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The design and construction of an apparatus for studying the simultaneous small angle neutron scattering (SANS) and steady shear viscosity behavior of polymer melts and concentrated solutions is discussed. Successful operation of the device is demonstrated on a blend of 20 weight percent deuterated polystyrene and 80 weight percent poly(vinylmethylether). The effects of shear on the critical behavior of the blend are observed in the SANS behavior as a function of temperature and shear rate and indicate shear induced mixing behavior for the range of shear rates examined. The steady shear viscosity results alone are insufficient for detecting the transition from one to two phases. The examination of shear effects in polymer blends is important for understanding the critical behavior of binary systems. Technologically, knowledge of the phase behavior of polymer blends under shear are important for the design and improvement of commercial blend processing.

A fast, flexible, and relatively inexpensive minicomputer based Rayleigh spectrometer has been constructed. This spectrometer can utilize photon pulses in a most efficient way by performing autocorrelation and/or FFT with any desired number of channels. Its capability has been demonstrated by measuring large latex particles, small sodium dodecyl sulfate micelles, and a polydisperse latex-gamma-globulin system. Detailed timing diagrams and circuit schematics are also included.

Linear polyethylene Standard Reference Materials SRM 1482, 1483, and 1484 are certified for weight-average molecular weight M w . In this paper the experimental procedures employed for the determination M w for these materials by light scattering are described, and the techniques used to analyze the data and to estimate limits of systematic error are discussed.

The translational diffusion coefficients of the 45S and 50S states of the large ribosomal subunit of E. coli were determined from the spectral distributions of quasielastically scattered light with a 5 mW He-Ne laser as the source. The spectral analysis was performed by directly Fourier transforming the photocurrent and fitting to double-Lorentzian profile via a non-linear regression routine. A small amount (about 1%) of strongly scattering contaminants required the double-Lorentzian profile in order to extract the diffusion coefficients of the principal components. The results are: D 20 °, w(45S) = (1.79 ± 0.12) × 10 -7 cm 2 /sec, and D 20 °, w(50S) = (1.91 ± 0.06) × 10 -7 cm 2 /sec, the latter being in accord with those reported in the literature. The transition from the 50S state to the 45S state is not attended by a change in its molecular weight if the partial specific volumes are assumed to be the same.