Regulation of rubber

This article presents views expressed during a presentation made at the recent Third Annual International Latex Conference, held in Ohio, on the subject of stringent natural rubber latex regulations in the US A. There is a fear that over-zealous regulation of latex products is threatening the entire US latex industry. 

Although European Directives have been issued on legislative requirements for food contact plastics, European harmonisation of regulations for rubber or thermoplastic elastomers used in contact with food is yet... 

Current environmental regulations necessitate that new concepts be used in the design of industrial cooling water systems. Equipment selection and component layout related to these regulations are discussed. Special emphasis is given to the power requirements needed for the system. The subject matter for this paper was developed from observations of rubber industry manufacturing operations. 

The nucleophilic curing system is most common and is used in about 80% of all applications. It is based on the cross-linker (bisphenol AF) and accelerator (phase transfer catalyst, such as phosphonium or amino-phosphonium salt). Both diaminic and bisphenol type cure systems are permitted by U.S. Food and Drug Administration (FDA) regulations governing rubber articles in contact with food. The diaminic curing system is also used in some coating and extrusion applications [42]. 

The objective of this chapter is to provide a comprehensive overview of the use of rubber as a food contact material, from an initial description of the types of rubber and rubber products that are used in the industry, through the formulation of products, and the contact regulations and migration testing regimes, to the research that is on-going to improve its safety and the trends for the future. 

UK legislation on food contact materials is published as a number of Statutory Instruments which were published in 1978 and came into operation in November 1979. The use of rubbers in contact with food is covered by the legislation included in Statutory Instrument 1987 No. 1523 Materials and Articles in Contact with Foodstuffs. This states that any food contact material should not be injurious to the health of the consumer and that any contamination should not have an adverse effect on the organoleptic properties of the food. The absence of any positive lists for compounding ingredients means that UK rubber compounders normally refer to either the FDA or the BfR regulations depending on the market to be addressed. 

FDA approved 1998 for use as an accelerator in the manufacture of rubber material (up to 1.5% of weight of rubber) intended for use in all stages of production, processing, packaging and transport of food 21CFR 177.2600. Regulated for use under 21CFR175.105 for components of adhesives. 

Use Polymerization regulator for rubber and polyester resins, synthesis of dyes and pharmaceuticals, fungicide, algicide. 

Another way of reducing the temperature of vulcanization of rubber binder is regulation of the micro structure and viscosity of the dienic oligomer. We know that liquid dienic rubbers are the macromolecules of oligomers withl,4-cis-, 1,4-trans-, and 1,2-vinyl- links with viscosities from 0.4 up to 10 Pac. It was found experimentally that production of cold-cured RubCon is possible if the content of 1,4-cis- links in a macromolecule of rubber is more than 65%, and the viscosity of the polymer is more than 17 Pa c. Increasing the viscosity of rubber up to 7 Pa c leads to lowering of the structurization temperature from 125°C to 60°C. 

The physical properties of mbber can be controlled by regulating the amount of sulfur used in the vulcanization process. Rubber made with 1-3% sulfur is soft and stretchy and is used to make mbber bands. Rubber made with 3-10% sulfur is more rigid and is used in the manufacture of tires. Goodyear s name can be found on many tires sold today. The story of rubber is an example of a scientist taking a natural material and finding ways to improve its useful properties. 

About 15 mL of nitrosyl chloride (bp —5.5°) is then distilled at room temperature through a length of rubber pressure tubing (only slowly attacked by nitrosyl chloride) into the ampule, where it condenses as a yellow-orange solid on the platinum. A suitable mark is made on the ampule to show when the approximate volume of nitrosyl chloride has been added. The nitrosyl chloride can be obtained from a cylinder [Matheson] or may be prepared by the reaction of dry hydrogen chloride with nitrosylsulfiiric acid or sodium nitrite.A corrosion-resistant nickel pressure regulator should be used to control the flow rate. Contrary to the woik of previous investigators, no attempt is made to dry the gas, since a trace of moisture appears to catalyze the reaction. 

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