Curing kinetics, mechanism and chemorheological behavior of methanol etherified amino/novolac epoxy systems

Abstract

Abstract. The curing kinetics and mechanism of epoxy novolac resin (DEN) and modified epoxy novolac resin (MDEN) with methanol etherified amino resin were studied by means of differential scanning calorimetry (DSC), Fourier transforminfrared (FT-IR) spectroscopy and chemorheological analysis. Their kinetics parameters and models of the curing were examined utilizing isoconversional methods, Flynn-Wall-Ozawa and Friedman methods. For the DEN mixture, its average activation energy (E a ) was 71.05 kJ/mol and the autocatalytic model was established to describe the curing reaction. The MDEN mixture exhibited three dominant curing processes, termed as reaction 1, reaction 2 and reaction 3; and their E a were 70.05, 106.55 and 101.91 kJ/mol, respectively. Besides, E a of reaction 1 was similar to that of DEN mixture, while E a of reactions 2 and 3 corresponded to that of the etherification reaction between hydroxyl and epoxide group. Moreover, these three dominant reactions were n th order in nature. Furthermore, their curing mechanisms were proposed from the results of DSC and FTIR. The chemorheological behavior was also investigated to obtain better plastics products via optimizing the processing schedules.

Flame‐Retarded Epoxy Resins with a Curing Agent of DOPO‐Triazine Based Anhydride

“…As can be observed, the plots are all not linearly related and there emerges induction period, particularly for the flame‐retarded epoxy system. Since the value of ln[ A f( α )] reaches the maxima at the curing conversion α of 0.2–0.4 (corresponding to ln(1− α ) of −0.22 to −0.51), it can be suggested that the curing mechanism of the system is classified as the autocatalytic reaction …”

Effects of Different Montmorillonite Nanoclay Loading on Cure Behavior and Properties of Diglycidyl Ether of Bisphenol A Epoxy

“…It was assumed that delay in gelation of 2 wt.% samples was caused by epoxy molecules trapped between layers. At this point, although temperature was increasing during curing, changes in viscosity were unnoticeable since this was occurring at the 6 Journal of Nanomaterials [35]. This interruption in gelation further influenced vitrification and development of material properties as can be expected.…”

“…Cure mechanism of epoxy molecules at this stage was controlled by diffusion, and lower activation energies exhibited by 2 wt.% samples are indicative of hindering effects of MMT on vitrification. Trapped epoxy molecules and tethering network within nanoclay layers in 2 wt.% samples produced sufficient hydroxyl groups during vitrification [35]. This facilitated the process and thus less energy was necessitated during diffusion controlled reaction as seen in Figure 7.…”

Curing Kinetics and Thermal Stability of Epoxy Composites Containing Newly Obtained Nano-Scale Aluminum Hypophosphite (AlPO2)

“…This reaction is inferior, or of lower likelihood, at low temperatures [26,27]. Increasing the heating rate to higher values shifted cure characteristics, including onset (T onset ), peak (T p ) and final (T endset ) temperatures, to higher values (Table 1) as a result of the fact that the shortage of time for cure moieties to react at high heating rates is compensated for at higher temperatures [28].…”