In situ FT‐IR and DSC investigation on the cure reaction of the dicyanate/diepoxide/diamine system

Abstract

Cure reactions of a liquid aromatic dicyanate ester (1,1′‐bis(4‐cyanatophenyl)ethane, BEDCy) with a liquid bisphenol A epoxide (2,2‐bis(4‐glycidyloxyphenyl)propane, BADGE) and 4,4′‐diaminodiphenyl sulfone (DDS) were studied through correlation of the in situ FT‐IR spectroscopy and DSC in dynamic scanning mode. Before this system was examined, cure reactions of precursory systems of BADGE/DDS, BEDCy/BADGE and BEDCy/DDS were investigated separately. Cure reaction paths for each system are proposed. Some reactions in the precursory systems, such as polycyclotrimerization of dicyanate to form sym‐triazine and formation of alkyl isocyanurate, were not observed in the combined curing system BEDCy/BADGE/DDS. Four principal reaction paths are proposed for this curing system: (1) formation of oxazoline from the reaction between the epoxide and cyanate group; (2) reaction of epoxide with primary amine to form a hydroxyl group; (3) reaction of epoxide with the hydroxyl group to form an ether linkage; and (4) rearrangement of oxazoline to form oxazolidinone. Two distinct, but somewhat overlapping, exothermic peaks were observed on the DSC thermogram. The lower temperature peak on the DSC thermogram was primarily contributed by the first reaction path, whereas the higher temperature peak can mainly be attributed to the reaction paths 2, 3 and 4. © 2001 Society of Chemical Industry

Cure reactions in the blend of cyanate ester with maleimide

“…Various aromatic dicyanates were substantially investigated in our laboratory on the cure kinetics and mechanisms of polycyclotrimerization [16 -18], effect of intramolecular cycles on the polycyclotrimerization [19,20], the glass transition temperature-conversion relationship in the polycyclotrimerization [21,22], the cure reaction of aromatic dicyanate ester with different type of epoxy resin [23] and the cure reaction of the dicyanate/diepoxide/diamine system [24]. The curing system of BMI/BADCy [17,25] blend without a specific catalyst was investigated and the crosslinking reactions between BMI and dicyanates were indeed detected in the FTIR spectra.…”

A cyanate ester/microcapsule system with low cure temperature and self-healing capacity

“…In particular, the released epoxy resin reacts with triazine rings in the matrix to form oxazolidinone rings [43,44]. The new network formation significantly increases the bond strength and restores the CE mechanical properties.…”

“…As the temperature reaches 170°C, the storage moduli of the CE/MCs demonstrate a significant drop because of the lower stiffness of the MCs and the low molecular weight epoxy resin core materials. In addition, the drop in storage modulus can also be attributed to the flexible chains in the new networks formed by ÀOH, amine groups, epoxy groups and AOCN [3,21,[38][39][40][41][42][43][44], which have lower thermal stability. The two tan delta peaks (T g1 and T g2 ) of CE/MCs systems marked in Fig.…”

Catalyst effect on cure reactions in the blend of aromatic dicyanate ester and bismaleimide

“…24 The curing system of BMI/ BADCy blend without a specific catalyst was investigated, 17,25 and the crosslinking reactions between BMI and BADCy were indeed detected in the FTIR spectra. No cyclotrimerization was observed in the blend BMI/BADCy without catalyst, suggesting that pyrimidine and/or pyridine structures were formed.…”