Copolyamides and copolyesters containing the phenoxasilin ring

Copolyamides and copolyesters containing the phenoxasilin ring were prepared from 2,8-dichloroformyl-10,10-diphenylphenoxasilin, isophthaloyl chloride and m-phenylenediamine or bisphenol A by interfacial polycondensation in chloroform-aqueous alkali mixture. They were obtained in yields of 80% or above and at relatively high viscosities up to 1.30 dl/g. The copolymers with high phenoxasilin content were freely soluble in dimethylacetamide, dimethylformamide and N-methyl-2-pyrrolidone, but decreasing phenoxasilin content led to copolymers with slight solubilities in these solvents; the copolyesters also dissolved in chloroform, m-cresol and phenol-sym tetrachloroethane (60:40 in wt%). Flexible transparent films were obtained from chloroform solutions of the copolyesters, but the films cast from DMF solutions of the copolyamides became brittle as the phenoxasilin content decreased. The phenoxasilin-containing copolymers hardly degraded below 400° and had good thermal stability. Introduction of the phenoxasilin ring into the polymer backbones by copolycondensation did not reduce thermal stability.     

Mechanical properties of fiber reinforced styrene-butadiene rubbers using surface-modified UHMWPE fibers under EB irradiation

Aiming to develop a high performance fiber reinforced rubber of SBR, a special technique using electron beam (EB) irradiation-induced graft-polymerization was applied to ultra-high molecular-weight polyethylene (UHMWPE) fibers. Although UHMWPE is chemically inert, N-vinyl formamide (NVF) could be graft-polymerized onto the UHMWPE fiber surface with this special technique. A maximum grafting percentage of 23.6% was achieved. The composite of SBR and grafted UHMWPE fibers with maximum grafting indicated a linear increase in the initial modulus and strength with the fiber content. At the fiber content of 10%, the initial modulus was improved about five times with respect to that of the pure SBR, while the strength was done about twice. At this moment, only a small reduction could be observed in the strain compared with that of pure SBR. The fiber reinforced rubber with a good performance was obtained in the system of SBR and grafted UHMWPE fibers.     

Reactions of sulfoxonium allylides with nitrile oxides and ring transformations of their reaction products

Reactions of allylides ($\text{1}$) with nitrile oxides ($\text{2}$) afforded furanylglyoxylate oxime ($\text{3}$) and 6H-l,2-oxazine ($\text{4}$). Ring transformations of $\text{3}$ and $\text{4}$ gave $\text{4}$ and pyrrolinone ($\text{6}$), respectively.     

Cationic polymerization of formaldehyde in liquid carbon dioxide. Part I

A cationic polymerization of formaldehyde which gave a high molecular weight polymer was studied in liquid carbon dioxide at 20–50°C. In the polymerization without any catalyst both the rate of polymerization and the molecular weight of the resulting polymer increased rapidly with a decrease in the loading density of the monomer solution to the reaction vessel, and also increased with an increase in the initial monomer concentration. From these results it was concluded that the initiating species could be ascribed to an impurity contained in the monomer solution. Both the rate of polymerization and the degree of polymerization of the polymer also increased with rising temperature. The carboxylic acid added acted as a catalyst in the polymerization because of increase in the polymer yield, the molecular weight of polymer formed, and the number of moles of polymer chain with increasing dissociation constant of acid used. It was concluded that the polymerization in liquid carbon dioxide proceeded by a cationic mechanism. Methyl formate had no influence on the polymerization, but methanol and water acted as a chain-transfer agent.     

A molecular-beam study of the collision dynamics of methane and ethane upon a graphitic monolayer on Pt(111)

Utilizing a supersonic molecular-beam scattering technique, the angular intensity distributions of alkane molecules (CH4 and C2H6) have been measured, which are scattered from a chemically inert and highly oriented monolayer graphite (MG) on Pt(111). A MG which covers the Pt(111) surface with a full monolayer is found to induce a large energy loss of alkanes during collision with the surface by phonon creation due to the large mass ratio of an alkane molecule with respect to MG. Based on the classical cube model, only applicable to the molecules without internal mode excitation, the effective masses of MG of 76 (six atoms of carbon) and Pt(111) of 585 (three atoms of platinum) are determined from rare-gas atom scattering data. Despite the difference in the degree of freedom between CH4 and rare-gas atoms, CH4 scattering is found to be well described by the simple hard-cube model as a result of the high symmetry of the CH4 structure. With the recently developed ellipsoid-washboard model, an extension of the hard-cube model to include some internal mode excitation of impinging molecules in addition to the surface corrugation, it is found that unlike CH4 the cartwheel rotation mode of C2H6 is significantly excited during collision, while the helicopter mode excitation is negligible on a flat MG surface.     

Distribution and dynamics of radionuclides and stable elements in the coastal waters off Rokkasho Village, Japan, prior to the opening of a nuclear reprocessing facility

A nuclear fuel reprocessing facility is currently under construction in Rokkasho Village, Aomori, Japan. After completion and start-up, this facility will discharge radionuclides into the Pacific Ocean through an outlet pipe set on the seafloor offshore. For future assessments of the stability of these radionuclides in the environment, a sufficient understanding of the behavior of radionuclides in this ocean ecosystem before the start-up of the facility is necessary. To understand the processes by which radionuclides and various other types of elements are eliminated from seawater, we measured the sedimentation flux of suspended particles in the coastal waters off Rokkasho Village where the sea emissions pipes will be placed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Dynamic coordination polymers with 4,4'-oxybis(benzoate): reversible transformations of nano- and nonporous coordination frameworks responding to present solvents

Reversible construction of a nanoporous framework from a nonporous framework has been found in the zinc(II) coordination polymer with 4,4'-oxybis(benzoate) (oba). [Zn(2)(oba)(2)(dmf)(2)].2DMF (1), which has 1 nm scale channels, transforms to the nonporous coordination polymer [Zn(oba)(H(2)O)] (2) with the loss of the open framework. Compound 2 on treatment with DMF reversibly yields nanoporous compound 1.