Design And Preparation Of Low Dielectric Loss And Antistatic Composites

The radome should not only possess sufficient intensities to endure the impactand destruction of external environment, but also should satisfy the using demand ofthe high penetration rate of waves, thus the material should have the low dielectricloss. Meanwhile, when the plane flies in the process of high-speed, large amounts ofstatic electricity and current will be produced inthe radome surface. If these were notpromptly eliminated, it will affect the normal work of the radar. So the materialshould require low surface resistivity. For a single material, at the same timesatisfying the low loss and antistatic both performances is very difficult. Therefore,for the radome, it is of great significance to develop polymer matrix composites withexcellent antistatic property and low dielectric loss.In this paper, ATO/HGB/EP and MWCNTs/HGB/EP composites were prepared.The epoxy resin with outstanding dielectric property served as matrix while thenanometer antimony doped tin oxide (ATO) powder, multi-walled carbon nanotubes(MWCNTs) and hollow glass beads (HGB) served as conductive fillers and lowdielectric loss fillers, respectively. The above three fillers were surface modified andthen introduced into EP matrix through mechanical blend and ultrasonic dispersion.The influence of different volume ratio between ATO and HGB as well as MWCNTsand HGB on the antistatic properties and dielectric properties of ATO/HGB/EP andMWCNTs/HGB/EP composites were investigated respectively.The electrical resistivities, dielectric properties and wave permeability of thecured products were investigated by insulation resistance tester, precision impedanceanalyzer and vector network analyzer. The results indicated that the increasingcontent of HGB resulted in the increased surface resistivity of composites, decreaseddielectric constant and dielectric loss and enhanced wave permeability. The increasingcontent of ATO led to the decreased surface resistivity of composites, increaseddielectric constant and dielectric loss and weakened wave permeability. And theincreasing content of MWCNTs contributed to the geometric level drop in surface resistivity of composites, increased dielectric constant and dielectric loss anddecreased wave permeability.Take antistatic property and dielectric property into comprehensive consideration,for ATO/HGB/EP system,10wt%content of ATO with a volume ratio of3:7betweenATO and HGB reached the best formula. And the surface resistivity was4.82×1010;the transmission coefficient was approximate0.82; the dielectric constant anddielectric loss was6.20and0.10respectively under an electromagnetic frequency of1.0×106Hz. For the MWCNTs/HGB/EP system,0.1wt%content of MWCNTs with avolume ratio of3:7between MWCNTs and HGB reached the best formula. And thesurface resistivity was4.50×1010; the transmission coefficient was approximate0.85;the dielectric constant and dielectric loss was5.68and0.15respectively under anelectromagnetic frequency of1.0×106Hz.