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In this work a cost-effective instrument for measuring the wettability of powder materials was designed and developed, which works on the modified Washburn method. The instrument measures the mass gain against time due to penetration of the liquid into the powder materials using a microbalance and LabVIEW-based data acquisition system. The wettability characteristic of different powders was determined from the contact angle using the modified Washburn equation. To demonstrate the performance of the developed instrument, the wettability of as-received corn starch and nano-coated corn starch powders was estimated with water as a test liquid. The corn starch powders coated with hydrophilic grade (Aerosil 200P) and hydrophobic grade (Aerosil R972) nanoparticles at different coating levels showed expected changes in their contact angle. Some of the results were also verified against the available standard instrument for wettability measurement and found to be consistent. The present configuration of the instrument costs about 500 US$ which is 15 to 20 times less than the available advanced models. The developed instrument is thus a cost-effective solution for wettability measurement which can be used for materials in food processing, pharmaceuticals, horticulture, textile manufacturing, civil engineering etc. The developed instrument is expected to help many small scale industries or research labs who cannot afford an expensive instrument for wettability studies.

The cholesteric mesophase of the PBLG‐BA system in concentrated solutions and in the gel phase has been investigated by static laser light scattering. The observed ‘distortion’ of the patterns in terms of their dependence on the azimuthal angle was studied. Effect of form‐optical rotation on the pattern is discussed. The manner of distortion in the Hv pattern determines the sense of cholesteric twisting. The observed scattering patterns are analogous to those obtained by previous investigators in other solvents. Quantitative measurements of the intensity as a function of scattering vector provide information on the sense and pitch of the cholesteric twisting, as a function of temperature and concentration. Optical microscopy studies reveal onset and build‐up of the cholesteric structure. Optical rotation and differential scanning calorimetry (DSC) studies support the conclusions obtained from light‐scattering experiments.

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SYNOPSISWe report the concentration and temperature dependencies of the diffusion coefficients obtained from dynamic light-scattering studies for the poly ( y-benzyl a, 1-glutamate) -benzyl alcohol (PBLG-BA) system. These studies were made at dilute and semidilute polymer concentrations, mainly in the isotropic phase. The measured translational and rotational diffusion coefficients in dilute solutions are consistent with predictions based on wormlike chain models. The mutual diffusion coefficient in semidilute solutions shows a marked deviation from scaling predictions, demonstrating the strong coupling between the translational and rotational motions. The measured time evolution of the scattered intensity after the PBLG-BA system is suddenly quenched into the gel phase demonstrates that aggregation is a significant mechanism in the formation of the gel phase.