Cellulose dissolved in ionic liquids as in situ generated filler in epoxy biocomposites with simultaneous curing initiated by ionic liquids

Abstract

Abstract Cellulose, a ubiquitous natural biopolymer, has found diverse applications in industries such as paper manufacturing, textiles, and food. The pivotal breakthrough emerged with the discovery that ionic liquids (ILs) can dissolve cellulose, initiating comprehensive studies over the past two decades. This study explores the effectiveness of a selected system comprising of [EMIM][OAc], [EMIM][DCA], and DMSO in cellulose dissolution, validated through a 5% cellulose solution and use of such systems as initiators of epoxy resin curing. In epoxy resin systems, the cellulose fibers formed in situ affect the mechanical properties of the final materials, which in the work presented here were flax fiber-reinforced epoxy composites. Differential Scanning Calorimetry (DSC) showed that cellulose inclusion minimally affected curing temperatures but reduced enthalpy. Scanning Electron Microscopy (SEM) demonstrated in situ cellulose fiber generation during mixing, ensuring high compatibility with the resin matrix. Mechanical testing revealed promising outcomes, including increased Glass Transition Temperature (Tg) and enhanced Heat Deflection Temperature (HDT). However, a 50% reduction in impact strength indicated increased brittleness.