Design And Simulation Of CF/PC Composite Interface

Carbon fiber reinforced thermoplastic composite materials are widely used in the automotive industry,aerospace,electronic appliances,machinery industry and other fields due to their advantages of high strength and hardness,no solvent in the preparation process,high performance at high temperature,and recyclability.Carbon fiber reinforced polycarbonate(CF/PC)composite materials can organically combine the advantages of CF and engineering plastic PC.However,due to the surface inertness of carbon fiber and the high processing difficulty of PC,the interface research of CF/PC composite system has been slow.The micro-level study of the interface of this material system can broaden the selection range and synthesis route of composite materials,and provide more theoretical basis for the interface research.In this paper,the CF/PC interface is taken as the research object to modify the interface design.The polyesterimide-polyether block copolymer with adjustable block ratio is blended with PC,based on the molecular dynamics calculation software Materials Studio,through the process of model building,structure optimization,molecular dynamics simulation,etc,the interface modification principles of mixed modification,carbon fiber surface oxidation,and sizing agent modification were explored,and the effectiveness of the sizing agent was verified,and the relationship between microstructure and macroscopic performance was established.In the resin blending modification,a polyesterimide-polyether block copolymer containing "soft segment" and "hard segment" was designed in order to increase the fluidity through the polyether soft segment and pass the polyester imide and to improve the insufficiency of polycarbonate processability though the amine "hard segment".The effect of block copolymers on polycarbonate was studied from two aspects: solubility parameter(δ)and glass transition temperature(Tg).The molecular dynamics simulation results of the solubility parameter indicate that when the proportion of the hard segment in the block copolymer is high,the compatibility of the two resins is good.At this time,the δ value of the polycarbonate is 18.16,and the δ value of the block is 17.25.The difference between the two is only 5%.From the results of Tg,the linear fitting curve has only one turning point,which proves that the compatibility of the two resins is better,and the addition of the block copolymer makes the glass transition temperature drop by 0.4K～20K to varying degrees.When the block polymers with segment ratios of 0:10,1:9,2:8,3:7,and 9:1 are blended with polycarbonate,the compatibility between the two is good and the Tg drops above 8K,improving PC The effect of processing performance is obvious.Through the molecular dynamics simulation of the deoxidized carbon fiber or oxygenated carbon fiber/polyurethane sizing agent model,the role of carbon fiber surface oxidation was explored.The results show that after grafting oxygen-containing functional groups,the sizing agent and carbon fiber are more tightly bound.The interface interaction energy of this model decreases from 874.19 kcal/mol to 604.77 kcal/mol,a decrease of 269.421 kcal/mol.This result shows that from the perspective of molecular simulation,surface oxidation is an effective way to enhance the infiltration effect of the composite interface.Through the carbon fiber/sizing agent/blended resin interface construction,geometric optimization,annealing simulation and molecular dynamics simulation,the role of the sizing agent on the CF/PC interface was explored.The results show that,compared with the interface without sizing treatment,after the sizing agent treatment,the combination of carbon fiber and polycarbonate is significantly tight.However,the effect of the addition of block copolymer on the interfacial wetting is not obvious.The higher the proportion of the polyether soft segment in the block copolymer,the better the interface bonding effect.The form of interface bonding is mainly van der Waals force.Sizing carbon fiber monofilament and composite material mechanical properties test confirmed the effectiveness of sizing agent.