Activation energy and curing behavior of resol‐ and novolac‐type phenolic resins by differential scanning calorimetry and thermogravimetric analysis

Abstract

ABSTRACT:The thermal behavior, thermal degradation kinetics, and pyrolysis of resol and novolac phenolic resins with different curing conditions, as a function of the formaldehyde/phenol (F/P) molar ratio (1.3, 1.9, and 2.5 for the resol resins and 0.5, 0.7, and 0.9 for the novolac resins) were investigated. The activation energy of the thermal reaction was studied with differential scanning calorimetry at five different heating rates (2, 5, 10, 20, and 40°C/min) between 50 and 300°C. The activation energy of the thermal decomposition was investigated with thermogravimetric analysis at five different heating rates (2, 5, 10, 20, and 40°C/min) from 30 to 800°C. The low molar ratio resins exhibited a higher activation energy than the high molar ratio resins in the curing process. This meant that less heat was needed to cure the high molar ratio resins. Therefore, the higher the molar ratio was, the lower the activation energy was of the reaction. As the thermal decomposition of the resol resins proceeded, the activation energy sharply decreased at first and then remained almost constant. The activation energy of the thermal decomposition for novolac resins with F/P ϭ 0.5 or F/P ϭ 0.7 was almost identical in all regions, whereas that for novolac resins with F/P ϭ 0.9 gradually decreased as the reaction proceeded.

Photonic Patterns Printed in Chiral Nematic Mesoporous Resins

“…In addition, sample MP1-p shows an endothermic peak at 356 8C that was attributed to the condensation of methylol groups with phenol or other methylol groups forming methylene or dibenzyl ether bridges, respectively, and thereby releasing formaldehyde. [39] A similar but more intense endothermic peak is observed at 280 8C for MP1-f, indicating the presence of more methylol groups obtained by the post-synthetic addition of formaldehyde. However, the acid-treated sample MP1-h did not show any endothermic peak in that temperature region ( Figure S5 b), confirming that most of the methylol groups are condensed by acidification with HCl, leading to enhanced crosslinking.…”

Aluminum Nitride Formation From Aluminum Oxide/Phenol Resin Solid-Gel Mixture By Carbothermal Reduction Nitridation Method

“…Resol type of phenol resin is bridged by methylene (-CH 2 -) and the formation of cresol, phenol and xylenol occurs, depending on the position of scission of formaldehyde-phenol resin [16], as shown in Fig. 1.…”

Effective Carbon Nanotube/Phenol Formaldehyde Resin Based Double‐Layer Absorbers of Microwave Radiation: Design and Modeling

“…[21] was used. First, the phenol À formaldehyde (37% water solution) À sodium hydroxide (10% water solution) mixture with the respective molar ratio of 1:1.3:0.27 was mixed with MWCNT (0; 2; 5 w.t.% relative to phenol).…”