Mitsuru Nakano

Preparation of Alkyl-Modified Silicon Nanosheets by Hydrosilylation of Layered Polysilane (Si6H6)

Alkyl-modified crystalline silicon nanosheets 2 were synthesized and maintained the crystal structure of a Si(111) plane, in which the dangling silicon bond is stabilized by capping with the alkyl group. 2 was characterized using UV-vis, Fourier transform-infrared, and X-ray photoelectron spectroscopies; X-ray diffraction; and X-ray absorption near edge structure analysis. A model structure is proposed that has a periodicity through the nanosheet surface.

Effects of amine, amine salt and amide on the behaviour of carbon dioxide absorption into calcium hydroxide suspension to precipitate calcium carbonate

The amount of carbon dioxide (CO2) absorption and calcium ion (Ca2+) concentration besides the pH of aqueous solution were observed during the CO2 absorption to precipitate calcium carbonate (CaCO3) from calcium hydroxide (Ca(OH)2). A reaction rate-limiting effect of an amount of CO2 absorption without any organic additives in the early stage of the precipitation was observed, which was attributed to an interruption effect of bicarbonate ion (HCO3(-)) on the precipitation of CaCO3. The improvement for the reaction rate was achieved not only by amine additives but also by neutral additives such as epsilon-caprolactam or amine salt. When the hexamethylene diamine was dissolved in the solution, successive change of crystal forms of CaCO3 aragonite to calcite in aqueous suspensions, confirmed by Ca2+ concentration change and X-ray diffraction, was concluded that a local environment around the amine group in aqueous solution and an interaction of the diamine with precipitated CaCO3 particles were important factors for these reactions.

Stereo- and regiospecific polymerization of cyclic conjugated dienes using highly active nickel catalysts

A markedly active and selective nickel catalyst, bis(allylnickel bromide)–methylaluminoxane, has been developed for cyclohexa-1,3-diene polymerization; the obtained crystalline polymer is a 1,4-linked cis-syndiotactic structure as determined by NMR and molecular dynamics using the COMPASS force field.

Improvement of Crystallization and Mechanical Properties of PLA by Means of Clay Nanocomposite

Some composite materials of poly (lactic acid) (PLA) with organophilic clays and an organic crystal accelerator (OCA) were prepared by melt compounding method to improve the rate of crystallization and mechanical properties, especially heat distortion temperature (HDT). The PLA/clay nanocomposite with 2.9wt% of finely dispersed organophilic clay and 1wt% of the OCA showed an exothermic peak corresponding to its crystallization at 1.9 minutes in the isothermal measurement of DSC at 100°C from its molten state, although PLA itself did not show a clear peak in the same procedure. Crystallized specimens of the nanocomposite were well obtained by injection molding when the hold time was set at more than 90 seconds. The HDT of the specimens that were held for more than 120 seconds in the mold exceeded 120°C. It is about 65°C higher than amorphous PLA. The crystallized specimen with 1wt% of the clay showed higher tensile modulus and Izod impact strength than the amorphous one.