Plasma copolymer membranes of acrylic acid and the adsorption of lysozyme on the surface

Plasma copolymerization was carried out from the monomer mixtures of acrylic acid with hexamethylxdisilozane and hexametydisillazane, and the membranes composed of the Si-C and/or Si-O networks sustaining carboxylic acid group were fabricated. The carboxylic acid contents were dependent on the discharge power conditions as well as the monomer ratio, and carboxylic acid was introduced at the more density in the polymerization by plasmas under the moderate power conditions. The plasma polymer coatings were effective for the adsorption of lysozyme especially on the plasma copolymer films of acrylic acid.     

Hydrolysis of nonionic ester surfactants facilitated by potassium β-glycyrrhizinate: Implication of catalytic functions played by the carboxyl groups

Two different types of methyl esters of β-glycyrrhizinate (GK2) have been prepared to delineate the mechanism of the catalytic action of each carboxyl group of GK2 in the hydrolysis of nonionic fatty acid surfactants. In the acidic pH region of less than 4, the hydrolysis is catalyzed by the carboxyl groups of the sugar moiety, while in the close-to-neutral acidic region, the carboxyl group at the hydrophobic triterpenoid end becomes important in catalysis.     

An application of the residual voltage for diagnoses for detecting irradiated degradation of insulating materials

Electrical cables in nuclear power generating stations must be highly reliable. For further improvement of reliability, the development of nondestructive diagnoses seems desirable for cable maintenance. The authors have been studying residual voltage for developing a diagnosis of electrical cables. The purpose of this paper is to give a foundation for development of diagnostic technology for detecting the irradiated degradation; the relations between γ-irradiation dose and the leakage current, the discharge current, and the residual voltage were studied and attempts made to calculate the amount of polarized charge and characteristic dielectric relaxation times by using data on the residual voltage. The calculated results agreed with the results obtained from the leakage current and the discharge current. These results suggest that the residual voltage in diagnostic technology for detecting the irradiated degradation can be employed.     

Effect of fluid motion on radiation-induced polymerization of ethylene in a tubular reactor

The influence of the turbulence of reactant on the radiation-induced polymerization of ethylene in 40 mole-% Freon-114 (C₂Cl₂F₄) was studied using a tubular reactor at 400 kg/cm² and 25°C with a dose rate of 1.3 × 10⁵ rad/hr. At constant linear velocity and tube diameter, the polymer concentration was shown to increase linearly with the reactor tube length. This indicates that the polymerization is in a stationary state. By changing the linear velocity from 3.5 to 42.7 cm/sec and the tube diameter from 5 to 14 mm, the space time yield and the molecular weight of polymer were found to vary between 0.21 and 0.46 mole ethylene/1.-hr and from 5.0×10³ to 10.5×10³, respectively. The space time yield and molecular weight decreased sharply to about one half those in the static polymerization with increasing fluid turbulence and then slowly increased in the highly turbulent state. Similar effects were observed in a tank reactor when the stirring speed was changed.     

Radiation-induced polymerization of ethylene in a pilot plant. I. Bulk process

Radiation-induced bulk polymerization of ethylene was carried out with use of a pilot plant with a 10 liter reactor at pressures of 225–400 kg/cm², temperatures of 30–95°C, ethylene feed rates of 5–28 kg/hr, and dose rate of 3.8 × 10⁵ rad/hr. Characteristics of the process are mild polymerization conditions and capability of producing medium density polyethylene in powder form. The spacetime yield and molecular weight of polymer were in the range of 3.5 to 13.1 g/liter hr and 2.2 × 10⁴ to 14 × 10⁴, respectively. The space-time yield increased with mean residence time and 2.4 powders of pressure, and decreased with temperature. Molecular weight changed similarly with the reaction conditions. These results were consistent with those of the bench plant experiment and the scale effect was small. Polymer deposit to the reactor wall limited a period of continuous operation of the plant. The amount of deposited polymer was increased with the square of reaction time. The rate of polymer deposit was proportional to polymer concentration and to the cube of pressure. The polymer deposit cannot be solved in the bulk process.     

Properties and structure of never-dried cotton fibers. III. Cotton fibers from bolls in early stages of growth

Like other kinds of cotton fibers already studied, American cotton fibers taken from cotton bolls immediately before and after opening show high angles of torsional rotation during ambient humidity changes. Cotton fibers taken from cotton bolls at 19 and 24 days postanthesis show remarkably higher angles of rotation and much lower dry and wet tensile strengths than the fibers taken from cotton bolls immediately before and after opening. The wet tensile strength of cotton fibers at 24 days postanthesis is higher than the dry strength like the fibers taken from bolls immediately before and after opening, but fibers at 19 days postanthesis show almost the same tensile strength in the never-dried, dried, and rewetted states. CP/MAS ¹³C NMR spectroscopy reveals that the never-dried cotton fibers at 19 days or longer postanthesis have high crystallinities. It seems that the degree of crystallinity is somewhat decreased in the dry state and restored by rewetting. The crystallinity increases with the age of growth.     

Fatigue life estimation of adhesive bonded shaft joints

Fatigue tests and analytical investigation of adhesive bonded shaft joints were conducted to propose the estimation method of fatigue strength. Two kinds of adhesive bonded joints were studied: one, shaft joints connected with adhesive coupling, the other, adhesive joints of thin wall tubes to obtain standard fatigue strength. Both pulsating tensile and torsional fatigue tests were conducted with each adhesive joint. Furthermore, the stress distributions under tensile and torsional load conditions were analyzed by finite element method. Based on the analytically computed maximum normal shear stress in the adhesive layer, fatigue strength of the shaft joints was tandardized and compared with that of adhesive joints of thin wall tubes. As a result, it is confirmed that the maximum normal and shear stresses are key parameters for estimating fatigue strength under pulsating tensile and forsional load conditions, respectively. Furthermore, this study indicates an improved method of estimating fatigue strength by using tapered coupling order to reduce the stress concentration at the end of the adhesive layer.     

Photoisomerization of the azobenzenes included in Langmuir-Blodgett films of cyclodextrins

A new type of photochemical Langmuir-Blodgett (LB) film containing azobenzenes (p-phenylazobenzoic acid (PAB), methyl red (MR) and methyl orange (MO)) without long alkyl chains was prepared by the host-guest interaction with an amphiphilic cyclodextrin derivative. The azobenzenes in the LB film of the host- guest complex exhibited an excellent cis-trans photoisomerization, while trans-to- cis photoisomerization was restricted for LB films of long chain azobenzene derivatives alone. The cavity of cyclodextrin provides a favourable environment for the photochemical reaction leading to an increase in the molecular area in the rigid LB film. The half-life times of cis isomers of PAB, MR and MO in the host-guest complex LB films were 35 h, 55 s and 13 min respectively at 20°C.     

Radiation-induced polymerization of ethylene in a pilot plant. II. Development of wet-wall process

Radiation-induced polymerization of ethylene using tert-butyl alcohol aqueous solution as a medium was carried out in a pilot plant with 10 liter reactor at pressures of 100 to 400 kg/cm², ethylene feed rates of 1.2 to 11.8 kg/hr, medium feed rates of 0 to 100 liter/hr, dose rates of 0.6 × 10⁵ to 1.4 × 10⁵ rad/hr, and at room temperature. The space-time yield and molecular weight of polymer were in the range of 1.2 to 16.7 g/liter hr and 6 × 10³ to 2 × 10⁵, respectively. The space-time yield and molecular weight increased with pressure and mean residence time. The space-time yield was the maximum at an ethylene molar fraction of 0.5. The produced polymer was continuously taken out from the high-pressure system as a slurry. The amount of deposited polymer to the reactor wall was markedly decreased, and five full days continuous operation was successfully performed with the space-time yield of 13.5 g/liter hr.