Toshiaki Matsunaga

Surface energy analysis of several organic polymers: Comparison of the two-liquid-contact-angle method with the one-liquid-contact-angle method

Abstract The dispersion force component of surface tension γ S d and the nondispersive interaction energy at the water/solid interface (or the nondispersive work of adhesion) I SW n were evaluated for poly-(tetrafluoroethylene) (PTFE), poly(vinylchloride) (PVC) and poly(methylmethacrylate) (PMMA) by the analysis of the contact angles of water drops in hydrocarbon (the two-liquid-contact-angle method). The results were compared with those obtained by the one-liquid-contact-angle method with α -bromonaphthalene and methylene iodide as probe liquids, which is the method usually adopted. The values of γ S d from the two-liquid method were considerably larger than those from the one-liquid method, whereas their high sensitivity to error in the measurement of contact angles was taken into account. This discrepancy may be attributed to the neglect of the surface pressure π in the one-liquid method and the π values of the liquids used on the sample solids were calculated.

Gasification of coals treated with non-aqueous solvents. 3. Swelling behaviour of a single coal particle

Abstract The swelling behaviour of a single coal particle was examined photographically under rapid heating up to 870 K in an atmosphere of nitrogen or hydrogen, to test how treatment with liquid ammonia affected the swelling property of a Japanese bituminous coal. It was found that the treated particle began to swell at higher temperature than the untreated one in either atmosphere, and that the impregnation of the treated coal with a nickel salt appreciably suppressed the swelling of coal particles especially those of smaller particle size.

Sedimentation potential measurement of suspended glass powders in polymer solution

Abstract The electric charges on a glass surface reacting with a silane agent, γ-aminopropyltriethoxysilane has been examined. The sedimentation potentials of glass powders treated under several conditions were measured in xylene solutions of poly(butoxymethylmelamine). The powders heated in vacuo showed relatively large negative potentials, similar to those untreated, whereas those heated in air and those dried at room temperature gave less negative values, in that order. These results as well as the wettability by water of glass plates treated similarly and the sedimentation rates of powders in the polymer solution seem to support the idea that both the amino groups and the silanol groups adhere to the glass surface when heated in vacuo, while the amino groups are likely to be oriented towards the solution when heated in air.

Effects of epoxy resin on mechanical and thermal characteristics of poly(propylene oxide)/poly(butyl acrylate) networks

We report mechanical and thermal characteristics of a network composed of poly(propylene oxide) (PPG) and poly(butyl acrylate) crosslinked with tolylene diisocyanate. It was found that addition of about 4 wt % of an epoxy resin resulted in a higher mechanical toughness and less discoloration. Furthermore, it was found that the epoxy has a self-restoration function against thermal degradation of the network. The reaction mechanism between the network and the epoxy was investigated with infrared spectroscopy and 13C-NMR and the effect of the epoxy resin on the thermal stability and physical properties is discussed.

Adsorption of 1-butanol and 1-pentanoic acid from the aqueous solution on polymers. Analysis of the solid—liquid interfacial activity

Abstract In order to evaluate the solid—liquid interfacial activity of surfactant, contact angles of aqueous solutions of 1—butanol and 1—pentanoic acid on polypropylene (PP), polystyrene (PSt), polyvinyl chloride (PVC), and polymethyl methacrylate (PMMA) were measured. In many cases, discontinuities in slope of the contact angle θ vs concentration x (mole fraction) curves were observed, which was attributed to the change of the adsorption state from the horizontal to the vertical one. From these data, the decrease of the solid—liquid interfacial tension Δ γSL due to adsorption of surfactant was calculated. A parameter α, defined as lim ( ΔγSL x ), was introduced which was determined by extrapolation of Δγ - x plot. x → 0 The free energy of adsorption ΔG ads 0 was calculated from α value, and ΔG ads ∗ was calculated by: ΔG ads ∗ = ΔG ads 0 - NA 0γLV 0 cos θ 0 , where the last term represents the work of immersion of polymer into water per the area NA 0 of one mole of solute. The α values (and also − ΔG ads 0 ) are large for PP and small for PMMA. However, −ΔG ads ∗ values are small for PP and large for PMMA, which corresponds to the stronger interaction of PMMA with surfactant than of PP due to the larger polarity of PMMA.