Masanobu Nishii

X-ray crystallographic study of solid-state polymerization of trioxane and tetraoxymethylene

Abstract An X-ray study has been applied to clarify the relationship between crystal structures and crystal orientations of tetraoxymethylene and polyoxymethylene obtained by solid- state polymerization of tetraoxymethylene. The polyoxymethylene crystal obtained by the solidstate polymerization of a tetraoxymethylene single crystal was found to be definitely oriented with respect to the original tetraoxymethylene single crystal without any aftertreatment; i.e., the polymer chain (the c-axis) is parallel to the b-axis of tetraoxymethylene and the a-axis of polyoxymethylene coincides to the c-axis of tetraoxymethylene. In addition to the main orientation, other preferred crystalline orientations (“twin structure”) of polyoxymethylene were observed in polymers polymerized at lower temperatures (60-80°C); i.e., the polymer chains are parallel to either the [100], [001], or [101] direction of the original tetraoxymethylene crystal, though the amount of such oriented crystallites is small. The twin structure is...

Effects of ion irradiation on the mechanical properties of several polymers

Abstract The effects of high-energy ion irradiation (8 MeV protons, 30 MeV He2+, 80 MeV C4+, and N4+) on the tensile properties of polymers were studied under conditions in which ions should pass completely through the specimen and the results were compared with 2 MeV electron irradiation effects. Experiments were carried out on polymers having various constituents and molecular structures, i.e. eight aliphatic polymers and four aromatic polymers. In the aliphatic polymers studied (PE, PP, PVdF, ETFE, EVA, nylon-6, EPDM, and PE-TPE), there was scarcely any difference in the dose dependence of the tensile strength and ultimate elongation between proton and electron irradiation. In aromatic polymers (PET, PES, U-PS, and U-polymer), however, the decrements in the tensile strength and ultimate elongation vs proton dose were less than those for electron irradiation. In heavy-ion irradiation, the radiation damage of PE (an aliphatic polymer) decreased with increase of LET, but no obvious LET effects were observed in PES (an aromatic polymer).

Radiation-induced polymerization of monomolecular film of octadecyl acrylate at gas-water interface

Abstract Studies have been carried out on radiation-induced polymerization of octadecylacrylate monolayers at gas-water interface using automatic surface balance techniques. The monolayers were irradiated with electron beams from a Van de Graaff electron accelerator either at a nitrogen-water or at an air-water interface, and the reaction was followed by measuring surface pressure-area curves at intervals or by recording surface pressure change during irradiation. The polymerization was found to proceed at the nitrogen-water interface, while no indication of the formation of poly(octaclecyl acrylate) was obtained for the monolayer when irradiated at the air-water interface.

Wavelength Dependence of Excimer Laser Irradiation Effects on Ethylene-Tetrafluoroethylene Copolymer

Irradiation with an ArF laser at wavelength of 193 nm formed diene in a whole ethylene-tetrafluoroethylene copolymer (ETFE) film and irradiation with a KrF and a XeCl laser at 248 and 308 nm induced the carbonization of ETFE. ArF-laser radiation at 193 nm formed diene in the bulk of ETFE via the process of single-photon absorption, and in case of KrF and XeCl-laser irradiation multiphoton absorption brought about the carbonization of ETFE. The surface analysis by X-ray photoelectron spectroscopy showed that excimer laser-induced elimination of fluorine atoms depended on the laser wavelength.

Radiation-induced chemical reactions of carbon monoxide and hydrogen mixture. I: Electron beam irradiation at atmospheric pressure

Abstract The radiation chemical reaction of CoH2 mixture has been studied in the pressure range from 104 to 1.3×105 Pa using 7 1. reaction vessel made of stainless. Various hydrocarbons and oxygen containing compounds such as methane, formadehyde, acetaldehyde, and methanol have been obtained as radiolytic products. The amounts and the G values of these products depended upon the irradiation conditions such as composition of reactant, total pressure, reaction temperature, and dose. It was found that the irradiation at low dose produced small amounts of trioxane and tetraoxane, which have not yet been reported in literature. The yields of these cyclic ethers increased at high pressure and at low temperature. An experiment was also made on CoH2 mixture containing ammonia as a cation scavenger to investigate the precursor of these products.

Radiation-induced chemical reactions of carbon monoxide and hydrogen mixture. II: Effects of reactant pressure and temperature on the yields of oxygen containing products

Abstract The radiation chemical reaction of CO-H2 mixture up to 8.4 x 105 Pa has been studied. The G values of oxygen containing organic compounds except methanol increased with increasing total pressure of reactant. The G values of most of products except trioxane and tetraoxane were increased with raising of temperature in the range from 210 to 350 K, while the G values of trioxane and tetraoxane reached the maxima at 243 K and decreased rapidly with raising of temperature. From the dependencies of G values of these cyclic ethers on pressure and temperature of the reactant, it is considered that these cyclic ethers produced from the neutralization reaction of HCO+ (CO)n cluster ions with electrons in an atmosphere of relatively large amount of hydrogen. The effects of CO content on G values of products did not change with the pressure change of the reactant.

Radiation-induced chemical reactions of carbon monoxide and hydrogen mixture—IV. On the water produced by the addition of small amounts of ammonia

Abstract The isotope content in water obtained from irradiated CO-H2 mixture with added small amounts of NH3 or their deuterated equivalents was compared. Compared with that in water obtained from CO-D2 mixture with added NH3, D content in water produced from the mixture with the substitution of ND3 for NH3 was increased remarkably. The NH3 added to the mixture contributes to the water formation under irradiation.

Radiation-induced chemical reactions of carbon monoxide and hydrogen mixture— V. Increase in product yields due to the addition of methane

Abstract When the CO-H 2 mixture containing 1 mol% CH 4 at 6.6 × 10 5 Pa in total pressure was irradiated by electron beam, the G values of trioxane and tetraoxane increased remarkably compared with those obtained by the irradiation of the CO-H 2 mixture in the absence of CH 4 . The result suggests that in the presence of CH 4 , the cyclic ethers are produced by the neutralization reaction of the cluster ion containing CH 4 , CH + 4 (CO) n , with electron. The G values of aldehydes and carboxylic acids constituted of C 2 or more carbon atoms, increased by the addition of CH 4 of 20 mol% or more. It is considered that the increase in the G values of these aldehydes and carboxylic acids by the addition of CH 4 was caused by the contribution of the acyl radicals, RCO, which formed by the reaction of hydrocarbon radicals produced from added CH 4 and CO.

Radiation-induced chemical reactions of carbon monoxide and hydrogen mixture—III. Solid materials produced under irradiation

Abstract Three varieties of nonvolatile solid products A, B, and C were obtained from the CO-H 2 mixtures irradiated by electron beam in different conditions. Solids A and B were obtained as a deposit on the wall of reaction vessel from the mixture containing 15 and 78 mol % CO, respectively. The solid C was obtained as the deposit in the cold traps set in the path of reactant (15 mol% CO) circulation. From the analyses by IR, GC, and mass spectrometer and characteristics of these solids, it was suggested that the solid A was the substance formed from the reaction of HCHO with carboxylic acid, the solid B was C 3 O 2 polymer having low molecular weight, and the solid C was paraformaldehyde.