Directional control of physico-chemical and mechanical properties of epoxide composites by the addition of graphite-graphene structures

Highly Aligned Ni-Decorated GO–CNT Nanostructures in Epoxy with Enhanced Thermal and Electrical Properties

In this study, graphene oxide–carbon nanotubes nanostructures decorated with nickel nanoparticles (NiGNT) were prepared through the molecular-level-mixing method, followed by a reduction process, and then applied as reinforcements to enhance the epoxy resin matrix. The ferromagnetism of the Ni nanoparticles allowed NiGNT nanostructures to be vertically aligned within the composite with the assistance of a magnetic field. Due to the alignment distribution of the NiGNT, the composites demonstrated enhanced anisotropic thermal and electrical conduction performances, compared with pure epoxy and randomly distributed composites. The aligned distribution of NiGNT–epoxy composites displayed 2.7 times higher thermal conductivity and around 10⁴ times better electrical conduction performance, compared with pure epoxy. The thermal expansion of NiGNT–epoxy composite was also restricted in the aligned direction of NiGNT nanostructures. Thus, NiGNT–epoxy composites show great potential as future aerospace, aviation, and automobile materials.

Influence of Elevated Temperature on the Mechanical Properties of Hybrid Flax-Fiber-Epoxy Composites Incorporating Graphene

Natural fibers are now becoming widely adopted as reinforcements for polymer matrices to produce biodegradable and renewable composites. These natural composites have mechanical properties acceptable for use in many industrial and structural applications under ambient temperatures. However, there is still limited understanding regarding the mechanical performance of natural fiber composites when exposed to in-service elevated temperatures. Moreover, nanoparticle additives are widely utilized in reinforced composites as they can enhance mechanical, thermal, and physical performance. Therefore, this research extensively investigates the interlaminar shear strength (ILSS) and flexural properties of flax fiber composites with graphene at different weight percentages (0%, 0.5%, 1%, and 1.5%) and exposed to in-service elevated temperatures (20, 40, 60, 80, and 100 °C). Mechanical tests were conducted followed by microscopic observations to analyze the interphase between the flax fibers and epoxy resin. The results showed that a significant improvement in flexural strength, modulus, and interlaminar shear strength of the composites was achieved by adding 0.5% of graphene. Increasing the graphene to 1.0% and 1.5% gradually decreased the enhancement in the flexural and ILSS strength. SEM observations showed that voids caused by filler agglomeration were increasingly formed in the natural fiber reinforced composites with the increase in graphene addition.

Reinforced Epoxy Composites Modified with Functionalized Graphene Oxide

The possibility of using graphene oxide as a modifying additive for polymer fiber-reinforced composites based on epoxy resin and basalt roving has been studied. The content of graphene oxide in the system has been experimentally selected, which has the best effect on the physico-mechanical properties of the obtained polymer composite material. The efficiency of the modification of the graphene oxide surface with APTES finishing additives and aminoacetic acid, which provides chemical interaction at the polymer matrix–filler interface, has been considered. The influence of graphene oxide and functionalizing additives on the polymer curing process was investigated using the thermometric method and differential scanning calorimetry.

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

The results of this study confirm the possibility of the directional regulation of operational properties of epoxy composites by the use of small additives of hexagonal boron nitride (h-BN), providing the creation of epoxy composites with high performance properties. The effectiveness of h-BN surface modification by γ-aminopropyltriethoxysilane and the formation of strong chemical bonds at the polymer matrix/filler interface has been proved, which ensures an increase in physico-mechanical characteristics of epoxy composites: bending stress increases by 142% and bending modulus increases by 52%, strength increases by 53% and tensile elastic modulus increases by 37%, toughness increases by 400% and Brinell hardness increases by 96%, compared with an unfilled plasticized epoxy composite.