Koji Shimoda

Effects of Chemical Vapor Surface Modification of Glass Air Filter with Fluoroalkylsilane on Its Particle Trapping Efficiency

With a view to improving the efficiency of particle trapping, the surface of glass air filters was chemically modified with (heptadecafluorodecyl)trichlorosilane (HFTS) in a vapor phase. The efficiency was greatly increased by the treatment with concurrent suppression of the rise in the resistance to air flow within a low level, while the treatment with (hexyl)trichlorosilane (HTS) was ineffective. Molecular orbital calculations on the clusters modeling the surface adsorbates indicated that the large dipole moment along the molecular chain axis of HFTS is responsible for the improvement of the particle trapping efficiency. It was further suggested that a well-ordered monolayer with the molecular orientation perpendicular to the surface plane serve for this purpose.

A Quantitative Method for Evaluating the Hydrophilicity of Sulfonated Polypropylene Mesh Sheets

The surface of polypropylene mesh sheets was sulfonated by heating in liquid H 2 SO 4 . Diffuse reflectance Fourier transform infrared spectroscopy confirmed that SO 3 H groups are immobilized on the surface and their amount increases with increasing treatment time. The hydrophilicity of the samples was examined by following the time-dependence of the uptake weight of H 2 O (W L ) after immersion in liquid H 2 O. It was shown that the intercept in the plots of In W L vs. In t provides quantitative information on the wetting property of the surface. The simulation based on Washburns theory predicted the limited intercepts with sulfonation.