基于界面改性的碳纳米管水泥基复合材料力学性能

Mechanical performance of carbon nanotubes reinforced cement composites based on interface modification

针对碳纳米管水泥基复合材料中碳纳米管与水泥基体界面结合弱的技术问题,以聚乙烯醇和聚丙烯酰胺分别作为界面桥连剂,探究桥连剂通过强化碳纳米管与水泥基体间的界面对碳纳米管水泥基复合材料力学性能的增强效果;利用阿拉伯树胶作为碳纳米管的水性分散剂,采用普通和表面带有羧基的2种碳纳米管制备5组不同碳纳米管掺量的水泥基复合材料,对其进行了不同龄期的抗压、抗折强度测试,并利用扫描电子显微镜(SEM)在断口处对碳纳米管与水泥基体界面区进行了微结构分析。结果表明:采用羧基碳纳米管并掺入桥连剂的水泥基复合材料力学强度得到最大提升,相较于配合比相同但未加入碳纳米管的基准组,加入桥连剂的羧基碳纳米管水泥基复合材料28 d抗折、抗压强度分别提升了47.4%和22.7%,仅加入羧基碳纳米管的水泥基复合材料则提高了15.4%和8.84%;SEM测试发现加入桥连剂的碳纳米管水泥基复合材料破坏断口处碳纳米管与水泥基体连接处结构密实,未加入桥连剂试件断口处碳纳米管被完全拔出,说明桥连剂改善了碳纳米管与水泥基体间界面结合,使二者近似成为一个整体进行受力,增强了碳纳米管的拔出效应,水泥基体断裂时碳纳米管拔出吸收了更多的破坏能,显著改善了水泥基复合材料的宏观力学性能。

Aiming at the technical problems of weak bonding capacity of interface between carbon nanotubes and cement substrate in carbon nanotubes reinforced cement composites. Polyvinyl alcohol and polyacrylamide were used as interfacial bridging agents to investigate the effect of bridging agents on the mechanical properties of carbon nanotube-based cement composites by strengthening the interface between the carbon nanotubes and the cement matrix, Arabic gum was used as water-based dispersant for carbon nanotubes. Five kinds of cement-based composites with different amounts of carbon nanotubes were prepared by using two kinds of carbon nanotubes with common and surface carboxyl groups. Different ages compressive, flexural strength of specimens were tested. The microstructure of the interfacial region of carbon nanotubes and cement was analyzed by scanning electron microscopy (SEM) at the fracture site. The results show that the mechanical strength of cement-based composites with carbon nanotubes and bridging agents is maximized. The 28-day flexural strength and compressive strength of the carboxy nanotube cement composites added with bridging agent are 47.4% and 22.7% higher than those of the same group without the addition of carbon nanotubes. The 28-day flexural strength and compressive strength of the carboxy nanotube cement composites are 15.4% and 8.84% higher than baseline group. The SEM test found that the carbon nanotubes and the cement matrix are closely connected at the fracture site of the carbon nanotubes cement-matrix composite material added with the bridging agent, while the carbon nanotubes at the fractures of the specimens without the bridging agent are completely pulled out.This shows that the bridging agent improves the bonding between the carbon nanotubes and the cement matrix, so that the two are approximately subjected to a force. The pull-out effect of carbon nanotubes is enhanced, more damage can be absorbed by the carbon nanotubes when the cement matrix is broken, and the macro-mechanical properties of the cement matrix composites are significantly improved. 2 tabs, 10 figs, 23 refs.