Abstract: This paper presented the fractionation of the amorphous polyepichlorohydrin sample with a high molecular weight by reprecipitation with toluene as the solvent and ethyalcohol as the precipitant (50℃).The intrinsic viscosities [η] of the narrow distribution fractions in the solvents cyclohexanone (35℃) and tetrahydrofuran (25℃) were determined, the average values of the constants of Huggins equation and kraemer equation were obtained by calculation as K' = 0.360,β=0.146(in THF) ; K' = 0.356,β=0.148 (in cyclohexanone).The weight-average molecular weight of the fractions were measured experimentally by the low angle laser light scattering (LALLS) photometer, and the Mark-Houwink equations were calibrated as [η]= 2.37 × 10^-5M_w^0.79(dL/g,THF, 25℃), [η]= 1.36 × 10^-5M_w^0.85 (dL/ g, cyclohexanone, 35℃).The unperturbed parameters of molecular chains of polyepichlorohydrin were obtained according to the stockmayer-Fixman equation, k₀= 5.25 ×10^-4 (dL/g),σ=l.57,C_∞ = 4.91(THF,25℃);k₀= 4.97× 10^-4(dL/g), σ=l.54,C_∞ = 4.73(cyclohexanone, 35 ℃).

Key words: Polyepichlorohydrin, Mark-Houwink equation, Unperturbed molecular parameter, Low angle laser light scattering