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91.
该文制备了一种利用结构色水凝胶作为导电电极的光电双响应传感器。以十二烷基衣康酸甘油酯(DGI)、丙烯酰胺、十二烷基硫酸钠(SDS)、氯化钠等为原料,通过双分子层自组装的方法,制备了结构色水凝胶。将这种结构色水凝胶与传统电容型传感器相结合,得到了光电双响应传感器。采用SEM、LCR数字电桥、拉力试验机、光纤光谱仪等对器件进行了结构、光学、电学及机械性能的表征。结果表明:传感器在拉伸状态(0~100%)和压缩状态(0~60.9k Pa)下,传感器的电容分别变化了31%和44%,其自身颜色在可见光光谱内可以动态可逆地从红色变化到紫色。经历15000次循环拉伸后,传感器性能依旧保持稳定。利用传感器颜色的刺激响应性,传感器在发生形变时,其表面可以清楚地显示出应变源的位置和形状,这样传感器在检测时就可以实现可视化效果。 相似文献
92.
Mahmoud A.‐Halim Abdel‐Goad 《应用聚合物科学杂志》2004,91(4):2543-2547
In efforts to contribute to community development, particularly in the context of Egyptian communities, waste plastics materials were successfully recycled without the difficult task of separation and reused to economically produce new structural material. Recycling was performed by mixing molten waste plastics with sand to produce these new materials. Samples with different percentages of plastics and different particle sizes of sand were used in the process. Materials showed acceptable density and high compressive strength, which was shown to be at a maximum with contents of about 30–40% waste plastic. Furthermore, certain types of sand having different colors were used to produce attractive materials, suitable for decorative uses. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2543–2547, 2004 相似文献
93.
Jeremy Gustin Brian Freeman James Stone Mohammad Mahinfalah Amin Salehi‐Khojin 《应用聚合物科学杂志》2005,96(6):2309-2315
Nanocomposites are more widely studied today because of higher stiffness, decreased permeability, thermal stability, and many other properties superior to those of regular polymers. However, manufacturers are concerned about implementing nanocomposites because of their lower impact properties with respect to the base polymer. This study focused on low‐velocity impact tests of a thermoplastic olefin by itself and with 5 wt % nanoclay. The impact tests were conducted at ?40, 23.9, and 65.6°C until the polymer and nanocomposite plates experienced complete striker penetration. The force–time and force–deflection responses obtained from the impact testing provided a means of comparing the impact performances of the two materials. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2309–2315, 2005 相似文献
94.
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96.
Humidity absorbed by epoxy film adhesives during low temperature storage or exposure to atmosphere may result in reversible changes and irreversible modifications. Vacuum treatment may partially remedy the reversible changes. The consequences of vacuum drying are manifested in enhancement of both the peel and shear properties of bonded joints (Part I and Part II of this series of papers) and the thermal, physical and mechanical properties of the bulk adhesive, characterized in the present study.
Experimental results have shown that the bulk properties of structural epoxy based adhesives are highly correlated with the aging processes caused by water absorption in the prepolymerized adhesive. Applying the vacuum process is harmful to fresh unaged adhesive due to devolatization of low molecular species of the film adhesive.
The characterization of bulk properties for the purpose of following the aging and recovery processes is advantageous, since the bulk is independent of geometrical and interfacial effects which dominate in the case of property evaluation of the adhesive in a bonded joint. 相似文献
Experimental results have shown that the bulk properties of structural epoxy based adhesives are highly correlated with the aging processes caused by water absorption in the prepolymerized adhesive. Applying the vacuum process is harmful to fresh unaged adhesive due to devolatization of low molecular species of the film adhesive.
The characterization of bulk properties for the purpose of following the aging and recovery processes is advantageous, since the bulk is independent of geometrical and interfacial effects which dominate in the case of property evaluation of the adhesive in a bonded joint. 相似文献
97.
Heloise O. Pastore Alberto Frache Enrico Boccaleri Leonardo Marchese Giovanni Camino 《大分子材料与工程》2004,289(9):783-786
Summary: The success of the use of layered silicates in polymer nanocomposites, to improve physical and chemical properties is strictly related to a deeper knowledge of the mechanistic aspects on which the final features are grounded. This work shows the temperature induced structural rearrangements of nanocomposites based on poly[ethylene‐co‐(vinyl acetate)] (EVA) intercalated‐organomodified clay (at 3–30 wt.‐% silicate addition) which occur in the range between 75 and 350 °C. In situ high temperature X‐ray diffraction (HT‐XRD) studies have been performed under both nitrogen and air to monitor the modifications of the nanocomposite structure at increasing temperatures under inert/oxidative atmosphere. Heating between 75 and 225 °C, under nitrogen or air, causes the layered silicate to migrate towards the nanocomposite surface and to increase its interlayer distance. The degradation of both the clay organomodifier and the VA units of the EVA polymer seems to play a key role in driving the evolution of the silicate phase in the low temperature range. The structural modifications of the nanocomposites in the high temperature range (250–350 °C), depended on the atmosphere, either inert or oxidizing, in which the samples were heated. Heating under nitrogen led to deintercalation and thus a decrease of the silicate interlayer space, whereas exfoliation was the main process under air leading to an increase of the silicate interlayer space.
98.
建筑结构粘结剂的研究进展 总被引:5,自引:1,他引:5
在综合分析国内外文献的基础上,本文简述了粘结剂的发展历史,它在建筑业中的应用现状及在现代建筑业中的地位;研究了建筑结构粘结剂的主要性能指标,粘结剂连接的优点和主要技术检验指标等.此外,对目前广受关注的粘结剂耐久性研究的试验方法做了总结,列举了最新研究进展.在此基础上,指出了目前研究的不足,提出了对研究方向的建议. 相似文献
99.
Although structural adhesives are becoming widespread in numerous applications, one important limitation at present is the long term behaviour of bonded assemblies under conditions of high humidity, especially at elevated temperatures. This study presents a comparison between bulk properties of a structural epoxy resin and its behaviour in a torsional joint consisting of a hollowed-out cylinder bonded to a plate—both substrates being in stainless steel. Exposure to ca. 100% relative humidity at 70°C leads to modification of the bulk properties of the polymer, notably reduction of its elastic modulus. Although this may explain some differences in behaviour of the torsional joint, premature failure is attributed to weaknesses in the interphase zone.
Auger Electron Spectroscopy (AES) has been employed to investigate both unbonded steel surfaces and fracture zones. Although prolonged exposure to water leads to a more extensive degree of (apparently) adhesive failure at the interface polymer/metal, AES has shown the presence of non-negligible quantities of carbon, attributed to residual polymer. Failure would seem to occur, at least partly, in a weak interphase of the polymer, near, but not at, the interface.
Various possible causes are evoked. For dry failure, residual polymer may be due to the topography of the metal surface and/or local modification of the adhesive during cure. In the case of aged joints, in addition there are potential effects due to swelling and differential stresses, secondary bond failure and molecular chain scission within the polymer, all provoked by the presence of water. 相似文献
Auger Electron Spectroscopy (AES) has been employed to investigate both unbonded steel surfaces and fracture zones. Although prolonged exposure to water leads to a more extensive degree of (apparently) adhesive failure at the interface polymer/metal, AES has shown the presence of non-negligible quantities of carbon, attributed to residual polymer. Failure would seem to occur, at least partly, in a weak interphase of the polymer, near, but not at, the interface.
Various possible causes are evoked. For dry failure, residual polymer may be due to the topography of the metal surface and/or local modification of the adhesive during cure. In the case of aged joints, in addition there are potential effects due to swelling and differential stresses, secondary bond failure and molecular chain scission within the polymer, all provoked by the presence of water. 相似文献
100.
This paper proposes a new technique which introduces the high-order single-step-β method(HSM)into the experimental study on the substructure pseudo-dynamic testing(SPDT).The technique is based on the proposed concept of equivalent shear stiffness which can meet the requirement of the HSM algorithm.A study is done to theoretically validate the technique by the numerical analysis of two-storey shear building structure,in comparison of the proposed substructure pseudo-dynamic testing algorithm with the central difference method(CDM).Then,a full-scale SPDT model,the three-storey frame-supported reinforced concrete short-limb masonry shear wall structure,is designed and tested to simulate the seismic response of the corresponding six-storey structure and verify the proposed force control HSM technique.Meanwhile,the techniques of both stiffness correction and force control are suggested to control algorithmic error,control error and measurement error.The results indicate that the force control HSM can be used in the full-scale multi-degree-of-freedom(MDOF)substructure pseudo-dynamic testing before descent segment of structure restoring force properties. 相似文献