Multi-scale modelling of carbon nanotube reinforced crosslinked interfaces

Abstract

In this paper, we study the crosslinking route and interface interactions for achieving superior properties in carbon nanotube (CNT)-reinforced epoxy based nanocomposites by using multiscale modelling. For that purpose, polymeric epoxy matrices consisting of EPON 862 epoxy and 15 TETA hardener molecules were coarse-grained and simulated using the dissipative particle dynamics (DPD) method. Furthermore, CNTs were coarse-grained as rigid rods and embedded into the uncrosslinked mesoscopic polymer system. Reverse-mapping of the atomistic details onto coarse-grained models was carried out to allow further simulations at the atomistic scale using molecular dynamics (MD) by keeping the periodicity of the CNTs structure. The 20 mechanism of crosslinking is simulated, and both neat and CNTs-reinforced thermoset nanocomposites with different degrees of crosslinking were reconstructed. Normal stresses in tensile and compressive loading direction up to 0.2% strain were calculated and yield strength (0.2% offset) and compressive/elastic modulus in both normal directions were reported, which match the experimental values as well. Overall, this paper explores a fast and straightforward 25 procedure to bridge periodic mesoscopic structures such as CNTs and their nanocomposites to experimentally tested material properties.

Molecular Dynamics Study of an Amorphous Polyethylene/Silica Interface with Shear Tests

“…In particular, the integrity of the bonded material system can be studied from a fundamental perspective by monitoring the interactions between two materials along the interfacial region at a molecular level by MD. Recently, some researchers used it to study the properties of bi-material systems, such as the chitin/protein interface [ 9 ], polyethylene/graphene interface [ 10 ], epoxy/S interface [ 11 ], carbon fiber reinforced polymers/wood interface [ 12 ], polyimides/S glass interface [ 13 ], hexagonal boron nitride/polyethylene interface [ 14 ], dihydroxyphenylalanine/S interface [ 15 ], S/polystyrene interface [ 16 ], carbon nanotubes/epoxy interface [ 17 ], polyvinylidene fluoride binder/copper interface [ 18 ], epoxy/copper interface [ 19 ], etc. The tensile strength, shear strength, effects of strain rate, effects of cell size, effects of conversion, effects of temperature, interaction bonding energy, effects of entanglement, failure mode, confined condition, density profile, and failure strain have been extensively investigated.…”

Revealing Chemical Heterogeneity of CNT Fiber Nanocomposites via Nanoscale Chemical Imaging

“…The radial characteristics of CNT bundles surrounded by a polymer could be particularly important if the structure is subject to transverse deformation. As has been shown for the CNT-fiber reinforced nanocomposites, their modulus and strength increase almost linearly with the volume fraction of CNTs, whereas the effective reinforcing potential is significantly affected by degree and “quality” of CNT alignment at the submicron scale. , At the same time, cross-linking process and interfacial interactions taking place at the nanoscale between CNT bundles and polymer chains in the polymer-infiltrated CNT assemblies are also substantial for achieving superior mechanical properties, according to the recent multiscale numerical simulations . The AFM-IR near-field infrared spectroscopy appears to be an advanced tool for the direct correlation of nanoscale chemistry and local elastic properties with CNT distribution in such complex systems as nanocomposites reinforced with CNT fibers or yarns.…”

“…In composite processing, a monomer (or a liquid polymer) intercalates the interbundle pores of a CNT fiber and occupies almost half of its volume, depending on the porosity (up to 50–70%). ,,, Therefore, the polymer-infiltrated CNT fiber appears as a hierarchical nanostructured composite, albeit in a preserved fibrous form. − Theoretical and experimental findings affirm the importance of the CNT fiber/polymer interface in governing a balance among strength, stiffness, and toughness of the CNT fiber-reinforced materials. ,, Although some insights on CNT fiber infiltration ,, and composite processing − have been provided, the evolution of chemical structure and the resultant fiber/matrix interface are yet poorly understood; and neither nanoscale FTIR recognition nor other direct chemical imaging has been implemented so far for their analysis.…”

Controlling the Meso-scale Assembly of CNTs/PBI Interlayers for Toughening of Thermoplastic Composites

“…Following the morphological characterizations of CNTs-PBI nanofibers, among various high-performance thermoplastic polymers including PES, Polysulphone (PS), and Polyetherimide (PEI), PES polymer was found to be yielding good compatibility with the PBI substrates according to the calculated Hildebrand solubility parameters, after a short molecular dynamics simulation using the software of Materials Studio [23]. Hildebrand solubility parameters, following the protocol in [23] were calculated for each monomer of the selected thermoplastic polymers using Equation 1 as follows:…”