Rubber products deterioration

The deterioration of the physical properties of rubber products when exposed to service conditions also the controlled exposure of rubber samples to a variety of deteriorating influences in the evaluation of antioxidants and antiozonants. See Accelerated Ageing. 

Materials and Structures. Building materials have become soiled and blackened by smoke, and damage by chemical attack from acid gases in the air has led to the deterioration of many marble statues in western Europe. Metals are also affected by air pollution for example, S02 causes many metals to corrode at a faster rate. Ozone is known to oxidize rubber products, and one of the effects of Los Angeles smog is cracking of rubber tires. Fabrics, leather, and paper are also affected by S02 and sulfuric acid, causing them to crack, become brittle, and tear more easily. 

Up till now, the purpose of most studies has been to protect rubber products from microbial deteriorations. Waste disposal of used rubber and estimation of the degradation rate in the natural environment will become more important subjects from now onward. 

The first development of antioxidants was for natural rubber. As early as 1861 August Hofinann [ 2 ] found that deterioration of natural rubber was associated with the absorption of oxygen. In 1870 Murphy [3 ] filed a patent to use phenol and cresol as antioxidants. For the next 40 years, the materials used as antioxidants were natural products including coal tar resins, coumarone resins, paraffins, and cresol. There was little or no understanding of their mechanisms. The stability of the natural rubber products was not very much improved. 

Deterioration by Ozone - Ozone is a highly reactive gas which can cause rubber products to crack and fail prematurely imless they are protected by antiozonants or made of an ozone-resistant elastomer. Ozone is present in the atmosphere, and is produced constantly by arcing in high voltage electrical devices. 

An ingredient added to a rubber compound to protect the product against deterioration by... 

Each type of rubber has a definite range of temperatures which may be used for vulcanization. These temperatures may vary somewhat, but it is quite important not to exceed the maximum for each since some form of deterioration will occur. This effect is either shown by the appearance of the finished product or by its physical properties. 

ANTIOXIDANTS. Usually an organic compound added to various types of materials, such as rubber, natural fats and oils, food products, gasoline, and lubricating oils, for the purposes of retarding oxidation and associated deterioration, rancidity, gum formation, reduction in shelf life, etc. 

It is a detrimental reaction because it leads to the deterioration of organic compounds exposed to air (e.g., rubber cracking). Furthermore, the product, ROOH, in common with virtually all organic compounds with —0—0— bonds, has the potential of undergoing rapid decomposition on heating, which in fact may occur with explosive violence. 

The Arrhenius treatment has been applied to aging studies on rubber (13), to predict the life of a polyester-glass laminate (14), to predict product stability of a thermosetting resin alone and in combination with two additives (15), in permanence tests on paper (16), to multi-component systems in which the principal component is paper (17), and to study the influence of temperature on the relative contributions of the oxygen-independent and oxygen-dependent processes to the total rate of newsprint deterioration (18-20). 

The miscellaneous materials committees include paint, paper, packaging, rubber textiles, and plastics. The miscellaneous subjects committees include emission spectroscopy, fire standards, appearance of materials, microscopy, and resource recovery. The materials for specific applications committees include electronics, tires, consumer products, and food-service equipment. The corrosion, deterioration, and degradation of materials committees include corrosion of metals, erosion and wear, and durability of nonmetallic materials. 

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