Research On Synthesis And Application Of GNP/CNT Mixture Powders

Graphene/carbon nanotubes with excellent physical and chemical properties have an advantage in improving composite material performance,but how to obtain cheaply large-scale preparation of graphene/carbon nanotube composite powder has always been a difficulty in the field of this material.In this article,the in-situ synthesis of graphene/CNT hybrid powders was mainly explored.In the process of that,the factors were investigated,including the types of carbon source,the proportion of raw materials,the types and mixing amount of modifiers,chemical deposition time,and so on.In the meanwhile,the influence of chemical deposition processing parameters and catalysts on the micro morphology of graphene/CNT composites were researched and discussed,in order to find the best processing parameters and prepare the graphene/CNT hybrid powders by in-situ methods.The composite powders were characterized by SEM,XRD,RAMAN,TEM,AFM and so on.The PBT plastics,with different amount and different mixed proportion of graphene/carbon nanotubes powder,were extruded after mixing.After that,the surface resistance of PBT composites was tested.The antistatic effect of graphene / carbon nanotube mixturse in PBT was comparatively studied.The influence of different content of carbon nanotubes,graphene and graphene/carbon nanotube composite powder,was investigated comparatively on the mechanical properties and the electromagnetic shielding effectiveness of cement slurry.At the same time,the mechanical properties are simulated by computer.The results show that:(1)It is possible to prepare graphene/carbon nanotube hybrid powders with low cost by using chemical vapor deposition method.The minimum thickness of the graphene is 10 nm.It can be achieved that the ratio of the carbon nanotubes/graphene ratio is between 0.625 ~ 8.250 by controlling the different modified liquid phase and different sedimentary process.Best proportion of expanded graphite modified fluid has been obtained.At the ratio of liquid to m(ferric nitrate): m(aluminum nitrate): m(ammonium carbonate): m(expanded graphite): m(water)= 3:1:1:0.5:36,the carbon nanotube composite powder is more,the pipe is fine.The obtained graphene with good quality is transparent and very thin.The best preparation technology was preliminary obtained.The best parameters,including the uniformity of the expanded graphite with iron,argon as carrier gas,the time of deposition appropriately extended,can improve the quality of the mixture of carbon nanotubes and flake graphite.(2)PBT / graphene / carbon nanotube ternary composites were prepared by melt-mixing method using in-situ prepared graphene / carbon nanotube composite powders.Within a certain range,the more the amount of powder is,the lower the surface resistivity of the composites is.The threshold of the conductive component is between 2% ~ 4%.When the composites added to the PBT,the conductive performance of graphene/carbon nanotube composite powder is,on average,higher 2 ~ 3 orders of magnitude than that of the purity of carbon nanotubes in the same conditions.(3)The incorporation of carbon nanotubes,graphene and graphene/CNT hybrid can raise the compressive strength of cement paste.And the early streng(3d)of the cement paste with grapheme,CNT or grapheme/CNT hybrid can also reach double of that of the controlled cement paste at the peak,meanwhile the 28 d strength is 50% higher or so.The ultrasonic dispersing samples has a better disperding effect and a higher compressive strength than that with the ball-mill dispersing.In addition,the compressive strength of graphene/CNT/cement samples is significantly higher than that of the compressive strength of samples only with grapheme or CNT.Through the simulation and comparative analysis of mechanical performance of grapheme/CNT cement-based materials by ANSYS,it can be concluded that the simulation results are consistent with experimental results.(4)Carbon nanotubes,graphene and graphene/carbon nanotube composite powder can availabely improve the electromagnetic shielding effectiveness of cement paste.The highest SE values of the grapheme/cement,CNT/cement and grapheme/CNT/cement samples are all more than 25 db.The highest SE of grapheme/CNT/cement is above 30 db and 5 ~ 40% higher than the other two cases.