弱磁场对EP/MWCNTs–Fe_3O_4复合材料结构与性能的影响

Effects of Low Magnetic Field on Structure and Properties of Epoxy/MWCNTs–Fe_3O_4 Composites

采用均匀沉淀法制备了多壁碳纳米管～四氧化三铁（MwcNTs-Fe3O4）复合粒子，并将复合粒子与环氧树脂（EP）复合，在弱磁场（0．2～0．3T）下固化制备了EP／MWCNTs-Fe3O4复合材料。采用x射线衍射仪、扫描电子显微镜和震动样品磁强计对复合粒子的结构和磁性能进行了表征，重点考察了弱磁场对该复合材料结构、电性能与压缩性能的影响。结果表明，复合粒子表现出顺磁性，其中Fe3O4和MWCNTs彼此相对独立，能够较均匀地分散在EP中；在外磁场作用下，复合粒子在EP中的分布表现为磁流体的特征，沿磁场方向定向排列形成链状结构；随复合粒子含量增加，复合材料的介电常数、导电性和压缩强度总体上呈上升趋势，压缩弹性模量先升高后降低；磁场诱导对复合材料性能的影响与粒子含量密切有关，当复合粒子质量分数不高于2％时，磁场诱导下的复合材料介电常数和导电性高于未施加磁场的复合材料，当复合粒子质量分数不高于5％时，前者的压缩强度高于后者，在考察的含量范围内，前者的压缩弹性模量始终高于后者。

Multi-walled carbon nanotubes-ferroferric oxide （MWCNTs-Fe3O4） compound particles were prepared by homogeneous precipitation method, then epoxy resin （EP） / MWCNTs-Fe3O4 composites were prepared by curing under low magnetic field （0.2-0.3 T）. The structure and magnetic properties of MWCNTs-Fe3O4 were characterized by XRD, SEM and vibrating sample magnetometer. The influences of the low magnetic field on structure, electrical and compression properties of the composites were focused on. The results show that the compound particles presents paramagnetism, Fe3O4 and MWCNTs in the compound particles are relatively independent and easily dispersed evenly in EP. Under external magnetic field, distribution of MWCNTs-Fe3O4 in EP shows a typical characteristics of magnetic fluid with a chain-like structure aligned along the magnetic field direction. With increasing the compound particles content, the dielectric constant, conductivity and compression strength of the composite are generally improved, but compression modulus of the composite is first increased and then decreased. The influences of the magnetic field induction on the properties of composites are closely related with the compound particles content. When the compound particles content is not higher than 2%, the dielectric constant and conductivity of the composites with magnetic field induction are higher than those of the composites without magnetic field induction. When the compound particles content is not higher than 5%, the compression strength of the former is higher than that of the latter. In the investigated range of the compound particles content, the compressive modulus of the former is always higher than that of the latter.