A Laser Light Scattering Study on Molecular Weight Distribution of Linear Polyethylene

Time-average and time-dependent intensity of light scattered by linear polyethylene (LPE), Dutch State Mines sample L30-4-6, in a good organic solvent, 1,2,4-trichlorobenzene at 135 "C, was measured as a function of polymer concentration at scattering angles between 35 and 145O. Molecular properties determined were the z-average radius of gyration, = 50 nm, the z-average hydrodynamic radius, (Rh-');l = 27 nm, the weight-average molecular weight, (M)w = 570, the weight distribution, Fw(M), and the second virial coefficient, Az = 1.5 X lom3 g" mL mol. The main purpose of this article was to determine F J M ) for a LPE based on (M)w, (R:),, A2, and the characteristic line width distribution G(r) computed from an inverse Laplace transform of the measured single-clipped time correlation function, Gk@)( 7). We have demonstrated thh nonintrusive technique to be particularly useful in obtaining an approximate Fw(M) for polydisperse synthetic high polymers which are difficult to characterize by more established analytical techniques such as gel permeation chromatography (GPC).