TGDDM Epoxide Homopolymerization

The homopolymerization reactions of impure TGDDM (MY720) in the presence and absence of a BF3 NH2C2H5 catalyst and, also, pure TGDDM were monitored by FTIR as a function of cure temperature from 177 to 300 °C. The intensities of the epoxide, hydroxyl, ether and carbonyl bands at 906, 3500, 1120 and 1720 cm-1 respectively were determined from spectral differences and are plotted as a function in cure conditions in Figs. 10,11,12 and 13 respectively. The 906,1120 and 1720 cm-1 band intensities were normalized to the 805 cm-1 band and the 3500 cm-1 to the 1615 cm 1 band. The 805 and 1615 cm-1 bands are associated with the phenyl group which is assumed to chemically unmodified during the homopolymerization reactions. 

Hydroxyl, ether and carbonyl band intensities (Figs. 11,12, and 13) simultaneously increase in the same temperature range as the epoxide band intensity decreases (Fig. 10). The carbonyl band appears to be directly correlated to epoxide consumption rather than general oxidation reactions because the carbonyl band intensity does not increase once the epoxide groups are all consumed. The intensities of the ether, 

In the 177-300 °C temperature range studied, epoxide isomerization, oxidation and homopolymerization can occur followed by complex degradation reactions. There have been numerous studies on the homopolymerization of epoxides including the effects of catalysts, alcohols, cure temperature and epoxide-amine ratio on the 

There is considerable evidence in the literature that chain extension reactions can occur between epoxide and hydroxyl groups and that this reaction (4) is enhanced in the presence of the tertiary amines 28.29,32,36,40,42-48,50) jn tjie case Qf TGDDM 

A number of workers have reported epoxides isomerize to allylic alcohols (5) 30, 35-38, o,4i,5i-56) Epo de isomerization to 

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Other possible reactions, such as homopolymerization (epoxide+epoxide) and epox-ide+hydroxyl group (in the latter stages of cure), can be neglected when the ratio of epoxide to amine is stoichiometric and in the absence of catalyst or accelerator [194], For TGDDM/DDS resins, the homopolymerization reaction may be neglected at cure temperature below 180°C [84], At temperatures between 177°C and 300°C, dehydration and/or network oxidation occur, which results in formation of ether cross-linkings with loss of water. Decomposition of the epoxy-OH cure reaction can also take place, which results in propenal... 

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