Abstract: A novel epoxy resin containing phosphonite was synthesized. First, dichloromethyl phosphine was reacted with bisphenol A to form phosphonite-containing bisphenol A, which was further reacted with epichlorohydrin to obtain phosphonite-containing epoxy resin. The structure of the product was characterized with FTIR and gel permeation chromatography (GPC). The epoxy value and phosphorus content were measured using HCl-acetone titration and molybdenum blue method. The thermal stability, flame retardant, and mechanical properties of cured epoxy resin were also investigated. It was foumd that number-average molecular weight (Mn, GPC), weight-average molecular weights (Mw, GPC) were 387, 404 g/mol , respectively. Epoxy value and phosphorus content were 0.437 and 4.3 wt %, respectively. The cured epoxy resin exhibited good thermal stability and flame retardancyt with limit oxygen index of 38 %. The tensile strength, tensile modulus, elongation at break, and impact strength of cured epoxy resin were 25 MPa, 975 MPa, 5.3 %, and 24.8 kJ/m2, respectively.

Key words: phosphonite-containing epoxy, synthesis, flame retardant, thermal stability, mechanical property