Masaaki Takehisa

Radiation-Induced Polymerization of Methyl Methacrylate at High Pressure

Abstract Radiation-induced polymerization of methyl methacrylate (MMA) was studied up to 7500 kg/cm2 at 20°C. The rate of polymerization increased to 3000 kg/cm2 with overall activation volume ΔVpol‡ of -23.6 cm3/mole, and then the pressure dependence of the rate was very small in the pressure range between 3000 and 3700 kg/cm2. The rate of polymerization increased again above 3700 kg/cm2 up to the crystallization pressure of MMA (5500 kg/cm2) with ΔVpol‡ of -13.7 cm3/ mole with increasing pressure. The volume contraction by polymerization decreased with increasing pressure up to 3000 kg/cm2 but hardly decreased with increasing pressure above 3000 kg/cm2. The stereoregulzarity (triad probability) of PMMA changed slightly at 3000 kg/cm; above 3000 kg/cm2, syndiotactic addition decreased and heterotactic addition increased. Marked change in P-V isotherms of MMA, however, was not observed about 3000 kg/cm2. We concluded from these facts that an alignment of monomer molecules, which does not cause large volum...

Pressure-Volume Behavior of PMMA-MMA Coexistence System as Polymerized at High Pressure

Abstract The pressure-volume (P-V) isotherms were measured for the poly(methy1 methacrylate) (PMMA)-methyl methacrylate (MMA) coexistence system polymerized by γ-ray irradiation at various pressures. The P-V isotherm of the coexistence system polymerized below 3000 kg/cm2 was similar to that of the monomer. The specific volume of the coexistence system polymerized above 3000 kg/cm2 hardly changes in the pressure range between 3000 kg/cm2 and the polymerization pressure when measurements are made with successively decreasing or successively increasing pressures. The compressibility was of the order of 10−6 (kg/cm2)−1 in this pressure range. This indicated that the coexistence system polymerized above 3000 kg/cm2 behaves like a solid in this pressure range. Above the polymerization pressure, the compressibility was of the order of 10−5 (kg/cm2)−1, indicating that the coexistence system behaves as liquid. We concluded that the solid-like behavior of the coexistence system polymerized above 3000 kg/cm2 is cau...

Radiation-Induced Polymerization and Pressure-Volume Behavior of Acrylonitrile at High Pressure

Abstract Radiation-induced polymerization and pressure-volume (P-V) measurements of acrylonitrile (AN) were studied up to 8000 kg/cm2 in the temperature range of 6–72°C. P-V isotherms of AN have several small breaks, A phase diagram of AN was obtained from the breaking pressures and temperatures. Liquid phases were named LI, LII, and LIII, from low to high pressure. The polymerization behavior and volume contraction on polymerization changed in LI, LII, and LIII. The difference in entropy between original and activated states decreased with increasing pressure at the same phase, but increased with phase change in LI to LII and LII to LIII. It was concluded from these results and from IR data on PAN that molecular packing of AN in liquid changed in LI, LII, and LIII. In LII and LIII, AN molecules aligned in a less suitable geometry for polymerization than in LI.

Pressure-volume-temperature behavior of several synthetic rubbers

Abstract The pressure-volume-temperature (P-V-T) relations were studied for cis-1,4-polybutadiene, cis-l,4-polyisoprene, and poly(styrene-butadiene) in the pressure range of 1 to 8000 kg/cm2 at 10 to 50°C. The specific volume of cis-1,4-polybutadiene and cis-1,4-polyisoprene decreased with increasing pressure and abruptly decreased at a certain pressure (low-pressure break). Above this pressure, the specific volume decreased smoothly with increasing pressure and then decreased abruptly again (high-pressure break). The compressibilities below and above the low-pressure break were of the order of 10−5 (kg/cm2)−1 up to the high-pressure break. Above the high-pressure break, the compressibilities reduced to the order of 10−6 (kg/cm2)−1. The P-V isotherms for poly(styrenebutadiene) showed only the high pressure break. An abrupt increase in specific volume occurred in the isobaric measurements for cis-l,4-polyisoprene at a pressure and temperature corresponding to the high-pressure break in the isotherms. From ...

Liquid-Liquid Phase Transition in α,β,β-Trifluoroacrylonitrile

A spin-lattice relaxation time T 1 of α, β, β-Trifluoroacrylonitrile (FAN) was measured in the temperature region of -85 to 0°C. In the T 1 -temperature diagram, T 1 changed discontinuously at -34°C where the liquid-liquid phase transition occurred. Pressure-volume relation had a break point which correspond to the phase transition. From analysis of relaxation mecchanism, the transition is mainly due to a rotational molecular motion. A temperature dependence of the correlation time was expressed as Arrhenius equation in both phases and activation energies were 7.4×10 -2 and 8.7×10 -2 eV in the high and low temperature phase, respectively.

Disinfection of sewage sludge cake by gamma-irradiation

Abstract Disinfection of municipal sewage sludge cake by gamma-irradiation was reviewed. Total bacterial count in the sludge cake did not vary markedly throughout all four seasons in Japan, and it was in the range of 1.6 × 10 8 /g to 4.1 × 10 9 /g. Coliform count in aerobically activated sludge was form 1.8 × 10 7 /g to 4.8 × 10 8 /g, while in anaerobically digested sludge it was less than 8.3 × 10 7 /g. The dose to reduce the coliforms to undetectable levels ranged from 0.3 to 0.5 Mrad, depending on the season. In addition, it was observed that no coliforms reappeared in 0.5 Mrad irradiated sludge cake during storage at room temperature (6 – 16°C) and at 30°C. The adequate disinfection dose is therefore considered to be 0.5 Mrad. Pseudomonas cepacia was a predominant bacterium in non-irradiated sludge cake. In a range of 0.5 to 0.7 Mrad, the residual flora consisted of Bacillus species, and radioresistant Deinococcus proteolyticus, Deinococcus radiodurans and Pseudomonas radiora were isolated from sludge cake irradiated at dose levels of more than 1 Mrad. Bacterial regrowth and the growth of Escherichia coli K-12 seeded in irradiated sludge cake are discussed.

Factors Affecting the Radiosensitization of Pseudomonas radiora O-1 by N2O

The radiosensitization of Pseudomonas radiora O-1 by N/sub 2/O was affected primarily by three factors: cell concentration, dose rate, and irradiation temperature. The influence of cell concentration was observed at levels higher than 6 X 10/sup 7/ cells/ml, and the inactivation constant decreased with increasing cell concentration. The dose rate affected sensitization by N/sub 2/O in dense suspensions (10/sup 7/ cells/ml) but not in dilute suspensions (10/sup 5/ cells/ml). Sensitization by N/sub 2/O in dense suspensions was almost prevented below 25 Gy/min at O/sup 0/C, while desensitization at 20/sup 0/C occurred below 60 Gy/min. The catalase activity of cell suspensions increased with increasing cell concentration. However, cell suspensions up to 1 X 10/sup 6/ cells/ml could not reduce the concentration of H/sub 2/O/sub 2/ accumulated by irradiation. In addition, an increase in catalase activity with rising temperature was almost identical to the change in dose-rate effects caused by a change in irradiation temperature. These results suggest that cellular catalase could correlate with factors affecting radiosensitization in the presence of N/sub 2/O.

Characteristics of a contract electron beam and bremsstrahlung (X-ray) irradiation facility of Radia industry

Abstract A contract electron beam(EB) and bremsstrahlung(X-ray) facility with use of NHV 5 MeV, 30 mA Cock-Croft Walton machine is operational for EB since April 1991, and X-ray commercial irradiation was started in 1992 summer. The facility is consisted of the EB machine, bremsstrahlung target, chain and roller conveyor, and automatic turnover machine for dual sided irradiation. The operation of the system is fully controlled by LAN of personal computers for clients order, EB characteristics, beam current control proportional to the conveyor speed, turnover of product in processing mid point, and output of processing record to clients. The control and recording systems avoid human errors. This paper mainly discusses X-ray processing.

A Novel Liquid State of trans-1,2-Dichloroethylene

The spin-lattice relaxation times ( T 1 ) of trans-1,2-.dichloroethylene (trans-DCE), cis-1,2-dichloroethylene (cis-DCE) and 1,2-dichloroethane (EDC) at atmospheric pressure were measured in a temperature region of each melting point to room temperature. Temperature dependences of T 1 of cis-DCE and EDC were those of an ordinary and isotropic liquid, however, T 1 -temperature curve of trans-DCE had a “jump” which indicates presence of a liquid-liquid phase transition at -16°C. The liquid state of trans-DCE was divided into two liquid states at this transition temperature as L 1 and L 2 corresponding to the high and low temperature states, respectively. In the L 1 state, a rotational motion accounts for a large part of the molecular motion as same as other ordinary liquid. In contrast to L 1 the rotational motion is suppressed and the molecules move only translationally in the L 2 state. The L 2 state is a mesomorphic state which lacks freedom of the molecular rotational motion and is similar to a nematic ...

Existence of Novel Liquid Phases of trans-1,2-Dichloroethylene at High Pressure

Spin-lattice relaxation time ( T 1 ) and specific volume of trans-1,2-dichloroethylene were measured at high pressure. T 1 -pressure curves at various temperatures had one or two jumps, and pressure dependence of specific volume had also a singular point besides the solidification. Magnitude of the T 1 values and the compressibility indicated that the state is liquid above and below the singular points. It is confirmed that there are three liquid phases and the novel liquid phases are similar to the liquid crystals.