羧基化碳纳米管/聚偏氟乙烯介电复合材料的制备与性能

Preparation and properties of carboxylated carbon nanotubes/poly(vinylidene fluoride)dielectric composites

采用混酸(H2SO4和HNO3体积比为3∶1)对多壁碳纳米管(MWCNTs)进行酸化处理使其羧基化,以此为填料,通过溶液共混法添加到聚偏氟乙烯(PVDF)中形成MWCNTs/PVDF介电复合材料。通过XRD、Raman、TEM、SEM对材料的结构和形貌进行了表征,使用TG、拉伸测试、LCR阻抗分析仪等考察了MWCNTs的用量对MWCNTs/PVDF复合材料热稳定性、力学性能和介电性能的影响。结果表明,随着羧基化MWCNTs含量的增加,复合材料的热力学性能和介电性能比纯的PVDF显著提高。当m(MWCNTs)=10%时,质量保持率达到76%;在室温1kHz频率下,m(MWCNTs)=8%时出现渗流阈值,复合材料的介电常数达到163.5,是纯的PVDF的16倍,介电损耗仅为0.06;此时复合材料的力学性能最佳,拉伸强度、断裂伸长率、弹性模量分别是58.92 MPa、215.83%、2025.42 MPa。

The multi walled carbon nanotubes(MWCNTs)were treated with acid mixture(volume ratio of H2SO4 and HNO3 was 3∶1)to make them carboxylated.And using carboxylated-MWCNTs as fillers,MWCNTs/PVDF dielectric composites were formed by solution blending into poly(vinylidene fluoride)(PVDF).The structures and morphologies of the materials were characterized by XRD,Raman,TEM and SEM.The effects of the amount of MWCNTs on the thermal stability,mechanical properties and dielectric properties of MWCNTs/PVDF composites were investigated by using TG,tensile test and LCR impedance analyzer.The result showed that with the increase of carboxylated-MWCNTs content,the thermodynamic and dielectric properties of the composites were significantly improved compared with those of pure PVDF.When m(MWCNTs)was10%,the mass retention rate of the composites reached 76%.At room temperature and 1 kHz frequency,apercolation threshold was achieved when m(MWCNTs)was 8%,and the dielectric constant of the composites reached 163.5,which was 16 times of that of the pure PVDF and the dielectric loss was 0.06.At this time,the mechanical properties of the composites were best.The tensile strength,elongation at break and modulus of elasticity were 58.92 MPa,215.83% and 2 025.42 MPa,respectively.