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961.
962.
Maria Pizzoli Giovanni Pezzin Giuseppina Ceccorulli 《Journal of Macromolecular Science: Physics》2013,52(2):241-250
Samples of poly(vinyl chloride) plasticized with variable amounts of either dibutyl phthalate (DPB) or dicyclohexyl phthalate (DCHP) were investigated by dynamic-mechanical measurements in the β relaxation temperature range. In this range of temperature, a superposition of the relaxation due to the cyclohexyl group with the PVC β peak was found for the samples plasticized with DCHP. By studying the dependence of the activation energy and of the peak broadness on the DCHP concentration it was possible to show that the PVC β relaxation is reduced to zero at the critical plasticizer weight fraction W1 = 0.2. For the PVC-DBP series the β peak disappears at the same plasticizer content. These results strengthen the hypothesis that the β peak of PVC is due to a kind of cooperative motion since 1 mole of plasticizer for every 20 repeating units of the polymer is sufficient to suppress the PVC β relaxation. 相似文献
963.
A semiempirical method has been used to study the electronic structures of some π-bonded purely organic materials that are either known or proposed to have multiplet ground states. These materials are the precursors of organic ferromagnets. Narrow energy bands formed from the radical π-orbitals of these materials are necessary for the π-electrons to be unpaired. Favorable topological arrangements of atoms in these materials are needed to enable the spins of these electrons to align parallel, and hence yield macroscopic ferromagnetic ordering. Following ideas based on these studies, a new model for a possible organic ferromagnet is proposed and studied. 相似文献
964.
Byeong-Gyu Park Ki-Sun Kim Sang-Min Lee Cheon-Koo Lee 《Journal of Dispersion Science and Technology》2013,34(11):1541-1546
The properties of solid surface on oil-wax gel are one of the most important factors which decide the quality of products such as cosmetics. The thixotropic property of solid surface depends on the velocity gradient and it is increased with higher velocity gradient as controlling the morphology on solid surface of oil-wax gel. The morphological change of oil-wax gel in compliance with surface properties of wax matrix can cause different rheological behaviors. Rheological behavior of oil-wax gel regarding the surface transition range in accordance with shear strain was observed to characterize surface properties. In an earlier article, the morphological mechanism of causing surface transition range and the factors of influencing surface transition range were examined by studying the rheological behaviors of a solid-state emulsion. Here, we investigated, in the lattice structure terms, the morphological change of oil-wax gel by measuring surface transition range depending on velocity gradient, which could influence the hardness and sweating phenomenon. We confirmed that the morphological change of oil-wax gel was accompanied by crystal size, crystal conformation, the degree of crystallinity. Surface transition range depending on velocity gradient was shown in large and regular lattice structure of oil-wax gel better than small and irregular one. 相似文献
965.
Recently, many studies have been started in search for materials which show a photoinduced phase transition (PIPT). In this work, we review two systems as typical examples of PIPT accompanied with changes in magnetic characteristics; (1) organo-metal complex [Fe(2-pic)3]Cl2 EtOH (2-pic = 2-amino-methyl-pyridine) and (2) III-V based magnetic semiconductors (In1-x , Mn x )As. In the former case, we show several nonlinear characteristics in dynamical process of photoinduced spin state transition from low-spin to high-spin states. In the latter one, photocarrier-induced ferromagnetic order has been observed by both magnetic and transport measurements. 相似文献
966.
Abstract The IR absorption and Raman scattering of OBBC have been investigated in the solid, ReN, SmA and nematic phases. The intensity of the 2229 cm?1 band assigned to the C[tbnd]N stretching mode decreases with increasing temperature in the reentrant nematic phase; this is attributed to a change in the overlap of the molecules. While the IR bands at 1728 and 841 cm?1 also show a remarkable temperature dependence, Raman bands do not show significant temperature dependence in the liquid-crystal phases. 相似文献
967.
Temperature-sensitive hybrid films were synthesized with a concentration gradient by casting and UV curing of N-isopropylacrylamide (NIPAAm) monomers (0%–70%) on the free surface of waterborne polyurethane (WPU) films on a Teflon substrate. The surface hardness and contact angle of the free surface with a water drop increased asymptotically with the addition of NIPAAm, whereas those on the substrate side were virtually unchanged. The diffusion coefficient (D), rates of swelling at 20°C (below the lower critical solution temperature (LCST) of poly(N-isopropylacrylamide) (PNIPAM)) and deswelling at 50°C (above the LCST) increased with increasing NIPAM content, showing favorable thermosensitivity. In addition, the glassy state modulus and glass transition temperature (Tg) of the film increased with increasing NIPAM content, whereas the rubbery modulus decreased due to the increased molecular weight between the crosslinks. In addition, as the NIPAM content increased, the film showed a positive yield with an increased yield and fracture stress and decreased ductility. Above 50% NIPAM, the film became brittle, showing a linear stress–strain relationship. 相似文献
968.
Role of compositional changes on thermal,magnetic,and mechanical properties of Fe-P-C-based amorphous alloys 下载免费PDF全文
Indah Raya Supat Chupradit Mustafa M Kadhim Mustafa Z Mahmoud Abduladheem Turki Jalil Aravindhan Surendar Sukaina Tuama Ghafel Yasser Fakri Mustafa Alexander N Bochvar 《中国物理 B》2022,31(1):16401-016401
This work aimed to tune the comprehensive properties of Fe-P-C-based amorphous system through investigating the role of microalloying process on the crystallization behavior,glass forming ability(GFA),soft magnetic features,and mechanical properties.Considering minor addition of elements into the system,it was found that the simultaneous microalloying of Ni and Co leads to the highest GFA,which was due to the optimization of compositional heterogeneity and creation of near-eutectic composition.Moreover,the FeCoNiCuPC amorphous alloy exhibited the best anelastic/viscoplastic behavior under the nanoindentation test,which was owing to the intensified structural fluctuations in the system.However,the improved plasticity by the extra Cu addition comes at the expense of magnetic properties,so that the saturation magnetization of this alloying system is significantly decreased compared to the FeCoPC amorphous alloy with the highest soft magnetic properties.In total,the results indicated that a combination of added elemental constitutes,i.e.,Fe69Co5Ni5Cu1P13C7 composition,provides an optimized state for the comprehensive properties in the alloying system. 相似文献
969.
970.
A structurally stable, 3d-4f heterometallic coordination polymer has been solvothermally synthesised and evaluated for its accomplished materials properties. The light absorption activity in the visible band was higher for unique Ce-Fe MOF than that of the homometallic Ce-MOF or Fe- MOF. The intimate overlap of two different metal clusters in heterometallic environmental induced the formation of low line conduction orbital, which ultimately lowered the transition energy. The heterometallic acquired an additional sensitisation from a Fe-μ3-oxo cluster that had vibrantly enhanced the light uptake activity. The vacancy created in the 6s, 5d orbital of Ce in Ce-Fe MOF contributed to the photo-excitation of electrons and reduced the recombination time. This distinct intramolecular arrangement assisted the exciton trapping characteristic. Also, the presence of multiple metal cores in the framework aided to confine the increased number of excitons for a redox reaction. The solar photocatalysis study with acetaminophen revealed these improved materialistic features by degrading it 94.6% with a rate constant of 0.0137 min−1. The recycle studies confirmed the robust stability of the synthesised MOF. 相似文献