Laser light scattering characterization of polyethylene in 1,2,4-trichlorobenzene

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Journal of Physical Chemistry


Angular distribution of absolute scattered intensity and translational diffusion coefficients of linear (DSM-L30-4-6) and branched (IUPAC sample α) polyethylene in 1,2,4-trichlorobenzene have been studied by using classical light scattering measurements and Rayleigh line width spectroscopy over a range of concentrations at 135° C. The light scattering intensity studies were used to compare our results on the molecular characterization of polyethylene samples with those reported by the Dutch State Mines (DSM) and by the Working Party, which was formed under the auspices of IUPAC,1-5 Evaluation of the time correlation function was performed according to the methods of cumulants, histogram, multiexponentials, and regularization. In addition to determining the molecular weight M0, the radius of gyration (r82)21/2 , and the second virial coefficient A2 of the IUPAC or branched polyethylene (BPE), we were able to establish the variance µ2/r2 of a moderately broad normalized line width distribution function G(r) for the DSM sample and to approximate G(r) by using either the time range of photon correlation measurements, and by taking account of molecular interactions at finite concentrations, it is feasible to obtain an estimate of the molecular weight distribution of moderately broad commercial polyethylene samples by using laser light scattering. Limitation of the Laplace inversion problem for very broad molecular weight distribution polyethylene, such as the IUPAC α sample, is discussed.


© 1984 American Chemical Society