Imidazolium Ionic Liquids as Compatibilizer Agents for Microcrystalline Cellulose/Epoxy Composites

• Published in: Polymers Vol. 15; no. 2; p. 333
• Main Authors: Kerche, Eduardo Fischer, Kairytė, Agnė, Członka, Sylwia, da Silva, Vinícius Demétrio, Salles, Nicholas Alves, Schrekker, Henri Stephan, Amico, Sandro Campos
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 09-01-2023; MDPI
• Subjects: biobased composite; Bonding strength; Carbon; Cellulose; Chemicals; Chloride; Chlorides; Compatibilizers; Composite materials; Crystalline cellulose; Curing; DGEBA/TETA epoxy; Epoxy resins; Ethanol; Flexural strength; Graphene; Hydrogen bonding; Hydrogen bonds; imidazolium salt; Ionic liquids; Manufacturing; mechanical behavior; Mechanical properties; Scanning electron microscopy; Spectrum analysis; Storage modulus; surface treatment; Thermal stability; Viscosity; United States > US; DGEBA/TETA epoxy; biobased composite; hydrogen bonding; surface treatment; imidazolium salt; mechanical behavior
• ISSN: 2073-4360; 2073-4360
• DOI: 10.3390/polym15020333

Four imidazolium-based ionic liquids (IL; 1-butyl-3-methylimidazolium chloride, 1-carboxymethyl-3-methylimidazolium chloride, 1,3-dicarboxymethylimidazolium chloride and 1-(2-hydroxyethyl) -3-methylimidazolium chloride) were tested as compatibilizers of microcrystalline cellulose (MCC). Subsequently, ethanolic IL solutions were prepared; MCC was mixed, and the mixtures were left to evaporate the ethanol at ambient conditions. These modified MCC were characterized and applied as reinforcements (5.0 and 10 phr) in an epoxy resin aiming to manufacture biobased composites with enhanced performances. The IL did not significantly modify the morphological and structural characteristics of such reinforcements. Regarding the thermal stability, the slight increase was associated with the MCC-IL affinity. The IL-modified MCC-epoxy composites presented improved mechanical responses, such as flexural strength (≈22.5%) and toughness behavior (≈18.6%), compared with pure epoxy. Such improvement was also obtained for the viscoelastic response, where the storage modulus at the glassy state depended on the MCC amount and IL type. These differences were associated with stronger hydrogen bonding between IL and epoxy hardener or the IL with MCC, causing a "bridging" effect between MCC and epoxy matrix.