Solid-state carbon-13 NMR study of resol-type phenol-formaldehyde resins

Maciel, Gary E.; Chuang, I. Ssuer; Gollob, Lawrence

doi:10.1021/ma00135a018

Cited by 138 publications

(65 citation statements)

References 3 publications

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“…The first signal of the DSC curves having the maximum at the temperature between 146 and 149°C is caused by the condensation of methylol groups with phenolic units to form methylene bridges and by the condensation of two methylol groups to form dibenzyl ether bridges. [15][16][17][18] The second signal of the thermograms (the maximum between 184 and 194°C) of resins 1-4 represents further reactions of the resin-for example, the condensation of the dibenzyl ether bridges to methylene bridges with the elimination of formaldehyde. [15][16][17][18] In the DSC graphs of the resins (5-10) with a high condensation alkalinity of 6.0 wt %, the signal having the peak temperature between 146 and 149°C represents the formation of methylene groups in the condensation of methylol groups with phenolic units (Fig.…”

Section: Dsc Resultsmentioning

confidence: 99%

Effect of alkalinity on the structure of phenol–formaldehyde resol resins

Luukko

Alvila

Holopainen³

et al. 2001

J of Applied Polymer Sci

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Two phenol-formaldehyde resol resin series with different methylationand condensation-stage alkalinities were studied. The first series was impregnation resins having a methylation alkalinity between 0.5 and 1.5 wt % and a condensation alkalinity of 1.5 wt %. The second series was adhesive resins with a methylation alkalinity between 0.5 and 3.5 wt % and a condensation alkalinity of 6.0 wt %. The chemical structure was analyzed by 13 C-NMR spectroscopy, and reactivity, by differential scanning calorimetry (DSC). The methylation alkalinity was found to affect the distribution of the structural groups of both phenol-formaldehyde impregnation and adhesive resins, but not to the same extent as did the total condensation alkalinity. Also, the results of the DSC analysis illustrate best the reactivity differences due to the condensation alkalinity.

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Section: Dsc Resultsmentioning

confidence: 99%

Effect of alkalinity on the structure of phenol–formaldehyde resol resins

Luukko

Alvila

Holopainen³

et al. 2001

J of Applied Polymer Sci

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“…Solid-state NMR spectroscopic support for this type of linking structure was shown by Maciel for cured furfuryl alcohol resins 15 and less certainly for cured phenol-formaldehyde resins. 16 The chemical shift prediction software predicts the methylene group signal at 39 ppm and the methine signal at 32 ppm, both of which could be accommodated by these spectra.…”

Section: Methylene Bridgesmentioning

confidence: 99%

Resorcinol-formaldehyde reactions in dilute solution observed by carbon-13 NMR spectroscopy

Christiansen

2000

J. Appl. Polym. Sci.

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ABSTRACT:A recently discovered coupling agent, hydroxymethylated resorcinol (HMR), based on resorcinol-formaldehyde, can greatly enhance wood-to-epoxy resin bond durability in exterior applications. However, for HMR to be most effective, it needs to be prepared a few hours before it is applied to the wood surface. In this study, carbon-13 nuclear magnetic resonance (NMR) spectroscopy was used to monitor composition of HMR as a function of time to characterize which chemical groups are present in solution when HMR is applied. A quantitative assessment of formaldehyde-derived groups required the use of 99% 13 C-enriched formaldehyde. Hydroxymethyl groups, primarily attached to the 4-position of resorcinol, and hemiformal groups formed very quickly. Signals from methylene linkages between resorcinol rings began to appear 20 min into the reaction. Formaldehyde was consumed quickly; 95% was bound to resorcinol rings within 1.7 h. By 3 h, 16% had been converted to methylene linkages, and by 8.3 h, 40% was converted. Another set of NMR experiments was used to monitor the dependency of peak positions of resorcinol solution as a function of pH. These experiments showed significant effects, especially between pH 7.7 and 9.1, which explains chemical shift changes observed during the HMR reaction.

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“…[36] The mesoporous-resin films show more red-shifted color when soaked in water than in ethanol, despite the similar refractive indices of both solvents. This observation confirms that although the infiltration of pores with solvents results in a net increase in the average refractive index of the materials, the red-shift in color is mainly caused by the lengthening of the helical pitch upon swelling.…”

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confidence: 95%

Photonic Patterns Printed in Chiral Nematic Mesoporous Resins

et al. 2015

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Chiral nematic mesoporous phenol-formaldehyde resins, which were prepared using cellulose nanocrystals as a template, can be used as a substrate to produce latent photonic images. These resins undergo swelling, which changes their reflected color. By writing on the films with chemical inks, the density of methylol groups in the resin changes, subsequently affecting their degree of swelling and, consequently, their color. Writing on the films gives latent images that are revealed only upon swelling of the films. Using inkjet printing, it is possible to make higher resolution photonic patterns both as text and images that can be visualized by swelling and erased by drying. This novel approach to printing photonic patterns in resin films may be applied to anti-counterfeit tags, signage, and decorative applications.

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Solid-state carbon-13 NMR study of resol-type phenol-formaldehyde resins

Abstract: side-chain reorientation, it seems necessary to discuss these two factors separately in a more quantitative approach concerning the side-chain motion. Lipari, G.; Szabo, A. J. Am.

Cited by 138 publications

References 3 publications

Effect of alkalinity on the structure of phenol–formaldehyde resol resins

Effect of alkalinity on the structure of phenol–formaldehyde resol resins

Resorcinol-formaldehyde reactions in dilute solution observed by carbon-13 NMR spectroscopy

Photonic Patterns Printed in Chiral Nematic Mesoporous Resins

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