Phenol‐formaldehyde resol resins studied by 13C‐NMR spectroscopy, gel permeation chromatography, and differential scanning calorimetry

Abstract

A series of phenol-formaldehyde resins was produced in the presence of NaOH catalyst. Detailed structural and quantitative information was provided by 13 C-NMR spectroscopy. The main interests were the relative quantities of bridge structures, methylol groups, and free phenol. Functionality and linearity of resins were also studied. The effects of the condensation F/P molar ratio on the structure and properties of the resins was studied by gel permeation chromatography (GPC) and differential scanning calorimetry (DSC) in addition to 13

Study on preparation and properties of phenol-formaldehyde-chinese fir liquefaction copolymer resin

“…According to the previous research (Christiansen and Gollob 1985), the lower exothermic peak in the range of 141,4-144,8°C has been attributed to the addition reaction of free formaldehyde to phenolic ring, and the upper exothermic peak in the range of 143,8-157,5°C was associated with the chain-building condensation reactions, involving hydroxymethyl groups attached to various phenolic species. The appearance of single exothermic peak is mainly due to the F/P molar ratio below 2,3 that resulted in the overlapping of exothermic signals, two well-separated exothermic peaks are revealed when the F/P molar ratio was larger than 2,3 (Holopainen et al 1997). Universidad del Bío -Bío Figure 6 shows the DSC curves of the Chinese fir-based adhesives (F/P=2) with a CF/PF ratio of 50/50, 55/45 and 60/40, respectively.…”

Online monitoring of synthesis and curing of phenol–formaldehyde resol resins by Raman spectroscopy

“…The resin sample (w1 ml) was dissolved in DMSO-d 6 (3 ml) and taken into a 5-mm NMR tube (VWR, 5 mm  178 mm, >400 MHz). The 13 C NMR shifts of the solid and liquid state resins were assigned according to the literature [11,17,18,23,25,26].…”

“…Since understanding of the advancement of resol resin synthesis and curing processes is essential for further development of the resins, methylolation and condensation reactions and structures of the resols have been followed and studied by various methods, such as FTIR spectroscopy [5,8,9], gel permeation chromatography (GPC) [10][11][12][13], 13 C NMR spectroscopy [14][15][16][17][18], and differential scanning calorimetry (DSC) [3,7,11,19]. However, none of these methods is well suited for gathering real-time information about the consumption of starting materials or structure of the resins during the resin processes, which could improve the safety and control of the synthesis and result in more uniform resin quality.…”

Preparation and characterization of para-tertiary-butylphenol formaldehyde resins using dual catalytic-extraction method

“…Also, the highest weight average molecular weight (M w ) is found with the longest reaction time. These results are consistent with Holopainen et al [6]. It could be explained that the condensation polymerization progresses more completely with longer reaction time which contributes to higher molecular weight.…”

“…Consequently, phenolic resins are widely applied in wood working industry, adhesives, hollow particles, thermal insulation and molding [5][6][7]. Traditionally, phenolic resins are prepared by the reaction of phenol with formaldehyde under acidic or basic conditions.…”