Introduction Of Water Molecules Research Articles

In situ FTIR studies on prussian blue (PB)-, polyaniline (PAn)- and inner PB|outer PAn film-modified electrodes

The electrochemical properties of the Pt electrodes modified with Prussian blue (PB), polyaniline (PAn) and inner PB|outer PAn films have been examined using in situ Fourier transform infrared spectroscopy. At the PB-modified electrode, two strong peaks were observed at 2040 and 2110cm −1 owing to the bridging CN ligand in the PB structure. Three absorption bands appeared at 2780, 1015, and 982 cm −1 by stepping the potential to more positive than +0.2V vs. Ag|AgCl|l M KCl, which were assigned to various vibrational modes of water molecules coordinated to the high-spin Fe 3+ ion of PB. It is suggested that doping or undoping of potassium ions during the polarization of the Pt|PB electrode is accompanied by expulsion or introduction of water molecules respectively. At the PB|PAn-modified electrode, the absorption spectrum of PAn in the vibrational region was searcely affected by the underlying PB. The spectral intensity of the PAn on Pt|PB was much larger than that of the PAn on Pt, which is brought about by the K + ions being more effective as the charge-compensating ions in the PB|PAn film.

Introduction of Water Molecules into Water Repellent Fabrics by Rubbing.

Cotton cloth coated with a fluorocarbon polymer lost its water repellency with rubbing but the repellency was recovered by a heat treatment. Rubbing of the cloth reduced its water repellency due to detachment of the water repellent film covering the textile fibers. The repellency also decreased by the introduction of water molecules into the water repellent film by rubbing with other cloths. These observations were verified from changes in the contact angle of water and electric surface resistance caused by the heat treatment of the rubbed cloths. Water molecules could also be introduced by dipping the finished cloth into hot water. The introduced water molecules could not be removed completely by vacuum drying at room temperature.

Contribution to the Study of the Porous Structure of Polyacrylonitrile (PAN) Fibers The Effects of Heat Treatments

The porous fraction of PAN fibers, as shown by the formation in situ of silver sulfide, consists of radial paths which may or may not be associated with different distributions of micropores. The radial paths generally originate from microlobes or surface faults. The size of these porous zones, their number, and their mode of distribution in the structure itself are generally affected by technological operations involving tension and heat treatment. During the dry heat treatments, the fibers have a tendency to collapse, with a simultaneously decrease of the void sizes and appearance of new gaps of the same sort that characterized the original sample. The wet-phase treatments are usually accompanied by swelling of the fibers, limited when fibers are maintained at constant length. The introduction of water molecules into the struc ture produces distortions in the ordered zones and the structural rearrangement that results eliminates the initial porosity but leaves many fine micropores which are localized in the periphery of the fibers. This latter effect can be compared to a fiber-skin rupture.