Effect of Catalysts and Curing Schedules on the Structure and Properties of Epoxy–Phenol Coatings

Acid catalyzedepoxy–methylolphenolthermosets: Astructure–propertystudy

“…The film based on the ortho‐isomer is the most brittle film of the series and broke at low ultimate strength values (42 ± 5 MPa) and %strain (1.9 ± 0.02%), which can be explained by the high degree of crosslinking ( M c = 709 g/mol, Table 7). Overall, the stress–strain data for this series were comparable to what is observed in the literature for high molecular weight epoxy‐resole networks 23,24 . Interestingly, the stress–strain behavior of the crosslinked films seems to be independent of the monomer feed ratio, perhaps with the exception of entry 2 (DGEBA‐ortho‐methylolphenol with r = 0.70), which exhibits an ultimate stress and strain‐at‐break roughly double that of the r = 0.50 and r = 0.94 samples (entries 1 and 3).…”

“…Overall, the stress-strain data for this series were comparable to what is observed in the literature for high molecular weight epoxy-resole networks. 23,24 Interestingly, the stress-strain behavior of the crosslinked films seems to be independent of the monomer feed ratio, perhaps with the exception of entry 2 (DGEBA-ortho-methylolphenol with r = 0.70), which exhibits an ultimate stress and strain-atbreak roughly double that of the r = 0.50 and r = 0.94 samples (entries 1 and 3). For all other samples, increasing the methylolphenol concentration in the final thermoset film does not result in a clear improvement in strength or strain-at break.…”

“…10 Epoxy-resole networks usually exhibit Young's moduli that are on the order of 2.5 GPa, tensile strengths of 36-90 MPa, and tensile elongation of 2.2%-7.5%. 19,23,24 Several studies have been reported on network formation of epoxy-resole networks using high molecular weight precursors. [25][26][27] Low molecular weight methylolphenols have been used as model systems to study the reaction mechanism and kinetics of the resole synthesis and cure behavior.…”

Acid‐ and base‐catalyzedepoxy‐phenolthermosets from catechol, resorcinol and hydroquinone: Astructure–propertystudy

“…31 In general, the difference in thermal stability between networks with different dihydroxybenzenes was minimal and all thermosets showed high thermal stabilities that are inline with what is observed for typical epoxy-phenol thermosets cured by an acid catalyst. 25 In Figure 5(b), the weight loss results are shown for the DGEBA-resorcinol cross-linked films prepared using different concentrations of resorcinol. The network with resorcinol r = 0.30 (this film contains only 30 mol% of resorcinol hardener) displayed a rapid decrease in thermal stability compared to other networks studied in this paper.…”

“…Although the films were highly cross-linked, the ultimate strength and % strain at break was higher than what has been reported in the literature on epoxy-phenol thermosetting resins. 23,25 The tensile behavior of the base catalyzed sample was different than that of the acid catalyzed thermoset films. Usually, in epoxy thermosets, the % strain at break increases with an increase in M c. [39][40][41][42] We observed a similar phenomenon as the base catalyzed sample showed a larger % strain at break than the acid catalyzed ones.…”