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Natural rubber chemical treatments

Carbon blacks are the most widely used fillers for elastomers, especially vulcanised natural rubber. They cause an improvement in stiffness, they increase the tensile strength, and they can also enhance the wear resistance. Other particulate fillers of an inorganic nature, such as metal oxides, carbonates, and silicates, generally do not prove to be nearly so effective as carbon black. This filler, which comes in various grades, is prepared by heat treatment of some sort of organic material, and comes in very small particle sizes, i.e. from 15 to 100 nm. These particles retain some chemical reactivity, and function in part by chemical reaction with the rubber molecules. They thus contribute to the crosslinking of the final material. [Pg.114]

An isomeric derivative of natural rubber produced by a variety of chemical treatments. The products are resinous and find application as reinforcing agents in natural rubber compounds (particularly in shoe soles) and as rubber-to-metal adhesives. [Pg.21]

Vulcanization The treatment of natural rubber with sulfur to reduce its tackiness and improve its strength and elasticity. Invented independently by C. Goodyear and N. Hayward in the United States in 1839, and by T. Hancock in London in 1842-1843. Various chemicals other than elemental sulfur are effective, for example, sulfur monochloride, selenium, and p-quinone dioxime. [Pg.286]

Water and Effluent Treatment in Nuclear and other chemical plants. Corrosion resistant linings for water treatment vessels and pipelines, pumps, valves, flowmeters, agitators, chemical dosing tanks, effluent tanks etc. Soft natural rubber or ebonite, EPDM, butyl, neoprene or hypalon. [Pg.55]

The molten asphalts used for waterproofing are a mixture of mineral fillers and bitumens. Because of its limited characteristics, bitumen was the subject of many studies aimed at improving its physical and mechanical properties. Several approaches were tried, such as chemical treatment and blending with natural or synthetic rubbers or latices. [Pg.761]

Solvent washing and abrading are common treatments for most elastomers, but chemical treatment is required for maximum properties. Many synthetic and natural rubbers require cyclizing with concentrated sulfuric acid until hairline fractures are evident on the surface. [Pg.472]

The mechanical properties of short isora fibre reinforced natural rubber composites are enhanced by chemical treatment on the fibre surface and by the use of bonding agent. Longitudinally oriented fibre composites have superior properties than transversely oriented ones. [Pg.323]

Costa HMD, Visconte LLY, Nunes RCR, Furtado CRG (2000) The effect of couplung agent and chemical treatment on rice husk ash-filled natural rubber composites. J Appl Polym Sci 76 1019-1027... [Pg.375]

Rubber, in its soft natural state is a polymer of isoprene it is only of limited use and for most purposes it must be vulcanized. This process involves the chemical reaction between natural rubber and varying amounts of sulphur under heat treatment. Soft rubbers may contain up to 5 per cent sulphur, whilst at the other end of the range, ebonites, which are hard and quite brittle, may contain up to 40 per cent sulphur. [Pg.10]

The copolymerization of a,p-unsaturated ketones has been studied extensively in order to improve the poor chemical and thermal stability exhibited by the homopolymers. The vinyl ketones have been copolymerized with most of the common vinyl and diene monomers. The data are given in Ref. [326]. For initiation, the same reagents could be used as for free-radical homopolymerization. Copolymerization was carried out in bulk [371] and in emulsion systems [372]. In copolymerization with methyl methacrylate, vinyl acetate [373], and styrene [371] it was concluded that the relative reactivities of the vinyl ketones increase with the increasing electron-withdrawing nature of the vinyl ketone substituent. Polar and steric effects are not observed. Most of the work has been directed toward the preparation of oil- and solvent-resistant rubbers to replaee styrene-butadiene rubber. Emulsion eopolymerization of butadiene with methyl isopropenyl ketone yielded rubbers with good solvent resistance and low temperature flexibility, but the products tended to harden on storage and were not compatible with natural rubber [374]. The reactive earbonyl function caused sensitivity to alkine reagents. Copolymers of butylacrylate and methyl vinyl ketone, for example, can be erosslinked by treatment with hydrazine [375]. [Pg.646]

Since it seems unlikely that synthetic c/5-polyisoprene will become economically attractive in the next 5 to 10 years, and excellent markets persist for natural rubber, there is every reason to expect that the natural rubber industry will remain viable into the next century. The substantial potential for increasing yields and lowering costs through chemical treatment and genetic studies should encourage continued research in this field. According to a recent estimate (10), Hevea produces 95 tons of dry matter per acre each year. Even under the best of conditions only about 5% of this is biochemically converted into rubber by the tree, but the... [Pg.1171]

Thermo-mechano-chemical changes of natural rubber SVR 3L under treatment internal mixer at self heating have been studied. Effeet of molecular mass and content of gel-fraction of natural rubber is shown. Properties of rubber compounds and vulcanized rubber are presented. [Pg.168]


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See also in sourсe #XX -- [ Pg.10 ]




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