Tetsuya Tsujii

Weight changes of the fibre/matrix interface in GRP panels immersed in hot water

Abstract The weight-change behaviour of the fibre/matrix interface in composite panels consisting of randomly orientated E-glass-fibre continuous strand mat in unsaturated polyester has been studied. Two matrix resins of different filler content were used. GRP and plain resin specimens were immersed in hot water (60°C and 80°C) and the weight of the specimens was measured as a function of time. The weight changes were evaluated in terms of three parameters: apparent weight gain, net weight gain and weight loss. The weight changes of the fibre/matrix interface were obtained from the differences in the weight changes of the GRP and the unreinforced resin. Water absorption at the interface occurred after water absorption of the matrix resin reached almost saturation level. Weight loss due to dissolution of binder from the interface occurred after water penetration into the interface. Debonding occurred at the fibre/matrix interface as a result of water penetration, and, in consequence, the binder dissolved into water at the interface. The net weight gain and weight loss of the interface increased linearly with the square root of immersion time, and the filler had little effect on these phenomena.

Metal-Insulator Transition in Nearly Stoichiometric CaVO3

A metal-to-insulator (MI) transition in perovskite-type vanadium oxide CaVOy in the vicinity of oxygen stoichiometry is reported. In spite of good metallic conductivity for Stoichiometric CaVOy (y=3.00), very slight oxidation (y\cong3.05) causes the system to be insulating but does not induce any significant structural changes. This type of MI transition is contrary to that reported on another d1 system LaTiOy, which is a Mott-Hubbard insulator for y=3.00 but becomes metallic by oxidation. We suggest that in CaVOy, extra oxygens primarily induce additional scattering which causes the metallic CaVO3 to be insulating.

Heat seal processing by using various seal bar shape

In this study, oriented polypropylene/cast polypropylene (OPP/CPP) laminated films were heat sealed by various stainless mesh sheets in order to evaluating the effect of heat sealing bar shape on heat sealed properties. The heat sealed conditions were set at heat sealed time of 1.0 s with a pressure of 0.3 MPa at various heat sealed temperatures of 100 to 120 °C. The difference of higher order structure of these films was discussed on the basis of results of micro-Raman spectroscopy, DSC and peel test. From the result, it was found that peel strength was affected by the heat sealing bar surface shape. It can be note that the relationship between the internal structure change and properties of the heat sealed films could be clarified by analyzed at very small area of the heat sealed films on the basis of the results by using micro-Raman spectroscopy imaging.

Metal-to-insulator transitions in CaVOy.

Abstract A metal-to-insulator transition in CaVO y by varying the oxygen stoichiometry is reported. Stoichiometric CaVO y (y=3.00) shows good metallic conductivity but slight oxidation (y≅3.05) causes the system to be insulating without any significant structural changes. This behavior is contrary to that seen in another d 1 system LaTiO y , which is a Mott insulator for y=3.00 but becomes metallic by oxidation. We suggest that, in CaVO y , oxygen defects primarily induce additional scattering which causes the metallic CaVO 3 to be insulating rather than add extra carriers.