In acrylic-silicone polymer solutions, silica micro particles were synthesized by addition of tetraethoxysilane and hydrophobic silane coupling agent. The surface properties of the coating deposited with composite silica dispersions were examined. The effect of added amount of H2O in reaction solutions on contact angles, haze values, and mean surface roughness (Mr) were also investigated. The diameters of the particles (Dn), contact angles and Mr were larger with increasing amount of H20 in preparation of colloid solutions. Further increasing the amount of H20 (>10-15vol%) abrupt increase in contact angles (>150°), Dn and Mr were observed. From these results, two major mechanisms yielding water repellency were considered. One was the region where contact angles increased with increase of the surface roughness (Wenzel eq.), and another was above a certain threshold of roughness; air pockets were generated by rough surface under a water droplet and drastic increase in contact angles were observed (Cassie-Baxter eq.).

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We developed a delamination evaluation diagram of glass fiber reinforced plastics/stainless steel adhesive joints by using stress singularity parameters. Using this diagram, we can evaluate the delamination strength of adhesive joints. First, we performed static tests on double lap adhesive joints and T-type adhesive joints. We developed a device that applies contact pressure to glass fiber reinforced plastics/stainless-steel double lap adhesive joints. The device is composed of a bolt adhered to a strain gauge for controling contact pressure. Using this device, we investigated the effect of contact pressure on the delamination strength of double lap adhesive joints. We applied tensile shear stress to double lap adhesive joints in order to apply contact pressure to their adhesive interfaces. We found that the delamination strength of the double lap adhesive joints increased with increasing contact pressure. On the contrary, when we applied compressive shear stress to the double lap adhesive joints, the delamination strength stayed constant. We therefore conclude that the delamination strength of double lap adhesive joints is dominated by normal stress when contact pressure under tensile shear stress is applied. On the other hand, it was dominated by shear stress when contact pressure under compressive shear stress was applied. Second, we analyzed stress singularity parameters on double lap adhesive joints and T-type adhesive joints by using FEM. Stress distributions near the bonding edge could be expressed by the stress singularity parameters. Finally, we made a delamination evaluation diagram using stress singularity parameters. We can evaluate the delamination strength of adhesive joints using this diagram.

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The following experiments were carried out in order to clarify the reason of the excellent wood bonding performance of AA PVA when used as an adhesive. The surface activity performance of AA PVA was evaluated, and the relationship between the pMDI dispersion property in the PVA aqueous solution and the ability to consume isocyanate (NCO) groups was examined in comparison with ordinary PVA, which was used with varying degrees of polymerization and varying quantities and distribution of hydrophobic groups introduced into the side chain. By the measurement of the surface tension of various PVA aqueous solutions and the interfacial tension between the various PVA aqueous solutions and n-hexane, it was found that the AA PVA aqueous solution has low surface tension and low interfacial tension with n-hexane. By testing pMDI dispersion in the various PVA aqueous solutions, the AA PVA aqueous solution was found to have high oil component dispersion performance and to have the ability to disperse the oil component in aqueous solution into smallerparticles than ordinary PVA does. AA PVA also demonstrated rapid consumption of NCO groups in the PVA aqueous solution. From the above mentioned, the AA group was found to have excellent interface activity, not only as a hydrophobic group, but also as a functional group, with reactivity that disperses the oil component into aqueous solution.

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