Degradation of unsaturated polymers

Degradation of Unsaturated Polymers by Metathesis 16.3.5 Polybutadienes modified by partial addition reactions... 

The action of certain metals (e.g., copper) on unsaturated rubbers, primarily natural rubber, is to catalyse the oxidative degradation of the polymer. The metal must be in an ionic form, i.e., straightforward contact with the metal such as a seal with a copper pipe will not promote such degradation. 

The metathesis reactions of cycloalkenes are discussed in detail in Ch. 11-14 and their cross-metathesis reactions with acyclic olefins in Ch. 15. Degradation reactions of unsaturated polymers by olefin metathesis are covered in Ch. 16. Industrial applications are described in Ch. 17. 

From Table 3.3 it is apparent that the same pattern of products occurs with degradation of the polymer of isopropyl as with that of the primary w-propyl ester, the saturated and unsaturated dimers being observed together with a higher molecular weight product indicated to be a mixture of saturated and unsaturated trimers. 

It is known that OC promote a faster sulfur-based cure of unsaturated polymer chains. The activation energy of the crosslinking reaction is decreased and the crosslinking density in enhanced. To explain these effects by OC, the formation of tertiary amines from the thermal degradation of ammonium cations and the enhanced mobility of sulfur-accelerating anionic species were proposed. ... 

Aliphatic polyamides do not absorb light above 290 nm and photo-oxidative degradation of these polymers in that region can be initiated by the presence of such impurities as hydroperoxides, [47, 139] carbonyl groups [1869], a,j -unsaturated carbonyl groups [47, 65, 89, 99, 103] and traces of metal ions [236]. 

Anderson and Ereeman [11] studied the thermal properties of a styrenated polyester synthesised by condensation involving a glycol and two dicarboxylic acids, one of which was unsaturated. A crosslinking reaction of the styrene (used as a solvent and copolymer) was effected by the use of free-radical initiators. TGA, dynamic thermal analysis, IR and mass spectrometric techniques were used to study the thermal degradation of this polymer in air and in argon. Based upon IR analysis, the unit basic structure of the polyester was taken to be as in Equation 3.18 ... 

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