Styrene-butadiene rubber structure

Polymers of chloroprene (structure [XII]) are called neoprene and copolymers of butadiene and styrene are called SBR, an acronym for styrene-butadiene rubber. Both are used for many of the same applications as natural rubber. Chloroprene displays the same assortment of possible isomers as isoprene the extra combinations afforded by copolymer composition and structure in SBR offsets the fact that structures [XIIll and [XIV] are identical for butadiene. 

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. ... 

BUTADIENE. [CAS 106-90-0]. CHrCH C CH3, 1,3-butadiene (methyl-allene), formula weight 54.09. bp —4.41cC, sp gr 0.6272, insoluble in H2 O. soluble in alcohol and edier in all proportions, Butadiene is a very reactive compound, arising from its conjugated double-bond structure. Most butadiene production goes into die manufacture of polymers, notably SBR (styrene-butadiene rubber) and ABS (acryloiiitrile-buladiene-slyrene) plastics. Several organic syntheses, such as Diels-Alder reaction, commence with the double-bond system provided by this compound. 

Styrene-Butadiene Rubbers. These synthetic rubbers, normally known as SBRs, are mainly used in the manufacture of tires. Their chemical structure corresponds to a random copolymer of styrene and butadiene units in a weight ratio of 23 77 and in a ratio of 1 6 in terms of structural units. 

Styrene-butadiene rubber could be produced by using emulsion and solution process, thus it can be divided into emulsion-polymerized styrene-butadiene rubber (E-SBR) and solution-polymerized styrene-butadiene rubber (S-SBR). In this entry, we will describe their development and introduce their synthesis process, relationship between structure and property, processing property, blends, and applications. 

The uses of mercaptans in polymers fall into three major categories chain transfer agents, additives such as stabilizers against heat or UV light, and monomers that incorporate an alkylmercapto group into their structure. Mercaptans r-dodecyl, n-dododecyl, etc. are excellent chain transfer agents used to control molecular weight of several different kinds of polymers, styrene butadiene rubber, acrylonitrile-butadiene-styrene, polyacrylates, to name a few. " " ... 

The catalytic capabilities of the Tp ML complexes for this transformation have also been applied to the functionalization of macromolecules such as polyolefins. Thus polybutadienes (Scheme 6a) or styrene-butadiene rubbers (Scheme 6b) have been modified upon addition of carbene units from EDA that were incorporated into the unsaturated C=C bonds of the polymeric chain, providing interesting features to the isolated materials the incorporation of polar groups provided distinct properties regarding their potential use as adhesives, but maintaining the structure of the parent polymer. 

In a complementary paper by Class and Chu, model resins - polystyrene and poly(vinylcyclohexane) - in combination with natural and styrene-butadiene rubbers, were used to study effects of resin structure, molecular weight and concentration on viscoelastic properties of pressure-sensitive adhesives resulting from these combinations. 

These studies demonstrate that in selecting resins to tackify either natural rubber or styrene-butadiene rubber, consideration must be given to the resin structure. An aliphatic resin is more likely to be compatible with natural rubber, while an aromatic resin would be compatible with styrene-butadiene rubber. 

The structure of the low molecular weight resin is very important to its compatibility with elastomers and, consequently, to its effect on viscoelastic properties and performance as a pressure sensitive adhesive. A completely aromatic resin such as polystyrene has poor compatibility with natural rubber, but is compatible with styrene-butadiene rubber. A cycloaliphatic resin such as poly(vinyl cyclohexane) is compatible with natural rubber and is incompatible with styrene-butadiene rubber. An alkyl aromatic resin such as poly-(tert-butyl styrene) is compatible with both elastomers. 

Resins of appropr iate structure are compatible but only to some limiting concentration. At 75% resin, two phases are observed in blends of natural rubber with poly(vinyl cyclohexane) resin (M 650) and styrene-butadiene rubber... 

As the PSA industry evolved, natural rubber (NR) and styrene-butadiene rubber (SBR) were the primary elastomers used. Other backbone polymers were available but were used to a lesser degree. These other elastomers include polychloroprene, butyl rubber and nitrile rubber. Traditionally, formulations containing natural rubber have made use of polyterpene resins as tackifiers, particularly beta-pinene resins. The probable structure of a beta-pinene resin is given as follows and represents the terpene class of resins. 

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