The epoxy compositions with ionic liquids (ILs) differing in the alkyl chain length of imidazolium cation (butyl or decyl), anion type [N(CN) 2 ¯, BF 4 ¯, Cl ¯], as well as ILs concentration (1, 3, and 9 phr) have been prepared, and their curing characteristics at ambient and elevated temperatures have been investigated. Rheometric, differential scanning calorimetry, and Fourier transform infrared measurements revealed substantial differences in the curing characteristics dependent mainly on the IL anion type and its concentration. TGA results showed that thermal decomposition of IL influenced the onset temperature of epoxy resins cross-linking reactions during heat treatment. Dynamic mechanical thermal analysis measurements showed that the type of IL anion had an effect on T g and tan δ values as well. For materials cross-linked with ILs containing dicyanamide anion the highest T g (ca. 170 °C) and the lowest tan δ (0.26) values have been found. On the basis of the obtained results and literature data the mechanism of epoxy resin cross-linking in the presence of imidazolium ionic liquids has been proposed.

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Abstract. Epoxy nanocomposites with commercial carbon nanotubes (CNT) or graphene (GN) have been prepared using phosphonium ionic liquid [trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl) phosphinate, IL-f]. IL-f served simultaneously as nanofiller dispersing medium and epoxy resin catalytic curing agent. An influence of IL-f/epoxy weight ratio (3, 6 and 9/100, phr), carbon nanofiller type and content on viscosity of epoxy compositions during storage at ambient temperature was evaluated. Curing process was controlled for neat and CNT or GN modified epoxy compositions (0.25-1.0 wt% load) using differential scanning calorimetry and rheometry. Epoxy nanocomposites exhibited slightly increased glass transition temperature values (146 to 149°C) whereas tan ! and storage modulus decreased (0.30 to 0.27 and 2087 to 1070 MPa, respectively) as compared to reference material. Crosslink density regularly decreased for composites with increasing CNT content (11 094 to 7020 mol/m 3 ). Electrical volume resistivity of the nanocomposites was improved in case of CNT to 4"10 1 #"m and GN to 2"10 5 #"m (nanofiller content 1 wt%). Flame retardancy was found for modified epoxy materials with as low GN and phosphorus content as 0.25 and 0.7 wt%, respectively (increase of limiting oxygen index to 26.5%).

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Epoxy resin crosslinked with conventional and deep eutectic ionic liquids Summary-Molecular ionic liquid, i.e. 1-ethyl-3-methylimidazolium chloride ([EMIM]Cl) and eutectic mixture of imidazole with choline chloride (IM + ChCl) have been used as epoxy resin hardeners. An influence of [EMIM]Cl and IM + ChCl content on pot life of epoxy compositions and runs of crosslinking process has been evaluated using DSC and ARES rheometry techniques. Epoxy compositions with [EMIM]Cl showed latent properties (pot life up to 50 days) while the systems with IM + ChCl gelled after few days. Comparative measurement of thermomechanical (T g , tan d) and mechanical properties (tensile, flexural and shear strength on aluminum substrates) as well as thermal decomposition of epoxy composites have been performed. Composite epoxy materials crosslinked with [EMIM]Cl exhibited more elastic properties (lower T g and higher tan d values) and generally better mechanical features than those hardened with imidazole + choline chloride eutectic mixture.