Study on foaming behavior of block copolymer/inorganic particles co-construction of toughened epoxy resin foams

Low toughness and brittleness limit its application range of thermosetting epoxy resin (EP) based foams. In current research, inorganic particles are commonly utilized as heterogeneous nucleating agents to enhance foaming quality and EP toughness. However, the increasing inorganic particle content usually leads to particle agglomeration, which negatively impacts foaming quality and reduces EP performance. Block copolymers, which appear as liquid to effectively mitigate agglomeration, are employed as toughening materials for EP. In this study, a small number of modified calcium silicate particles (MCS) were used as anchor points to induce the distribution of block copolymers (P-F68) to improve EP toughness and effectively enhance cell nucleation, thus, EP/MCS/P-F68 foams performance was improved. The research results showed that EP foams obtained excellent cell structure and very small foam density (0.256 g/cm3) at the P-F68 content of 10 wt%. The continuous increase of P-F68 content would lead to the thickening of cell wall and the increase of cell size. Simultaneously, the core-shell structure formed by P-F68 in EP effectively enhanced the toughness of EP foams and mitigated its brittleness, offering crucial theoretical guidance for toughening and regulating the cell structure of EP foams. Block copolymer and inorganic particles co-construction of EP foam material. image