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Fourier transform infrared analysis of polycarbonate/epoxy mixtures cured with an aromatic amine

โœ Scribed by Trong-Ming Don; J. P. Bell


Publisher
John Wiley and Sons
Year
1998
Tongue
English
Weight
313 KB
Volume
69
Category
Article
ISSN
0021-8995

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โœฆ Synopsis


In our previous article, we established that polycarbonate (PC) can react with the diglycidyl ether of bisphenol-A (DGEBA) at 200ะŠC through transesterification and addition reactions, resulting in degraded PC chains with phenolic end groups and also in PC/DGEBA copolymers. However, these reactions can be minimized or eliminated at lower temperatures, below 160ะŠC. In this article, Fourier transform infrared analysis (FTIR) was used to study the curing kinetics of epoxies in the presence of PC. The curing agent was an aromatic amine, diaminodiphenyl methane (DDM). FTIR results showed that the presence of a small amount of PC promoted the amineepoxide reactions, probably due to the catalytic effect of the phenolic end groups in the PC chains. However, the PC did not alter the epoxy cure reaction mechanism. Two different blending processes were used to premix the PC and DGEBA, namely, solutionblending and melt-blending processes, in order to give different extents of prereactions. If a solution-blending process was used, PC tended to undergo crystallization during an early stage of cure. When a melt-blending process was used, no melting peak was observed in the thermograms of the differential scanning calorimeter (DSC) for the modified epoxies; PC chains bonded to DGEBA during prereaction at 200ะŠC, thus inhibiting the crystallization of PC during cure.


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