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931.
932.
Diblock copolymer composed of azobenzene-containing polyacrylate and poly(acrylic acid) (PAzoM-b-PAA) was prepared using reversible addition-fragmentation chain transfer (RAFT) radical polymerization, which was found to form micro-particles through self-assembly. Under irradiation of light at 436 nm sphere to disk transformation of the micron-particle was observed in situ through an optical microscope. Detailed spectral analysis showed that a disruption of H-aggregate of azobenzene units had taken place during the transformation, from which it is realized that possible driving force of the transformation comes from the photoinduced disruption of H-aggregates within the micro-particles. 相似文献
933.
The present paper shows how a standard volumetric adsorption device can be used to measure solvent desorption isotherms on
gels. As gels are very soft materials, they shrink significantly during the measurement, and the data have to be analyzed
in terms of the mechanical properties of the gel’s skeleton. Methanol desorption isotherms are measured on a series of silica
gels, and the results are compared with independent characterizations, notably beam bending. 相似文献
934.
超高效液相色谱法同时测定食品塑料包装材料中的紫外吸收剂和抗氧化剂 总被引:2,自引:0,他引:2
超声萃取结合超高效液相色谱(UPLC)技术,建立了食品塑料包装材料中14种紫外吸收剂及抗氧化剂(UV-0,UV-9,UV-71,UV-329,UV-326,UV-327,UV-234,UV-360,抗氧化剂2246,抗氧化剂425,TH-1790,抗氧化剂3114,抗氧化剂1010和抗氧化剂1076)的高通量检测方法。样品经三氯甲烷-甲醇超声提取,C18色谱柱分离后,乙腈和0.1%甲酸水为流动相梯度洗脱,二极管阵列检测器测定。14种物质在一定的浓度范围内线性关系良好,相关系数(r2)均不低于0.999 2,方法定量下限(S/N=10)为8.0~33.0 mg/kg,平均回收率为83.6%~116.2%,相对标准偏差(RSD,n=6)为1.3%~9.5%。方法具有前处理简单、净化效果好等特点,适用于食品塑料包装中14种紫外吸收剂及抗氧化剂的同时测定。 相似文献
935.
Ling Chen Shing‐Chung Wong Tianxi Liu Xuehong Lu Chaobin He 《Journal of Polymer Science.Polymer Physics》2004,42(14):2759-2768
Fracture properties and deformation mechanisms of nanoclay‐reinforced maleic anhydride‐modified polypropylene (MAPP) were investigated. Elastic–plastic fracture mechanics was employed to characterize the toughness in light of substantial postyield deformation for the reinforced MAPP. Upon introduction of 2.5 wt % clay loading in maleated MAPP, it was observed that tensile strength, modulus, and fracture initiation toughness concomitantly increased substantially. Continued increase in clay loading thereafter only led to stiffening and strengthening effects to the detriment of fracture toughness. A plot of the J‐integral initiation fracture toughness versus the plastic zone size demonstrated that toughening arose from plastic deformation in the reinforced matrix. Careful examination of deformed tensile specimens using small angle X‐ray scattering (SAXS) showed 2.5 wt % clay gave rise to the highest equatorial scattering, which indicates the presence of microvoids in the matrix. The SAXS results were consistent with that shown in subcritically loaded crack‐tip deformation zone using transmission electron microscopy. Thus, both macroscale three‐point bend fracture data and SAXS results led us to consistent findings and conclusions. Further increase in clay loading above 2.5 wt % reduced the scattering the matrix plasticity and thus the fracture toughness. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2759–2768, 2004 相似文献
936.
We consider the associative superalgebra of smooth compactly supported functions on ℝ
n taking values in a Grassmann algebra. We find the lower Hochschild cohomologies and also the deformations of this superalgebra
under certain additional conditions.
__________
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 158, No. 3, pp. 323–346, March, 2009. 相似文献
937.
The interaction potential between a spherical and a deformed nucleus is calculated within the double-folding model for deformed nuclei.We solve the double folding potential numerically by using the truncated multipole expansion method.The shape,separation and orientation dependence of the interaction potential,fusion cross section and barrier distribution of the system 16O+154Sm are investigated by considering the quadrupole and hexadecapole deformations of 154Sm.It is shown that the height and the position of the barrier depend strongly on the deformation and the orientation angles of the deformed nucleus.These are quite important quantities for heavy-ion fusion reactions,and hence produce great effects on the fusion cross section and barrier distribution. 相似文献
938.
In this study we consider a model of wet pressing of paper. We use the techniques and results from the first part of this
paper, where a simplified model is studied in details. The model is, using suitable transformation, rewritten in the standard
parabolic-hyperbolic form. Numerical solution for typical example is given and the effects of plastic deformations of paper
are investigated. Finally, the model is employed to adres the problem of choosing an optimal pressing regime. 相似文献
939.
S. V. Stebnovskii 《Journal of Applied Mechanics and Technical Physics》2007,48(4):519-524
Based on a qualitative analysis of results of experimental studies, the main mechanisms of fragmentation of polar liquids
and liquid-plastic media under dynamic loading are determined. In the case of low-viscosity liquids, such mechanisms are thermodynamic
instability of foam, hydrodynamic instability of initial disturbances of the free surface, and the action of capillary forces.
In the case of a polar high-viscosity liquid, the main mechanisms are shear instability of the structure, responsible for
stratification of the medium along the lines of local failure of structural viscosity, and the action of capillary forces.
The main mechanisms acting in liquid-plastic structured media (gels) are “spalling” in the zone of tensile stresses if the
time of their formation is smaller than the time needed for the gel to transform to the sol state, as well as thermodynamic
instability of foam and the action of capillary forces after the medium transition to the sol state.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 4, pp. 62–68, July–August, 2007. 相似文献
940.
S. V. Shil’ko E. M. Petrokovets Yu. M. Pleskachevskii 《Mechanics of Composite Materials》2006,42(5):477-484
The adaptive mode of frictional interaction has been studied as a self-locking effect upon contact deformation of isotropic
and anisotropic auxetic materials with a negative Poisson ratio. This effect manifests itself in the fact that the bearing
capacity of the joint rises with increasing shear load. In particular, the parameters of stress state (contact load, tangential
stresses, slippage, etc.) were determined for a double-lap joint under conditions of compression with or with out shear. The
contact interaction was analyzed by the finite-element method for three profiles of symmetrically located contact elements
(plane, cylindrical, and wedge-shaped). The Poisson ratio was varied within the range theoretically admissible for isotropic
elastic media. Analogous calculations were also performed for a joint with a deformed element made of an anisotropic auxetic
composite, whose reinforcement angle was varied. The maximum loads, tangential stresses, and slippage are obtained as nonlinear
functions of Poisson ratio (in the isotropic case) and reinforcement angle of the composite material. The stress concentration
and the increased ultimate shear forces are also estimated.
__________
Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 5, pp. 681–692, September–October, 2006. 相似文献