For the fractionation we used a copolymer with the following composition (mole y!): BMA : GMA : MA 74.10 : 9.65 : 16.25, synthesized in 30% cyclohexanone solution at 80” with azobisisobutyronitrile as described in [l]. Then the specimen was fractionally precipitated by water from a 2% dioxane solution at 20’. The jelly-like fractions separated were washed in a mixture of dioxane and water and dried to constant weight in a vacuum cupboard. The molecular weight, intrinsic viscosity and composition of the copolymer were determined for each fraction, the latter from the carboxyl and glycidyl group content. The molecular weight was determined by light scattering in acetone solution at 20’ on a NFM-66 nephelometer at an angle of 90”. The solutions were passed through porous glass filters to remove dust. The molecular weight was derived by graphical extrapolation of the concentration dependence (KC/R,,) = l/M to inllnite dilution where K = ( 2nani/N1*) ( An/c)a; K is a constant, x=3.14, no is the refractive index of the pure solvent, N the Avogadro number, t= 6.461 x lo-* mm the wave length of the incident light, c the concentration of the solution (g/100 ml), R,, the excess scattering, An/c=0.148 the concetration gradient of the refractive index, which was established on an ITR-2 interferometer. The viscosity of the fractions was measured on an Ubbelohde viscometer at 20+O*05° in acetone solution. The intrinsic viscosity was found by extrapolating the reduced viscosities &a/c) to in6nite dilution. The oarboxyl group concentration was determined by titrating weighed amounts of the copolymer dissolved in acetone with a 0.05 N solution of potassium hydroxide using phenolphthalein. The glycidyl group concentrationwas established by the method of King [2] using acetone as solvent. DISCUSSION