[P2-68] Durability analysis on the environmental aging of epoxybased nanocomposite
Aging is a slow and steady process which occurs by various environmental factors including moisture, uv light, changes in temperature and pressure. Hygroscopic aging of polymer nanocomposite occurs by consistent exposure to moisture in service condition. As bounded water in the material causes microscopic changes in chemical and physical structure of the composite material, it eventually leads to swelling, plasticization, degradation of mechanical and interfacial properties. Thus, to properly examine the long-time process of aging, correlation between aging time-structure-corresponding properties should be developed. Therefore, in this study, multiscale bridging method incorporating atomistic approach of molecular dynamics (MD) simulation and continuum modeling is presented.
To define the relationship between aged structure and corresponding properties, MD simulation is firstly adopted. Different crosslinking ratio of 30% to 70% is established by crosslinking reaction between bisphenol F type epoxy (EPON862®) resin and triethylenetetramine (TETA) curing agent. A single layered defect-free graphene is added as fiber reinforcement in the nanocomposite structure. Also, to observe the hygroelastic behavior of nanocomposite, weight fraction of 0, 2, 4wt% water is included in the nanocomposite unit cell. After isobaric-isothermal (NPT) ensemble simulation, diffusion coefficient of water, coefficient of moisture expansion (CME), elastic modulus and cohesive zone law of epoxy/graphene nanocomposite models are predicted. Based on the results of MD simulation, equilibrium hygroelastic constitutive models incorporating interfacial properties between epoxy and graphene are used to accurately measure the nanoscale effect observed in MD simulations with moisture.
To define the relationship between aged structure and corresponding properties, MD simulation is firstly adopted. Different crosslinking ratio of 30% to 70% is established by crosslinking reaction between bisphenol F type epoxy (EPON862®) resin and triethylenetetramine (TETA) curing agent. A single layered defect-free graphene is added as fiber reinforcement in the nanocomposite structure. Also, to observe the hygroelastic behavior of nanocomposite, weight fraction of 0, 2, 4wt% water is included in the nanocomposite unit cell. After isobaric-isothermal (NPT) ensemble simulation, diffusion coefficient of water, coefficient of moisture expansion (CME), elastic modulus and cohesive zone law of epoxy/graphene nanocomposite models are predicted. Based on the results of MD simulation, equilibrium hygroelastic constitutive models incorporating interfacial properties between epoxy and graphene are used to accurately measure the nanoscale effect observed in MD simulations with moisture.