排序方式： 共有11条查询结果，搜索用时 125 毫秒
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大尺寸薄壁钢筋混凝土结构,对温度的变化和基础的不均匀沉降较为敏感。制定合理的施工方案,材料的合理选择、施工流程精心组织保证了裂缝控制效果良好。 相似文献
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采用空气等离子体对聚丙烯微孔膜进行表面改性,用X射线光电子能谱,扫描电镜表征膜表面形态和微观结构的变化。考察了改性膜的水接触角、水通量以及在浸没式膜-生物反应器中的动态抗污染性能力。结果表明,改性后聚丙烯微孔膜的水接触角从100°减小到40°,膜的水通量提高,污染率下降。改性后聚丙烯微孔膜的亲水性和抗污染能力得到较大提高。 相似文献
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采用空气等离子体对聚丙烯微孔膜进行表面改性,用X射线光电子能谱,扫描电镜表征膜表面形态和微观结构的变化。考察了改性膜的水接触角、水通量以及在浸没式膜-生物反应器中的动态抗污染性能力。结果表明,改性后聚丙烯微孔膜的水接触角从100°减小到40°,膜的水通量提高,污染率下降。改性后聚丙烯微孔膜的亲水性和抗污染能力得到较大提高。 相似文献
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本文利用加入各种类型的成核剂的方法得到了不同结晶形态的聚乙烯(PE)和聚丙烯(PP);用偏光显微镜研究了各种成核剂的成核作用和结晶形态;用显微激光分析仪和差动热分析(DSC)研究了各成核剂对结晶和熔融过程的依赖关系,并测定了它们对结晶度的依赖关系,研究了它们对拉伸力学性能的影响。研究结果表明,成核剂可以明显地使晶粒细而均匀,能改变结晶和熔融速率,以适应各种工艺性要求,但对力学性能的影响较小,因此可以根据工艺和使用要求选用不同的成核剂。 相似文献
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应用一种简单而鲁棒性较强的鲁棒PID控制算法,即将模型输出上下界和统计的两种辨识方法应用到聚丙稀反应过程带有滞后环节对象的鲁棒辨识中,将所得的PID控制器参数区间和MinMax算法相结合来进行PID参数整定。仿真实验结果表明该算法具有良好的控制效果。最后分析、设计和实现了该算法。 相似文献
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郭勇君 《石家庄铁路职业技术学院学报》2019,(1):53-57
通过测试不同纤维掺量湿喷混凝土的抗压强度及其长期浸泡在5%浓度的硫酸盐溶液中腐蚀规律,研究其在硫酸盐腐蚀环境下的适用性和耐久性,以此建立喷射纤维混凝土寿命预测模型。试验表明:掺量8kg/m3左右的粗纤维喷射混凝土抗压强度和抗腐蚀性能均表现良好,说明聚丙烯粗纤维混凝土有其适合掺量的。 相似文献
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SUJI D. NATESAN S. C. MURUGESAN R. 《浙江大学学报(A卷英文版)》2007,8(7):1101-1109
Synthetic fibers made from nylon or polypropylene have gained application when loose and woven into geo textile form although no information on the matrix＇s mechanical performance is obtained so that more understanding of their structural contribution to resist cracking can be determined. This paper presents the results of an experimental investigation to determine the performance characteristics of concrete reinforced with a polypropylene structural fiber. In this investigation ＂Fiber mesh＂ brand of fibers manufactured by SL Concrete System, Tennessee, USA and marketed by M/S Millennium Building System, Inc., Bangalore, India are used. The lengths of the fibers used were 24 mm. Fiber dosages used were 0.9, 1.8, 2.7 kg/m^3. A total of three mixtures, one for each fiber dosage were made. A standard slump cone test was conducted on the fresh concrete mix with and without fibers to determine the workability of the mix. The test program included the evaluation of hardened concrete properties such as compressive, split tensile, modulus of rupture and flexural strengths. The increase in compressive strength is about 36.25%, 26.20%, and 23.75% respectively that of plain concrete. This increase in strength was directly proportional to amount of fibers present in the mix. The increase in flexural strength for Mixes I-III is about 21%, 16.6%, and 23% respectively that of plain concrete specimens. An experimental investigation was also made to study the behaviors of reinforced fibers concrete beams （with longitudinal reinforcements） under two-point loading. The deflection and crack patterns were also studied. The improvements in strength and ductility characteristics were discussed. 相似文献
8.
《Journal of Cultural Heritage》2014,15(2):136-143
The artist Jordi Teixidor is one of the leading exponents of twentieth century Spanish abstract art. In recent years, he has used a synthetic polymer as a support for his art work, namely polypropylene. The behaviour of this material in combination with layers of oil paint has not been studied until now. One of the objectives of this study was to chemically characterise the material present in Jordi Teixidor's work, using FT-IR spectroscopy, in order to be able to examine the behaviour of this set of materials after undergoing cycles of accelerated aging. After subjecting the samples to temperature and relative humidity cycles and ultraviolet radiation, their physico-mechanical behaviour was determined via tensile and bend tests, with the results being processed further by means of spectroscopic techniques and colour measurements. It was found that the possible migration of the additives present in the PP support and the gradual degradation of the materials could affect the adherence between the paint layers in the future. 相似文献
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In this work, polypropylene （PP）/polystyrene （PS） blends with different organoclay concentrations were prepared via melt compounding. Differing from the results of previous reports, the organoclay platelets are mostly located in the dispersed PS phase instead of the interface. The dimensions of the dispersed PS droplets are greatly reduced and apparent compatibilization effect still exists, which cannot be explained by the traditional compatibilization mechanism. A novel compatibilization mechanism, ＂cutting＂ to apparently compatibilize the immiscible PP/PS blends was proposed. The organoclay platelets tend to form a special ＂knife-like structure＂ in the PS domain under the shear stress of the continuous PP phase during compounding. The ＂clay knife＂ can split the dispersed PS domain apart and lead to the dramatic reduction of the dispersed domain size. 相似文献