Papers by Author: Yin Chun Hu

Abstract: We report a peculiar surface of poly(ethylene oxide) (PEO) film from droplet of water-PEO solution dried at heating substrate. The drying process contains two stages. The contact line is pinned initially. When substrate temperature reaches 60 °C, it starts to recede and continues to leave a film. The resulted film contains an edge-ring and middle-step surface profile. The rheological properties of PEO solution were studied. We found that capillary flow is dominant in the first drying stage and Marangoni flow appears because concentration gradient induced strong Marangoni effect and high temperature induced sharply decrease of viscous stress resulted in the contact line receding in the later drying stage. We confirm that the ringlike deposit is formed by outward capillary flow and the step in the middle is formed by Marangoni flow which carries solute to the inner, and these flows compete with the viscous force.

Abstract: Magnetic nickel nanoparticles are prepared by NaBH₄ reducing agent in AOT reverse microemulsion, the influence of water content on the morphology and magnetic properties of nickel nanoparticles are investigated by TEM study, size distribution, XRD characterization and magnetization curves. The results show that spherical and polydispered particles are obtained in microemulsion. The dimension and polydispersity of particles increased with the increasing of water content. Magnetization curves clearly indicate a ferromagnetic behavior with high coercivity values. At water content of W₀=41.7, the product has a high saturated magnetization 70.68 emu/g with its residual magnetizations 28.02 emu/g, higher than the sample obtained at water content of W₀=13.9.

Abstract: Montmorillonite was introduced into the multicomponent epoxy resin by using the intercalation polymerization. Intercalation effect of epoxy/montmorillonite composite system and the influence of the addition of montmorillonite on the glass transition temperature (Tg), mechanical properties and barrier of H2S to coating under high temperature and pressure conditions were investigated. The results showed that it was easy to intercalate epoxy resin into the organic montmorillonite layers, and the interlayer spacing of Montmorillonite was further swelled. In addition, the epoxy/montmorillonite nanocomposite coating with intercalated/ exfoliated structures were prepared. Compared to pure epoxy coating, the heat resistance and mechanical properties of epoxy/montmorillonite nanocomposite coating were slightly improved, and the barrier efficiency to H2S was substantially increased under high temperature and pressure oil-gas environment.