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1.
均三嗪荒氨酸衍生物添加剂在菜籽油中的摩擦学性能研究   总被引:5,自引:0,他引:5  
合成了一系列具有不同烷基结构的均三嗪荒氨酸衍生物,采用热重分析对其热稳定性进行了评价,利用四球摩擦磨损试验考察了合成衍生物添加剂在菜籽油中的摩擦学性能。结果表明,这一类添加剂可以大幅度提高菜籽油的极压性能,但是其抗磨减摩作用并不明显。  相似文献
2.
Zusammenfassung Es wird der Einfluß von Konzentration, Temperatur und Schubspannung auf die effektive Viskosität der Lösungen von basischem Aluminiumchlorid (BACh) der Formel m Al2O3 · m HCl · 55,5 H2O ([m] = mol Al2O3/1000 g H2O) untersucht. Dabei werden Lösungen betrachtet, für die M = m/m = 1 ist. Je nach der Konzentration zeigen die BACh-Salze entweder ein newtonsches oder aber ein nicht-newtonsches Fließverhalten. Aus der Aktivierungsenergie, der Fließenthalpie und der Fließentropie und deren Abhängigkeit von der Konzentration und der Schubspannung kann man Schlüsse betreffend die Struktur der Lösungen ziehen. Es wird gezeigt, daß hierfür Wasserstoffbrückenbindungen eine entscheidende Rolle spielen.
The influence of concentration, temperature and shear stress on the effective viscosity of basic aluminium chloride (BACh) solutions with the formula m Al2O3 · m HCl · 55.5 H2O ([m] = mol Al2O3/1000 g H2O) has been investigated for solutions with M = m/m = 1. Depending on the concentration these solutions show rheological behaviour of either Newtonian or non-Newtonian type. Conclusions about the solution's structure can be obtained from the activation energy, enthalpy and entropy of the flow and their dependence on the concentration and the shear stress. It is shown that hydrogenbond networks play a decisive role in the formation of the solution structure.
  相似文献
3.
The volume flow of poly (vinyl chloride) ( = 45,000,T g = 350 K) has been measured in an Instron Capillary Rheometer.The elastic modulus in longitudinal compression, the longitudinal volume viscosity and initial longitudinal volume viscosity, and retardation times were determined at temperatures both below (324 – 343 K) and above (403 – 453 K) the glass transition temperatureT g , and at compression rates between approximately 10–5 and 200 · 10–5 s–1.An increase in the longitudinal volume viscosity was observed for decreases in the volume deformation, increases in the compression rate and increases in temperature.T g decreased at 0.16 K/MPa. The volume flow activation energy was found to be equal to that for shear flow with a constant value of 91.37 kJ/mol.  相似文献
4.
The determination of the chloride diffusion coefficient of a concrete is needed to help the prediction of the service life of concrete structure. In this paper, we propose first a critical review of models for chloride diffusion coefficients already used in literature at different scales and then we develop an analytical model, which takes into account the characteristics of the different phases of concrete. These materials are treated as a three-phase composite, consisting of a cement continuous phase, of an aggregates dispersed phase and of an interface transition zone. Chloride diffusion coefficient using an n-layered inclusion-based micromechanical modeling is predicted. The details of calculations are summarized hereafter and experimental measurements obtained on mortars are compared with predicted results.  相似文献
5.
6.
Poly(vinyl chloride) (PVC)/di-isononyl phthalate systems with PVC content of 45.5 (PVC8) and 70.4 wt% (PVC6) were prepared by a hot roller at 150 °C and press molded at 180 °C. The dynamic viscoelasticity and elongational viscosity of PVC8 and PVC6 were measured in the temperature range from 150 to 220 °C. We have found that the storage and loss shear moduli, G′ and G″, of PVC8 and PVC6 exhibited the power-law dependence on the angular frequency ω at 190 and 210 °C, respectively. Correspondingly, the tan δ values did not depend on ω. These temperatures indicate the critical gel temperature T gel of each system. The critical relaxation exponent n obtained from these data was 0.75 irrespective of PVC content, which was in agreement with the n values reported previously for the low PVC concentration samples. These results suggest that the PVC gels of different plasticizer content have a similar fractal structure. Below T gel, the gradual melting of the PVC crystallites takes place with elevating temperature, and above T gel, a densely connected network throughout the whole system disappears. Correspondingly, the elongational viscosity behavior of PVC8 and PVC6 exhibited strong strain hardening below T gel, although it did not show any strain hardening above T gel. These changes in rheological behavior are attributed to the gradual melting of the PVC crystallites worked as the cross-linking domains in this physical gel, thereby inapplicability of the of time–temperature superposition for PVC/plasticizer systems.  相似文献
7.
Polymethyl methacrylate (PMMA)-coated nano-CaCO3 particles were prepared by in-situ emulsion polymerization. The mechanical properties of nano-CaCO3 particles-reinforced PVC were investigated using an AG-2000A universal testing machine and an XJU-2.75 izod impact tester; interracial adhesion between CaCO3 nanoparticles and PVC matrix by SEM, and structure of PMMA coated on the surface of CaCO3 by FTIR and ^1H-NMR. The results indicate that the PMMA coated on the nano CaCO3 particles consists mainly of syndiotactic structure, and their three tacticity contents were rr 52.8%, mm 7.3% and mr 39.9%, respectively. The interfacial adhesion between CaCO3 nanoparticles and PVC matrix was significantly improved when the CaCO3 nanoparticles were coated with PMMA, which led to increased Young's moduli and tensile strengths of the PMMA-coated CaCO3/PVC composites. The izod impact strengths of the composites were strongly affected by the PMMA coating thickness and increased significantly with increasing the volume fraction of CaCO3 filler in the composites.  相似文献
8.
The oxidation reactor plays a key role in producing rutile titanium dioxide (TiO2) from vapor-phase titanium tetrachloride (TiCl4) by employing a swirling flow operation for enhanced gas mixing. This work aims to understand the effect of reactor configuration on the 3-D swirling flow field using computational fluid dynamics (CFD) simulation. Considering the anisotropic turbulence involved, the Reynolds stress model is applied to describe the complex swirling flow together with the cross-flow mixing of gases. The results show significant effect of the flow angle between the wall jet of air stream (representing TiCl4 in practice) and the axial direction on the initial flow field of cross-flow mixing, where 60° gives smooth profiles of axial velocity development while 90° may provide the fastest mixing between the jet and the axial bulk flow. The pipe shape for the reaction and developing zone, i.e., straight, expanding and shrinking, shows slight influence on the hydrodynamics.  相似文献
9.
Using thermodynamic principles, the general relationship describing the equilibrium vapor content in the gas phase above a saline liquid and across a curved liquid–gas interface is developed. Since high salt concentration affects the intensive and extensive liquid properties, it is also necessary to account for these effects in liquid water content/liquid water pressure relationship curves so that experimentally derived curves for pure water may be useful for elevated salt concentrations. The appropriate thermodynamic relationships are derived to describe the salt effects on liquid and vapor properties. The resulting equations are valid for salt concentrations between zero and saturation, and for any temperatures that nominally occur in nearsurface geologic materials.  相似文献
10.
本文对晶体光塑性材料氯化银在单轴和双轴应力状态下的屈服轨迹进行了测试,给出了在σ_1σ_2平面上的屈服轨迹,为深入了解该材料屈服特性和用该材料模拟研究实际问题提供了实验根据。  相似文献
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