Effects on Rubber

Paints and coatings for automobiles have not been immune to damage by air polluhon. Wolff and co-workers (13) found that damage to automobile finishes was the result of scarring by calcium sulfate crystals formed when sulfuric acid in rain or dew reacted with dry deposited calcium. 

Natural rubber is composed of polymerized isoprene units. When rubber is under tension, ozone attacks the carbon-carbon double bond, breaking the bond. The broken bond leaves adjacent C = C bonds under additional stress, eventually breaking and placing shll more stress on surrounding C = C bonds. This domino effect can be discerned from the structural formulas in Fig. 9-4. The number of cracks and the depth of the cracks in rubber under tension are related to ambient concentrations of ozone. 

Rubber products may be protected against ozone attack by the use of a highly saturated rubber molecule, the use of a wax inhibitor which will bloom to the surface, and the use of paper or plastic wrappings to protect the surface. Despite these efforts, rubber products still crack more on the West Coast than on the East Coast of the United States. 

Salvin, V. S., Proceeding of Annual Conference, American Society for Quality Control, Textile and Needle Trades Division, Vol. 16, pp. 56-64 (1969). 

Newiiin, R TheDeteriorationandConservationof Painted Glass A Critical Bibliography, Oxford University Press, Oxford, 1982. 

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With rubber base adhesives, it is necessary to prevent their properties from changing during service life. Oxidative changes induced by thermal, ozone exposure and UV light can dramatically affect service life of rubber base adhesives. More precisely, the rubber and the resin are quite susceptible to oxidative degradation. Environmental and physical factors exert detrimental effects on rubber base adhesive performance. These effects can be mitigated by the incorporation of low levels of stabilizers during the fabrication process of the adhesive. 

An allotropic form of oxygen (03) (see Allotropy) of considerably greater degradative effect on rubber than oxygen itself. The ozone content of the atmosphere normally varies from 0.5 to 5.0 parts per 100 million (pphm) of air, but in certain areas (notably Los Angeles, USA) it may reach as much as 40 pphm of air. 

Heat, See also High temperature entries Hot entries Temperature entries Therm- entries effect on rubber aging, 27 785 in ethylene oxidation, 70 650 exponents of dimensions, 8 585t external resistance to, 25 312-316 in industrial hygiene, 74 221 wood reaction to, 26 348-351 Heat aging, of polychloroprene polymers, 79 844-845... 

In the oil field industry fluids such as well fluids, completion fluids and stimulation fluids [1,2,3] are used. It would be meaningful to know about these fluids and their corrosive characteristics since they have an adverse effect on rubber components such as packings, gaskets and seals exposed to such environment. The details of these fluids are given below. 

Conventional materials like different metal oxides are used in the curing systems of the rubber compounds. When used, these are freely present in the compound, soluble in the inorganic acids that are used in the oil exploration industry and lead to high swelling effects on rubber. 

Crazing - A surface effect on rubber articles characterized by many minute cracks. This is generally not a serious degradation for a tank lining, unlike cracking. 

Pearson and Lee (1991) examined the effects of particle-size and particle-distribution effects on rubber-toughened epoxy resins. They examined a variety of CTBN liquid rubbers and a methacrylated butadiene styrene core-shell particle in a DGEBA-piperidine system. They found that the toughening mechanism for small particles was internal cavitation of the... 

Even before the discovery of vulcanisation by Goodyear [1], the effects on rubber of heat, light, acids and alkalies were studied. Testing became necessary when early investigators faced problems with rubber and its vulcanisates. Possibly the earliest chemical resistance test on rubber was undertaken by Goodyear when he treated rubber with nitric acid and this yielded a hardened mass [2, 3]. He mistakenly called this phenomenon vulcanisation, before he accidentally discovered vulcanisation with sulfur at a later point. 

Resins with solubility close to that of rubber (I, 14), the terpene, and olefin polymers have a softening effect on rubber. Indene polymers... 

Excellent adhesion to a wide range of substrates very effective on rubber and on most plastics... 

Both of these curatives are added in the lower temperature, final mixing stage. HMTA must be isolated from the other rubber curatives during storage and batch preparation since its basicity can cause premature decomposition of the rubber cure accelerators and can accelerate the conversion of insoluble sulfur into the soluble form. The structure of HMTA and the reaction with resorcinol are illustrated in Scheme 4.1. Classical chemical studies indicate that as much as 75% of nitrogen remains chemically bonded to the rubber though some ammonia is released during the cure of the resin and the rubber, which can have detrimental effects on rubber composites reinforced with brass coated steel cords. 

H. Hamaguchi, Y. Samejima and N. Kani, A study of aging effect on rubber bearings after about twenty years in use, 11th World Conference on Seismic Isolation, Energy Dissipation and Active Vibration Control of Structures, Guangzhou, China, 17-21 November 2009. 

Knowledge of these units helps to understand the effects on rubber and humans of radioactive substances such as those that may leak from nuclear reactors. 

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