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1.
The dynamic mechanical behavior of uncrosslinked (thermoplastic) and crosslinked (thermosetting) acrylonitrile butadiene rubber/poly(ethylene‐co‐vinyl acetate) (NBR/EVA) blends was studied with reference to the effect of blend ratio, crosslinking systems, frequency, and temperature. Different crosslinked systems were prepared using peroxide (DCP), sulfur, and mixed crosslink systems. The glass‐transition behavior of the blends was affected by the blend ratio, the nature of crosslinking, and frequency. sThe damping properties of the blends increased with NBR content. The variations in tan δmax were in accordance with morphology changes in the blends. From tan δ values of peroxide‐cured NBR, EVA, and blends the crosslinking effect of DCP was more predominant in NBR. The morphology of the uncrosslinked blends was examined using scanning electron and optical microscopes. Cocontinuous morphology was observed between 40 and 60 wt % of NBR. The particle size distribution curve of the blends was also drawn. The Arrhenius relationship was used to calculate the activation energy for the glass transition of the blends, and it decreased with an increase in the NBR content. Various theoretical models were used to predict the modulus of the blends. From wide‐angle X‐ray scattering studies, the degree of crystallinity of the blends decreased with an increasing NBR content. The thermal behavior of the uncrosslinked and crosslinked systems of NBR/EVA blends was analyzed using a differential scanning calorimeter. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1556–1570, 2002  相似文献   
2.
The electron donating properties of sulfated zirconia were studied from the adsorption of electron acceptors of various electron affinity. The surface acidity and basicity of the oxides have also been determined by titration method using a set of Hammett indicators. The data have been correlated with the catalytic activity of the oxide towards esterification of acetic acid usingn-butanol, reduction of cyclohexanol in 2-propanol and oxidation of cyclohexanol with benzophenone.  相似文献   
3.
The crystal structure of 2-hydroxyacetophenone N(4)-cyclohexyl thiosemicarbazone is described. The compound crystallizes in the triclinic crystal system, space group , Z = 4, V = 1569.6(3) ?3 with unit cell parameters a = 6.9436(8) ?, b = 12.4762(15) ?, c = 18.588(2) ?, α = 100.187(2)°, β = 97.069(2)° and γ = 92.340(2)°. There are two independent molecules in the asymmetric unit. The crystal structure reveals that the compound exists in the thione form and S1 and N1 are at E configuration to each other with respect to N2-C8 bond. Similarly, S2 and N4 are trans to each other with respect to N5-C23 bond in the second molecule of the asymmetric unit. The packing of the molecules in the crystal lattice is stabilized by intermolecular hydrogen bonds.  相似文献   
4.
Four molybdenum(VI) thiosemicarbazonato complexes have been synthesized and characterized. The dinuclear complexes [(MoO2L1)2] (1) and [(MoO2L2)2] (3) have been prepared by the reaction of [MoO2(acac)2] with 2-hydroxyacetophenone N(4)-cyclohexyl (H2L1) and N(4)-phenyl (H2L2) thiosemicarbazones in alcoholic medium. Mononuclear dioxomolybdenum(VI) complexes of the type [MoO2L1py] (2) and [MoO2L2py] (4) have been prepared by the reaction of 1 or 3 with pyridine (py) in alcoholic medium. In all the complexes, molybdenum is coordinated by two terminal oxo-oxygen atoms, (Ot), oxygen, nitrogen and sulfur atoms from the principal ligand and by an oxygen atom from the second unit in 1, and by a nitrogen atom from pyridine in complexes 2 and 4. All complexes have been spectroscopically characterized. The molecular structures of complexes 1, 2 and 4 have been determined by the single crystal X-ray diffraction method.  相似文献   
5.
Given the advantages of network-on-chips (NoCs), they are rapidly improving to replace other forms of System-on-Chip (SoC) designs. Although various factors improve the NoC's performance, many challenges should be addressed when designing an NoC, one of which is congestion and its impacts on performance and efficiency. Hence, numerous routing algorithms have been proposed that contemplate the congestion influences to deal with its complexities. Nevertheless, given the significant impacts of overheads on performance and efficiency, it is crucial to consider them when designing an enhanced NoC. The proposed routing algorithm employs regional traffic information within multiple clusters and has a decent view of the traffic condition when choosing the path to the destination. Each node generates one bit of traffic information and propagates it only when the node is congested, thus preventing the information overhead. Finally, the path diversity parameter is utilized to identify the best route from the source to the destination. The proposed algorithm's results show that the number of received packets, average latency, average throughput, maximum latency, and energy consumption while using different traffic patterns are improved by 10.9%, 35.3%, 15.8%, 43%, and 15.3%, respectively.  相似文献   
6.
Five Zn(II) complexes of salicylaldehyde N(4)-phenylthiosemicarbazone (H(2)L) have been synthesized and physicochemically characterized. Out of the five Zn(II) complexes, one is binuclear {[(ZnL)(2)].3C(2)H(5)OH (1)} and the other four are mononuclear {[Zn(HL)(2)].C(2)H(5)OH (2), [ZnLbipy].1/2H(2)O (3), [ZnLphen].H(2)O (4) and [ZnLdmbipy] (5)} in nature. In complex 2, IR band due to nu(Zn-O) is absent and also the -OH signal due to the phenolic -OH group appears at delta=11.38ppm obtained from the (1)H NMR spectrum supports the existence of free -OH group. Complexes 3-5 are heterocyclic base adducts and their IR spectra display bands characteristic of coordinated heterocyclic bases. The molecular structure of one of the complex 3 is resolved by single crystal X-ray diffraction studies. The complex 3 is orthorhombic with a space group P2(1)cn. The Zn(II) in 3 is five coordinated and is having an approximately trigonal bipyramidal geometry with distortion from square based pyramid (TBDSBP).  相似文献   
7.
Micro fabricated sensors based on nanomechanical motion with piezoresistive electrical readout have become a promising biochemical sensing tool. The conventional microcantilever materials are mostly silicon-based. The sensitivity of the sensor depends on Young's modulus of the structural material, thickness of the cantilever as well as on the gauge factor of the piezoresistor. UV patternable polymers such as SU-8 have a very low Young's modulus compared to the silicon-based materials. Polymer cantilevers with a piezoresistive material having a large gauge factor and a lower Young's modulus are therefore highly suited for sensing applications. In this work, a spin coatable and photopatternable mixture of carbon black (CB) and SU-8, with proper dispersion characteristics, has been demonstrated as a piezoresistive thin film for polymer microcantilevers. Results on percolation experiments of SU-8/CB composite and fabrication of piezoresistive SU-8 microcantilevers using this composite are presented. With our controlled dispersion experiments, we could get a uniform piezoresistive thin film of thickness less than 1.2 μm and resistivity of 2.7 Ω cm using 10 wt% of CB in SU-8. The overall thickness of the SU-8/composite/SU-8 is approximately 3 μm. We further present results on the electromechanical characterization and biofunctionalization of the cantilever structures for biochemical sensing applications. These cantilevers show a deflection sensitivity of 0.55 ppm/nm. Since the surface stress sensitivity is 4.1 × 10−3 [N/m]1, these cantilevers can well be used for detection of protein markers for pathological applications.  相似文献   
8.
Zirconium hydroxide gel has been prepared by a novel aqueous gelation process by the controlled hydrolysis of zirconium oxychloride in the presence of sodium acetate. The gel thus formed has been subjected to thermal analysis: TG, DTG, and DSC. Thermal analysis shows that the gel is continuously dehydrated in the temperature range between room temperature and 500?°C. The total mass loss relative to the initial mass is about 44.1%. Thermal analysis shows that the decomposition takes place in three stages. The gel contains absorbed and coordinated water. In the second stage of dehydration, dehydration of the Zr(OH)4 gel also takes place along with the removal of the coordinated water. The DSC analysis coupled with TG and structural information, indicate that the exothermic processes between 349 and 460?°C can be attributed to the nucleation process of the formation of tetragonal zirconia, with phase transformation at 460?°C.  相似文献   
9.
Self-sustained oscillations in a cavity arise due to the unsteady separation of boundary layers at the leading edge. The dynamic mode decomposition method was employed to analyze the self-sustained oscillations. Two cavity flow data sets, with or without self-sustained oscillations and possessing thin or thick incoming boundary layers (ReD = 12,000 and 3000), were analyzed. The ratios between the cavity depth and the momentum thickness (D/θ) were 40 and 4.5, respectively, and the cavity aspect ratio was L/D = 2. The dynamic modes extracted from the thick boundary layer indicated that the upcoming boundary layer structures and the shear layer structures along the cavity lip line coexisted with coincident frequency space but with different wavenumber space, whereas structures with a thin boundary layer showed complete coherence among the modes to produce self-sustained oscillations. This result suggests that the hydrodynamic resonances that gave rise to the self-sustained oscillations occurred if the upcoming boundary layer structures and the shear layer structures coincided, not only in frequencies, but also in wavenumbers. The influences of the cavity dimensions and incoming momentum thickness on the self-sustained oscillations were examined.  相似文献   
10.

Abstract  

Oxovanadium(IV/V) complexes of 2-hydroxyacetophenone-3-hydroxy-2-naphthoylhydrazone (H2L) have been synthesized and characterized. The complexes were characterized by elemental analyses, IR, electronic and EPR spectra. The oxovanadium(V) complex [VOL(OCH3)] is crystallized in two polymorphic forms, denoted by 1a and 1b, with space groups Pn21a and P[`1] P_{{\bar{1}}} , respectively. Both have distorted square pyramidal structures.  相似文献   
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