Effect of imidazolium ionic liquid type on the properties of nitrile rubber composites: Effect of imidazolium ionic liquid on nitrile rubber composites

Structures and Materials in Stretchable Electroluminescent Devices

Stretchable electroluminescent (EL) devices are obtained by partitioning a large emission area into areas specifically for stretching and light-emission (island-bridge structure). Buckled and textile structures are also shown effective to combine the conventional light emitting diode fabrication with elastic substrates for structure-enabled stretchable EL devices. Meanwhile, intrinsically stretchable EL devices which are characterized with uniform stretchability down to microscopic scale are relatively less developed but promise simpler device structure and higher impact resistance. The challenges in fabricating intrinsically stretchable EL devices with high and robust performance are in many facets, including stretchable conductors, emissive materials, and compatible processes. For the stretchable transparent electrode, ionically conductive gel, conductive polymer coating, and conductor network in surface of elastomer are all proven useful. The stretchable EL materials are currently limited to conjugated polymers, conjugated polymers with surfactants and ionic conductors added to boost stretchability, and phosphor particles embedded in elastomer matrices. These emissive materials operate under different mechanisms, require different electrode materials and fabrication processes, and the corresponding EL devices face distinctive challenges. This review aims to provide a basic understanding of the materials meeting both the mechanical and electronic requirements and important techniques to fabricate the stretchable EL devices.

Bromide and Chloride Ionic Liquids Applied to Enhance the Vulcanization and Performance of Natural Rubber Biocomposites Filled with Nanosized Silica

In this study, the possibility of using ionic liquids (ILs) as auxiliary substances improving the vulcanization and physicochemical properties of natural rubber (NR) biocomposites filled with nanosized silica was investigated. Hence, the influence of ILs with bromide and chloride anions and various cations, i.e., alkylimidazolium, alkylpyrrolidinium and alkylpiperidinium cation, on the curing characteristics and crosslink density of NR compounds was determined. Furthermore, the effect of nanosized silica and ILs on the functional properties of the obtained vulcanizates, including mechanical properties under static and dynamic conditions, hardness, thermal stability and resistance to thermo-oxidative aging, were explored. Applying nanosized silica improved the processing safety of NR compounds but significantly increased the optimal vulcanization time compared to the unfilled rubber. ILs significantly improved the cure characteristics of NR compounds by increasing the rate of vulcanization and the crosslink density of NR biocomposites. Consequently, the tensile strength and hardness of the vulcanizates significantly increased compared to that without ILs. Moreover, the use of nanosized silica and ILs had a favorable impact on the thermal stability of the vulcanizates and their resistance to prolonged thermo-oxidation.

Synthesis of Low Temperature Resistant Hydrogenated Nitrile Rubber Based on Esterification Reaction

Hydrogenated Nitrile Rubber (HNBR) is widely used in aerospace, petroleum exploration and other fields because of its excellent performances. However, there remains a challenge of balancing the oil resistance and the low temperature resistance for HNBR. In this work, a series of grafted carboxyl nitrile rubber (XNBR) was prepared by the esterification reaction between active functional groups (-COOH) of XNBR and alkanols of different molecular chain lengths (C8H17OH, C12H25OH, C16H33OH, C18H37OH) or Methoxypolyethylene glycols (MPEG) of different molecular weights (Mn = 350, 750, 1000). The structure and low temperature resistance of as-obtained grafted polymers were characterized by Fourier Transform Infrared (FTIR), 1H-NMR and Differential scanning calorimetry (DSC). It was found that the glass transition temperatures (Tg) of grafted XNBR were significantly decreased. MPEG grafted polymers with better low temperature resistance were then selected for hydrogenation. As-prepared hydrogenated XNBR grafted with MPEG-1000 (HXNBR-g-1000) showed the lowest Tg of -29.8 °C and the best low temperature resistance. This work provides a novel and simple preparation method for low temperature resistant HNBR, which might be used potentially in extremely cold environments.

Systematic Literature Review of the Effect of Layered Double Hydroxides on the Mechanical Properties of Rubber

Layered double hydroxides (LDHs) have attracted interest as reinforcing fillers in elastomers due to their ease of synthesis and customisability. A systematic review was performed on the effect of LDHs on the mechanical properties of elastomers using the Scopus database. Of the 61 articles relevant to the search criteria, the majority were published on polyurethane (PU) and nitrile butadiene rubber (NBR). Mg-Al LDH was used in most of the studies and Zn-Al LDH was used second most common. LDH can act as a reinforcing filler, typically increasing tensile strength even at low concentrations, so it could be used as an alternative to traditional reinforcing fillers for elastomers. LDH can also be made a functional filler by selecting the right metals and interlayer anions. It was found that Mg-Al LDH and Zn-Al LDH can both participate in crosslinking reactions and can replace MgO and ZnO, respectively. Less Zn ions are required for crosslinking when LDH is used than when ZnO is used, making LDH more environmentally friendly. Organic modification is usually required to improve compatibility with the elastomer matrix, especially in non-polar elastomers. It enables exfoliation of the LDH and intercalation of polymer chains into the LDH interlayer to occur. Organic modifiers can also be used to functionalise the LDH. Stearic acid used in crosslinking systems can be replaced by stearate anions from stearate-modified LDH.

Rheological and Mechanical Properties of Silica/Nitrile Butadiene Rubber Vulcanizates with Eco-Friendly Ionic Liquid

In this paper we designed greener rubber nanocomposites exhibiting high crosslinking density, and excellent mechanical and thermal properties, with a potential application in technical fields including high-strength and heat-resistance products. Herein 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc) ionic liquid was combined with silane coupling agent to formulate the nanocomposites. The impact of [EMIM]OAc on silica dispersion in a nitrile rubber (NBR) matrix was investigated by a transmission electron microscope and scanning electron microscopy. The combined use of the ionic liquid and silane in an NBR/silica system facilitates the homogeneous dispersion of the silica volume fraction (φ) from 0.041 to 0.177 and enhances crosslinking density of the matrix up to three-fold in comparison with neat NBR, and also it is beneficial for solving the risks of alcohol emission and ignition during the rubber manufacturing. The introduction of ionic liquid greatly improves the mechanical strength (9.7 MPa) with respect to neat NBR vulcanizate, especially at high temperatures e.g., 100 °C. Furthermore, it impacts on rheological behaviors of the nanocomposites and tends to reduce energy dissipation for the vulcanizates under large amplitude dynamic shear deformation.

The Essential Role of 1-Butyl-3-Methylimidazolium-Based Ionic Liquids in the Development of Transparent Silica-Filled Elastomer Systems

In this paper, we present the design of reinforced silica-filled elastomer composites exhibiting a high transparency, high mechanical performance in static and dynamic conditions, and improved electrical conductivity. Two different imidazolium ionic liquids (ILs) were used with increasing loads: 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMIMTFSI) and 1-butyl-3-methylimidazolium tetrachloroaluminate (BMIMAlCl4). The composites were prepared in a two-roll mill. The influence of the ILs on the dispersion of the silica in the nitrile rubber (NBR) matrix was assessed by scanning electron microscopy (SEM). The presence of ILs in the NBR/SiO2 systems improved the crosslink density and ionic conductivity of the composites. Their mechanical properties and aging stability remained almost unchanged, at a very satisfactory level. Greater crosslinking was observed for the NBR/SiO2 composites containing BMIMAlCl4, due to its catalytic effect on the efficiency of interface crosslinking reactions. We found the optimal formulation for obtaining transparent reinforced NBR/SiO2 composites. The application of 2.5 phr of BMIMAlCl4 resulted in a high transparency in the case of NBR composites filled with 30 phr of silica.

MA, Kailas L, Kalarikkal N, George SC, Thomas S. Developing highly conducting and mechanically durable styrene butadiene rubber composites with tailored microstructural properties by a green approach using ionic liquid modified MWCNTs

Present paper is focussed on the fabrication of styrene-butadiene rubber–ionic liquid modified CNT nano composites by using a more sustainable chemistry and a clean process with the use of a green solvent ionic liquid.