水對(duì)碳纖維-環(huán)氧樹脂界面粘結(jié)作用的分子動(dòng)力學(xué)模擬.pdf

1、 Classified Index: TB332 U.D.C: 624 Dissertation for the Master Degree in Engineering EFFECTS OF MOISTURE INGRESS ON THE BOND BETWEEN CARBON FIBER AND EPOXY RESIN INVESTIGATED WITH MOLECULAR DYNAMICS SIMULA

2、TION Candidate： Yanrong Xiao Supervisor： Prof.Guijun Xian Academic Degree Applied for： Master of Engineering Speciality： Civil Engineering Affiliation： School of Civil Engineering Date of Defence： June, 2017 Degre

3、e-Conferring-Institution： Harbin Institute of Technology Abstract Abstract Considering the long service life of FRP in extensive applications under extreme environment, it is inevitably to have a high requirment for its

4、 duribility. The water effect on the properties of the interface for FRP material is vital and difficult. Interfaces between CF and resin matrix are intrinsically inhomogeneous and anisotropic. Interface bonds include in

5、terdiffusion of elements, molecular entanglement, mechanical interlocking, electrostatic atraction, chemical reaction, etc. It is hard to achieve the mechanisms of the interaction between the interface through trandition

6、al experimental methods and theories. In this paper, molecular dynamics methods are used to study the interface adhesion of CF/epoxy interface under dry and water ingress environment. The main results and conclusions are

7、 as follows: First, the atomic model of the carbon fiber / epoxy interface at the nanometer scale was established through Molecular Dynamics method. The configures of the epoxy resin under equilibrated state on the surfa

8、ce of the carbon fiber were calculated and in the environment of drying and water ingress environment respectively. As shown,with the intermolecular forces, water molecules are adsorbed onto the surface of the carbon fib

9、er, immersed into the gap between the epoxy resin and the carbon fiber epoxy resin molecules. Thus leading to part of Epoxy resin chains detached from the carbon fiber surface. Water effectively deteriorate the epoxy res

10、in and carbon fiber interface. Second, A quantitative analysis of the surface free energy variation of the carbon fiber/epoxy resin interface with and without water ingress was performed using the enhanced sampling metho

11、d metadynamics. Epoxy molecules were pulled away from the surface of the carbon fiber. The potential mean force of the CF/epoxy interface in the process were calculated by Metadynamics simulation. Compared to the dry env

12、ironment, a reduction by 58% of the surface free energy was found with saturated water uptake. This results was comparable with that by the microbond test, in which carbon fiber/ epoxy samples were respectively treated w

13、ith various immersion in water. Third, to study the mechanisms of moisture uptake-induced carbon fiber/ epoxy interface adhesive degradation, the effects of Van der Waals force and Coulomb forces between water and interf

14、ace molecules were studied. The simulation results show that the van der Waals force between the water molecule and the epoxy resin molecules will slow down the movement of the molecular segments of the epoxy resin and p