RADIOPAQUE EPOXY-RESINS

Transparent, X-ray contrast (radiopaque) epoxy resins were obtained by dissolving up to 25 wt % triphenylbismuth in the commercial epoxy res in prepolymers EPON-815, DER-330, DER-383, and DEN-431 which were then hardened with diethylenetriamine. The radiopacities of the mixtures w ere found to be proportional to the molar concentration of the radiopa que additive. The systems follow the relationship, R = R(o) + (R(a) - R(o))(V) over bar(a) M(a) where R, R(o), and R(a) are the radiopacitie s of the mixture, the pure epoxy resin, and triphenylbismuth, respecti vely (expressed in mm aluminum/mm resin); M(a) and (V) over bar(a) den ote the molar concentration and molar volume of the bismuth compound. R(a) for triphenylbismuth was found to be 7.4 +/- 0.2 mm Al/mm resin; the average value of R(o) for the four epoxies equals 0.16 +/- 0.1 mm Al/mm resin. The amount of amine required to harden the radiopaque res ins was far less for the epoxy novolac resin DEN-431 than for the thre e bisphenol-A based epoxies. The concentration of triphenylbismuth req uired to impart a radiopacity equivalent to that of aluminum measures 14.6 wt % in EPON-815, 14.8 wt % in DER-330, 14.9 wt % in DER-383, and 15.9 wt % in DEN-431. The radiopaque resins remain transparent indefi nitely, even when exposed to water. (C) 1995 John Wiley and Sons, Inc.