Study on the mechanism of thermodynamic properties of nano SiO2 modified epoxy resin composites

Nanoparticles are expected to be excellent candidates for improving the thermodynamic, mechanical or viscoelastic properties of crosslinked epoxy resin matrix. It is reported that the nanocomposites prepared with novel properties have great application potential in the electronics, coatings, automotive and aerospace industries. In general, the properties of composite materials depend on the combined action of polymer matrix and filler. In order to improve the comprehensive properties of polymer materials, the surface modification of nanoparticles must be carried out. The interface between the modified chain and the free chain is connected by chemical bond, which can further improve the structure and thermodynamic stability of the composite.

By using the molecular dynamics simulation method, the Amorphous cell module, Forcite plus module and COMPASS force field in the Materials Studio software are used to set up the surface-modified silica nanospheres and epoxy resin composite material system. The effects of temperature, SiO2 surface modification rate and epoxy resin crosslinking rate on the structure and kinetic properties of the interfacial layer were studied, and the mechanism of interfacial chemical bonding on the properties of the composite was explored. This study provides theoretical guidance for the interfacial phase mechanism of composite materials and has certain reference significance for the design and manufacture of composite materials.

ACS Appl. Mater. Interfaces 2016, 8, 7499−7508

Simulation of interfacial bonding properties of graphene epoxy resin composites modified by carbon nanotubes

Graphene and carbon nanotubes are popular carbon nanomaterials, and many researchers use carbon nanomaterials to modify resin materials. In this paper, Forcite plus, Amorphous cell and COMPASS force field in Materials studio software are used to study the interface bonding properties of carbon nanotubes/graphene/epoxy resin composites. The binding effect of graphene was studied by means of interface binding energy, interface binding force and other parameters, such as the change of carbon nanotube radius, wall number, distance and Angle between carbon nanotube and graphene.

(Polymers 2019, 11, 121)

Thermal conductivity of graphene-polymer composites

With the development of science and technology, the size of electronic equipment gradually becomes smaller and the power becomes larger, so it is necessary to have good heat dissipation materials; Usually, the materials in electronic equipment are mainly polyamide 6 (PA6), polypropylene (PP) and high-density polyethylene (HDPE), which have low density, corrosion resistance, excellent mechanical properties and good preparation and processing properties. In order to further improve their thermal conductivity, researchers often add Al2O3, AlN, BN, SiC, graphene and other nanomaterials to the material, of which graphene has a special two-dimensional structure, its thermal conductivity is 5300 W/(m·K); It has been reported that graphene modified polymer has a very obvious effect on the thermal conductivity of composite materials.

For nanomaterial modified polymers, the dispersion effect of fillers and the interface bonding effect between fillers and matrix will affect the comprehensive properties of composites. Good interface plays a role in the transfer of stress and heat in the composite material. The composite material is affected by external stress, and the matrix transfers the stress to the reinforcement phase through the interface, so that the reinforcement phase can bear the stress. Therefore, the interface bonding effect determines the properties of composite materials. However, it is difficult to characterize the interface bonding effect in nanomaterial experiments.

Heat and Mass Transfer (2020) 56:1931–1945
 

Molecular dynamics simulation of thermal conductivity of MXene/ epoxy resin composites

With the rapid development of the electronic industry, electronic equipment is becoming more and more intelligent and integrated. However, these precision devices have poor heat dissipation, which directly affects their life and performance. Therefore, the use of thermal interface materials at the junction of devices to reduce thermal resistance is of great significance to the thermal management of devices. At present, the thermal interface materials are mainly polymer, because of its good processing performance, light weight and low cost. Considering the relatively low thermal conductivity of the polymer, it is necessary to add a filler with a high thermal conductivity. Compared with traditional fillers such as metal particles (Cu, Ag, Ni, etc.), two-dimensional materials (graphene, hexagonal boron nitride, etc.) have higher thermal conductivity, and their specific morphology makes it easy to construct conduction paths in the polymer matrix, which can significantly improve the thermal conductivity of their composites.

MXenes has the mixed properties of metal/covalent/ion in M-X bond, and introduces surface functional groups (F, O, OH) through acid etching. It has outstanding advantages such as good electrical conductivity, outstanding mechanical properties, adjustable band gap, high volume capacitance, strong hydrophilicity and high thermal conductivity. Therefore, they have potential applications in many fields such as energy storage, microwave absorption, catalysts, sensors, biomedicine and so on. In addition, many studies have revealed the thermal applications of MXene and provided a better understanding of its heat transport behavior.

In this study, epoxy resin, which is widely used at present, was selected as the polymer matrix, and the thermal conductivity of four MXenes(non-functional and F, O, OH) composites was studied by molecular dynamics method, as shown in Figure 1. And the effect of these functional groups on the thermal properties of the interface between the reinforced phase and the matrix. The results contribute to a better understanding of the heat transport behavior of MXene nanocomposites and provide guidance for their thermal applications.

（International Journal of Heat and Mass Transfer 194 (2022) 123027）

Simulation study of interface bonding between modified SiO2 surface and polyimide

Polyimide/silicon dioxide (PI/SiO2) nanocomposites are typical polymer composites with excellent dielectric, thermal, mechanical and tribological properties, and have been widely used in electronics, machinery, aerospace and other fields. The properties of polymer nanocomposites largely depend on the dispersion of the nanoparticles and the interface bonding between the polymer matrix and the nano-filler. The surface modification of SiO2 nanoparticles by silane coupling agent is an effective way to improve the dispersion and interface bonding properties of SiO2 nanoparticles. Because different types of silane coupling agents have different functional groups, the effect may be different. Thus, the comprehensive properties of composite materials are affected. In this paper, three silane coupling agents, namely GOTMS, APTES and APTMOS, are studied by molecular dynamics method. By modifying the surface of SiO2 with three silane coupling agents, the binding effect between polyimide and SIO2 surface is evaluated by molecular simulation technology, and the binding mechanism is revealed from the atomic scale.

J. APPL. POLYM. SCI. 2018, DOI: 10.1002/APP.45725