Structure and deformation recovery of the thermoplastic polyurethane spherulite

We investigated the structure and deformation behavior of the thermoplastic polyurethane (TPU) spherulite by optical microscopy, tensile testing, Hv light scattering, and small angle X‐ray scattering. The TPU spherulite structure obtained by melt crystallization was coarse consisting of bundle‐like structure containing hard segment (HS) lamellar domain in which the HS domains were stacked and the HS chain direction was perpendicular to the longitudinal axis of the HS domain. By stretching, the spherulite was deformed to ellipsoidal one and the stacked HS lamellar domains were tilted in the stretching direction. The deformed spherulite and the tilted HS domain in the spherulite were recovered to the unstretched state by retraction. The recovery of the structure is ascribed to the characteristic spherulite structure consisting of rubbery soft segment matrix physically cross‐linked with the stacked HS domain. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 1585–1594     

Precise and fast secondary ion mass spectrometry depth profiling of polymer materials with large Ar cluster ion beams

We demonstrate depth profiling of polymer materials by using large argon (Ar) cluster ion beams. In general, depth profiling with secondary ion mass spectrometry (SIMS) presents serious problems in organic materials, because the primary keV atomic ion beams often damage them and the molecular ion yields decrease with increasing incident ion fluence. Recently, we have found reduced damage of organic materials during sputtering with large gas cluster ions, and reported on the unique secondary ion emission of organic materials. Secondary ions from the polymer films were measured with a linear type time‐of‐flight (TOF) technique; the films were also etched with large Ar cluster ion beams. The mean cluster size of the primary ion beams was Ar₇₀₀ and incident energy was 5.5 keV. Although the primary ion fluence exceeded the static SIMS limit, the molecular ion intensities from the polymer films remained constant, indicating that irradiation with large Ar cluster ion beams rarely leads to damage accumulation on the surface of the films, and this characteristic is excellently suitable for SIMS depth profiling of organic materials. Copyright © 2009 John Wiley & Sons, Ltd.     

Practical method for crystalline-liquid resolution of chrysanthemic acids utilizing chiral 1,1′-binaphthol monoethyl ethers directed for process chemistry

We have developed an efficient practical resolution method for (1R,3R)-trans-chrysanthemic acid 1 and (1R,3S)-trans-2,2-dimethyl-3-(2,2-dichloroethenyl)cyclopropanecarboxylic acid 2, based on the preliminary results of the simpler analogues, (1R)-2,2-dichlorocyclopropanecarboxylic acid 3 and (1R)-2,2-dimethylcyclopropanecarboxylic acid 4, using a crystalline-liquid separation procedure (without column chromatography) with chiral 1,1′-binaphthol monoethyl ethers (R)-5b as the key auxiliary. Direct esterifications of 1, 2, 3, and 4 with (R)-5b gave four sets of (1R)- and (1S)-diastereomeric esters 8, 9, 6, and 7, respectively, with markedly different melting points. All of these diastereomers were easily obtained using a simple and one-step crystalline-liquid separation. The separated diastereomers 8 and 9 were easily hydrolyzed to the desired enantiopure acids 1 (>98%) and 2 (>99%), respectively, with recovery of (R)-5b (>90%).     

Evaluation of supercritical fluid extraction for isotope dilution gas chromatography-mass spectrometric quantification of polychlorinated biphenyls in sediment.

Supercritical fluid extraction (SFE) has been evaluated as an extraction technique for the isotope-dilution quantification of polychlorinated biphenyls (PCBs) in a sediment sample. A high-resolution mass-spectrometric system equipped with a gas chromatograph was employed for the determination of seven target PCB congeners. The effect of the operation parameters on the SFE efficiency was investigated, in which the analytical values of five target PCB congeners significantly increased with increases in the extraction temperature and pressure, and that of 4,4'-dichlorobiphenyl further increased by applying static extraction. The following conditions were found to be optimal: extraction temperature, 140 degrees C; pressure, 30 MPa; time and mode, static for 15 min then dynamic for 30 min. Under these conditions, the addition of modifiers influenced the extraction of polar compounds, but did not affect the analytical values of the PCB congeners. The optimized method was suitable for high-throughput analysis as well as for providing accurate analytical results, which were comparable to or better than the analytical results obtained by Soxhlet extraction.     

Color changes in wood during heating: kinetic analysis by applying a time-temperature superposition method

This paper deals with the kinetics of the color properties of hinoki (Chamaecyparis obtusa Endl.) wood. Specimens cut from the wood were heated at 90–180°C as accelerated aging treatment. The specimens completely dried and heated in the presence of oxygen allowed us to evaluate the effects of thermal oxidation on wood color change. Color properties measured by a spectrophotometer showed similar behavior irrespective of the treatment temperature with each time scale. Kinetic analysis using the time-temperature superposition principle, which uses the whole data set, was successfully applied to the color changes. The calculated values of the apparent activation energy in terms of L ^*, a ^*, b ^*, and DE^*_ab\Delta E^{*}_{ab} were 117, 95, 114, and 113 kJ/mol, respectively, which are similar to the values of the literature obtained for other properties such as the physical and mechanical properties of wood.     

A Hamiltonian-conserving Galerkin scheme for the Camassa-Holm equation

A new Hamiltonian-conserving Galerkin scheme for the Camassa-Holm equation is presented. The scheme has an additional welcome feature that in exact arithmetic it is unconditionally stable in the sense that the solution is always bounded. Numerical examples that confirm the theory and the effectiveness of the scheme are also given.