High‐temperature dynamic laser light‐scattering characterization of polyethylene in trichlorobenzene

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Abstract
Polyethylene samples were characterized in trichlorobenzene at 135°C by high‐temperature dynamic laser light scattering (LLS). Precise measurements of the intensity‐intensity time correlation function permit us to make a Laplace inversion to obtain an estimate of the normalized translational diffusion coefficient distribution [G(D)]. After establishing a calibration between the translational diffusion coefficient (D) and molar mass, by using six moderately dispersed polyethylene samples, we were able to transform G(D) to molecular weight distribution (MWD), and to calculate the weight average molecular weight (Mw), which weights were comparable with the ones obtained by using static LLS and size exclusion chromatograph (SEC). The advantages and limitations of using dynamic LLS as a routine method to characterize of polyethylene are discussed. © 1993 John Wiley & Sons, Inc.