polyisoprene... 

Natural rubber Styrene-butadiene rubber Polybutadiene Polyisoprene Nitrile rubber Halogenated nitrile rubber Ethylene-propylene rubber EPDM... 

Mixing process Technical rubbers are blends of up to about 30 different compounds like natural rubber, styrene-butadiene rubber, silicate and carbon-black fillers, and mobile components like oils and waxes. These components show a large variety of physical, chemical, and NMR properties. Improper mixing leads to inhomogeneties in the final product with corresponding variations in mechanical and thermal properties (cf. Figure 7.4). 

Resin as the Disperse Phase. Several kinds of resins (10) have been used to reinforce rubbers—e.g., phenolic or coumarone resins for natural rubber, styrene-butadiene resin for styrene-butadiene rubber, etc. One other important system, pressure-sensitive adhesive, also belongs to this class. These adhesives generally contain a low molecular weight resin functioning as a tackifier. In 1957, Wetzel (68) and Hock (19) found that these adhesives were actually two-phase systems (Figure 1). Under... 

The major general purpose rubbers are natural rubber, styrene-butadiene rubber, butadiene rubber, isoprene rubber, and ethylene-propylene rubber. These rubbers are used in tires, mechanical goods, and similar applications. Specialty elastomers provide unique properties such as oil resistance or extreme heat stability. Although this differentiation is rather arbitrary, it tends also to classify the polymers according to volumes used. Styrene-butadiene rubber, butadiene rubber, and ethylene-propylene rubber account for 78 percent of all synthetic rubber consumed. 

These may be used for low hardness compounds in areas where impact abrasion is predominant. EPDM is at times referred as crackless rubber5 since it has high tear resistance. For producing high hardness compounds blends with natural rubber, styrene-butadiene rubber (SBR) and high styrene resins are recommended. 

AI3-14877 Ancazate ET Bis(diethyldithiocarbamato)-zinc Carbamodithioic acid, diethyl-, zinc salt CCRIS 4908 Diethyidithiocarbamic acid zinc salt EINECS 238-270-9 Ethazate Ethyl cymate Ethyl zimate Ethyl Ziram Ethylzimate Hermat ZDK HSDB 2907 Nocceler EZ NSC 177699 Octocure ZDE-50 Perkacit ZDEC Soxinol EZ Vulcacure ZE Vulkacit LDA Vulkacit ZDK Zimate, ethyl Zinc bis(diethyldithiocarbamate) Zinc, bis(diethyldithiocarbamato) Zinc, bis(diethylcarbamo-dithioato-S,S )- Zinc diethyidithiocarbamate Zinc N,N-diethyldithiocarbamate Zinc, tetrakis(diethylcarbamo-dithioato)di-. Latex and rubber accelerator. An accelerator and activator for natural rubber, styrene-butadiene, nitrile-butadiene and butyl rubber. Akzo Chemie Tiarco. 

FIGURE 8.8 Pyrograms of (a) natural rubber/styrene butadiene blend, (b) polyurethane, and (c) butyl rubbers. 1 = isoprene, 2 = vinylcyclohexene, 3 = styrene, 4 = dipentene, 5 = tetrahydrofuran, 6 = cyclopentanone, 7 = butanediol, 8 = isobutene oligomers. 

All diene rubbers discussed so far, natural rubber, styrene-butadiene rubbers, poly-butadienes), butyl rubbers, and ethylene-propylene rubbers, consist of aliphatic or aromatic monomeric units. They swell readily in aliphatics they have poor oil resistance. But the free radical copolymerization of acrylonitrile with butadiene leads to what is known as nitrile rubber, which has good oil resistance because of the many polar nitrile groups. However, the rebound elasticity and the low-temperature flexibility decrease with increasing nitrile fraction. Consequently, NBR is mainly used for fuel hoses, motor gaskets, transport belts, etc. 

Like natural rubber, styrene butadiene rubber (SBR) can be blended in all proportions with bromobutyl rubber. However, SBR is less desirable for blending than natural rubber due to its low tack and green strength properties. In addition, heat, flex fatigue resistance, and weathering resistance are poorer with SBR blends than with natural rubber blends. Suggested cure systems are the same as those for bromobutyl/natural rubber blends. 

Uses antidegradant in natural rubber, styrene-butadiene and chloroprene rubber... 

Uses protection of rubber against oxidation, ozone, flex-cracking, and poisoning by copper and manganese antidegradant in natural rubber, styrene-butadiene, nitrile-butadiene, butadiene, and chloroprene rubber A... 

Uses rubber vulcanization accelerator for natural rubber, styrene-butadiene, and butyl rubber in adhesives including those used in food packaging, paper coats for non-food contact, industrial cooling water, latex-coated articles, neoprene, paper and paperboard, plastics (polyethylene and polystyrene), and textiles agricultural fungicide for seed, plants, and fruits repellant to birds and rodents. 

Non-oil Resistant (swelling or Natural rubber Styrene-Butadiene GRS Elastic cord, tires -65 to 220 High resilience, abrasion resistance, tear strength... 

Aromatic amine antioxidants are also known as rubber antiaging agents they have the largest production quantity and are used mainly in rubber products. These antioxidants have low prices and remarkable antioxidant effects however, they could change the color of products, which limits their application in light colored and white goods. Significant aromatic amine antioxidants are diphenylamine, jo-phenylenediamine, quinoline, and their derivatives or polymers, and they can be used in natural rubber, styrene butadiene rubber (SBR), chloroprene rubber, and isoprene rubber. 

Walters and Keyte [82] first observed dispersed particles in blends of rubber polymers by phase contrast optical microscopy. Marsh et al. [83] studied elastomer blends by both optical phase contrast and TEM. Electron microscopy was applied to study blends of natural rubber, styrene-butadiene rubber (SBR), cis-polybutadiene (PB) and chlorobutyl rubber [84]. It became obvious that both hardening of the rubber and staining were necessary for producing sections with contrast for TEM. Today, the most common methods of observing multiphase polymers are by phase contrast OM of thin sections, TEM of stained ultrathin sections and SEM of etched or fractured surfaces. 

Polyurethane adhesives also are suitable for bonding nonpolar elastomers, for example, natural rubber, styrene-butadiene rubber, or ethylene-propylene terpol-ymers, after chemical pretreatment of the surface. 

Sircar and co-workers [8] compared experimental and data from the literature for the Tg of some common elastomers determined by different thermal analysis techniques, including DSC, TMTA, DMTA, dielectric analysis and thermally stimulated current methods. Elastomers examined include natural rubber, styrene-butadiene rubber, polyisoprene, polybutadiene, polychloroprene, nitrile rubber, ethylene-propylene diene terpolymer and butyl rubber. Tg values obtained by DSC, TMA and DMTA were compared. Experimental variables and sample details, which should be included along with Tg data were described, and the use of Tg as an indication of low temperature properties was discussed. 

Rubbers with very poor resistance Diene mbbers (e.g., natural rubber, styrene butadiene rubber, nitrile mbber, budadiene mbber)... 

Krishen [119] has described a procedure for the determination of these monomer units. He quantitatively analysed the gaseous pyrolysis products from natural rubber, styrene-butadiene rubber and ethylene-propylene diene terpolymer rubber by gas chromatography. He showed that the 2-methyl-2-butene peak was linear with the natural rubber content of the sample. Styrene-butadiene rubber was determined from the peak area of the 1,3-butadiene peak. The ethylene-propylene-terpolymer content was deducted from the 1-pentane peak area of the pyrolysis products. Some of the pyrolysis products identified are shown in Table 4.10. 

NATURAL RUBBER, STYRENE-BUTADIENE RUBBER AND ETHYLENE-PROPYLENE-DIENE TERPOL YMER IN CURED STOCKS... 

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