微波辐射生长CNTs@微珠核壳料优化合成及其增强水泥基复合材料力电传感性能

Synthesis optimization of CNTs@glass beads core-shell material by microwave radiation and piezoresistive sensing performance of its reinforced cement-based composites

  • 摘要: 通过微波辐射方法在微珠(Gb)表面原位生长出碳纳米管(CNTs),合成CNTs@微珠核壳材料(CNTs@Gb),结合微观形貌、红外、热重、拉曼光谱、电导特性探索CNTs@Gb最佳合成条件;然后将最优CNTs@Gb掺入水泥基体中制备CNTs@Gb增强水泥基复合材料(CNTs@Gb/C),系统评价其力学、电学特性及力电传感性能。结果发现:Gb与吡咯配比为3.3∶1时,得到聚吡咯(PPY)包覆良好的PPY@Gb,PPY@Gb与二茂铁配比为1∶1.5、微波处理50 s合成CNTs@Gb性能最佳。2.5%质量掺量下CNTs@Gb/C的28 d抗折、抗压强度较空白组分别提高了10.3%、6.8%,其直流(DC)电阻率降低至9.3 kΩ·cm,频率为100 Hz时的交流(AC)电阻率降低至5.89 kΩ·cm,较空白组分别降低77%和87%。在速率分别为1 kN/s、2.5 kN/s和5 kN/s的变速率循环荷载(0~15 MPa幅值)下平均电阻率变化率可达76%,且最高应力、应变灵敏度分别达5.57%/MPa、13.2%,传感性能优异,显然有利于发展成一种结构健康监测用高性能本征传感器。

     

    Abstract: In this paper, carbon nanotubes (CNTs) were grown in situ on the surface of glass beads using a microwave radiation method, resulting in the synthesis of CNTs@glass beads core-shell material (CNTs@Gb). The properties of CNTs@Gb were optimized through a combination investigations of microscopic morphology, infrared spectroscopy, thermogravimetric analysis, Raman spectroscopy and conductance measurements. Secondly, CNTs@Gb reinforced cement-matrix composites (CNTs@Gb/C) were prepared by incorporating the optimized CNTs@Gb into cement matrix, and their mechanical and electrical properties and piezoresistivity were systematically evaluated. The results show that when the ratio of microbeads to pyrrole is 3.3∶1, the well-coated polypyrrole (PPY)@Gb is obtained, the ratio of PPY@Gb to ferrocene is 1∶1.5, and the performance of CNTs@Gb is the best after 50 s microwave treatment. The 28 d flexural, compressive strength of CNTs@Gb/C at 2.5% CNTs@Gb mass dosage are increased by 10.3% and 6.8% compared with the blank group, and the direct current (DC) resistivity, alternating current (AC) resistivity at 100 Hz are decreased to 9.3 kΩ·cm, 5.89 kΩ·cm, which are 77% and 84% lower than that of the blank group, respectively. Under variable rate cyclic loading at rates of 1 kN/s, 2.5 kN/s, and 5 kN/s (0—15 MPa amplitude), the average resistivity rate can reach 76%, with the highest stress and strain sensitivity reaching 5.57%/MPa and 13.2%, respectively, which have excellent sensing performance. It is favors to develop CNTs@Gb/C as high-performance intrinsic sensors applied in structural health monitoring.

     

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