Synthesis of π-conjugated organoboron polymers by haloboration-phenylboration polymerization of aromatic diynes

π-Conjugated organoboron polymers were prepared by haloboration-phenylboration polymerization beween diyne monomers and bromodiphenylborane. The polymerization was carried out by adding a slightly excess amount of bromodiphenylborane to a tetrachloroethane solution of diynes at room temperature under nitrogen and stirring the reaction mixture for 4 hours at 100°C. The obtained polymers were soluble in common organic solvents such as THF and chloroform. Their molecular weights were estimated to be several thousands by gel permeation chromatographic analysis. In UV-vis absorption spectra, bathochromic shift of λ_max and absorption edge in comparison with the corresponding monomers were observed, which indicates the π-conjugation via vacant p-orbital of boron atom.     

Combustion Mechanism of Consolidated Mixtures of 5‐amino‐1H‐tetrazole with Potassium Nitrate or Sodium Nitrate

Recently, 5‐amino‐1H‐tetrazole is developed for practical use as a substitute for sodium azide, which is conventionally used as a fuel component of gas generating agents for automobile airbags. In this study, the combustion mechanisms of the mixtures 5‐amino‐1H‐tetrazole/potassium nitrate and 5‐amino‐1H‐tetrazole/sodium nitrate have been examined. It has been found that the Granular Diffusion Flame model is applicable to the tested samples even when a molten layer exists at the burning surface. In addition, it is shown that within the pressure range of 1–5 MPa, the greatest factor which affects the burning rate is the diffusion process. It is also demonstrated that the fuel component decomposes first, and the oxidizer decomposes next. Meanwhile, it has also been confirmed that the burning rate increases with an increase in pressure because the flame approaches the burning surface and the amount of heat transfer to the solid phase increases. In spite of a decrease in the amount of heat transfer from the gas phase to the solid phase and an increase in the thickness of the condensed phase reaction zone for a mixture with higher fuel content, there are little differences in the burning rates probably because of an increase in the rate of decomposition of the solid phase.     

Rheological properties for binary blends of i-PP and ethylene-1-hexene copolymer

The dynamic viscoelastic properties for binary blends consisting of an isotactic polypropylene (i-PP) and an ethylene-1-hexene copolymer (EHR) were investigated in both solid and molten states to reveal the relation between miscibility in the molten state and the morphology in the solid state. In this study, two types of EHRs were employed: “ethylene-rich” EHR and “1-hexene-rich” EHR. The blend of i-PP and EHR of 30 mol % 1-hexene content shows a very long time relaxation due to the phase separation in the molten state. The blend film shows two separate glass-relaxation processes associated with those of the pure components. These indicate that the blend shows phase-separated morphology in the solid state as well as in the molten state. On the other hand, dynamic moduli in the molten state of the blends of i-PP and EHR of 57 mol % 1-hexene were found to be intermediate between those of individual pure components. Furthermore, the apparent activation energy of the blends is constant and is identical with those of i-PP and the EHR. The blend films show a single glass-relaxation process at the temperatures between those of the pure components, indicating that the EHR molecules are incorporated in the amorphous region of i-PP in the solid state. Accordingly, it was found that the polymer miscibility in the molten state for the i-PP/EHR blends directly affects the morphology in the solid state. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 467–474, 1997     

An occurrence mechanism and method for improving the output waveform distortion of CMOS logic ICs

Waveform distortion at a signal edge generally falls into two categories: hysteresis type and non-hysteresis type. Non-hysteresis type distortion has a flat portion in the signal transition, but it will not give any serious problem except for timing oriented circuits. Hysteresis type distortion which makes a round trip between two threshold levels will affect logic judgment. Incorrect information will be transmitted if the signal is seriously distorted. It is important to understand the relationship between spectrum modification and waveform distortion. In this paper, an occurrence mechanism for the output waveform distortion of CMOS logic ICs is analyzed and an improved method for dealing with these distortions is proposed. Waveform distortion occurs when series resonance circuits are composed on the load side of the driving device. The relationship between the rise time per period [%] and the limit frequency at which waveform distortion begins to appear will be made clear. There are two methods to improve waveform distortion. One is to change the spectrum distribution of a rectangular wave by modifying the rise time. The other is to change the resonance frequency by modifying such parasitic elements as inductance (pattern length) and capacitance (number of ICs). © 1998 Scripta Technica. Electr Eng Jpn, 123(3): 11–18, 1998     

An experimental study on static solid-liquid phase equilibrium in the pores of a porous medium

The so-called Clausius-Clapeyron equation, that is, the static equation of state for “solid-liquid-porous media” systems without liquid flow through the pores, has been experimentally examined by measuring the pore liqiud pressure at the solid-liquid interface in order to verify the accuracy of our method of measuring unfrozen pore liquid pressure. Several series of experiments have been carried out using water-saturated Ohya-Tuff as a porous medium specimen cooled from the top down. In these experiments, the solid-liquid interface was always fixed at the top surface of the specimen. The experimental results imply that the measurement method should be useful in determining the relative value of the unfrozen pore water pressure. © 1998 Scripta Technica, Inc. Heat Trans Jpn Res, 26(2): 69–83, 1997     

Preparation of polydimethylsiloxane/polystyrene interpenetrating polymer network membranes and permeation of aqueous ethanol solutions through the membranes by pervaporation

Polydimethylsiloxane (PDMS)/polystyrene (PSt) interpenetrating polymer network (IPN) membranes were prepared by the bulk copolymerization of styrene and divinylbenzene in the PDMS networks. The interpenetration of PDMS and PSt resulted in the improvement of mechanical properties of PDMS. Transmission electron microscope (TEM) observation demonstrated that the PDMS/PSt IPN membranes have microphase-separated structures consisting of a continuous PDMS phase and a discontinuous PSt phase. When an aqueous ethanol solution was permeated through the PDMS/PSt IPN membranes by pervaporation, the PDMS/PSt IPN membranes exhibited ethanol permselectivity, regardless of the PDMS content. The effects of their microphase-separated structures on the permeability and selectivity for aqueous ethanol solutions are discussed experimentally and theoretically. © 1996 John Wiley & Sons, Inc.     

Combustion of Ti and Zr Particles with KNO3

This paper describes the thermochemical properties and combustion characteristics of pyrolants consisting of Ti/KNO₃ and Zr/KNO₃ mixtures. Differential thermal analysis (DTA) and thermogravimetry (TG) were conducted in order to elucidate the reaction processes of these pyrolants. The results of the experiments suggest that Ti particles react exothermically at 970 K with the decomposed gases of KNO₃, and Zr particles react also exothermically at 700 K with liquified product of KNO₃. Burning rates of the pyrolants were measured with a chimney type strand burner which was pressurized with argon gas. The burning rate of Ti/KNO₃ is more sensitive to pressure than that of Zr/KNO₃. The results indicate that a major exothermic reaction on the combustion wave of Zr/KNO₃ pyrolants is in the condensed phase. The burning rates of both pyrolants are dependent on the oxidizer/fuel ratio and initial temperature of the pyrolants.