Curing mechanism of resole phenolic resin based on variable temperature FTIR spectra and thermogravimetry-mass spectrometry

Abstract

To solve the problem that the curing mechanism evolution of phenolic resin catalyzed by Ba(OH)2 remained unclear, the p-p methylene index, o-p methylene index, o-o methylene index, hydroxymethyl index, and ether index were introduced to quantitatively investigate the chemical structure of resin in the curing temperature range of 90–230°C. The chemical structures were investigated by variable temperature FT-IR. The gas products released with the increase of curing temperature were characterized by Thermogravimetry-Mass Spectrometry. The curing mechanism from 90°C to 230°C was concluded finally. The results show that the main reaction is the formation of the p-p methylene group in the range of 90–120°C. It is difficult to form the o-p methylene bridge at this stage. In the range of 120–160°C, the main reaction is the formation of the p-p methylene group. From 160°C to 190°C, the main reactions are the breaking of the ether bond, the formation of the carbonyl group and the propyl bridge. Above 190°C, the main reactions are polycondensation reaction among phenolic hydroxyl groups, and the formation reaction of carbonyl groups. The ether bond breaks completely above 230°C. This work provides a new method to investigate the curing mechanism. It is a benefit for the rational design of the curing process of phenolic resin-based composites.

Surface Characteristics of Phenolic Resin Coatings

“…Most likely, the absence of chemical changes with curing atmosphere is the result of the relatively low curing temperature, which limits both oxidation and selective evaporation of formaldehyde from dimethylene ether bridges. This is in line with results previously reported by Hu et al [69], where only for curing resoles at temperatures above 160 • C the formation of carbonyl groups and breaking down of ether bridges was observed.…”

Ink-Based Additive Manufacturing of a Polymer/Coal Composite: A Non-Traditional Reinforcement

“…In this study, an organic acid (pTSA) was added to the J2027L phenolic resin (Figure a). The H + ions in the acid promote the nucleophilic formation of ionic phenol and formaldehyde compounds, which leads to the formation of methylene bridges (−CH 2 −), through which the phenol and formaldehyde molecules form a 3D intricate cross-linking (Figure b). , …”

“…The H + ions in the acid promote the nucleophilic formation of ionic phenol and formaldehyde compounds, which leads to the formation of methylene bridges (−CH 2 −), through which the phenol and formaldehyde molecules form a 3D intricate crosslinking (Figure 1b). 37,38 The initial curing studies were conducted with varying concentrations of pTSA on a hot plate. The temperature and time to cure are noted.…”

Structural Evolution in Glassy Carbon Investigated Based on the Temperature Dependence of Young’s Modulus

“…The quick increase in sample height associated with mass reduction in the temperature ranges of 140–150 and 210–220 °C were noted. At temperatures below 230 °C, a series of dehydration and condensation reactions occurred in the precursor, as described in [ 31 ]. The gaseous products escaped from the precursor leading to the formation of micropores.…”