Study On Preparation Of Structural-conductive Composties And Their Conducting Properties

In the aeronautical industry,one of the most urgent demands is to improve the feeble electrical conductivity of carbon fiber reinforced composites(CFRPs).The contradiction could attributed to the anisotropy nature of CFRP,against the tradditional idea for designing composite structure s,which is to focus on their mechanical strengths.The state of art techniques for the electrically conductive CFRP structures usually involving auxilary materials and devices.However,for a morden aircraft,these auxilary systems consumed their limited margin of struc tural design,increased their overall cost of material procurement and manufracture,and reduced their effic iency of the composite airplane.Therefore,the integration of structural strength and electrical conductivity is an important direction and research goal of developing the advanceed aeronautical composite materials.Aiming the aforementioned target,this paper studied the preparation method of structural-conductive composties and their conducting properties.The main research contents and foundings of this study are as follows:(1)Research on structural-medium conductive(resistance: 1~100?/?)CFRP: Using Multi-Walled Carbon Nano-Tubes(MWCNTs)as condutive infillings and optimize them via BET analysis approach,X-ray photoelectron spectroscopy,and Raman spectroscopy;improve the efficiency of the ultrasonic cavitation and high-shearing dispersion method,establish the protocol for evenly modifying epoxy resin with the selected MWCNT;study the mechanis m of the improved mechanical and electrically conductive properties of the MWCNT modified CFRP,find the cooresponding relation between the MWCNT amount and the changed CFRP properties,prepare the structural-medium conductive CFRP;design specific experiments to characterize the availibilities of the structural-conductive CFRP in anti-static and electromagnetic shielding scenarios and discuss the impact of CFRP conductivity on its anti-static and electromagnetic shielding behavior.(2)Research on structural-conductive adhesive film: Select the continous toughening structure in the multi-phase epoxy resin and explore the possible approaches for conductive ly modify it;establish and ameliorate the chemical coating protocols for the light-weight polymer toughening fabrics,and substitute the original toughening gradients in the epoxy with the conductive toughening fabrics,commence the research on the structural-highly conductive(resistance?1?/?)polymers,and prepare structural-conductive adhesive film;research the second-step condutive modification method for the decreased conductivity along the bonding interfaces between the adhesive film and adherends;via comparing the bonding strength and conductivity of the structural-conductive adhesive film to commercial structural adhesives and conductive adhesives,respective ly;characterize its comprehensive property,and analyse the establish manner insided the structural-conductive bonding joint.(3)Preparation of structural-highly conductive CFRP: Study and improve the interleaving modification method for mechanically and conductive enhance the performance of epoxy and bismalimide(BMI)resin based CFRPs,via introduce the light-weight conductive toughening fabric in to these CFRP system,explore the possible methods for fabracting structural-highly conductive CFRP,analyze the mechanis m of the enhanced interlaminar fracture toughness by the aid of the continous conductive toughening structure and the cooresponding relation between the conductively modified resin in the interlaminar regions and the improved overall conductivity of CFRP;via the direct lighting effect experiment and the research on the lightning strike protection effectiveness of structural-condutive CFRP,study theinfluence of the increased interlaminar conductivity on the overall lightning sstrike protection effectiveness of the CFRP.(4)Research on multi-functional isolated LSP adhesive film: Analyze the distinctive influence of the direct lightning effect: thermal radiation and the high density current injection to the CFRP and the cooresponding damage modes they led to;besides conductive modify the polymer fabric and evenly modify the thermosetting resin,endow thermal insulating capability to the lightning strike protection material,prepare multi-functional lightning strike protection film mainly consist of polymer and carbon materials,study its lighnting strike protection effectiveness,and characterize it by comparing it with the commercial metal carrying lightning strike protection solutions.By the aid of these new preparation techniques and new theories,this paper successfully prepared: carbon nanotube modified structural-medium conductive CFRP with medium enhanced through thickness conductivity,its compression and interlaminar strength was improved significantly by 29% and 17%,its through thickness conductivity reached 16.4S/m,its electromagnetic shielding effectiveness increased to 68 dB,and oil surface potential reduced to less than 7V;metal/polymer fiber/carbon fiber hybrid nonwoven modified structural-highly conductive CFRP,of which the throught thickness conductivity increased to 27.9S/m,60 times higher than its original state;structural-conductive adhesives of which the lap shear strength,peel strength,and joint conductivity increased to 26.8MPa,4.2N/mm,and 1700S/cm;electrically and thermally conductive layer/intumescent thermally insulated layer stacked multi-functional LSP adhesive film,with 37% lighter weight,the lightning strike damage of the protected CFRP reduced to 0.24 mm,and the residual strength increased to 401 MPa.The 3 new developed materials represent better comprehensive properties than the state-of-art structural material/auxiliary system solution for conductive CFRP parts.In this paper,the aforementioned materials and relative material designing protocols were studied systematically,their feasibilities were also validated.