Polyaniline-modified Fe2O3 / expandable graphite: A system for promoting the flame retardancy, mechanical properties and electrical properties of epoxy resin

Role of Copper Nanoparticles in the Thermal and Mechanical Properties of Expanded Graphite-Reinforced Epoxy Hybrids

Epoxy resin is extensively applied in the electronics and electrical fields because of its outstanding comprehensive performance. However, the low thermal conductivity (TC) limits its application in thermal interface materials. In the present work, epoxy-based hybrid composites with high TC were prepared by using expanded graphite (EG) and copper (Cu) nanoparticles as thermally conductive hybrid fillers via hot blending and compression-curing processes. Additionally, the influence of the Cu content on the thermal properties, mechanical properties, and morphology of each epoxy/EG/Cu composite was investigated. According to the results, the epoxy/EG/Cu composite showed a maximum TC of 9.74 W/(m·K) at a fixed EG content of 60 wt % owing to the addition of 10 wt % Cu. After the addition of 10 wt % Cu, the flexural strength, flexural modulus, and impact strengths of epoxy/EG/Cu composites were improved from 27.9 MPa, 9.72 GPa, and 0.81 kJ/m2 to 37.5 MPa, 10.88 GPa, and 0.91 kJ/m2, respectively. Hence, this study offers a feasible strategy for the design of epoxy hybrid composites with excellent TC that can be applied to thermal interface materials.

Hollow Superstructure In Situ Assembled by Single-Layer Janus Nanospheres toward Electromagnetic Shielding Flame-Retardant Polyurea Composites

A dodecahedral superstructure consisting of a single layer of Janus spheres containing ZIF-67 nanodots is prepared by in situ polymerization, with ZIF-67 and bio-based phytic acid (PA) as templates and dopants. It is used to improve the flame retardant, electromagnetic (EMI) shielding, and thermal conductivity properties of polyurea (PUA). By adding 5 wt% polyaniline@cobalt phytate-2.0 (PANI@Co-PA-2.0), the peak of heat release rate and the peak of smoke production rate are reduced by 54.9 and 59.9%, respectively. The peak of CO and CO2 production also decreased by 46.2 and 53.1%, respectively. A decrease in the absorption intensity of aliphatic and aromatic volatiles is also observed. The fire safety of PUA is greatly improved. In addition, PUA/PANI@Co-PA-2.0 exhibits an EMI shielding capability of 22.4 dB with the help of reduced graphene oxide, which confirms the possibility of PUA material application in the field of electromagnetic shielding. The 5 wt% filler increases the tensile strength of the PUA matrix to 6.3 MPa, and the composite material obtains good thermal conductivity. This work provides a viable method for the preparation of a flame-retardant, conductive, and electromagnetic refractory PUA substrate.