Concentration dependence of the flory‐huggins interaction parameter of a polymer blend as determined by small‐angle X‐ray scattering experiments

Abstract

SynopsisDirect determination of the Flory-Huggins interaction parameter x of a polymer blend by small-angle x-ray scattering experiments is possible on the basis of the random phase approximation, if absolute intensities are measured. The usually superposed void scattering has to be properly accounted for. Investigations on a series of blends of polystyrene and poly(styrene-cobromostyrene) yielded x dependent upon the blend composition. x shows only slight variations.Scattering data also give the radii of gyration of the two components in the blend.

Discrepancy in determination of χ parameters by melting point depression versus small-angle neutron scattering in blends of deuterated polycarbonate and isotactic poly(methyl methacrylate)

“…1b). The excess SANS as seen here for all the dPC/iPMMA blends at small scattering angles leading to the deviations from linearity has been reported in the literature for a number of miscible blends and has been attributed to several sources, including uneven quenching, cavitation (Murray, Gilmer & Stein, 1985;Koch & Strobl, 1990), or residual phase separation (Clark et al, 1993).…”

“…1b). The excess SANS as seen here for all the dPC/iPMMA blends at small scattering angles leading to the deviations from linearity has been reported in the literature for a number of miscible blends and has been attributed to several sources, including uneven quenching, cavitation (Murray, Gilmer & Stein, 1985;Koch & Strobl, 1990), or residual phase separation (Clark et al, 1993).In the present study, the analysis was carried out with emphasis on the larger q values. In accordance with the above Ornstein-Zernike equation, the correlation distance and the parameter were determined from the linear slope at larger q and the intercept at q ¼ 0 (Fig.…”

Effect of Polydispersity on the Phase Behavior of Polymer Blends

“…The absolute intensity ( I ) as a function of modulus of the scattering vector, q , is shown in Figure 1, in which q is given by 4πsin( θ /2)/ λ , where θ is the scattering angle. The scattering from microvoids in the blend21 (which is important in the low q region) are corrected using the Porod law so that the intensity ( Iq 2 ) over the Debye region, which describes the random coil behavior of polymer molecules, is independent of q 8,22,23…”

Understanding polyanhydride blend phase behavior using scattering, microscopy, and molecular simulations

“…Provided that the voids have radii larger than the radii of gyration of the polymer chains, the constant, C; can be determined from the intercept of a plot of Iq 4 vs. q 4 [42]. The region over which this correction is fit was chosen as the region below the Debye region from the Kratky-Porod plot [30].…”