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911.
Nlon 6 fibers were zone drawn and zone annealed by using a continuous wave carbon dioxide laser to develop their mechanical properties. A laser‐heating zone drawing was carried out under a applied tension of 35.4 MPa at a power density of 9.65 W · cm?2, and then the zone‐drawn fiber was annealed. A laser‐heating zone annealing was carried out in two steps at a power density of 9.65 W · cm?2; the first step was carried out under 423 MPa and the second under 517 MPa. The treating temperature of the fiber heated by the CO2 laser was measured by using an infrared thermographic camera equipped with a magnifying lens. The treating temperature at the zone drawing is 138°C, and those at the first and the second zone annealing are 121 and 125°C, respectively. The second laser‐heated zone‐annealed fiber has a birefringence of 65.2 × 10?3, a degree of crystallinity of 54%, and a storage modulus of 21 GPa at 25°C. Wide‐angle X‐ray diffraction patterns for the laser‐heated zone‐drawn and the zone‐annealed fibers show (200) reflection and (002/202) doublet due to only an α form on the equator. The laser‐heated zone‐drawn fiber has a melting endotherm peaking at 216°C and a trace of shoulder on the higher temperature side of its peak, and the laser‐heated zone‐annealed fibers have a single melting endotherm peaking at 216°C. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1711–1716, 2002 相似文献
912.
Jun Yang Wenfei Dong Yucheng Luan Jingjiang Liu Shue Liu Xingyuan Guo Xudong Zhao Wenhui Su 《应用聚合物科学杂志》2002,83(12):2522-2527
The structure and thermal properties of polyamide‐1010 (PA1010), treated at 250°C for 30 min under pressures of 0.7–2.5 GPa, were studied with wide‐angle X‐ray diffraction (WAXD), infrared (IR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Crystals were formed when the pressures were less than 1.0 GPa or greater than 1.2 GPa. With increasing pressure, the intensity of the diffraction peak at approximately 24° was enhanced, whereas the peak at approximately 20° was depressed. The triclinic crystal structure of PA1010 was preserved. The highest melting temperature of the crystals obtained in this work was 208°C for PA1010 treated at 1.5 GPa. Crosslinking occurred under pressures of 1.0–1.2 GPa. Only a broad diffraction peak centered at approximately 20° was observed on WAXD patterns, and no melting and crystallization peaks were found on DSC curves. IR spectra of crosslinked PA1010 showed a remarkable absorption band at 1370 cm?1. The N? H stretching vibration band at 3305 cm?1 was weakened. Crystallized PA1010 had a higher thermal stability than crosslinked PA1010, as indicated on TGA curves by a higher onset temperature of decomposition. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2522–2527, 2002 相似文献
913.
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915.
连续电镀锌镍合金的研究 总被引:4,自引:0,他引:4
提出了一种高氯化铵弱酸型镀液体系连续电镀锌镍合金工艺,研究了m(Ni^2 )/[m(Ni^2 ) m(Zn^2 )]、氯化铵浓度,电流密度、温度、PH值对镀层镍含量的影响,推导出连续镀的镀速计算公式,采用此工艺可获得外观良好、镍含量在13%-15%的锌镍合金镀层。 相似文献
916.
P.B. Spoor L. Koene W.R. Ter Veen L.J.J. Janssen 《Journal of Applied Electrochemistry》2002,32(1):1-10
The removal of nickel ions from dilute solutions using a process that combines an ion-exchange bed with electrodialysis has been studied. The main aspects include: the concentration of nickel ions in the diluate, the voltage over the cell and the current density distribution along the ion-exchange bed. The current density distribution provides insight into the state of the bed as it is simultaneously loaded with Ni2+ and regenerated with an electric potential difference applied perpendicular to it. A simple model is used to describe the state of the bed and the quantity of nickel removed from it as a function of time. Under specific conditions the precipitation of metal hydroxides is observed in the compartment containing the ion-exchange bed. The results show that hydroxide precipitation is related to the nickel concentration in solution and the electric potential gradient across the bed. 相似文献
917.
This paper addresses the application of stochastic optimization approaches to the synthesis of heat integrated complex distillation system, which is characterized by large-scale combinatorial feature. Conventional and complex columns, thermally coupled (linked) side strippers and side rectifiers as well as heat integration between the different columns axe simultaneously considered. The problem is formulated as an MINLP (mixed-integer nonlinear programming) problem. A simulated annealing algorithm is proposed to deal with the MINLP problem and a shortcut method is applied to evaluate all required design paxameters as well as the total cost function. Two illustrating examples are presented. 相似文献
918.
Rong-Jun Xie Mamoru Mitomo Wonjoong Kim Young-Wook Kim Guo-Dong Zhan Yoshio Akimune 《Journal of the American Ceramic Society》2002,85(2):459-465
Starting from three powder mixtures of 80 vol% SiC (100α, 50α/50β, 100β) and 20 vol% YAG, liquid-phase-sintered silicon carbide ceramics were prepared by hot pressing at 1800°C for 1 h under 25 MPa, and then by hot forging or annealing at 1900°C for 4 h under an applied stress of 25 MPa in argon. The phase transformation and texture development in the as-hot-pressed, hot-forged, and annealed SiC ceramics were investigated via X-ray diffraction (XRD) and the pole figure measurements. The 6H → 4H polytypic transformation was observed in samples consisting of both α- and β-SiC phases when subjected to compressive deformation but absent in the case of annealing, suggesting the deformation-enhanced solubility of aluminum in SiC. Deformation was also found to enhance the 3C → 4H transformation in the sample containing entirely β-phase, which is due to the accelerated solution-precipitation process assisted by grain boundary sliding. The current study showed that the β- →α-phase transformation had little effect on texture development in SiC. Hot forging generally produced the strongest texture, with the calculated maximum of 2.2 times random in samples started with pure α-SiC phase. The mechanism for texture development was explained based on the microstructural observations. 相似文献
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920.