Microstructure evolution of ammonia-catalyzed phenolic resin during thermooxidative aging

• Published in: Journal of applied polymer science Vol. 126; no. 6; pp. 2010 - 2016
• Main Authors: Guo, Dan-Dan, Zhan, Mao-Sheng, Wang, Kai
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 15.12.2012; Wiley; Wiley Subscription Services, Inc
• Subjects: Ageing; Applied sciences; Bridges (structures); degradation; Exact sciences and technology; FT-IR; Hydroxyl groups; Materials science; Methylene; Phenolic resins; Physical properties; Polymer industry, paints, wood; Polymers; Properties and testing; Reflectance; Reproduction; resins; Spectroscopy; Technology of polymers; Thermal properties; Thermal properties; ageing; resins; Thermal ageing; Thermooxidative degradation; Reaction mechanism; FT-IR; degradation; Experimental study; Phenolic resin; Glass transition temperature; Thermal stability
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.36550

The thermooxidative aging of ammonia‐catalyzed phenolic resin for 30 days at 60–170°C was investigated in this article. The aging mechanism and thermal properties of the phenolic resin during thermooxidative aging were described by thermogravimetry (TG)–Fourier transform infrared (FTIR) spectroscopy, attenuated total reflectance (ATR)–FTIR spectroscopy, and dynamic mechanical thermal analysis. The results show that the CN bond decomposed into ammonia and the dehydration condensation between the residual hydroxyl groups occurred during the thermooxidative aging. Because of the presence of oxygen, the methylene bridges were oxidized into carbonyl groups. After aging for 30 days, the mass loss ratio reached 4.50%. The results of weight change at high temperatures coincided with the results of TG–FTIR spectroscopy and ATR–FTIR spectroscopy. The glass‐transition temperature (Tg) increased from 240 to 312°C after thermooxidative aging for 30 days, which revealed the postcuring of phenolic resins. In addition, an empirical equation between the weight change ratio and Tg was obtained. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012