A poly (vinyl chloride diethyl maleate) copolymer has been fractionated by repeated precipitation method. All fractions and the unfractionated sample have been characterized by viscometry

dynamic osmometry

Zimm static osmometry

light scattering and gel permeation chromatography. After correction for polydispersity

a monodis-persed [η] -M relationship has been obtaind:[η] = 1.99 × 10-3M0.87 (ml/g

at 25℃

in cyclohexanone)For the copolymer solution in THF

the second virial coefficient a decreases as the molecular weight increases. The relationship is.