Reinforcement of Epoxy Composites with Graphite-Graphene Structures

Abstract

As a result of the research, the possibility of directional control of the operational properties of epoxy composites by the use of small additives of thermally expanded graphite-graphene structures has been proved. The rational content of the structuring additive in the composition of the epoxy composite (0.05 parts by mass.) was selected, which ensured an increase in the studied complex of physico-mechanical properties. The influence of thermally expanded graphite on the process of structure formation of an epoxy composite has been established. The addition of thermally expanded graphite increases thermal, fire and heat resistance as well as the coefficient of heat-conducting epoxy composite.

Reinforcing effects of aminosilane-functionalized h-BN on the physicochemical and mechanical behaviors of epoxy nanocomposites

“…An important characteristic of materials used in electronic equipment is thermal conductivity. Unmodified epoxy composites have a low thermal conductivity (0.1 W/m K), therefore, when locally heated, they work as thermal insulation, which can lead to overheating and thermal decomposition of the composite 18,25 .…”

“…The compositions were developed on the basis of epoxy resin ED-20 (GOST 10587-93), because it has low viscosity, a narrow limit of the epoxy groups content, stability of physico-chemical properties, epoxy equivalent-195-216 g/mol, epoxy groups content 20.0-22.5%, manufactured by CHIMEX Limited (Russia). As a hardener of an epoxy oligomer, an amine type hardener was used-polyethylene polyamine (PEPA) (TS 6-02-594-85) manufactured by CHIMEX Limited (Russia), capable of forming a three-dimensional network structure without heating, molecular mass-230-250 g/mol, amine number-1,250 mg KOH/g 18,19 .…”

“…During thermal decomposition of the composite, the presence of phosphorus provides an increase in the yield of carbonized structures, which are a physical barrier for the inter-diffusion of the oxidant and combustible gases to the combustion zone. Chlorine, being formed during the pyrolysis of the compositions, gets into the gas phase and dilutes the combustible gases, reducing the concentration limit of ignition, which, in general, reduces the flammability of epoxy composite 18 .…”

“…The preparation method of the composition: addition of TCEP to epoxy oligomer → mechanical stirring of the composition (ED-20 + TCEP) for 15 min → addition of h-BN to the epoxy composition (ED-20 + TCEP) → mechanical stirring of the composition for 15 min → further dispersion by sonication for 1 h (400 W; 22 kHz) → addition of the curing agent PEPA to the mixture at 25 ± 5 °C → degasification to remove air bubbles at 25 ± 5 °C for 30 min under vacuum before curing → pouring into a mould and curing at 25 ± 5 °C for 24 h → heat treatment of the epoxy composite at 100 ± 5 °C for 2 h; 120 ± 5 °C for 2 h 19 . 2004]; change in mass, rate of change in mass and magnitude of thermal effects during the heating of the samples was studied using the method of thermogravimetric analysis with the help of a derivator of the "Paulik-Paulik-Erdei" system of the MOM brand Q-1500D under the experimental conditions: weight-100 mg, medium-air, heating interval-up to 800 °C, heating rate-10 °C/min, relative error does not exceed 1%; the study of the surface morphology of the samples was carried out using a Tescan VEGA 3 SBH scanning electron microscope; determination of thermal conductivity and thermal resistance was carried out using the ITP-MG4 "100" instrument [ISO 22007-2: 2015]; FT-IR spectroscopy of TEG particles was carried out using the Shimadzu IRTracer-100; X-ray phase analysis was performed using ARL X'TRA X-ray diffractometer 18 ; determination of the curing kinetics of the epoxy composition was carried out according to the method described in 24 ; the specific surface area of the samples was determined by means of the Quantachrome Nova 2200 specific surface area and porosity analyzer using the initial portion of the isotherm of physical nitrogen sorption (99.999%). The studied samples were placed in a cell preliminarily calibrated with respect to internal volume at a temperature of liquid nitrogen (about 78 K), which was degassed in vacuum to a constant mass at a given temperature (150 °C) for 3 h. After that, the cell was installed in the device and the isotherm of nitrogen adsorption was measured in the pressure range 0.03-0.3 P/Po.…”

Thermal Behavior and Flammability of Epoxy Composites Based on Multi-Walled Carbon Nanotubes and Expanded Graphite: A Comparative Study

“…Owing to their unique physical properties, carbon nanomaterials, such as carbon nanotubes [16] and nanofibers [17], graphene [18][19][20], graphene nanoplatelets [21], reduced graphene oxide [22], graphene oxide [23,24], and expanded graphite [25], have attracted great attention in recent years, particularly for the improvement of flame retardancy of epoxy composites [26][27][28][29][30][31][32][33][34].…”