Curing reaction characteristics and phase behaviors of biphenol type epoxy resins with phenol novolac resins

Ren, Shaoping; Lan, Ya‐Qian; Zhen, Yi-quan; Ling, Youdao; Lu, Mangeng

doi:10.1016/j.tca.2005.10.009

Cited by 37 publications

(20 citation statements)

References 27 publications

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“…Parameters for these models were determined by fitting to experimental differential scanning calorimetry data. Although the fittings were reported to be reasonable, they cannot confirm whether the mechanism is complete. Consequently, such kinetic models cannot be extrapolated to other experimental conditions.…”

Section: Introductionmentioning

confidence: 85%

Density functional theory study on mechanisms of epoxy‐phenol curing reaction

Pham

Huynh

et al. 2014

J Comput Chem

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A comprehensive picture on the mechanism of the epoxy-phenol curing reactions is presented using the density functional theory B3LYP/ 6-31G(d,p) and simplified physical molecular models to examine all possible reaction pathways. Phenol can act as its own promoter by using an addition phenol molecule to stabilize the transition states, and thus lower the rate-limiting barriers by 27.0-48.9 kJ/mol. In the uncatalyzed reaction, an epoxy ring is opened by a phenol with an apparent barrier of about 129.6 kJ/mol. In catalyzed reaction, catalysts facilitate the epoxy ring opening prior to curing that lowers the apparent barriers by 48.9-50.6 kJ/mol. However, this can be competed in highly basic catalysts such as amine-based catalysts, where catalysts are trapped in forms of hydrogen-bonded complex with phenol. Our theoretical results predict the activation energy in the range of 79.0-80.7 kJ/mol in phosphine-based catalyzed reactions, which agrees well with the reported experimental range of 54-86 kJ/mol.

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Section: Introductionmentioning

confidence: 85%

Density functional theory study on mechanisms of epoxy‐phenol curing reaction

Pham

Huynh

et al. 2014

J Comput Chem

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“…The curing kinetics of E n E/THPA was investigated by non‐isothermal DSC scans at multiple heating‐rate (Fig. 2) using an iso‐conversion method from Flynn, Wall, and Ozawa [8]: where α is the fractional conversion at any time; E a the activation energy; R the gas constant; β i = dT / dt is the heating rate (here i is ordial number of DSC runs performed at different heating rate, β i ).…”

Section: Resultsmentioning

confidence: 99%

“…Curing reaction of epoxy resins is a complex process due to the simultaneous occurrence of many reactions. Coupled with phase changes in the curing of LC epoxy resins, curing behavior is influenced by the motions of mesogens and the final network depends on the curing kinetics of the curing reaction [8, 9]. The curing kinetic researches lead to a better knowledge of the curing behavior and the final structures of networks.…”

Section: Introductionmentioning

confidence: 99%

Curing behavior of Azo‐containing twin liquid crystalline epoxy resins with anhydride

Zhou

Liang

et al. 2012

Polymer Engineering & Sci

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A series of novel azo‐containing twin liquid crystalline (LC) epoxy monomers were cured with anhydrides without extra catalyst, and the curing kinetics was investigated by non‐isothermal differential scanning calorimetry (DSC) technique. The results showed that the effect of phase behavior on activation energy (Ea) was enormous, which increased first and then decreased quickly with the curing reaction processing. The chemical kinetic control and diffusion‐control mechanisms dominate the curing together, which gives large values of Ea. Azo group also served as a catalyst to accelerate the curing reaction. The curing mechanism was confirmed by the UV–Vis spectra of azo‐doped curing system in which the absorbance values at 366 nm and 475 nm changed with the curing reaction processing. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers

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“…An abrupt decrease in the E a values at the end of the curing process for MLN and PF occurred because the overall process kinetics were controlled by the diffusion stage. [32][33][34] The value of E a for LN curing (92-97 kJ/mol) did not change significantly with temperature, including the anomalous data in the a range of 10-30%. This may have been because the overall process rate was governed by the diffusion stage.…”

Section: Curing Kineticsmentioning

confidence: 86%

Time–temperature–transformation cure diagrams of phenol–formaldehyde and lignin–phenol–formaldehyde novolac resins

Pérez

Rodrı́guez

Alonso

et al. 2010

J of Applied Polymer Sci

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In this study, the time-temperaturetransformation (TTT) cure diagrams of the curing processes of several novolac resins were determined. Each diagram corresponded to a mixture of commercial phenol-formaldehyde novolac, lignin-phenol-formaldehyde novolac, and methylolated lignin-phenol-formaldehyde novolac resins with hexamethylenetetramine as a curing agent. Thermomechanical analysis and differential scanning calorimetry techniques were applied to study the resin gelation and the kinetics of the curing process to obtain the isoconversional curves. The temperature at which the material gelled and vitrified [the glass-transition temperature at the gel point ( gel T g )], the glass-transition temperature of the uncured material (without crosslinking; T g0 ), and the glass-transition temperature with full crosslinking were also obtained. On the basis of the measured of conversion degree at gelation, the approximate glass-transition temperature/conversion relationship, and the thermokinetic results of the curing process of the resins, TTT cure diagrams of the novolac samples were constructed. The TTT diagrams showed that the lignin-novolac and methylolated lignin-novolac resins presented lower T g0 and gel T g values than the commercial resin. The TTT diagram is a suitable tool for understanding novolac resin behavior during the isothermal curing process.

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Curing reaction characteristics and phase behaviors of biphenol type epoxy resins with phenol novolac resins

Cited by 37 publications

References 27 publications

Density functional theory study on mechanisms of epoxy‐phenol curing reaction

Density functional theory study on mechanisms of epoxy‐phenol curing reaction

Curing behavior of Azo‐containing twin liquid crystalline epoxy resins with anhydride

Time–temperature–transformation cure diagrams of phenol–formaldehyde and lignin–phenol–formaldehyde novolac resins

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