UV, Luminescence, and FTIR Characterization of Cure Reaction in Bisphenol A Dicyanate Ester Resin

Abstract

To develop cure monitoring techniques for bisphenol A dicyanate ester (BPADCY) resin, UV, fluorescence, phosphorescence, and IR spectra were investigated. UV−vis spectra during the cure reaction indicates that the cyclotrimerization of cyanate esters to form triazine rings is the principal reaction, as supported by IR spectroscopic results. During the cure reaction, very strong luminescence emission has been found. Fluorescence emission intensity around 420 nm first increases, followed by decrease with a small red shift as the cure reaction proceeds. The aromatically substituted cyanurates formed during the cure reaction and their inner filter effect are responsible for the observed emission and its trend in intensity. In-situ fluorescence characterization showed similar results for the catalyzed cure reaction with cobalt acetylacetonate/nonylphenol as well as bisphenol A catalyzed resin in comparison to purified BPADCY, except for the faster rate in fluorescence spectral change. Phosphorescence emission of polycyanate resins appears at a 440 nm, which is about 20 nm longer than that of fluorescence. The phosphorescence lifetime has been found to be about 20 ms at room temperature and remains relatively unchanged throughout the cure reaction. FTIR in situ cure studies of BPADCY monomer indicates a linear relationship between the consumption rate of cyanate ester groups and the formation rate of the substituted triazine rings. Fluorescence changes are correlated to the extent of cure by IR technique.

Photoluminescent carbon nanocapsule/polycyanate composites with hydrogen bond interactions

“…The absorption result from CNC shows a main absorption centered at 300 nm. On the other hand, LECy‐derived PCn exhibits a broad absorption pattern, extending from 200 to 350 nm, just as the same with reported pattern 16. However, the absorption edge of the cured CNC‐COOHs/PCn blend was broad compared with the pure CNC‐COOHs and PCn, because of the π–π stacking of the aromatic ring between the CNC‐COOHs and PCn.…”

“…Fig. 1) counterpart reported previously 16, 17. Therefore, the light emitting properties of the CNC‐COOHs/PCn blend are described as well.…”

Preparation and properties of catalyzed polyimide/dicyanate semi‐interpenetrating networks for polymer gas membrane with suppressed CO2‐plasticization

“…To prepare the semi‐IPNs, Matrimid was first dissolved in dichloromethane, and DCFT was added to the Matrimid solution in ratios Matrimid/DCFT 90/10, 80/20, and 70/30 and the catalyst was added in the last step. Although many classes of compounds can be used as catalyst, particularly protic acids and Lewis acids and bases,32 combinations of active hydrogen compounds with transition metal complexes are at present widely used to prepare cyanate ester resins at temperatures around 200°C 33–36. The reaction proceeds in two main steps: first the phenol forms an imidocarbonate with one cyanate group, which reacts then with two more cyanate groups to generate a triazine ring.…”

Thermal curing of glass‐epoxy prepregs by luminescence spectroscopy

“…Figure 5(b) shows the excitation spectra of the F161 prepreg at an emission wavelength of 420 nm before and after heat treatment and reveals a broad band before the heat treatment with a maxima at 361 nm. After the heat treatment, the excitation spectra showed a similar trend as in the emission spectra as a function of the curing time;38 the excitation maximum showed a redshift up to 13 nm, related to the crosslink process 5…”