Cross natural rubber latex

The prevulcanization of natural rubber in latex form has also been a subject of much investigation. The cross-linking mechanism is not yet fully understood, but the water apparently plays a major role in it. Irradiation results in the cross-linking of the rubber molecules and in coarsening of the latex particles. A process of cross-linking of natural rubber latex has been developed to the point that it can be used for an industrial-scale application. The irradiation is performed in aqueous media by electron beam without a prorad (sensitizer) at a dose of 200 kGy (20 Mrad) or in the presence of n-butyl acrylate at considerably lower doses, typically 15 kGy. The cross-linked film exhibits physical properties comparable to those obtained from sulfur cured (vulcanized) film. As an alternative, the addition of a variety of chloroal-kanes makes it possible to achieve a maximum tensile strength with radiation doses of less than 5 Mrad (50 kGy). ... 

A process of cross-linking of natural rubber latex has been developed to where it should be soon ready for an industrial-scale process.149 The irradiation is performed in aqueous media by electron beam without a prorad ( sensitizer ) at a dose of 200 kGy (20 Mrad) or, in the presence of n-butyl acrylate at considerably lower doses, typically 15 kGy. The cross-linked film exhibits physical properties comparable to those obtained from sulfur-cured (vulcanized) film. 

Cross-Hnked elastomers natural rubber, natural rubber latex (NR)... 

The practice of cross-linking the polyisoprene chains in natural rubber to form a usable elastomer was discovered by Goodyear, in 1839. He heated natural rubber latex with sulphur, a process called vulcanisation. This transforms the sticky runny natural latex into a product in which the elastic... 

The radiation cross-linking of natural rubber latex has been studied by a number of workers, and again it was found that the addition of carbon black appreciably reduces the dose required for cross-linking. A feature of the vulcanizates obtained using carbon black was that the electrical conductivity was 10,000 times lower than that of smoked sheet rubber... 

Ahlroth M, Alenius H, Turjanmaa K, Makinen-Kiljunen S, Reunala T, Palosuo T (1995) Cross-reacting allergens in natural rubber latex and avocado. J Allergy Clin Immunol 96 167-173... 

Siler, D. X, Cornish, K., Hamilton, R. G. Absence of cross-reactivity of IgE antibodies from subjects allergic to Hevea brasiliensis with new sources of natural rubber latex from guayule (Parthenium argentatum). J. Allergy Clin. Immunol. 1996, 98, 895-902. 

Elastomeric fibers can be made out of natural rubber. Rubber latex, which is a suspension of rubber spheres in water, is mixed with a vulcanizing agent, and the mixture is wet spun. The fibers from the spinneret are extruded into a coagulating bath and then vulcanized to produce the cross-linking of chains. Such fibers are used in woven and knitted fabrics, and more often than not they are mixed with other textile fibers to form fabrics for garments. Most natural rubber fibers, however, have been supplanted by synthetic elastomeric fibers, especially in the area of athletic wear. This is attributable to the poor dyeability, abrasion resis-... 

Although foamed rubber and foamed urethanes have many similar properties, the processes by which they are made differ radically. In a simple process a solution of soap is added to natural rubber (NR) latex so that a froth will result on beating. Antioxidants, cross-linking agents, and a foam stabilizer are added as aqueous dispersions. 

Silicone, natural, and synthetic rubbers have been used for the fabrication of implants. Natural rubber is made mostly from the latex of the Hevea brasiliensis tree and the chemical formula is the same as that of cw-1,4 polyisoprene. Natural rubber was found to be compatible with blood in its pure form. Also, cross-linking by x-ray and organic peroxides produces rubber with superior blood compatibility compared with rubbers made by the conventional sulfur vulcanization. 

Elastomers elastic = flexible meros = part) earniot be fused or dissolved, but ean be made to swell. They cross-link in a wide mesh pattern and therefore exist in a soft, elastic condition at room temperature. Examples of molded parts made from elastomers include seals, bellows, and tires. Natural rubber (NR) represents a special case within the group of elastomers. It is obtained fi om the sap (latex) of tropical trees. 

Water-based dispersions or emulsions such as polyvinyl acetate, acrylics, polyvinyl chloride and polyvinyl alcohol with plasticizers and tackifiers. In addition, this range can include urea formaldehyde and phenolic adhesives, resins, natural adhesives produced from starch, dextrin, casein, animal glues (see Polyvinyl alcohol in adhesives, Phenolic adhesives single-stage resoles. Phenolic adhesives two-stage novolacs. Animal glues and technical gelatins) and rubber latex (see Emulsion and dispersion adhesives). Solvent-free 100% solids such as polyurethane. Hot melt adhesives include Ethylene-vinyl acetate copolymers, polyolefins, polyamides, polyesters with tackifiers and waxes. More recent additions include cross-linkable systems. 

The commercial base for natural rubber (NR) is latex, a milklike serum produced by the tropical tree Hevea brasiliensis. Naturally occurring latex is the rubber that exudes from these trees in an aqueous serum containing various inorganic and organic substances. The rubber precipitated out of this solution can be characterized as a coherent TS elastic solid. It is against NR that all the other rubbers and elastomers are measured. For centuries it was the only rubber available it was extensively used even prior to the discovery of vulcanization (TS cross-link curing), in 1883. To date no synthetic material has yet equaled the overall depth of engineering characteristics and consequent wide latitude of applications available in NR. 

These allergy risk ingredients could include proteins in natural rubber (e.g., latex gloves) or the vulcanization accelerators used to cure or cross-link the polymer materials used in CPCs or other manufacturing process additives. The accelerators/cross-linkers are not limited to natural rubber. 

A condition of flow in which all elements of a fluid passing a certain point follow the same path, or streamline there is no turbulence. Also referred to as streamline flow . A dispersion (suspension or emulsion) of polymer in water. Latex rubber, a heavily cross-linked polymer solid, is produced either by coagulating natural latex or by synthetic means through emulsion polymerization. Example Latex paint is a latex containing pigments and filling additives. 

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