John E. Sohn

The determination of interfacial tension by video image processing of pendant fluid drops

Abstract A novel technique is presented for the determination of interfacial tension by analysis of axisymmetric fluid drop profiles. The technique couples recent developments in digital image acquisition and processing with modern methods for robust shape comparison. The entire algorithm for drop profile acquisition and analysis is executable on a personal computer and includes a facility for rotationally resistant smoothing of the drop profile. The general performance of the robust shape comparison algorithm and improvement in accuracy resulting from smoothing is illustrated by analysis of simulated pendant drop profiles. The overall performance of the image acquisition hardware and profile analysis software is assessed by evaluating the surface tension of glycerin. The resultant value of 62.6 ± 0.3 dyn/cm (at 24.2 ± 0.2°C) agrees well with the literature data for glycerin.

The measurement of polymer surface tension by drop image processing: Application to PDMS and comparison with theory

Digital image processing techniques are applied toward the determination of polymer surface tension by pendant drop measurements. Experimental values for poly(dimethylsiloxane) as a function of molecular weight and temperature correspond well with previous measurements of poly(dimethylsiloxane) surface tension, testifying to the applicability of the new technique. Current thermodynamic treatments are found to provide excellent predictions of poly(dimethylsiloxane) surface tension for molecular weights of 3900 and 75,000 at temperatures ranging from 20 to 120°C. Theories developed by K. M. Hong and J. Noolandi (Macromolecules, 14, 1223, 1981) and Y. Rabin (J. Polym. Sci. Polym. Lett. Ed. 22, 335, 1984) yield predictions within 5% of t he experimental results for the materials and conditions studied. The proposed relation of Sanchez

Improved Matrix-Filler Adhesion

Abstract Enhanced matrix-filler adhesion is realized after filler treatment with a surface treatment process. The hydrosol/coupling agent treatment was applied to a wide range of inorganic and organic fillers, and adhesion to a variety of matrix resins was improved. Scanning Electron Microscopy (SEM) was used to determine the locus of failure in the filled systems. The locus of failure shows the relative degree of adhesion between the filler and the polymer matrix. Significant improvement in adhesion in humid environments is also observed.

Exceptional Second-Order Nonlinear Optical Susceptibilities in Organic Compounds

Abstract Molecular second-order nonlinear optical susceptibilities (β) of donor-acceptor substituted organic compounds compunds were measured in dimethyl sulfoxide solution using electric fields induced second harmonic gneration. The experimental data and theoretical interpretations of the trends led to compounds with values of β useful for imparting high bluk susceptibilities on polymeric materials. Exceptionally high values of β were reached relative to analogues of similar size through the use of tricyanovinyl and dithiolylidenmethyl substituents.