Products Cited in Publications Worldwide Improved cure kinetics of phthalonitrile resins using dicyanamide‐based ionic liquids

Improved cure kinetics of phthalonitrile resins using dicyanamide‐based ionic liquids

Josh D. Wolfgang; Jennifer L. Dysart; Matthew Laskoski

DOI:

Abstract

Phthalonitrile (PN) polymers are high-temperature thermosetting resins with excellent thermal and mechanical performance, but they exhibit notably long cure-times hindering their use in certain applications. Ionic liquids (ILs) and aromatic amines provide an opportunity to cure at lower temperatures and shorter times. Dicyanamide-based ILs are an interesting class of high-temperature organic salts due to their high thermal stability and –CN functionality. The addition of ionic liquid in concentrations of 10 and 20 wt% enabled a decrease of the crossover modulus by 30 and 45℃, respectively. When the samples were mixed with both 3 wt% of an amine curing additive and the ionic liquid, the temperature of the crossover modulus was decreased even more dramatically with cure temperatures up to 96℃ below that of the PN resin without additives. The differential scanning calorimetry results support the rheological findings that the ILs decrease the temperature and/or time required to cure PN resins. Herein, a dicyanamide-based ionic liquid catalyzed the curing of PN resins by lowering the gelation temperature by up to 40℃, decreased the processing viscosity by five- to eight-fold, and increased the density of the resin thermosets by nearly 3% on average.

Keywords

composite ; crosslinking ; ionic liquid ; phthalonitrile ; thermal stability

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Ethylmethylimidazolium dicyanamide

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