The Structure of Some Phenol-Formaldehyde Condensates for Wood Adhesives

Smit, Robert; Pizzi, A.; Schutte, C. J. H.; Paul, S.O.

doi:10.1080/00222338908052014

Cited by 6 publications

(7 citation statements)

References 8 publications

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“…The assignment of chemical shifts for the commercial and BPF resins in this study was therefore consistent with what had been observed by [11,14,17,18,19,20] as summarized in Table 2.…”

Section: Structural Compositional Characterization Of the 75 Wt% Bio-supporting

confidence: 90%

Structural Characterization of Cure Bio-based Phenol Formaldehyde Wood Adhesive

Olayiwola

2020

AJOCS

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Bio-phenol formaldehyde (BPF) resole resins were characterized by liquid-state 13C Nuclear Magnetic Resonance (NMR) spectroscopy. The liquid 13C NMR analysis indicated that the condensation reactions between the bark phenolic compounds and the formaldehyde occurred during the synthesis of the resins. Methylene ether bridges in the resins were more pronounced in the BPF resin when compared to the PF resin system. The liquid-state 13C NMR study revealed significant differences in the resins structures induced by the inclusion of bark-phenolic components. The bark-phenolic components favored the formation of para-ortho methylene linkages in the BPF resins and also enhanced the cure rate of the BPF resin system.

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“…The assignment of chemical shifts for the commercial and BPF resins in this study was therefore consistent with what had been observed by [11,14,17,18,19,20] as summarized in Table 2.…”

Section: Structural Compositional Characterization Of the 75 Wt% Bio-supporting

confidence: 90%

Structural Characterization of Cure Bio-based Phenol Formaldehyde Wood Adhesive

Olayiwola

2020

AJOCS

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“…It is understandable because the ortho−ortho methylene links are not favored in the presence of sodium hydroxide. 21,22 The peaks at 114−116 ppm of unsubstituted ortho aromatic carbons of phenol and the peaks at 120−124 ppm of unsubstituted para aromatic carbons of phenol were observed. The peaks at 60.4−63.4 ppm represented the methylol groups (Ph−CH 2 OH) in the PF resins, with the ortho link at 60.4−62.8 ppm and the para link at 63.1−63.4 ppm.…”

Section: ■ Results and Discussionmentioning

confidence: 97%

“…The chemical shifts were assigned to the corresponding functional groups based on previous findings. 17,18,21,22 The chemical shifts at 153.5−163.9 ppm were assigned to phenoxy carbons. The chemical shifts of para-alkylated phenolic groups were between 158.0 and 159.5 ppm, which showed higher The chemical shift at 48.7 ppm was due to methanol (CH 3 OH).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Liquid-state 13 C nuclear magnetic resonance (NMR) spectroscopy has been successfully applied to characterize the composition of phenol-liquefied cellulose, phenol-liquefied cellulose and lignin model compounds, bark tannin extractives, and PF resins. − The NMR studies on the phenol liquefaction of cellulose, cellobiose, and guaiacylglycerol-β-guaiacyl ether (GG) showed that phenol reacted with these compounds during the liquefaction. − It was found that compounds formed during cellulose liquefaction had structural units, such as methylol phenol, that highly resembled conventional PF resins . The liquefaction of GG formed intermediates that were highly reactive and could further condense with each other or with phenol.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Biobased Phenol Formaldehyde Resins Derived from Beetle-Infested Pine Barks—Structure and Composition

Zhao

Yan

Feng

2012

ACS Sustainable Chem. Eng.

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In this study, two types of biobased bark-derived phenol formaldehyde (PF) resins, namely, liquefied bark-PF and bark extractive-PF, were synthesized from acid-catalyzed phenol-liquefied bark and bark alkaline extractives, respectively. The biobased resins were characterized for their chemical compositions and molecular structures using the liquid-state 13C nuclear magnetic resonance (NMR) technique. The results indicated that the introduction of bark components (either as liquefied bark or as bark extractives) to the phenolic resin synthesis affected resin structures and curing performance. Methylene ether bridges were found in the bark-derived PF resins. Bark components made the formation of para–ortho-methylene linkage more favorable in bark-derived PF resins than in lab PF resins. Molecular structures of the liquefied bark-PF resin differed significantly from those of the bark extractive-PF resins. The liquefied bark-PF resin showed a higher ratio of para–para/ortho–para-methylene link (−CH2−), a higher unsubstituted/substituted hydrogen (−H/–CH2OH) ratio and a higher methylol/methylene (−CH2OH/–CH2−) ratio than the bark extractive-PF resin. The tannin components of the bark extractives accelerated the curing rate of the resulting bark extractive-PF resin. The bark extractives made the ortho position of phenol react more favorably with formaldehyde than the para position. The liquefied bark with phenolated structures had more reactive sites toward formaldehyde than the bark extractives and accelerated the curing rate of the resulting liquefied bark-PF resin.

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“…The signals are assigned according to previous literatures. 3,[31][32][33] The LPF adhesives had NMR spectra similar to those of the CPF resin adhesive, suggesting that the LPF resin adhesives exhibited similar molecular structure as compared to the CPF resin adhesive. This result was in agreement with some previous publications.…”

mentioning

confidence: 76%

Lignin–phenol–formaldehyde resin adhesives prepared with biorefinery technical lignins

Yang

Zhang

Yuan

et al. 2015

J of Applied Polymer Sci

103

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In this study, four biorefinery technical lignins were used to synthesize lignin-phenol-formaldehyde (LPF) resin adhesives with a proposed formulation that was designed based on accurate analysis of the active sites in lignin with 31 P nuclear magnetic resonance (NMR). The properties of the LPF resin adhesives and the plywoods prepared with them were tested. The structural features and curing behavior of the LPF resin adhesives were thoroughly investigated by solution-and solid-state 13 C NMR. Results indicated that the proposed formulation exhibited favorable adaptability for all four of these technical lignins for synthesis of LPF resin adhesives. High-performance plywood with low emissions of formaldehyde could be successfully prepared with the synthesized LPF resin adhesives. All the LPF resin adhesives exhibited similar structure and curing behavior with the commercial phenol-formaldehyde (CPF) resin adhesive. However, the LPF resin adhesives showed relatively higher curing temperatures as compared with the CPF resin adhesive.

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The Structure of Some Phenol-Formaldehyde Condensates for Wood Adhesives

Cited by 6 publications

References 8 publications

Structural Characterization of Cure Bio-based Phenol Formaldehyde Wood Adhesive

Structural Characterization of Cure Bio-based Phenol Formaldehyde Wood Adhesive

Biobased Phenol Formaldehyde Resins Derived from Beetle-Infested Pine Barks—Structure and Composition

Lignin–phenol–formaldehyde resin adhesives prepared with biorefinery technical lignins

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