No abstract

A novel epoxy system was developed through the in situ curing of bisphenol A type epoxy and 4,4Ј-diaminodiphenylmethane with the sol-gel reaction of a phosphorus-containing trimethoxysilane (DOPO-GPTMS), which was prepared from the reaction of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) with 3-glycidoxypropyltrimethoxysilane (GPTMS). The preparation of DOPO-GPTMS was confirmed with Fourier transform infrared, 1 H and 31 P NMR, and elemental analysis. The resulting organic-inorganic hybrid epoxy resins exhibited a high glass-transition temperature (167°C), good thermal stability over 320°C, and a high limited oxygen index of 28.5. The synergism of phosphorus and silicon on flame retardance was observed. Moreover, the kinetics of the thermal oxidative degradation of the hybrid epoxy resins were studied.

Two phosphorus-containing diamine compounds, bis(4-aminophenoxy)-phenyl phosphine oxide and bis(3-aminophenyl)phenyl phosphine oxide, were synthesized for use as curing agents of epoxy resins. Phosphorylated epoxy resins were obtained by curing Epon 828 and Eponex 1510 with these two diamine agents. For raising the phosphorus contents of the resulting epoxy resins, the phosphorus-containing epoxy, bis(glycidyloxy)phenyl phosphine oxide (BGPPO), was also used. These two diamine agents showed similar reactivity toward epoxies. Their reactivities were higher than DDS and lower than DDM. High char yields in TGA evaluation were found for all the phosphorylated epoxy resins, implying their high flame retardancy. The excellent flameretardant properties of these phosphorylated epoxy resins were also demonstrated by the high limiting oxygen index (LOI) values of 33 to 51.

A new phosphorus-containing oxirane, bis-(3-glycidyloxy) phenylphosphine oxide (BGPPO), was synthesized. Further curing BGPPO with diamine curing agents, dicyanodiamide (DICY), 4,4'-diaminodiphenylmethane (DDM), and 4,4'-diaminodiphenylsulfone (DDS), respectively, resulted in several phosphorylated epoxy resins. Compared with Epon 828, Eponex 1015, and DER 732, BGPPO showed relatively high reactivity toward diamine agents via DSC studies. Furthermore, the reactivity of the three curing agents toward BGPPO were found to be in the order of DDM > DICY > DDS. Thermal stability and the weight loss behavior of the cured polymers were studied by TGA. The phosphorylated resins showed lower weight loss temperatures and higher char yields than did the Epon 828-based resins. The high char yields as well as high limited oxygen index (LOI) values of the BGPPO-based resins confirmed the effectiveness of phosphorus-containing epoxy resins as flame retardants.

A new phosphorus‐containing oxirane bis‐glycidyl phenylphosphate (BGPP), and a diamine, bis(4‐aminophenyl)phenylphosphate (BAPP), were synthesized. Both of these two phosphorus‐containing compounds lead to phosphate‐containing epoxy resin via curing reaction. The kinetics of the curing reaction of BGPP with various curing agents, including BAPP, were studied. The introduction of electron‐withdrawing group into the compounds increases the BGPP and decreases the BAPP reactivity in the curing reaction. The thermal and the weight loss behavior of the cured epoxy resins were studied by TGA. High char yields (32–52%) as well as high limiting oxygen index (LOI) values (34–49) of these phosphorylated resins were found, confirming the usefulness of these phosphorus‐containing epoxy resins as flame retardants. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 565–574, 1997.