The critical surface tension of wool fibers was measured using the sink-float technique with various classes of test liquids. Nonpolar organic liquids and aqueous surfactants gave similar values of γ, but much lower values were obtained with butanol/water mixtures. Adsorption of butanol on the surface of the fibers is thought to be responsible for the low values of γ in the latter case. Removal of lipid material from the surface of fibers by extraction increases γ from 30 mN/m to 37 mN/m, similar to that obtained for horn keratin or polypeptide material. Exposure of fibers to a corona discharge in air at atmospheric pressure also increases γ.

The effect of added chemically inactive gases, helium, argon, carbon dioxide and sulphur hexafluoride, on (i) the rate of photochlorination of vinylidene chloride and cis-l,2-dichloroethylene, (ii) the rate of geometrical isomerization of cis-l,2-dichloroethylene, has been studied. The effects have been interpreted in terms of the deactivation of vibrationally excited chloroalkyl radicals for which a mean lifetime of the order of 10-7 sec is estimated. Relative efficiencies of deactivation by inert gases and by chlorine and olefin molecules have been estimated. Some data relating to the geometrical isomerization of cis-and trans-1 ,Zdichloroethylene given in part 5 have been corrected and amplified.

The sorption by wool of two water-soluble, anionic polymers based on poly-(propylene oxide) with molecular weights in the range 3,000-10,000 has been investigated. Despite their high molecular weights, both polymers readily diffused into wool fibers under acidic conditions. Staining tests show that the polymers are preferentially sorbed into the orthocortex of the fibers.

No abstract

The durability of wool/polymer adhesive Joints in wash liquors of different surface tension was determined by measuring the rate of felting shrinkage of polymer-treated wool sliver and fabric in each liquor. The rate of felting shrinkage increased as the surface tension of the liquor decreased. This trend in the rate of felting shrinkage of polymer-treated wool agreed well with the trend in the magnitude of the thermodynamic work of adhesion of a wool/polymer “adhint” in different liquids, calculated assuming only secondary bonding forces across the wool/polymer interface. Limitations of the theory are discussed