Thermal degradation/oxidation groups

Most of these furan polycondensates are more sensitive to thermal and oxidative degradation than their benzene counterparts. Particularly affected are the polyesters obtained from 2,5 -fci sfhydroxymethyl) furan indicating that one of the vulnerable groups must be the -Fu—CH2—0-, and not the -Fu—CO—O-, since polycondensates obtained from 2,5-dicarboxylic acid are more stable, as expected from the... 

The temperature resistance of the polysiloxane on the samples was tested by stepwise heating up to 500°C. Whereas the pure hydrolysis product undergoes a complete thermal degradation via oxidative conversion of the CH3-Si groups into HO-Si groups, the polysiloxane persists on the silica sample. This stabilization effect most likely results from the covalent attachment of the methyl-polysiloxane. 

Any chemical reaction, whether involving the main chain or side groups, results in a change of composition of one or more groups and consequently in the IR spectrum. This makes it possible to study oxidation, thermal degradation, cyclization, grafting, and other reactions of polymers [2,4]. Evaluation of both qualitative and quantitative changes, as well as determination of kinetic constants of the reaction, is possible [2]. 

It appears that the nadimide end-cap is the main contribution to the thermal degradation of crosslinked PMR. This is confirmed by a comparison between two similar fluorinated PMRs with two different end-capping groups nadimide or styrene. The styrene end-capped system exhibits the best thermo-oxidative stability. 

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