Butadiene-co-styrene

Maleimides Alkyl and aryl maleimides in small concentrations, e.g., 5-10 wt% significantly enhance yield of cross-link for y-irradiated (in vacuo) NR, cw-l,4-polyisoprene, poly(styrene-co-butadiene) rubber, and polychloroprene rubber. A-phenyhnaleimide and m-phenylene dimaleimide have been found to be most effective. The solubihty of the maleimides in the polymer matrix, reactivity of the double bond and the influence of substituent groups also affect the cross-fink promoting ability of these promoters [82]. The mechanism for the cross-link promotion of maleimides is considered to be the copolymerization of the rubber via its unsaturations with the maleimide molecules initiated by radicals and, in particular, by allyfic radicals produced during the radiolysis of the elastomer. Maleimides have also been found to increase the rate of cross-linking in saturated polymers like PE and poly vinylacetate [33]. 

Styrene co-butadiene is a rubbery amorphous polymer with a glass transition temperature well below room temperature. Polystyrene co-butadiene is an important component of several commercial families of plastic that contain polystyrene blocks. 

We commonly copolymerize styrene to produce random and block copolymers. The most common random copolymers are styrene-co-acrylonitrile and styrene-co-butadiene, which is a synthetic rubber. Block copolymerization yields tough or rubbery products. 

Poly(vinyl acetate) and copolymers Poly(vinyl chloride) organosols Poly(styrene-co-butadiene)... 

Research Focus Preparation of amine-containing polymerization initiators for synthesis of high interaction poly(styrene-co-butadiene). 

Figure 13.6 Film cast from a 1 2 mixture of poly(styrene-co-butadiene) and poly(2-vinyl pyridine-co-butadiene) with about 15 mol% butadiene content (10 wt% solution of the copolymers in tetrahydrofuran). Dark areas, poly(styrene-co-butadiene) light areas, poly (2-vinyl pyridine-co-butadiene) [15]. Courtesy of Dr A. Schindler...

Direct experimental observation of the rupture of agglomerates in uncured styrene-co-butadiene rubber (SBR) in simple shear flow was obtained by Collin and Peuvrel-Disdier (48), supporting the previously discussed mechanism. It is shown on Fig. 7.27. The shear rate was 6 s 1, yielding a shear stress of 130,000 Pa s. The agglomerate is broken into two large, about equal-sized pieces with some debris, and separated. 

A catalyst combination consisting of the barium salt of tri(ethyleneglycol)ethyl ether, Ba(0CH2CH20CH2CH20CH2CH3)2, with tri-n-octyl aluminum and n-butyl lithium has been used to prepare random poly(styrene-co-butadiene) containing a high butadiene transcontent. These polymers were designed to be co-cured with natural rubber and used as components in automotive tires. 

Sulfur-vulcanizable elastomers have been prepared that are designed to reduce hysteresis in tires by reducing the number of polymer free ends. The method for this preparation entails anionically preparing poly(styrene-co-butadiene) using a lithium thioacetal initiator followed by incorporation of a vulcanization agent into the elastomer terminus. 

Preparation of Poly(Styrene-co-Butadiene) with 2-Lithio-2-Methyl-1,3-Dithiane... 

TABLE 1. Effect of lithium thioacetal anionic initiators on poly(styrene-co-butadiene) properties. 

Tires having reduced hysteresis were prepared by Kerns [3] by vulcanizing high vinyl content poly(styrene-co-butadiene) using butadienyllithium or styryl-lithium as the catalyst. 

Tire tread rubber formulations were prepared by Parker [4] and consisted of poly(styrene-co-butadiene) rubber terminated with iV-isopropylphenylnitrone, (III), to promote interaction between the polymer end-groups and carbon black and silica fillers to reduce hysteresis. 

Composite particles which have been made using the monomer-starved process (8) include the poly(styrene-co-butadiene)-poly(ethyl acrylate-co-methacrylic acid) system. 

Deslandes, Y., Morphology of hydroxyapatite as suspension stabilizer in the polymerization of poly(styrene-co-butadiene), J. Appl. Polym. Sci. 34 (1987) 2249. 

Emulsion polymerization first gained industrial importance during World War II when a crash research program in the United States resulted in the production of styrene-co-butadiene [SBR] synthetic rubber. The Harkins-Smith-Ewart model [5-6] summarized the results of early research, which focussed on this and similar systems. Current thinking is not entirely in accord with this mechanism. It is still worthwhile to review it very brielly here, however, because it is still widely referenced in the technical literature and because some aspects of the model provide valuable insights into operating procedures. 

SBR poly(styrene-co-butadiene) PVA poly(vlnyl alcohol)... 

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