Styrene-butadiene rubber SBR

SBR offers excellent abrasion resistance so is used mainly for automotive tyres. Other applications include shoe soles, waterproof materials and asphalt. 

SBR generally bonds well with cyanoacrylates and a surface primer is not usually required (Table 4.13). 

FIGURE 10. Glass transition temperatures of block copolymer (SBS) and random copolymer (SBR). 

SBR latex D has a tan 8 peak maximum temperature at - 17°C (7g) and higher modulus values (G = 1.3 x 10 dyn/cm at 100°C) than two other latices. This latex contains 46% styrene according to the calculation using Eq. (4) and is confirmed by an NMR method. This latex is not tackified well by a resin addition. Tack values are low, but shear adhesion is good. This is due to its high molecular weight and the high bounded styrene concentration. 

FIGURE 11. Dynamic mechanical properties of SBR latex with different concentration of styrene. 

Latex E is also high in styrene content, 44% as indicated from its tan 8 peak temperature (—18°C). Its molecular weight is lower than latex D as indicated from its G value at 100°C, although it has almost the same styrene content. Consequently, latex E generates better tack but lower shear compared to Latex D when compounded with a tackifying resin such as Foral 85 (see Table 1). 

Latex F has 25% styrene and a tan 8 peak temperature of -46°C. The lower level of styrene (25%), lower glass transition temperature ( 46°C), and balanced viscoelastic properties (G values) of the latex generate good tack properties without sacrificing the good shear properties when formulated with a tackifying resin (see Table 1). 

In the 1970s there was no argument that, in tonnage terms, SBR was the world s most important rubber. At that time about half of the total global consumption of rubber of about 8 X 10 tonnes per annum was accounted for by SBR. Today natural rubber has about half the market, which has now grown to about 11 X 10 tonnes, and the share of SBR has fallen to about 24%. Nevertheless SBR remains a material of great importance. 

In many respects it is not a particularly good rubber, but it has achieved a high market penetration on account of three factors  

Although first prepared about 1930 by scientists at the German chemical company of IG Farben the early products showed no properties meriting production on technical grounds. However, towards the end of the 1930s commercial production of the copolymer commenced in Germany as Buna S. (The term Buna arose from the fact that the early polymers of butadiene were made by sodium (Na) catalysed 

292 Aliphatic Polyolefins other than Polyethylene, and Diene Rubbers 

Since the early 1950s there have been a number of further important technical developments. These include  

Like NR, SBR is an unsaturated hydrocarbon polymer. Hence unvulcanised compounds will dissolve in most hydrocarbon solvents and other liquids of similar solubility parameter, whilst vulcanised stocks will swell extensively. Both materials will also undergo many olefinic-type reactions such as oxidation, ozone attack, halogenation, hydrohalogenation and so on, although the activity and detailed reactions differ because of the presence of the adjacent methyl group to the double bond in the natural rubber molecule. Both rubbers may be reinforced by carbon black and neither can be classed as heat-resisting rubbers. 

As one of the most versatile copolymers in the world today, styrene-butadiene rubber is used in a number of different applications around the world. Some facts about the development of styrene-butadiene rubber and some of the products that are created with this strong and reliable synthetic rubber are described below. 

Styrene-butadiene rubber, or E-SBR as it is known in manufacturing circles, was first developed in the 1930s. Known as Buna S, the compound was prepared by I.G. Farbenindustrie in Germany. Manufacturing styrene-butadiene rubber was through an emulsion polymerization process which produced a material that had a low reaction viscosity, yet had all the attributes of natural rubber. 

One of the other advantages was that the production of SBR was very cost-effective. The synthetic rubber was competing with natural rubber resources, especially in the area of the manufacture of tyres, which at the time were still solid rubber. Other countries began to duplicate the efforts and by the dawn of the subsequent decade, many developed nations were in the business of producing SBR for use in a number of products. 

Peak Notation Assignment of Main Peaks Molecular Retention Weight Index Relative Intensity 

SS but-3-ene-1,3-diyldibenzene (styrene dimer) SSS 5-hexene-1,3,5-trlyltrlbenzene (styrene trimer) 

081 Styrene-ethylene-butadiene-styrene block copolymer hydrogenated SBS (SEBS) 

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The elastomer produced in greatest amount is styrene-butadiene rubber (SBR) Annually just under 10 lb of SBR IS produced in the United States and al most all of it IS used in automobile tires As its name suggests SBR is prepared from styrene and 1 3 buta diene It is an example of a copolymer a polymer as sembled from two or more different monomers Free radical polymerization of a mixture of styrene and 1 3 butadiene gives SBR... 

Styrene-butadiene rubber (SBR) is also known as government rubber styrene (GRS) and Buna S. 

Styrene-butadiene rubber (SBR) (also known as Buna S) 0.94 40-100 400-600 1600-3700 -60 107... 

Styrene—Butadiene Rubber (SBR). This elastomer is used primarily in tires, vehicle parts, and electrical components. 

Styrene—Butadiene Rubber (SBR). This is the most important synthetic mbber and represents more than half of all synthetic mbber production (Table 3) (see Styrene-butadiene rubber). It is a copolymer of 1,3-butadiene, CH2=CH—CH=CH2, and styrene, CgH5CH=CH2, and is a descendant of the original Buna S first produced in Germany during the 1930s. The polymerization is carried out in an emulsion system where a mixture of the two monomers is mixed with a soap solution containing the necessary catalysts (initiators). The final product is an emulsion of the copolymer, ie, a fluid latex (see Latex technology). 

A copolymer is made by polymerisation of two monomers, adding them randomly (a random copolymer) or in an ordered way (a block copolymer). An example is styrene-butadiene rubber, SBR. Styrene, extreme left, loses its double bond in the marriage butadiene, richer in double bonds to start with, keeps one. 

Other polymers used in the PSA industry include synthetic polyisoprenes and polybutadienes, styrene-butadiene rubbers, butadiene-acrylonitrile rubbers, polychloroprenes, and some polyisobutylenes. With the exception of pure polyisobutylenes, these polymer backbones retain some unsaturation, which makes them susceptible to oxidation and UV degradation. The rubbers require compounding with tackifiers and, if desired, plasticizers or oils to make them tacky. To improve performance and to make them more processible, diene-based polymers are typically compounded with additional stabilizers, chemical crosslinkers, and solvents for coating. Emulsion polymerized styrene butadiene rubbers (SBRs) are a common basis for PSA formulation [121]. The tackified SBR PSAs show improved cohesive strength as the Mooney viscosity and percent bound styrene in the rubber increases. The peel performance typically is best with 24—40% bound styrene in the rubber. To increase adhesion to polar surfaces, carboxylated SBRs have been used for PSA formulation. Blends of SBR and natural rubber are commonly used to improve long-term stability of the adhesives. 

Standard-grade PSAs are usually made from styrene-butadiene rubber (SBR), natural rubber, or blends thereof in solution. In addition to rubbers, polyacrylates, polymethylacrylates, polyfvinyl ethers), polychloroprene, and polyisobutenes are often components of the system ([198], pp. 25-39). These are often modified with phenolic resins, or resins based on rosin esters, coumarones, or hydrocarbons. Phenolic resins improve temperature resistance, solvent resistance, and cohesive strength of PSA ([196], pp. 276-278). Antioxidants and tackifiers are also essential components. Sometimes the tackifier will be a lower molecular weight component of the high polymer system. The phenolic resins may be standard resoles, alkyl phenolics, or terpene-phenolic systems ([198], pp. 25-39 and 80-81). Pressure-sensitive dispersions are normally comprised of special acrylic ester copolymers with resin modifiers. The high polymer base used determines adhesive and cohesive properties of the PSA. 

Rubbers, including styrene butadiene rubber (SBR) and polybutadiene rubber (PBR) ... 

Plastics, such as PE, PP, polystyrene (PS), polyester, and nylon, etc., and elastomers such as natural rubber, EPDM, butyl rubber, NR, and styrene butadiene rubber (SBR), etc., are usually used as blend components in making thermoplastic elastomers. Such blends have certain advantages over the other type of TPEs. The desired properties are achieved by suitable elasto-mers/plastic selection and their proportion in the blend. 

Butadiene is by far the most important monomer for synthetic rubber production. It can be polymerized to polybutadiene or copolymerized with styrene to styrene-butadiene rubber (SBR). Butadiene is an important intermediate for the synthesis of many chemicals such as hexa-methylenediamine and adipic acid. Both are monomers for producing nylon. Chloroprene is another butadiene derivative for the synthesis of neoprene rubber. 

Styrene-butadiene rubber (SBR) is the most widely used synthetic rubber. It can be produced by the copolymerization of butadiene (= 75%) and styrene (=25%) using free radical initiators. A random copolymer is obtained. The micro structure of the polymer is 60-68% trans, 14-19% cis, and 17-21% 1,2-. Wet methods are normally used to characterize polybutadiene polymers and copolymers. Solid state NMR provides a more convenient way to determine the polymer micro structure. ... 

High-impact polystyrene (polystyrene modified with styrene-butadiene rubber (SBR) or polybutadiene rubber). 

In a block copolymer, a long segment made from one monomer is followed by a segment formed from the other monomer. One example is the block copolymer formed from styrene and butadiene. Pure polystyrene is a transparent, brittle material that is easily broken polybutadiene is a synthetic rubber that is very resilient, but soft and opaque. A block copolymer of the two monomers produces high-impact polystyrene, a material that is a durable, strong, yet transparent plastic. A different formulation of the two polymers produces styrene-butadiene rubber (SBR), which is used mainly for automobile tires and running shoes, but also in chewing gum. 

FIGURE 2.9 X-ray diffractogram (XRD) spectra of unmodified and modified nanoclays and styrene-butadiene rubber (SBR)-based nanocomposites with styrene content of (a) 15% and 40% and (b) 23%. (From Sadhu, S. and Bhowmick, A.K., J. Polym. Set, Part B Polym. Phys., 42, 1573, 2(304. Courtesy of Wiley InterScience.)... 

FIGURE 2.10 Variation in mechanical properties with styrene content in styrene-butadiene rubber (SBR)-based nanocomposites. 

In one of the first reports on fiber reinforcement of rubber, natural rubber (NR) was used by Collier [9] as the rubber matrix, which was reinforced using short cotton fibers. Some of the most commonly used rubber matrices for fiber reinforcement are NR, ethylene-propylene-diene monomer (EPDM) rubber, styrene-butadiene rubber (SBR), polychloroprene rubber, and nitrile rubber [10-13]. These rubbers were reinforced using short and long fibers including jute, silk, and rayon [14—16]. 

The accelerated sulfur vulcanization of general-purpose diene rubbers (e.g., NR, styrene-butadiene rubber [SBR], and butadiene rubber [BR]) by sulfur in the presence of organic accelerators and other rubbers, which are vulcanized by closely related technology (e.g., ethylene-propylene-diene monomer [EPDM] mbber, butyl rubber [HR], halobutyl mbber [XIIR], nitrile rubber [NBR]) comprises more than 90% of all vulcanizations. 

Comparison of Secondary Accelerators in Styrene-Butadiene Rubber (SBR)... 

FIGURE 16.13 Fourth pass viscosity of a multistage mixing experiment of butadiene rubber-natural rubber (BR-NR) and styrene-butadiene rubber (SBR)-NR blends (60/40) with 50 pbr of N-234 carbon black. 

FIGURE 18.2 Tensile strength of styrene-butadiene rubber (SBR) as a function of network chain density. (From Bueche, F. and Dudek, T.J., Rubber Chem. Tech., 36, 1, 1963.)... 

FIGURE 18.20 Relation between input energy and hysteresis energy at break for HAF carbon-filled and unfilled styrene-butadiene rubber (SBR). (From Payne, A.R., J. Polymer, Sci., 48, 169, 1974.)... 

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