碳纳米管水泥基纤维增强复合材料压敏性能研究

文中对比分析了几种不同碳纳米管掺量试件的电阻变化规律,评价碳纳米管水泥基纤维增强复合材料的压敏性能。试验结果表明,随着多壁碳纳米管掺量的增加,电阻率将减低并最终趋于稳定,同时,试件压敏性存在差异。当多壁碳纳米管掺量为胶凝材料质量的0.1%时,电阻变化率幅度较大,可以达到0.133,此时,碳纳米管复合材料具备较好的自感知特性,可应用于结构健康监测研究。     

碳纳米管水泥基复合材料研究进展

碳纳米管是近几年国际新材料领域的研究前沿和热点,作者结合自己的研究详细综述了碳纳米管水泥基复合材料的国内外研究进展,分析了当前研究中存在的问题、碳纳米管水泥基复合材料的发展趋势及应用前景,并就今后研究的方向给出了建议.     

MDF水泥基复合材料的性能及其应用

ＭＤＦ水泥基复合材料是一种高技术精细胶凝材料制品,属化学键合陶瓷范畴。本文对它的性能和应用进行了全面的介绍,并分析了其使用过程中存在的湿敏性问题及耐湿性改进措施。     

早龄期氧化石墨烯增强碳纳米管水泥基复合材料的性能研究

文中报道了氧化石墨烯(GO)改善碳纳米管(CNTs)水泥基复合材料的抗折、抗压强度及电学性能的研究。当掺入2wt%CNTs时,CNTs水泥基复合材料抗折、抗压强度分别达最大值9.9、56.7MPa,然而随着CNTs掺入量的增加,CNTs水泥基复合材料的抗折、抗压强度出现了明显的降低趋势。此时在CNTs水泥基体中掺入一定量的GO,可以明显提高水泥基复合材料的抗折、抗压性能。同时GO的掺入可以提高CNTs水泥基复合材料的电学性能,仅掺入0.01wt%的GO时,GO/CNTs-1试样中的平均电阻率从CNTs-1样品的38.4Ω·m下降到了31.5Ω·m,降幅达到了17.9%。     

表面改性对碳纳米管-水泥基复合材料导电性能及机敏性的影响

采用一种由浓硝酸和浓硫酸组成的混合液对碳纳米管进行表面改性后分散到水泥净浆中（SPCNT）,采用四电极法测试了复合材料导电性能和机敏性能,并与未改性碳纳米管增强水泥净浆（PCNT）及普通水泥净浆（PCC）进行了对比;同时采用扫描电镜观察了复合材料的微观结构。结果表明：水泥净浆中掺入碳纳米管后具有优良的导电性能和机敏性能,碳纳米管经表面改性后复合材料的体积电阻较未改性碳纳米管复合材料高,而机敏性能表现更稳定;在复合材料中碳纳米管分布非常均匀,碳纳米管之间互相搭接,形成完好的导电网络,未改性碳纳米管表面光滑未覆盖水泥水化产物,而改性碳纳米管表面被水泥水化产物包裹。     

含生物质基温敏胞衣复合材料研究

以石蜡、硬脂酸作为基体材料,生物质基、玻璃粉末和氢氧化镁作为添加材料制备出温敏胞衣球体,分析了不同直径、厚度、配比下该温敏胞衣球体的力学性能。结果表明,温敏胞衣球体的最佳直径为20.5 mm,最佳厚度为2 mm,材料的最佳配比为︰石蜡︰硬脂酸︰氢氧化镁︰玻璃粉末：生物质基为4︰1︰2︰2︰1,此时温敏胞衣球体可承受最大压力为43.72 N。     

碳纳米管水泥基复合材料机敏性能研究

为了研究碳纳米管水泥基复合材料在循环荷载下的机敏性能,将多壁碳纳米管作为增强相,采用非共价表面活性剂吸附分散技术,使多壁碳纳米管尽可能均匀地分散在水泥净浆中制备碳纳米管水泥基复合材料,分析了碳纳米管掺量、试件尺寸、循环荷载等因素对其机敏性能的影响。试验结果表明:在循环荷载作用下,纳米管水泥基复合材料的电阻率ρ随着加卸载出现可逆性循环变化,表现出了良好的机敏性能,多壁碳纳米管的较佳掺量为0.2%,且尺寸较小的试件表现出的机敏性更优。因此,碳纳米管复合材料可发展成为一种新型的传感器用于结构的健康监测。     

多壁碳纳米管增强DSP水泥基复合材料的探讨

在介绍碳纳米管的结构特征、力学性能和含均匀分布的超细颗粒致密体系即DSP材料的特征、技术性能以及应用前景的基础上,分析了多壁碳纳米管增强DSP材料的可能性,得出拟解决的关键问题是碳纳米管在基体中的均匀分散和与基体的相容性,提出与分析化学专家合作是进行这一领域研究的一条高效途径.     

碳纤维水泥基复合材料的压敏特性研究

研究了内掺含活性化学物质的CCCW材料及碳纤维表面氧化处理后不同碳纤维掺量下水泥净浆试样在循环荷载作用下的压敏特性,并讨论了其压敏机理,分析了三种碳纤维掺量下试样压敏性能差异产生的原因。实验结果表明：添加CCCW材料和使用经浓硝酸处理后的碳纤维混凝土试样,在循环荷载下其电阻稳定性得到了有效提高,并且不同碳纤维掺量下试样的电阻和应力均存在较好的对应关系,碳纤维掺量为水泥质量的1．2％时,试样的压敏性最好。     

碳纤维水泥基复合材料电性能的若干研究

着重探讨了碳纤维长度与掺量、水灰比、龄期及成型工艺对碳纤维增强水泥基复合材料导电性的影响,结果表明,采用振动压制成型工艺且碳纤维长度为10mm时,可以较小的纤维掺量（0.5%)使复合材料获得较强的导电性。     

分散剂对碳纤维水泥砂浆力学性能及压敏性的影响研究

研究了分散剂的种类(HPMC、MC、HEC)和掺量(0、0.2%、0.4%)对碳纤维水泥砂浆(CFRM)力学性能和压敏性的影响。结果表明:当分散剂掺量为0.2%时,掺HPMC和MC的CFRM试件抗压、抗折强度均高于基准组,其中,HPMC对力学性能的提升效果最好;各组试件的电阻变化率均随着应力的增大而减小,其中,HPMC掺量为0.2%的试件灵敏度最高。综合考虑,采用0.2%的HPMC时,CFRM的力学性能和压敏性达到最佳。     

Impact of Temperature and Humidity on the Perception of Indoor Air Quality

Abstract Sensory responses to clean air and air polluted by five building materials under different combinations of temperature and humidity in the ranges 18-28°C and 30-70%RH were studied in the laboratory. A specially designed test system was built and a set of experiments was designed to observe separately the impact of temperature and humidity on the perception of air quality/odour intensity, and on the emission of pollutants from the materials. This paper reports on the impact on perception. The odour intensity of air did not change significantly with temperature and humidity; however, a strong and significant impact of temperature and humidity on the perception of air quality was found. The air was perceived as less acceptable with increasing temperature and humidity. This impact decreased with an increasing level of air pollution. Significant linear correlations were found between acceptability and enthalpy of the air at all pollution levels tested, and a linear model was established to describe the dependence of perceived air quality on temperature and humidity at different pollution levels.     

不同绿量的园林绿地对温湿度变化影响的研究

选择北京紫竹院公园4块不同绿量的乔灌草型绿地为研究对象，进行了连续3天的测试，通过测定分析，得出了不同绿量的园林绿地水平温度、垂直温度、水平湿度和垂直湿度的变化规律。在一定范围内的乔灌草绿量比下，绿地中乔灌的绿量越大，对温湿度的改善作用越大，降温增湿效果明显，具有较好的生态效益。并探讨了绿量及乔灌草绿量比对环境温、湿度的改善作用。     

铺装及园路用地比例对园林绿地温、湿度影响的研究

选取万寿公园作为研究地点，连续测定了0～40％不同比例铺装及园路的温、湿度，结果表明园林绿地铺装及园路用地比例逐渐减小时降温增湿效果趋于稳定，从而从生态改善的角度得出园林绿地铺装及园路用地比例的最大值为17％。本研究以探讨园林绿地铺装及园路用地比例的最大值为目的，旨在为园林绿地的建设提供科学依据。     

Impact of Temperature and Humidity on Perception of Indoor Air Quality During Immediate and Longer Whole-Body Exposures

Abstract Acceptability of clean air and air polluted by building materials was studied in climate chambers with different levels of air temperature and humidity in the ranges 18–28°C and 30-70% relative humidity (RH). The acceptability of the air quality immediately after entering a chamber and during the following 20-min whole-body exposure was assessed by 36 untrained subjects who maintained thermal neutrality by modifying their clothing. The results confirm the significant decrement of the acceptability with increasing temperature and humidity, as shown in a previous study with facial exposures. The odour intensity was found to be independent of temperature and humidity. A linear relation between acceptability and enthalpy of air was again observed by this experiment. No significant difference was observed between the immediate acceptability and the acceptability during the following 20-min exposure, i.e., no adaptation took place. Both the immediate assessment of acceptability and the assessments during the 20-min exposure were independent of the air temperature and humidity to which the subjects were exposed before entering the chamber. The results further indicate that a notable decrement of the ventilation requirement may be achieved by maintaining a moderate enthalpy of air in spaces.     

Impact of Temperature and Humidity on Chemical and Sensory Emissions from Building Materials

Abstract The chemical and sensory emissions from five building materials (carpet, polyvinyl chloride (PVC) flooring, sealant, floor varnish and wall paint) were tested under different combinations of temperature and relative humidity in the ranges 18–28°C and 30–70% relative humidity (RH). The experiment was performed in a climate chamber where a specially designed test system was built to study emissions from the five materials. The test system could provide different temperatures and humidities of air around the materials, while the air, after being polluted by the emissions from the materials, could be reconditioned to 23°C and 50% RH for sensory assessments. The experiment was designed to separate the direct impact of temperature and humidity on perception from the impact on sensory emission. The study found little influence of temperature on the emissions from the five materials whether expressed in chemical or sensory terms. The effect of humidity was found to be significant only for the waterborne materials – floor varnish and wall paint. Compared with the direct impact of temperature and humidity on the perception of air quality, the impact of temperature and humidity on sensory emissions from the building materials has a secondary influence on perceived air quality.     

城市绿地面积与温湿效益之间关系的研究

城市园林绿地由于自然环境条件、天气气候条件、绿地类型、绿化树木种类、树冠郁闭度以及面积大小等的不同,其降温增湿效应是不一样的。本试验选择了北京四环以内绿化覆盖率相当、面积不同的8块园林绿地,进行了绿地面积与温湿效益之间关系的探究。研究表明：当城市绿地面积为1～2hm^2时,其具有一定的增湿效应,但降温效果不明显;当绿地面积为3hm^2时,其降温增湿效果较明显;当绿地面积为5hm^2时,其降温增湿效果极其明显;当绿地面积大于5hm^2时,其降温增湿效果极其明显且恒定。因此可以认为：城市园林绿地可以明显发挥温湿效益的最小面积为3hm^2（绿化覆盖率80%左右）,最佳面积为5hm^2（绿化覆盖率80%左右）。     

碳纤维混凝土导电压敏性的研究

碳纤维水泥基材料具有应力、应变自感知功能,所以可以利用碳纤维混凝土的这种性能制备碳纤维混凝土压敏传感器。本文主要研究用于融雪化冰的碳纤维混凝土的制作工艺;碳纤维混凝土最佳配合比;探讨碳纤维混凝土电阻随碳纤维掺量的变化规律以及混凝土的压敏性。研究结果表明：碳纤维混凝土的电阻随龄期增长而下降,21d后趋于稳定;碳纤维混凝土电阻随碳纤维掺量增加而下降,当碳纤维掺量达0．7％时碳纤维混凝土的电阻迅速下降,此后碳纤维混凝土的电阻随碳纤维掺量增加无显著降低;通过碳纤维混凝土压敏性研究可以测知碳纤维混凝土随压应力增加其内部裂纹的闭合及新裂纹的产生。     

碳纤维水泥基复合材料中纤维分散性的研究

利用新拌料浆法及硬化试件电阻测试法,从碳纤维水泥基复合材料（CFCC）的纤维分散系数及变异系数分析等几个方面着手,探讨了碳纤维长度及掺量、搅拌工艺、分散剂和水灰比等诸因素对CFCC中碳纤维分散性能的影响,并确定了制备CFCC材料的适宜工艺。