With unique physicochemical properties, multiwalled carbon nanotubes (MWCNTs) have enabled major achievement in polymer composites as reinforcing fillers. Nevertheless, high conductivity of raw MWCNTs (R‐MWCNTs) limits their wider applications in certain fields, which require outstanding thermal conductivity, mechanical, and insulation properties simultaneously. In this article, silica (SiO2) coated MWCNTs core–shell hybrids (SiO2@MWCNTs) and organically modified montmorillonite (O‐MMT) are employed to modify epoxy (EP) simultaneously. The epoxy‐clay system is cured by using anhydride curing agent. The impact strength and flexural strength of final nanocomposites are greatly improved. Meanwhile, the final composites remain in high electrical insulation. Compared to mixed acid treated MWCNTs (C‐MWCNTs) (0.5 wt%)/EP nanocomposites, the volume resistivity of the O‐MMT(4 wt%)/SiO2@MWCNTs(0.5 wt%)/EP nanocomposites increases more than six orders of magnitude. Synergistic toughening effect occurs when using core–shell SiO2@MWCNTs and MMT bifillers. The electrical insulation is attributed to the suppressed electron transport effect by SiO2 layer on the CNTs surface, and the blocked conductive CNTs network by the buried 2D structural O‐MMT. The SiO2@MWCNTs core–shell hybrids also benefit to decrease the dielectric constant and dielectric loss of CNTs/EP composites. This work provides guidance to using CNTs as reinforcement fillers to toughen the polymers for electric insulating applications.
A series
of amide-functionalized ionic liquids (ILs), e.g., 1-R-3-(2-amino-2-oxoethyl)-imidazolium
(R = −vinyl, −methyl–butyl) cations combined
with Cl–, N(CN)2–, or NTf2
– anions, were synthesized and fully characterized
as curing agent for diglycidyl-4,5-epoxy-cyclohexane-1,2-dicarboxylate
(TDE-85). Studies of curing behaviors showed that ILs with N(CN)2
– anions exhibit moderate curing conditions.
As to thermosets of TDE-85 cured by these curing agents, their tensile
strength (95.1–111.7 MPa) and elongation at break (2.69 to
4.20%) are significantly improved compared with the traditional curing
systems of DDS/TDE-85 (DDS, 4,4′-diamino diphenyl sulphone).
These thermosets also exhibit good thermal mechanical properties with
the glass transition temperature (T
g)
> 200 °C and thermal degradation temperature (T
d) > 300 °C. The possible mechanisms of curing
reactions
were analyzed by using IR, and results indicated that curing reactions
of TDE-85 with amide-functionalized ionic liquids may include three
steps, −NH2 groups reacted with oxirane at lower
temperatures, and then the anions further participated in the reaction
to strengthen the cross-linking networks. This study provides informative
guidelines for designing new curing agents.
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