Molecular Simulation And Experimental Study On The Mechanism Of The Adhesive Interface Of Glass/aluminum Alloy Modified By Low Temperature Plasma

Adhesive bonding,as an important connection technology,is widely used in the field of high-speed trains,due to the characteristics of uniform stress distribution,simple process and wide application range.However,after the train runs for a period of time,the adhesive on the glass side is easy to fall off in the glass/aluminum alloy adhesive structure,and the durability of adhesive joint is poor,which affects the sealing and safety of the train.Therefore,it is of great significance to investigate the connection mechanism of glass/aluminum alloy bonding interface and the activation mechanism of the glass surface.In this paper,glass and 6005 A aluminum alloy were bonded by using Bostik 7003 polyurethane adhesive.The experimental method was used to study the effect of low temperature plasma modification on the surface properties of glass.Then,the molecular models of polyurethane adhesive/aluminum alloy interface,polyurethane adhesive/glass interface and activated glass surface/polyurethane adhesive were established by molecular dynamics simulation.The connection mechanism of glass/aluminum alloy bonding interface and the joint strengthening mechanism when glass surface is modified by oxygen low temperature plasma were studied theoretically.The experimental results show that the relative content of oxygen on the glass surface increases,while the carbon content decreases,the surfaces morphology hardly changes,and the wettability is improved after the low temperature plasma modification with oxygen.The calculation results show that the polyurethane adhesive interacts strongly with the aluminum alloy side and weakly with the glass side in the glass/aluminum alloy bonded structure.The interface between the polyurethane adhesive and the aluminum alloy and glass is connected by hydrogen bonding,chemical bonding,Van Der Waals force or electrostatic force.However,the number of chemical bonds and hydrogen bonds in the polyurethane adhesive/aluminum alloy interface system is greater than that of the polyurethane adhesive/glass interface.The surface of the glass is activated by hydroxyl,carboxyl and free active particles to enhance the interaction between the polyurethane adhesive and the glass surface.The effect of the hydroxyl group and carboxyl group activation is the best.From the analysis of the calculation results of the radial distribution function,it can be seen that polyurethane tends to form chemical bonds and hydrogen bonds with hydroxyl groups and carboxyl groups on the surface of activated glass,which increases the number of chemical bonds and hydrogen bonds in the interface system,resulting in enhanced interaction of the polyurethane adhesive/glass bonding interface.