The paper is concerned with the conformational characteristics of polyacryl
onitrile in dilute solutions. The observed dependences of the solution prop
erties, P, on the molecular weight (P = K .M-3) in the oligomers and in the
ultrahigh molecular weight regions were quantitatively explained by the Ya
makawa theory that takes into account the effects of chain ends and chain s
tiffness and by the statistical mechanics theory.