Abstract
AbstractA sample of a commercial low‐density polyethylene was fractionated and values of number − Mn and weight‐average Mw, molecular weights obtained together with intrinsic viscosities [η], measured in decalin at 135° and in a theta‐solvent, diphenyl at 118°. Results are compared with those obtained using samples of high‐density polyethylene, of narrow molecular weight distribution, in decalin at 135° and in diphenyl at 125°.Values of the z‐average mean square radius of gyration (S−2)z, are converted to the weight‐average unperturbed state. The branching parameters g and g1 thus obtained, indicate that long‐chain branching increases with increasing molecular weight. Intrinsic ivscosities under theta‐conditions for the low‐density polyethylene fractions lead to a relationship [η]θ = Kw0·20, agreeing with the treatment of Zimm and Kilb.Some of the approximations involved in the estimation of long‐chain branching are discussed.
Published Version
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