Preparation of a Novel Phosphorus-Nitrogen Containing Novolac Curing Agent for Epoxy Resin and flame-retardancy of its cured epoxy resin

ABSTRACT

In this study, DICY (dicyandiamide)-containing novolac (NN) was first prepared, and then DOPO (9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) was introduced to react with the unsaturated bonds from DICY to obtain a novel phosphorus-nitrogen-containing novolac resin (PNN), which was used as a curing agent for epoxy resins. The curing condition was confirmed by a non-isothermal curing kinetics study. The thermal stability and flame retardancy of the cured epoxy resin system were studied by thermogravimetric analysis (TGA), limited oxygen index (LOI) measurement, UL-94 test and cone calorimeter. The morphology of the burned chard residues was observed by Scanning electron microscopy (SEM). The results show that epoxy resin cured by the prepared PNN curing system presents excellent flame retardancy. The cured resin system, which contains only 1.31wt% phosphorus and 2.48wt% nitrogen, can achieve UL 94 V-0 rating.

KEYWORDS:

• P-N-containing novolac
• curing agent
• flame retardancy
• P-N synergistic effect

Acknowledgments

The authors are grateful for the financial support by the National Key R&D Program of China (2017YF0308100), Ministry of Education Project (6141A02011704) and The Open Fund of the State Key Lab of Pulp and Paper Engineering (201834).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by National Key R&D Program of China [2017YF0308100];The Open Fund of the State Key Lab of Pulp and Paper Engineering [201834];Ministry of Education Project [6141A02011704].