Study On Fabrication And Properties Of PP/MWCNTs Conductive Composites With Alternating Microlayers

With the coming of the information times,the anisotropic conductive polymer composites(ACPCs)have been applied in various fields owing to their unique conductive property.A number of methods have been reported to fabricate the ACPCs.However,there are many deficiencies of existing ACPCs(e.g.,insufficient conductivity,low conductive anisotropy and small size)besides the complicated manufacturing process with quite high cost and sophisticated fabrication facilities,which make it difficult for the mass production in practical applications.Inspired by the alternating microlayers presented commonly in nature and life,the thermoplastic polypropylene(PP)and multi-walled carbon nanotubes(MWCNTs)were used as polymer matrix and conductive filler,respectively.The PP/MWCNTs composites with alternating microlayers were prepared by the conventional polymer melt processing methods of"trilayered blow molding-multilayered compression molding".A combination of POM,3D CLSM and SEM was performed to observe the morphological structure.The DSC,TGA,tensile tests and electrical measurements were respectively carried out to study the effects of alternating microlayers on the thermal,mechanical and electrical properties.Then the electrical/thermal anisotropic behaviors were monitored macroscopically by the LED integrated circuits,IR thermal camera and finite element analysis,further to explore its potential applications in the fields of electrical interconnection,directional conduction and thermal management.After that,based on the above research results,the anisotropic PP/MWCNTs films(A-PP/MWCNTs),approximately 25 ?m in thickness,were obtained by a microtome.The vapor sensing behaviors of A-PP/MWCNTs films towards saturated cyclohexane,xylene,dichloromethane and ethyl acetate vapors were investigated.(1)The relationship of "structure-properties-applications" was systematically studied.The alternating arrangement of the PP and PPCNTs microlayers were successfully fabricated at the compression temperature of 170?,and there was no structural defect(e.g.,layer breakup or phase migration)in the microlayers,which indicated good adhesion in the multilayered structure.Such alternating microlayers endowed the composites with inner layer conduction but interlayer insulation.The electrical conductivity in X direction reached up to 1 S/m and exhibited a value almost 16 orders of magnitude higher than the value in Z direction.The composites also demonstrated improved thermal stability and enhanced mechanical property,breaking the mutual restriction between the mechanical and electrical property.Furthermore,the composites exhibited excellent current-carrying capability and remarkable conductive anisotropy in the functional LED circuit.Additionally,the thermal anisotropic behavior was simulated by finite element analysis,opening a new pathway toward the combination of experimental characterization and theoretical simulation in future research.(2)The comparison study of the vapor sensing behaviors between A-PP/MWCNTs films and isotropic PP/MWCNTs films(I-PP/MWCNTs)was performed.Compared with the I-PP/MWCNTs films,the A-PP/MWCNTs films immersed in saturated cyclohexane,xylene,dichloromethane and ethyl acetate vapors had higher and faster responsibility as well as lower residual resistance,suggesting such prepared A-PP/MWCNTs films had great potential applications in high performance organic vapor sensors.At the room temperature(25?),the ranking of maximum responsivity was:cyclohexane>xylene>dichloromethane>ethyl acetate,and the maximum responsivity increased with the increase in temperature.Therefore,the vapor sensing behaviors of composites were determined together by the microstructure,properties of solvents and temperature.