Rubbers double heating method

The double heating method is suggested as an improvement of the continuous method. By the continuous method, the determined value for rubber is lower and that for carbon black is higher than the real values. Using the double heating method, it becomes possible to distinguish between mass losses due to oxidation of the polymeric residue after the first stage decomposition and those due to oxidation of the carbon black. 

Although, the heat resistance of NBR is directly related to the increase in acrylonitrile content (ACN) of the elastomer, the presence of double bond in the polymer backbone makes it susceptible to heat, ozone, and light. Therefore, several strategies have been adopted to modify the nitrile rubber by physical and chemical methods in order to improve its properties and degradation behavior. The physical modification involves the mechanical blending of NBR with other polymers or chemical ingredients to achieve the desired set of properties. The chemical modifications, on the other hand, include chemical reactions, which impart structural changes in the polymer chain. 

Also called hot air cure. A method of curing, mainly used for footwear. The articles are placed in a double-walled vulcaniser, the heat for curing being obtained from steam circulating between the double walls. Steam does not therefore come in contact with the articles in the vulcaniser itself. Dry Rubber Compound... 

Unsaturated rubber polymers are especially important grafting vehicles. Consider, for example, the polymerization of styrene in the presence of l,4-poly(l,3-butadiene). A method consists of dissolving the polybutadiene rubber (about 5 to 10%) in monomeric styrene containing benzoyl peroxide initiator and applying heat. Polymer radicals, formed by (a) chain transfer between the propagating radical and polymer or (b) addition (copolymerization) of the propagating radical to the -double bonds of the polymer. 

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