“…Since analysis of data on the dependence of the intrinsic viscosity on molecular weight indicates that b a=M L is about the same for PnBuA and poly(ethyl acrylate), PEA [15], the published data on h as a function of DP w and DP c for PEA provide a convenient comparison with the data here on PnBuA, and will be introduced in the following. The simple expression gzl þ h ð3p À 2Þ=p 2 i ð1 À lÞ 7=3 (8) for g ¼ ðR 2 G Þ br =ðR 2 G Þ lin provides a close representation of g for star and comb-shaped branched chains, with p the number of branches and l the fraction of chain units in the backbone (e.g., tending to unity and zero as the chain adopts linear or star-shaped structures, respectively) [16]. It has been suggested that an equivalent expression with g replaced by the ratio b g ¼ ðR 2 G Þ long =ðR 2 G Þ lin ¼ M long =M be used to estimate h for randomly-branched chains, where ðR 2 G Þ long and M long are the mean-square radius of gyration and the molecular weight, respectively, of the longest linear sequence that exists in the branched structure [17].…”