Journal ArticleDOI
Determination of polymer branching with gel‐permeation chromatography. I. Theory
E. E. Drott,R. A. Mendelson +1 more
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In this paper, the effect of long and short-chain branching in polymer molecules on gel-permeation chromatographic (GPC) separation is discussed, and the calculation of calibration curves for branched polymers is developed from the universal calibration technique based on the hydrodynamic volume concept.Abstract:
The effect of long-and short-chain branching in polymer molecules on gel-permeation chromatographic (GPC) separation is discussed. The calculation of calibration curves for branched polymers is developed from the universal calibration technique based on the hydrodynamic volume concept and previously established relationships for the effect of branching on molecular dimensions. Typical calibration curves are shown for different branching models and degrees of branching. As branching increases, the curves are shown to converge. Methods of characterizing branching and molecular weight distributions of franctions and whole polymers from GPC and intrinsic viscosity data are presented.read more
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Viscoelasticity and molecular parameters of commercial polymers
TL;DR: In this article, the influence of the accuracy of determining the molecular weight distribution (MWD) of polymers on the accuracy for calculating the mean molecular weight is discussed, which is satisfactory only for the description of similar MWD's.
Journal ArticleDOI
Rheology and molecular structure of polyethylene melts
TL;DR: In this paper, the molecular structure indices of low-density polyethylene (LDPE), i.e., the weighted average (wt.-av.) molecular weight, the number of branch points of long-chain branchings per molecule, and polydispersity index, were calculated from the data of gel-permeation chromatography, assuming that the Mendelson-Drott hypothesis holds.
Journal ArticleDOI
Calibration procedures for branched poly(vinyl acetate) in size exclusion chromatography.
T. A. Coleman,J. V. Dawkins +1 more
TL;DR: In this paper, a calibration procedure in size exclusion chromatography (SEC) involving the off-line experimental measurement of the intrinsic viscosity of polymers and fractions was examined, from which it was concluded that long-chain branching in samples of poly(vinyl acetate) obtained by the high conversion polymerisations at 353 K is of the hydrolysable type.
Journal ArticleDOI
Characterization of Randomly Branched Polydisperse Polymers
TL;DR: In this article, a new method for characterizing randomly branched polydisperse polymers is proposed, based on measurements of sedimentation velocity and diffusion of the branching polymer at the θ point of the corresponding linear polymer, which gives two apparent molecular weight distribution curves.