Effect of Ionic Liquid Modified Synthetic Layered Silicates on Thermal and Mechanical Properties of High Density Polyethylene Nanocomposites

Clay-Based Polymer Nanocomposites: Essential Work of Fracture

This work details the general structure of the clays used as a reinforcement phase in polymer nanocomposites. Clays are formed by the molecular arrangement of atomic planes described through diagrams to improve their visualization. The molecular knowledge of clays can facilitate the selection of the polymer matrix and achieve a suitable process to obtain clay-based polymer nanocomposite systems. This work highlights the development of polymer nanocomposites using the melt intercalation method. The essential work of fracture (EWF) technique has been used to characterize the fracture behavior of materials that show ductility and where complete yielding of the ligament region occurs before the crack propagation. In this sense, the EWF technique characterizes the post-yielding fracture mechanics, determining two parameters: the specific essential work of fracture (we), related to the surface where the actual fracture process occurs, and the specific non-essential work of fracture (wp), related to the plastic work carried out in the outer zone of the fracture zone. The EWF technique has been used successfully in nano-reinforced polymers to study the influence of different variables on fracture behavior. In this work, the fundamentals of the EWF technique are described, and some examples of its application are compiled, presenting a summary of the most relevant contributions in recent years.

Practical Determination of the Solubility Parameters of 1-Alkyl-3-methylimidazolium Bromide ([CnC₁im]Br, n = 5, 6, 7, 8) Ionic Liquids by Inverse Gas Chromatography and the Hansen Solubility Parameter

The physicochemical properties of four 1-alkyl-3-methylimidazolium bromide ([C_nC₁im]Br, n = 5, 6, 7, 8) ionic liquids (ILs) were investigated in this work by using inverse gas chromatography (IGC) from 303.15 K to 343.15 K. Twenty-eight organic solvents were used to obtain the physicochemical properties between each IL and solvent via the IGC method, including the specific retention volume and the Flory–Huggins interaction parameter. The Hildebrand solubility parameters of the four [C_nC₁im]Br ILs were determined by linear extrapolation to be δ2([C5C1im]Br) = 25.78 (J·cm⁻³)^0.5, δ2([C6C1im]Br) = 25.38 (J·cm⁻³)^0.5, δ2([C7C1im]Br) =24.78 (J·cm⁻³)^0.5 and δ2([C8C1im]Br) = 24.23 (J·cm⁻³)^0.5 at room temperature (298.15 K). At the same time, the Hansen solubility parameters of the four [C_nC₁im]Br ILs were simulated by using the Hansen Solubility Parameter in Practice (HSPiP) at room temperature (298.15 K). The results were as follows: δt([C5C1im]Br) = 25.86 (J·cm⁻³)^0.5, δt([C6C1im]Br) = 25.39 (J·cm⁻³)^0.5, δt([C7C1im]Br) = 24.81 (J·cm⁻³)^0.5 and δt([C8C1im]Br) = 24.33 (J·cm⁻³)^0.5. These values were slightly higher than those obtained by the IGC method, but they only exhibited small errors, covering a range of 0.01 to 0.1 (J·cm⁻³)^0.5. In addition, the miscibility between the IL and the probe was evaluated by IGC, and it exhibited a basic agreement with the HSPiP. This study confirms that the combination of the two methods can accurately calculate solubility parameters and select solvents.

Organometal-catalyzed synthesis of high molecular weight poly-(l-lactic acid) with a covalently attached imidazolium salt: performance-enhanced reduced graphene oxide–PLLA biomaterials

Herein, we report on the synthesis of imidazolium salt end-functionalized PLLA (PLLA-IS) and its application in the preparation of reduced graphene oxide–PLLA composites.