Ionic Liquids Applied to Improve the Dispersion of Coagent Particles in an Elastomer

Abstract

The aim of this work was to study the activity of several ionic liquids (alkylimidazolium salts) that are used to improve the dispersion of coagent particles in peroxide-cross-linked hydrogenated acrylonitrile butadiene elastomer (HNBR). Hydrotalcite grafted with monoallyl maleate was applied as a coagent for the HNBR vulcanization. In this paper, we discuss the effect of the ionic liquids (alkylimidazolium salts) with respect to their anion (bromide, chloride, tetrafluoroborate, and hexafluorophosphate) and the length of alkyl chain in the cation (allyl-, ethyl-, butyl-, hexyl-, and octyl-) on the vulcanization kinetics of rubber compounds. The influence of ionic liquids on the cross-link density, the mechanical properties of the vulcanizates, and their resistance to weather ageing were also studied. Alkylimidazolium salts seem to improve the dispersion of the coagent particles and to be active in the cross-linking of HNBR with peroxide. The type of ionic liquid considerably influences the activity of the coagent particles toward the HNBR. The application of ionic liquids increases the cross-link density of the vulcanizates and improves their resistance to weather aging.

Effect of carbon nanofibers on mechanical and electrical behaviors of acrylonitrile‐butadiene rubber composites

“…In spite of the apparent dispersing properties of AMC, the mixing process during preparation of rubber compounds and resulting shear stresses could lead to the reagglomeration of CNFs in this system, as evidenced by SEM images (Figure 9A and B). In other works, it has been also observed that elastomer composites containing imidazolium ionic liquids with chloride anion exhibiting poor mechanical properties when compared with the bromides, tetrafluoroborates, and hexafluorophosphates . Le et al presented also that tetrafluoroborates considerably affect the tensile strength in contrast to the ionic liquids with chloride anion in polymer matrix filled with carbon nanotubes.…”

“…In other works, it has been also observed that elastomer composites containing imidazolium ionic liquids with chloride anion exhibiting poor mechanical properties when compared with the bromides, tetrafluoroborates, and hexafluorophosphates. 27,28 Le et al 29 presented also that tetrafluoroborates considerably affect the tensile strength in contrast to the ionic liquids with chloride anion in polymer matrix filled with carbon nanotubes. This effect has been also observed in our study.…”

Ionic Liquids and Calcium Oxide Grafted with Allylmalonic Acid Applied to Support the Peroxide Crosslinking of an Ethylene–Propylene Copolymer

“…This may result from the worse dispersion of the coagent particles in the elastomer matrix containing this ionic liquid and the aforementioned high-thermal and -chemical stability of BmimPF 6 . Additionally, ILs are believed to catalyze the interfacial crosslinking reactions, as reported for the peroxide crosslinking of a hydrogenated acrylonitrile–butadiene elastomer [ 16 ] and for the sulfur vulcanization of unsaturated rubbers [ 35 , 39 , 40 ].…”

“…Therefore, it is necessary to develop substances that improve the dispersion degree of coagent nanoparticles in the elastomer matrix. These potential dispersing agents can be ionic liquids (ILs) that, owing to their catalytic activity in interfacial reactions (including crosslinking reactions), can also increase the efficiency of crosslinking [ 16 ].…”

“…ILs with 1-butyl-3-methylimidazolium (Bmim) cation were chosen due to their positive influence on the vulcanization, crosslink density and performance of other elastomers, such as acrylonitrile–butadiene elastomer (NBR) and hydrogenated acrylonitrile–butadiene elastomer (HNBR), as was confirmed by our previous studies [ 39 , 41 ]. Furthermore, ILs with Bmim cation and different anions were reported to promote the dispersion of various fillers in the elastomer composites [ 34 , 42 , 43 ].…”