Ozonides polymerization initiators

Due to the retractive forces in stretched mbber, the aldehyde and zwitterion fragments are separated at the molecular-relaxation rate. Therefore, the ozonides and peroxides form at sites remote from the initial cleavage, and underlying mbber chains are exposed to ozone. These unstable ozonides and polymeric peroxides cleave to a variety of oxygenated products, such as acids, esters, ketones, and aldehydes, and also expose new mbber chains to the effects of ozone. The net result is that when mbber chains are cleaved, they retract in the direction of the stress and expose underlying unsaturation. Continuation of this process results in the formation of the characteristic ozone cracks. It should be noted that in the case of butadiene mbbers a small amount of cross-linking occurs during ozonation. This is considered to be due to the reaction between the biradical of the carbonyl oxide and the double bonds of the butadiene mbber [47]. 

Initiators, ozonides for polymerization, 622 Inorganic peroxides, commercial availability, 620-1, 622... 

The decomposition of ozonides up to acids and aldehydes goes in main on the ionic mechanism and is accompanied by destraction. However in parallel, the small amounts of free radicals are formed and it can initiate polymerization processes. Due to this before and ozonized rubbers it is easy modify by an grafting [65,66],... 

Ozonides are reasonably stable in neutral environments, but they will decompose readily imder the influence of heat or various reducing agents to yield such chain scission products as aldehydes, ketones, acids, and alcohols. Polymeric peroxides may be formed initially from the carbonyl oxide, but these are unstable and will eventually decompose to yield chain scission products. 

Peroxide catalysts and ozonides are generally employed as initiators for cross-linking unsaturated polyesters. The formation of active radicals that can initiate the hardening copolymerization reaction may be begun also by ferrocene and some of its derivatives (acetyl ferrocene, benzyl ferrocene, etc.) [73]. Note that styrene-containing unsaturated polyesters will polymerize at room temperature without a... 

As mentioned in section 20.2.3, natural rubber (in common with other diene elastomers) is readily attacked by ozone. The mechanism of the reaction is probably the same as that established for simple olefins [10]. In this case, the initial product is a -complex which cleaves to form an aldehyde or ketone and a zwitterion. Several subsequent reactions may then occur, depending on the nature of the reactants and conditions. The zwitterion may dimerize or polymerize or react with the carbonyl compound to form an ozonide ... 

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