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In this article, the deposition of TiO on cotton fabric using sol-gel technique has been described. Various process routes (pad-dry-cure, pad-dry-hydrothermal and pad-dry-solvothermal) were examined to impart a stable coating of TiO on fabric. The role of precursor concentration, process temperature and time of treatment were studied to aim at a wash durable, UV protective and self-cleaning property in the treated fabric. EDX and ICP-MS techniques were used to examine the add-on percentage of TiO on cotton fabrics treated via different routes. It has been found that the TiO remains largely amorphous and nondurable if it is given a short thermal treatment. To convert the deposited TiO to its anatase crystal form, a prolonged hydrothermal treatment for at least 3 h needs to be given. TiO deposition levels of less than 0.1% were found to be effective in imparting reasonable degree of UV protection and self-cleaning property to the cotton fabric. The self-cleaning ability of the treated fabric against coffee stain was also studied and was found to be related to the process route and the deposition levels of TiO .

SynopsisPolystyrene and its various alkyl and halo derivatives have been studied as homoelectrets and their stabilities under different environmental conditions determined. The stabilities of the homoelectrets prepared from these polymers depended on their volume resistivities, glass transition temperatures, and interactions with electron-acceptor impurities. Excellent stabilities were exhibited by the homoelectrets prepared from polystyrene, poly(vinyltoluene), poly(chlorostyrene), and poly(t-butylstyrene). It is postulated that the charged particles are trapped by the 7r-orbitals of the phenyl rings present in these polymers and that they are adversely affected by the presence of electron-acceptor compounds that generally form charge-transfer complexes with the phenyl groups.

SynopsisCharge stabilities of various polar polymer homoelectrets were determined. Although these electrets are reasonably stable in dry environments, they rapidly discharge when exposed to humidity. The rate of charge decay was found to depend directly on the ability of these polymers to absorb water under equilibrium conditions. Protection from humidity is obtained if these polar,polymers are coated on both sides with nonpolar polymers. If, however, two different polymer films are laminated, the electret behavior follows a pattern that can be explained on the basis of charging at the interface. Difference in stabilities of the electrets of polar and nonpolar polymers is attributed to the differing natures of the charge traps present in these two classes of polymers.