Fractionation of polyethylene

A procedure and apparatus are described for the large scale (50‐gram) fractionation of high‐density polyethylene by Desreaux's fractional extraction technique. Two samples of Ziegler polyethylene were fractionated by this technique and the intrinsic viscosity in decalin at 135°C. and molecular weight by light scattering were measured on the fractions. The relationship [η] = 4.6 × 10⁻⁴ M̄_w^0.73 was found to hold for molecular weights between 25,000 and 640,000. The samples differed in polydispersity, one having a broad distribution and the other a rather narrow distribution. Evidence for the sharpness of the fractions obtained by the new technique was provided by refractionating of one fraction and the resolation of two fractions which were combined and refractionated.