Synthesis of a DOPO-containing imidazole curing agent and its application in reactive flame retarded epoxy resin

By S. Huo, Jun Wang, Shuang Yang, Chuan Li, Xiaolei Wang, H. Cai. Polymer degradation and stability, 2019

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Abstract A novel DOPO-containing imidazole curing agent (DIB) was successfully synthesized, and served as a co-curing agent of 4,4‘-diaminediphenyl sulfone (DDS) to prepare a reactive flame-retarded epoxy thermoset (EP/DDS/DIB). The DSC results showed that the curing temperature of EP/DDS/DIB mixture was much lower than that of EP/DDS mixture due to the catalytic curing effect of imidazole group. Although the Tg values of EP/DDS/DIB thermosets decreased in some degree, they were still obviously higher than that of EP/DDS/DOPO thermoset. The combustion tests indicated that DIB was a high-efficiency flame retardant for epoxy resin. The LOI value and UL94 rating of EP/DDS/DIB-0.75 sample reached 36.8% and V-0, respectively. In addition, the pk-HRR, av-HRR and THR of EP/DDS/DIB-1.0 thermoset were decreased by 57.2%, 37.9% and 36.0%, respectively, compared with those of EP/DDS thermoset. The studies concerning decomposition products in both condensed and gaseous phases revealed that the introduction of DIB brought about the formation of a protective intumescent char layer and the release of phosphorus-containing radicals and noncombustible nitrogen-containing fragments during combustion. DIB exerted bi-phase flame retardant effect on epoxy resin.

Subfields: Mechanical Engineering, Organic Chemistry, Polymers and Plastics

View Paper: https://www.semanticscholar.org/paper/7cfec5606a0cdac7a20590441313d060a0662dd8