Investigation of a resorcinol–formaldehyde resin by ¹³C‐NMR spectroscopy and intrinsic viscosity measurement

Abstract

SYNOPSISVarious molecular weight fractions and oligomers isolated from a novolac type resorcinolformaldehyde ( R F ) wood adhesive resin were studied by 13C-NMR, gel permeation chromatography ( GPC ) , and intrinsic viscosity measurements. The 13C-NMR results indicate that methylene groups occur mostly between C4-C; and C2-C> carbons and in minor amounts between C2-Cg carbons of resorcinol rings. By suppressing the nuclear Overhauser effect (nOe) and using a long delay time for 13C-NMR measurements, reasonable methylene/ aromatic carbon ratios were obtained from the aromatic C, carbon patterns that have resulted from different numbers of methylene groups bonded on the aromatic ring. This analysis results indicate that the RF resin has a n appreciable amount of branch structures and compare favorably with the gel permeation chromatography and intrinsic viscosity measurement results. 0 1993 John Wiley & Sons, Inc.

High-surface-area and high-nitrogen-content carbon microspheres prepared by a pre-oxidation and mild KOH activation for superior supercapacitor

“…Furthermore, 13 C NMR spectra (Fig.2b) ppm [34,35]. Thus, all the above results indicate that the thermal oxidation of NPMs could not only release the thermally-instable -CH 2 , -OH groups, but also enrich the N species such as -HN-CH 2 -NH-and aromatic C-N (see possible reaction pathways in Fig.…”

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

“…Although 13 C-NMR has been used to determine the structure of R-F resins, most of those resins have been novolaks, [7][8][9][10] which had lost the ability to react further. Werstler 11 analyzed slowly reacting resols and assigned dozens of resonance peaks to carbons of many of the reacting species.…”

Solution‐state NMR analysis of hydroxymethylated resorcinol cured in the presence of crude milled‐wood lignin from Acer saccharum

“…Chemical shift assignments of the lignin subunits were made using the NMR database of lignin and cell wall model compounds . HMR and resocinolic moiety chemical shift assignments were made using 1 H, 13 C, and HSQC experiments, along with literature values . O ‐acetyl‐(4‐ O ‐methylglucurono)xylan chemical shift assignments were made using 1 H, 13 C, and HSQC experiments, along with literature values .…”

“…The most predominant linkage in HMR, once polymerized, is a methylene between the two resorcinolic units (i.e., a diarylmethane). The chemical shifts in NMR spectra of RF monomeric, oligomeric, and polymeric structures have been well studied . However, what also may occur as HMR cures with wood is the formation of new linkages between lignin or xylan and an HMR moiety.…”