酸化碳纳米管增强水泥基复合材料的力学性能及碳纳米管在水泥基复合材料中的微观研究(硕士)(论文23000字)
摘 要
由于碳纳米管在水泥浆里面容易发生团聚或者缠绕，所以影响碳纳米管增强水泥基复合材料力学性能的指标之一是碳纳米管在水泥浆中能否很好的分散。聚乙烯吡咯烷酮（PVP）分散剂是近年来一些研究学者发现的能较好的使碳纳米管在水泥基材料中分散。但是即便如此，碳纳米管之间的范德华引力依然影响着碳纳米管在水泥浆体中的分散。本文利用二氯甲烷和间氯过氧苯甲酸对碳纳米管进行处理来研究酸化以后的碳纳米管对于增强水泥基复合材料力学性能的影响。碳纳米管在近年来被广泛使用，理论和实践已经证实其具有优异的力学和光电学性能。本文将其加入水泥基材中，利用纳米压痕仪研究其弹性模量和硬度的变化规律。主要研究结论如下：
（1）采用羧甲基纤维素钠（CMC），聚乙烯吡咯烷酮（PVP）这两种种分散剂进行比较试验，从试验现象和试验效果来看，聚乙烯吡咯烷酮（PVP）作为分散剂能够更好提高碳纳米管在水泥基体中的分散性；
（2）采用聚乙烯吡咯烷酮（PVP）作为分散剂，与碳纳米管进行混合，制备水泥砂浆标准试块，标准养护28天后测量其抗压强度达到最大为59.2MPa，较素水泥砂浆提高了40.3%；抗折强度达到最大为8.9MPa，较素水泥砂浆提高了20.2%；挠曲强度达到最大为8.3MPa，较素水泥砂浆提高了30.7%。实验结果证明，碳纳米管掺量在0.10wt%时，抗压强度和抗折强度达到最大，掺量在0.08wt%时挠曲强度达到最大，随后随着掺量的增加抗压强度，抗折强度，挠曲强度逐渐降低；
（3）采用酸化之后的碳纳米管制备的水泥砂浆,经过对试件的抗压，抗折，三点弯曲试验，分析了酸化之后的碳纳米管对水泥砂浆宏观力学性能的影响。结果表明酸化以后的碳纳米管制备的水泥砂浆的抗压强度最大为62.4MPa，较素水泥砂浆提高了47.5%；抗折强度最大为11.3MPa，较素水泥砂浆提高了52.7%；挠曲强度最大为9.3MPa，较素水泥砂浆提高了47.6%。实验结果证明，酸化之后的碳纳米管掺量在0.05%时，其试块的抗压强度、抗折强度、挠曲强度达到最大，随后随着掺量的增加其强度逐渐降低；
（4）利用纳米压痕仪测试掺加碳纳米管的水泥浆的弹性模量和硬度，试验发现碳纳米管掺量在从0.0%到0.08%的过程中，水泥浆的弹性模量均值从26.1GPa提高到28.8GPa，硬度均值没有太大影响。随着碳纳米管掺量的增加，低密度硅酸钙凝胶的体积分数逐渐降低，高密度硅酸钙凝胶的体积分数逐渐增加。
关键词：碳纳米管；抗压强度；挠曲强度；硬度；弹性模量；水泥基材料；力学性能；纳米压痕仪
The mechanical properties of the cement-based composites reinforced by the acidified carbon nanotubes
Major: Architectural And Civil Engineering
Abstract
Due to carbon nanotubes or winding in cement slurry are prone to get together, so the influence of carbon nanotubes reinforced cement base composite materials mechanics performance is one of the indicators of carbon nanotubes can good dispersed in the slurry. Polyvinyl pyrrolidone (PVP) dispersants have been found by some researchers in recent years to be able to disperse carbon nanotubes in cement-based materials. But even then, the van der Waals attraction between carbon nanotubes still affects the dispersion of carbon nanotubes in the water mud. In this paper, carbon nanotubes are treated with dichloromethane and interchlorinated peroxybenzoic acid to study the effect of carbon nanotubes on the mechanical properties of cement-based composites. Because carbon nanotubes have been widely used in recent years, theory and practice have proved that they have excellent mechanical and photoelectric properties. In this paper, the variation of elastic modulus and hardness is studied by using nanometer indentation instrument.The main research conclusions are as follows:
(1) Sodium carboxymethyl cellulose (CMC), hexadecyl trimethyl ammonium bromide (C16TAB), polyvinylpyrrolidone (PVP), three kinds of dispersants contrast experiment was carried out, from the point of experimental phenomena and results, polyvinylpyrrolidone (PVP) as a dispersant can better improve the dispersion of carbon nanotubes in cement matrix;.
(2) Selection of polyvinylpyrrolidone (PVP) as a dispersant, adding carbon nanotubes, preparation of cement mortar beam, the standard curing 28 days after measuring its compressive strength, flexural strength, three-point bending strength, the experimental results show that the carbon nanotube content at 0.08 wt % compressive strength, flexural strength, three point bending strength reached maximum, then gradually reduce with the increase of dosage of strength.
(3) Choose after acidification of cement mortar, carbon nanotubes prepared carbon nanotubes after the specimen of compressive strength, flexural, three point bending test, studied the acidification of the influence of carbon nanotubes on the mechanical properties of cement mortars. Results show that the carbon nanotubes after acidification is not dealing with the mechanical properties of cement mortar of carbon nanotubes had certain increase, and adding acid exists an optimal value of carbon nanotubes (adding acidification of carbon nanotube content of 0.10%). When adding quantity is less than this value, with the increase of adding quantity, anti-pressure, anti-folding and flexural strength are improved accordingly. The mechanical properties of cement slurry decrease with the increase of adding quantity.
(4) Using the nanometer indentation instrument to test the elastic modulus and hardness of the water slurry with carbon nanotubes, the test found that the content of carbon nanotubes in 0.05 wt % and 0.08 wt % can increase the content of HD c-s-h and UHD c-s-h .
Keywords: Carbon nanotubes; Compressive strength; Flexural strength; Hardness. Elastic modulus; Cement material; Mechanical properties; nanometer.
目录
1. 4
1.1 研究背景 4
1.1.1 纳米材料以及碳纳米管 4
1.1.2 水泥基复合材料 5
1.1.3 纳米压痕技术 6
1.2 研究目的和意义 7
1.3 国内外研究现状 7
1.3.1碳纳米管在水泥基材中的分散性研究进展 8
1.3.2碳纳米管对水泥基材料的力学性能的研究进展 9
1.4 本文研究的主要内容和创新点 9
1.4.1本文研究的主要内容 9
1.4.2本文的创新点 9
2. 碳纳米管分散剂选用的研究 10
2.1 原材料和试验方法 10
2.1.1 原材料 10
2.2 本章小结 11
3. 碳纳米管增强水泥基复合材料的力学性能研究 12
3.1 引言 12
3.2 原材料、配合比和实验方法 12
3.2.1 原材料 12
3.2.2 配合比 13
3.2.3 实验方法 13
3.3 碳纳米管对水泥砂浆强度的影响规律 14
3.3.1 不同掺量对抗压强度的影响规律 14
3.3.2 不同掺量对抗折强度的影响规律 15
3.3.3 不同掺量对挠曲强度的影响规律 15
3.4 本章小结 15
4.1 引言 16
4.2 原材料、配合比和实验方法 16
4.2.1 原材料 16
4.2.2 配合比 17
4.2.3 实验方法 17
4.3 酸化碳纳米管对水泥砂浆强度的影响规律 18
4.3.1 不同掺量对抗压强度的影响规律 18
4.3.2 不同掺量对抗折强度的影响规律 19
4.3.3 不同掺量对挠曲强度的影响规律 19
4.4 机理分析 20
4.5 本章小结 21
5. 碳纳米管水泥基材的微观力学研究 21
5.1 引言 21
5.2.1 纳米压痕仪试验原理 22
5.2.2 纳米压痕仪参数 23
5.2.3 样品制备 24
5.2.4 纳米压痕仪加载方式 25
5.3 硬化水泥各相的弹性模量和硬度特征值 27
5.4 碳纳米管对水泥基材料纳米力学性能的影响 28
5.4.1 碳纳米管对水泥基材料弹性模量的影响 28
5.4.2 碳纳米管对水泥基材料压痕硬度的影响 29
5.5 本章小结 30
6. 结论与展望 31
6.1 主要研究结论 31
6.2 研究展望 32 |
