The effect of different GNP/BNNP foam structures in the infiltration of epoxy resin: A fundamental study

Abstract

Hierarchical 3D architecture of nanoplatelets, also known as foams, has arisen as a promising alternative to overcome agglomeration and promote mechanical reinforcement and electrical and thermal conductivity of polymer composites. Freeze‐drying is a cost‐effective method to manufacture foams with different structures and tailored thermal and electrical properties. This study used freeze‐drying to produce graphene (GNP), boron‐nitride (BNNP), and hybrid foams of different ratios. The interaction between these structures and high‐temperature epoxy grade was investigated via contact angle analysis. The foams were also infiltrated with epoxy to achieve a fully dense nanocomposite. The contact angle monitoring reveals solid loading content, composition, and structure as the main factors affecting wettability. Despite the slight variation in porosity among the foams, all the samples achieved a densification above 96%, suggesting that the epoxy viscosity of 2.34 Pa∙s combined with optimized infiltration parameters can successfully produce dense nanocomposites. The contact angle analysis is a suitable method to compare the infiltration quality of freeze‐dried foams and can be applied to evaluate the production feasibility of other polymer/foam nanocomposites. Furthermore, preliminary thermal data shows a clear temperature increase for the epoxy/foam structures, with GNP and 50:50 GNP:BNNP being the most thermally conductive compositions. This study serves as a starting point for freeze‐dried foams/polymer nanocomposite investigation and may broaden the possibilities for manufacturing and future application of these structures.Highlights The freeze‐dried foams were successfully fabricated and infiltrated with high‐temperature epoxy, obtaining densifications above 96%. The main factors affecting infiltration are foam morphology, porosity, and chemical affinity between polymer and foam platelets. Thermal conductivity has significantly improved by adding GNP and BNNP foam network to epoxy matrix.