Chlorination of rubber

USE In the manuf of pharmaceutical hydrochlorides, vinyl chloride from acetylene, alkyl chlorides from olefins, and arsenious chloride from arsenious oxide. In the chlorination of rubber, as a gaseous flux for babbitting operations. In Organic reactions involving isomerization, polymerization, and alkylation. For making chlorine where economical. 

OTHER COMMENTS used in the manufacture of pharmaceutical hydrochlorides, alkyl chlorides for olefins, and vinyl chloride from acetylene used in the chlorination of rubber and for making chlorine used in isomerization, polymerization, and alkylation reactions used in the cleaning of membranes in desalination plants. 

Chlorinations of rubber, however, are fairly complex, because several reactions occur simultaneously. These appear to be (1) additions to the double bond (2) substitutions (3) cyclizations and (4) crosslinkings. As a result, the additions of halogens to the double bonds are only a minor portion of the overall reaction scheme. In CCI4 the following steps are known to occur ... 

Hydro chlorination of rubber in solution causes a different kind of double bond shirt [121] ... 

This chapter is divided into four sections. The first section provides an overview of the bonding in the shoe industry. Conventional surface preparation of different sole and upper materials is described in Sect. 51.2, with special attention to the chlorination of rubber soles... 

Butyl rubber and other isobutylene polymers of technological importance iaclude various homopolymers and isobutylene copolymers containing unsaturation achieved by copolymerization with isoprene. Bromination or chlorination of the unsaturated site is practiced commercially, and other modifications are beiag iavestigated. 

There have been some attempts to develop chlorinated polyethylene elastomers. The rubbers possess such attractive properties as very good oil, heat, flame, ozone, and weathering resistance and are also available in a convenient powder form. In spite of being marketed at competitive prices, the chlorinated polyethylene rubbers (designated as CM rubbers by ASTM) took... 

Fig. 6. Transmission IR spectra of chlorinated natural rubber, solvent cast from xylene, (a) Before heating, and (b) after heating at 170°C for 30 min [62].

Chlorobutyl rubber is prepared by chlorination of butyl rubber (chlorine content is about 1 wt%). This is a substitution reaction produced at the allylic position, so little carbon-carbon double unsaturation is lost. Therefore, chlorobutyl rubber has enhanced reactivity of the carbon-carbon double bonds and supplies additional reactive sites for cross-linking. Furthermore, enhanced adhesion is obtained to polar substrates and it can be blended with other, more unsaturated elastomers. 

Chemistry of polychloroprene rubber. Polychloroprene elastomers are produced by free-radical emulsion polymerization of the 2-chloro-1,3-butadiene monomer. The monomer is prepared by either addition of hydrogen chloride to monovinyl acetylene or by the vapour phase chlorination of butadiene at 290-300°C. This latter process was developed in 1960 and produces a mixture of 3,4-dichlorobut-l-ene and 1,4-dichlorobut-2-ene, which has to be dehydrochlorinated with alkali to produce chloroprene. 

Cohesive strength of these adhesives can be modified by blending butyl rubber and polyisobutylene. Higher strength is obtained by using high molecular weight PIB or butyl rubber. On the other hand, blends of butyl rubber or PIB with chlorinated butyl rubber show improved cure properties. 

One of the products of the reaction of sulfur with chlorine is disulfur dichloride, S2C12, a yellow liquid with a nauseating smell it is used for the vulcanization of rubber. When disulfur dichloride reacts with more chlorine in the presence of iron(III) chloride as a catalyst, the foul-smelling red liquid sulfur dichloride, SC12, is produced. Sulfur dichloride reacts with ethene to give mustard gas (16), which has been used in chemical warfare. Mustard gas causes blisters, discharges from the nose, and vomiting it also destroys the cornea of the eye. All in all, it is easy to see why ancient civilizations associated sulfur with the underworld. 

Femandez-Garcfa J.C., Orgiles-Barcelo, and A.C., Martm-Martmez J.M., 1991, Halogenation of styrene-butadiene rubber to improve its adhesion to polyurethanes, J. Adhes. Sci Technol, 5, 1065-1080. Oldfield D. and Symes T.E.F., 1983, Surface modification of elastomers for bonding, J. Adhes., 16, 77-96. Pastor-Bias M.M., Ferrandiz-Gomez T.P., and Martm-Martmez J.M., 2000, Chlorination of vulcanized styrene-butadiene rubber using solutions of trichloroisocyanuric acid in different solvents, J. Adhes. Sci. Technol, 14, 561-581. 

Amit Kumar Naskar A.K., De S.K., and Bhowmick A.K., 2001, Surface chlorination of ground rubber tire and its characterization. Rubber Chem. Technol, 74, 645-661. 

Pastor-Bias M.M., Martfn-Martfnez J.M., and Boerio F.J., 2002, Mechanisms of adhesion in surface chlorinated thermoplastic rubber/thermoplastic pol3uirethane adhesive joints. Rubber Chem. Technol., 75(5), 825-837. 

Chlorination of butyl rubber in naphtha with chlorine-nitrogen mixtures may lead to explosion if N contents below 77% or Cl contents above 16% are used. 

Chlorination of natural rubber, involving both addition and substitution (with some cyclization), yields a product with improved chemical and corrosion resistance. Chlorination of polyethylene in the presence of sulfur dioxide results in substituting both chloride and sulfonyl chloride groups into the polymer. A commercially useful material is one which contains about 12 chlorides and one sulfonyl chloride per 40-45 repeating units. This extensive substitution converts the polyethylene, a plastic, into an elastomer by destroying crystallinity. 

A white fibrous product obtained when chlorine is passed into a solution of rubber. It was used mainly in corrosion-resistant paints and varnishes but has been superseded by tailored synthetic polymers systems. 

Chlorinated butyl rubber. Chlorination or bromination of butyl rubber overcomes the difficulty of vulcanising butyl rubber in mixtures with more highly unsaturated substances due to the preferential absorption of the sulphur by the more highly unsaturated component. Chlorohydrin Rubbers... 

As with chlorinated polyethylene rubber, chlorosulphonated polyethylene exhibits good resistance to oxygen, ozone and light. The polar nature of the polymer chain also confers oil resistance. 

The S2C12 obtained has many uses, including the vulcanization of rubber. The reaction of methane with chlorine also produces CC14. 

The most important binary compounds of sulfur and chlorine are S2C12 and SC12. Both of these compounds are used in large quantities in many ways, but one of the important uses for S2C12 is in the vulcanization of rubber. This compound is prepared by chlorinating sulfur. 

Chlorinated additive flame retardants, 11 468-470, 471-473t Chlorinated aromatics, 6 242 decomposition using microwaves, 16 555 Chlorinated butyl rubber, 4 436 development of, 4 434 manufacture, 4 400, 442-444 Chlorinated ethanes... 

The chlorination of low molecular weight natural rubber from Guayule (Parthenium Argentatum Grey) has been accomplished. The structure of the chlorinated product is consistent with that of chlorinated Hevea rubber. The use of Azo-bis-isobutyronitrile was as a catalyst resulted in increased chlorine content with a concomitant reduction in molecular weight, thereby allowing the preparation of lower viscosity grades of chlorinated rubber. 

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