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41.
The molecular orientation at the outer surface of injection–stretch–blow‐molded bottles made from poly(ethylene terephthalate) was characterized and quantified by means of front‐surface reflection infrared spectroscopy based on a method developed previously. Results were obtained for two different bottle shapes (cylindrical and rectangular) molded at different injection mold temperatures (16, 38, and 60°C). For the cylindrical bottles, the preferred molecular chain orientation was found to be in the axial direction, with the Hermans orientation function near 0.3 for all three mold temperatures. For the less symmetrical rectangular bottles, a significant difference was observed between the large and small faces. For the large face, the orientation was mainly in the hoop direction; the Hermans orientation function was in the range of 0.3–0.5 and was essentially the same at all mold temperatures and positions along the bottle height. For the small face, on the other hand, the preferred orientation changed from the hoop direction near the bottom to the axial direction near the top, and the variation was more pronounced at lower mold temperatures. The utility of the front‐surface reflection technique was clearly demonstrated. It was also applied, with the use of an infrared microscope, to examine the orientation gradient across the wall thickness. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1319–1327, 2007 相似文献
42.
The objective of this work is to study the transfer of oxygen from gas to liquid phase in an electroflotation cell. The measurements
were performed in a laboratory scale cell using insoluble electrodes, titanium coated with ruthenium oxide as anode and stainless
steel as cathode. The volumetric mass transfer coefficient K
L
a, was characterized for clean tap water as liquid phase for different values of current density (J). The global coefficient
of mass transfer based on the liquid film, K
L
, and the specific interfacial area, a, were characterized. A model which relates K
L
a to current density was established. Different evaluation criteria of oxygen transfer in electroflotation process were determined
and compared with other aeration process. 相似文献
43.
废旧电池中有价金属回收利用探讨 总被引:1,自引:0,他引:1
随着中国经济的稳步发展和投资环境的不断优化,中国已成为电池的制造和消费大国,每年产生数亿只废旧电池。对废旧电池的回收利用已成为全社会关注的问题。介绍了废旧电池中有价金属的回收利用方法,着重介绍了锂离子二次电池正极材料有价金属的回收利用方法。指出,中国商品化的正极材料只有钴酸锂(LiCoO2),这种正极材料钴含量高,且钴价值高,并且回收工艺可行,因此,从钴酸锂正极材料中回收钴等有价金属,对发展中国的循环经济具有重要意义。同时介绍了锂离子二次电池正极材料的研究现状。 相似文献
44.
45.
J. G. Benítez-Morales H. Rodríguez-Cortés R. Castro-Linares 《Journal of Intelligent and Robotic Systems》2014,73(1-4):99-121
A nonlinear control scheme is proposed for the trajectory tracking problem of a small scale helicopter’s longitudinal dynamics. The control scheme is based on a control design procedure that constructs static feedback regulators for nonlinear systems which are linearizable by dynamic feedback. Besides, the flatness characteristics of the helicopter’s longitudinal dynamics are used to design the desired trajectory. The controller proposed is based on the longitudinal model of the small scale helicopter including the main rotor and stabilizer bar dynamics. Sufficient conditions are given to guarantee asymptotic convergence to zero of the tracking error and to keep the main rotor thrust always negative assuming that all the helicopter’s parameters are known and that all helicopter’s states are measured. Numerical simulations are given to show the performance of the controller in the presence of the main rotor and stabilizer bar dynamics. 相似文献
46.
47.
聚乙二醇-400催化合成橙花醚的研究 总被引:3,自引:0,他引:3
研究了利用多种相转移催化剂在不同条件下合成橙花醚。结果表明:采用聚乙二醇 400(PEG 400)为催化剂,当β 萘酚:溴乙烷:催化剂=1:12:007(摩尔比)、温度为76℃、反应7h时,产率可高达981%。 相似文献
48.
Ben Huybrechts Kozo Ishizaiki Masasuke Takata 《Journal of the American Ceramic Society》1994,77(1):286-288
The positive temperature coefficient of resistivity (PTCR) behavior of semiconductive BaTiO3 is well explained by the Heywang model, which predicts the resistivity behavior above the Curie point based on the acceptor state density at the grain boundaries, the charge carrier density, and the energy gap, E s , between the conduction band and the acceptor levels. However, the relationship between these parameters and the production parameters (sintering time, composition, and cooling rate) is not well understood. Recently, the present authors have found that E s can be increased by thorough oxidation. This increase is attributed to a change in the oxidation state of the acceptor. Based on this finding and results from the literature, a phenomenological PTCR model and an accompanying PTCR chart for acceptor–donor-codoped BaTiO3 are proposed to clarify this relationship. The PTCR chart clarifies that acceptor dopant concentrations, oxidation time, and oxygen partial pressure during oxidation or cooling can be optimized simultaneously to obtain optical PTCR properties. 相似文献
49.
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