Thermal properties of side‐chain phosphorus‐containing epoxide cured with amine

Abstract

AbstractGlycidyloxy diphenylphosphine oxide (GDPPO), a side‐chain phosphorus‐containing monoepoxide, was prepared. The compound, GDPPO, was mixed with 4,4′‐diglycidylether of bisphenol A‐type epoxy resin, DER 331. The reaction kinetics of the mixture, GDPPO–DER 331, cured with diethyltriamine (DETA), and the thermal decomposition properties of the thermosets were studied. For the GDPPO–DER 331–DETA curing systems, it was found that the activation energy of the curing reaction is 45.0 kJ/mol for the GDPPO–DETA system, and it decreases with the content of GDPPO. According to the method of Ozawa, the average apparent thermal decomposition activation energies of the thermosets with phosphorus‐containing monoepoxide are from 138.5 to 178.1 kJ/mol, which are higher than that of the DER 331–DETA system (95.8 kJ/mol). However, the lower crosslinking density and gel fraction of the system with the phosphorus‐containing monoepoxide, GDPPO, result in poor protection of the intumescent char during thermal decomposition; thus, the char yield and limiting oxygen index (LOI) of the cured specimens decrease with increasing GDPPO. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2741–2748, 2002; DOI 10.1002/app.10161