Polymer structure of cured alkaline phenol–formaldehyde resol resins with respect to resin synthesis mole ratio and oxidative side reactions
✍ Scribed by Moon G. Kim; Yimin Wu; Larry W. Amos
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 198 KB
- Volume
- 35
- Category
- Article
- ISSN
- 0887-624X
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✦ Synopsis
A wood adhesive-type phenol-formaldehyde (PF) resol resin synthesized with a typical formaldehyde to phenol mol ratio of 2.10 was thoroughly cured and studied by the solid-state crosspolarization/magic angle spinning 13 C nuclear magnetic resonance (CP/MAS NMR) spectroscopy. The methylene group/phenol mol ratio values found were between 1.35 and 1.46, close to the value of a completely cured PF polymer structure. The amount of formaldehyde emitted during resin curing was very small. Other formaldehyde-derived groups determined from CP/MAS NMR spectra and relatively high levels of oxidation products of formaldehyde determined from water extracts of cured resin raised the total formaldehyde-derived groups/phenol mol ratio value to close to that of the synthesis mol ratio. Technological implications of these findings are discussed.