Dielectric Properties Of Modified Graphene Oxide/Bismaleimide Composites

Compared with the traditional inorganic dielectric materials， polymer-matrix dielectric materialnot only has good dielectric properties， but also the characteristics of lightweight， goodmachinability and comprehensive mechanical properties that it the research hotspot of dielectricmaterials at present. Grapheme is a novel two-dimensional carbon nanomaterial， and the electricconductivity is the best of all the existing conducting materials at room temperature. BMI(bismaleimide) has outstanding heat resisting property， wave permeability， electrical insulatingproperty， fire resistance， radiation resisting property， good mechanical properties and dimensionalstability. A functional composite material that has high dielectric constant and good flame retardantproperty can be obtained through recombination.However， as the common BMI resin has the disadvantages of high melting point， highcrosslinking density， high curing temperature and high friability， allyl compound should be usedfirst to have toughening modification on BMI. In addition，since the compatibility of grapheme oxideis worse than BMI， in this task， the surface of grapheme oxide should be modified to improve thecompatibility in matrix. Last， in-situ composite technique will be used to prepare a high dielectricfunctional composite material whose flame retardant properties and mechanical properties areoutstanding.First， Diallyl bisphenol A (BA) was used to have toughening modification on BMI， by whichthe influence of the content of dallyl bisphenol A on the mechanical property and flame retardantproperty of BMI was studied. Beside， the interaction mechanism with BMI was analyzed. The resultindicated that the limit oxygen index was decreasing while the impact toughness of BMI wasincreasing with the increasing dosage of BA. When the additive amount of BA was45wt%， theimpact toughness of BMI was increased by83.3%， and the comprehensive mechanical property wasmaintained well. Second，1-(2-diethyl aminoethyl)-3-methylimidazolium Bromide was used tomodify grapheme oxide based on preparing grapheme oxide. The analysis result indicated that theinfluence of modifier on the total weight loss and heat stability of graphene oxide was small.Ultrasonic treatment can disperse and strip graphene oxide to gain single-layer grapheme which has afew wrinkles and multi-layer grapheme which has a small number of plies. Last， in-situ compositetechnique was used to prepare BMI resin-matrix functional composite material whose additiveamount of grapheme oxide was different. Besides， the mechanical property， heat-resistant qualityand dielectric properties were detected and analyzed. The result indicated that when the content ofgrapheme oxide is4.13%in an extra electric field of1kHz， the dielectric constant of this materials can be1331.4. When the content of grapheme oxide is1wt%，tensile strength，bending strength andimpact strength can be91.2MPa，145.1MPa and15.9kJ/m2， and the thermal decompositiontemperature of composite material can be455℃. With the frequency increasing， the dielectricconstant of composite material decreases. Finally，when the content of graphene oxide is4.13%，themodified grapheme oxide and BMI high dielectric composite material acquired have the highestdielectric constants. Besides， the combination property is favorable that it‘s an ideal polymer-matrixdielectric composite material...