Thermal Percolation Behavior in Thermal Conductivity of Polymer Nanocomposite with Lateral Size of Graphene Nanoplatelet

In this study, the thermal percolation behavior for the thermal conductivity of nanocomposites according to the lateral size of graphene nanoplatelets (GNPs) was studied. When the amount of GNPs reached the critical concentration, a rapid increase in thermal conductivity and thermal percolation behavior of the nanocomposites were induced by the GNP network. Interestingly, as the size of GNPs increased, higher thermal conductivity and a lower percolation threshold were observed. The in-plane thermal conductivity of the nanocomposite containing 30 wt.% M25 GNP (the largest size) was 8.094 W/m·K, and it was improved by 1518.8% compared to the polymer matrix. These experimentally obtained thermal conductivity results for below and above the critical content were theoretically explained by applying Nan’s model and the percolation model, respectively, in relation to the GNP size. The thermal percolation behavior according to the GNP size identified in this study can provide insight into the design of nanocomposite materials with excellent heat dissipation properties.

A Comprehensive Methodology to Support Decision-Making Towards Sustainability on Nanocomposite Materials in Additive Manufacturing Sector

Innovative nanocomposite materials and resultant additive manufacturing products are necessary to be assessed for their carbon footprint towards top priorities of EU for plastics, including the European Green Deal principles and the Action Plan for Circular Economy. Life Cycle Assessment (LCA) is widely applied standardized methodology that aims to study potential environmental impacts of novel products. Nano-scale materials (NM) are usually dispersed in polymer to enhance their limited functional properties resulting in a spectrum of end-products for multiple applications. However, little information exists on their environmental impact. Within this context, this study presents a ‘cradle-to-gate plus end-of-life’ LCA approach, studying different types of 3D printing nanocomposite filaments across the supply chain. Three different types of polymer matrixes were examined: polyamide (PA), polypropylene (PP) and polylactic acid (PLA), additivated with three different types of nanomaterial additives: multiwall carbon nanotubes (MWCNTs), graphene oxide (GO) forms and graphene nanoplatelets (GNPs), considering lab-scale production. In addition, several different EoL scenarios have been examined for the materials. Finally, LCA findings are coupled with the performance (taken here as conductivity) of these new materials to assist the decision-making process for selecting efficient scenarios with the least environmental impact. The outputs of this examination enable identification of potential sustainability issues for novel nanocomposite materials at an early design stage, while also assisting in the definition of actions to mitigate such issues. Thus, LCA studies can generate knowledge on the environmental impacts of nano-enabled materials, while also serving as a valuable decision support tool towards optimizing material sustainability aspects.

Nanocomposite Materials: A Section of Nanomaterials

“Nanocomposite materials” is one of the main sections of Nanomaterials and it has contributed with more than 440 publications during the last two years to increase the reputation and recognition of the journal by the scientific community [...]

Study the Effects of Carbon Nanotubes and Graphene Oxide Combinations on the Mechanical Properties and Flame Retardance of Epoxy Nanocomposites

Carbon-based fillers have attracted a lot of interest in polymer composites because of their ability to alter beneficial properties at low filler concentrations, good surface bonding with polymers, availability in different forms, etc. Carbon-based materials (such as fullerene, CNTs, graphene, and graphite) have been studied as fillers with enhanced fire resistance to epoxy resins. In order to reduce the flammability and improve the thermal stability of epoxy resin-based nanocomposite materials, which can be achieved by a simultaneous combination of graphene oxide and multiwall carbon nanotubes, the graphite oxide (GO) epoxy nanomaterial was developed by 1% wt.% GO combined with 0.02 wand 0.04 wt.% MWCNT. The homogeneous dispersion of GO and MWCNTs in epoxy resins is supported by ultrasonic vibrations. The results showed that when nanocomposite materials were present at the same time MWCNTs and GO, their mechanical properties and fire resistance were significantly improved. Nanomaterials are characterized by FT-IR spectroscopy and SEM imaging, mechanical strength, and flame retardant properties (LOI, UL94).