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Ozone and its reactions with diene rubbers

Rakovsky S.K., Anachkov M.P., Kubica S., Zaikov G.E.

Elastomery

2012

T. 16, nr 1

11-23

The reactions ofozone with l,4-cis-pofybutadiene (SKD); Diene 35NFA [having thefollowing linking of the butadiene units in the rubber macromolecules: 1,4-cis (47%), 1,4-trans (42%), 1,2- (11%)]; 1,4-cis-polyisoprene (Carom IR 2200), 1,4-trans-polychloroprene (Denka M 40), and l ,4-trans-polyiso-prene have been investigated in CC14 solutions. The changes ofthe viscosity of the polymer solutions dur-ing the ozonolysis have been characterized by the number of chain scissions per molecule of reacted ozone (cpj. The influence ofthe conditions of mass-transfer ofthe reagents in a bubble reactor on the re-spectwe cp values has been discussed. The basie functional groups-products from the rubbers ozonolysis have been identified and quantitatively characterized by means of IR-spectroscopy and 2H-NMR spec-troscopy. A reaction mechanism, that explains theformation ofall identified functional groups, has been proposed. It has been shown that the basie route ofthe reaction ofozone with elastomer double bonds -theformation ofnormal ozonides does not lead directly to a decrease in the molecular mass ofthe elastomer macromolecules, because the respectwe l,2,4-trioxolanes arę relatively stable at ambient temperaturę. The most favourable conditions for ozone degradation emerge when the cage interaction between Criegee intermediates and respectwe carbonyl groups does notproceed. The amounts ofmeasured different carbonyl groups have been used as an alternatwe wayfor evaluation ofthe intensity and efficiency ofthe ozone degradation. The thermal decomposition ofpartially ozonized diene rubbers has been investigated by DSC. The respectwe values ofthe enthalpy, the activation energy and the reaction order ofthe l,2,4-trioxolanes have been determined.

Zbadano działanie ozonu na następujące kauczuki (w postaci roztworów w CCl^: 1,4-cis-polibutadien (SKD); Diene 35 NFA [o konfiguracjach merów butadienowych w makrocząsteczkach: 1,4-cis- (47%), 1,4-trans- (42%), 1,2- (11%)]; 1,4-cis-poliizopren (Carom IR 2200), 1,4-trans-polichloropren (Denka M40) i 1,4-trans-poliizopren. Zmiany lepkości roztworów polimerowych podczas ozonolizy powiązano z liczbą rozszczepień łańcucha przypadającą na cząsteczkę oddziaływującego ozonu (