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61.
Microfibrillar composites (MFC) are polymer-polymer composites with many advantages, including good dispersion and bonding of in-situ generated fibrils. Recently, it has been shown that their performance can be enhanced by suitable addition of organophilized montmorillonite (oMMT) provided the numerous oMMT-induced effects are harmonized. This work deals with evaluation of resistance against unstable crack propagation (J-integral) in combination with Charpy and tensile impact strength methods, and SEM observation of fibrils shape and size and fracture surfaces. The results indicate that addition of PA6 inclusions and oMMT to relatively ductile HDPE reduces toughness evaluated using Charpy and J-integral. The fact that tensile impact strength is not reduced by oMMT indicates the importance of the impact testing mode for MFC. Of importance is the fact that formation of PA6 fibres reinforced with oMMT practically does not reduce toughness. Hence, the drawn oMMT-modified system with significantly higher stiffness and practically unchanged fracture resistance can be obtained. Combination of the complex effect of oMMT and in-situ fibrils reinforcement present a tool to attain polymer systems with enhanced well-balanced properties. 相似文献
62.
Q.G. Meng H.Y. Fang J.G. Yang S.D. Ji 《Theoretical and Applied Fracture Mechanics》2005,44(2):178-186
By analyzing the shape of twin wire welding’s arcs and the track of droplets’ transition, the phenomenon that the twin wire welding’s fore arc and rear arc all deflect to the middle of the two arcs is found. Based on this the double ellipsoid heat source model is amended, and a heat source model which can apply to calculate the twin wire welding’s temperature field is put forward. This model is testified by actual experiment of temperature sampling. By comparing the temperature field of twin wire welding and single wire welding, the results show that twin wire welding has slender weld pool the end part of which is ellipsoid, and its HAZ is narrower than that of single wire welding. So, twin wire welding can not only reduce the Al alloy generating hot crack, but can also weaken the “overaging” softened phenomenon of heat treated strengthening Al alloy. In the end, the evolving rules of 2219 Al alloy’s longitudinal and transverse stress when welded with twin wire welding are analyzed. 相似文献
63.
A novel solid-phase microextraction fiber based on a stainless steel wire coated with Au nanoparticles was prepared and has been applied, coupled with gas chromatography, to the extraction of aromatic hydrophobic organic chemical pollutants in rainwater and soil extract. The solid-phase microextraction fiber exhibited excellent extraction efficiency and selectivity. Effects of extraction time, extraction temperature, ionic strength, stirring rate and desorption conditions were investigated and optimized. Single fiber repeatability and fiber-to-fiber reproducibility were less than 7.90% and 26.40%, respectively. The calibration curves were linear in a wide range for all analytes. Correlation coefficients ranged from 0.9941 to 0.9993. The as-established SPME-GC method was used successfully to two real natural samples. Recovery of analytes spiked at 10 μg L(-1) and 100 μg L(-1) ranged from 78.4% to 119.9% and the relative standard deviations were less than 11.3%. 相似文献
64.
65.
Wear-resistant coatings were prepared on the surface of the Q235 low-carbon steel plate by HVAS with the carbonitride alloying self-shielded flux-cored wire. Detection and analysis on the microstructure and properties of the coatings were carried out by using scanning electron microscope, microhardness tester and wear tester. The forming, the wear resistance and its mechanism of the coatings were studied. The results show that the coatings have good forming, homogeneous microstructure and compact structure. The coatings have good hardness, the average microhardness value reaches 520 HV0.1, and the highest value is up to about 560 HV0.1. As a result, the coatings have good abrasive wear performance and adhesion strength. 相似文献
66.
67.
李伟青 《浙江大学学报(理学版)》2005,32(4):392-398
基于电子版的建筑图纸识别是工程图纸识别领域的一个重要分支.与纸质图纸的扫描识别研究相比较,对电子版图纸识别的研究工作还不够深入.详细分析了经由AutoCAD绘制的电子版建筑图纸的绘制特点,提出了一套针对主体构件的智能识别方法,描述了各类构件的识别过程,最后讨论了智能识别方法的特点和下一步的工作. 相似文献
68.
绘系统状态轨线的一种方法 总被引:4,自引:1,他引:3
介绍了一种作系统运动积分曲线的方法,并运用该方法绘出几个常见动力学系统的状态轨线,说明其实用价值。 相似文献
69.
Karger-Kocsis J. Shang P. P. Moskala E. J. 《Journal of Thermal Analysis and Calorimetry》1999,55(1):21-28
The tensile loading-induced necking in notched specimens of an amorphous copolyester (aCOP) was studied by modulated differential
scanning calorimetry (MDSC). It was shown that necking occurred by cold drawing since the enthalpy of cold crystallization
and that of the subsequent melting agreed fairly with each other. Increasing deformation in the necking zone and increasing
deformation rate of the specimens shifted the onset of cold crystallization toward lower temperatures and yielded a slightly
higher glass transition temperature (Tg). This was attributed to the molecular orientation caused by mechanical loading. The finding that the melting contained a
non-reversing part was considered as appearance of possible microcrystallinity. The Tg range was strongly influenced by the deformation rate and reflects the thermomechanical history of the samples accordingly.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
70.
Yanhui Chen Ganji Zhong Benjamin S. Hsiao Zhongming Li 《Journal of Polymer Science.Polymer Physics》2013,51(22):1618-1631
The structure evolution of the oriented layer (skin) and unoriented layer (core) from injection‐molded isotactic polypropylene samples upon uniaxial drawing is probed by in situ synchrotron X‐ray scattering. The X‐ray data analysis approach, called “halo method”, is used to semiquantitatively identify the transformation process of crystal phase upon uniaxial drawing. The results verify the validation of the stress‐induced crystal fragmentation and recrystallization process in the deformation of the injection‐molded samples under different temperatures. Furthermore, the end of strain softening region in the engineering stress‐strain curves explicitly corresponds to the transition point from the stress‐induced crystal fragmentation to recrystallization process. Basically, the skin and core layers of the injection‐molded parts share the similar deformation mechanism as aforementioned. The stretching temperature which dramatically affects the relative strength between the entanglement‐induced tie chains and the adjacent crystalline lamellae determines the crystal structural evolution upon drawing. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1618–1631 相似文献