Non-Einstein Viscosity Phenomenon of Acrylonitrile–Butadiene–Styrene Composites Containing Lignin–Polycaprolactone Particulates Highly Dispersed by High-Shear Stress

Lignin powder was modified via ring-opening polymerization of caprolactone to form a lignin–polycaprolactone (LPCL) particulate. The LPCL particulates were mixed with an acrylonitrile–butadiene–styrene (ABS) matrix at an extremely high rotational speed of up to 3000 rpm, which was achieved by a closed-loop screw mixer and in-line melt extruder. Using this high-shear extruding mixer, the LPCL particulate size was controlled in the range of 3395 nm (conventional twin-screw extrusion) down to 638 nm (high-shear mixer of 3000 rpm) by altering the mixing speed and time. The resulting LPCL/ABS composites clearly showed non-Einstein viscosity phenomena, exhibiting reduced viscosity (2130 Pa·s) compared to the general extruded composite one (4270 Pa·s) at 1 s–1 and 210 °C. This is due to the conformational rearrangement and the increased free volume of ABS molecular chains in the vicinity of LPCL particulates. This was supported by the decreased glass transition temperature (Tg, 83.7 °C) of the LPCL/ABS composite specimens, for example, giving a 21.8% decrement compared to that (107 °C) of the neat ABS by the incorporation of 10 wt % LPCL particulates in ABS. The LPCL particulate morphology, damping characteristics, and light transmittance of the developed composites were thoroughly investigated at various levels of applied shear rates and mixing conditions. The non-Einstein rheological phenomena stemming from the incorporation of LPCL particulates suggest an interesting plasticization methodology: to improve the processability of high-loading filler/polymer composites and ultra-high molecular weight polymers that are difficult to process because of their high viscosity

Understanding the Thermal Properties of Precursor-Ionomers to Optimize Fabrication Processes for Ionic Polymer-Metal Composites (IPMCs)

Ionic polymer-metal composites (IPMCs) are one of many smart materials and have ionomer bases with a noble metal plated on the surface. The ionomer is usually Nafion, but recently Aquivion has been shown to be a promising alternative. Ionomers are available in the form of precursor pellets. This is an un-activated form that is able to melt, unlike the activated form. However, there is little study on the thermal characteristics of these precursor ionomers. This lack of knowledge causes issues when trying to fabricate ionomer shapes using methods such as extrusion, hot-pressing, and more recently, injection molding and 3D printing. To understand the two precursor-ionomers, a set of tests were conducted to measure the thermal degradation temperature, viscosity, melting temperature, and glass transition. The results have shown that the precursor Aquivion has a higher melting temperature (240 °C) than precursor Nafion (200 °C) and a larger glass transition range (32–65°C compared with 21–45 °C). The two have the same thermal degradation temperature (~400 °C). Precursor Aquivion is more viscous than precursor Nafion as temperature increases. Based on the results gathered, it seems that the precursor Aquivion is more stable as temperature increases, facilitating the manufacturing processes. This paper presents the data collected to assist researchers in thermal-based fabrication processes

Microfibrillated Cellulose Suspension and Its Electrorheology

Microfibrillated cellulose (MFC) particles were synthesized by a low-pressure alkaline delignification process, and their shape and chemical structure were investigated by SEM and Fourier transformation infrared spectroscopy, respectively. As a novel electrorheological (ER) material, the MFC particulate sample was suspended in insulating oil to fabricate an ER fluid. Its rheological properties—steady shear stress, shear viscosity, yield stress, and dynamic moduli—under electric field strength were characterized by a rotational rheometer. The MFC-based ER fluid demonstrated typical ER characteristics, in which the shear stresses followed the Cho–Choi–Jhon model well under electric field strength. In addition, the solid-like behavior of the ER fluid was investigated with the Schwarzl equation. The elevated value of both dynamic and elastic yield stresses at applied electric field strengths was well described using a power law model (~E1.5). The reversible and quick response of the ER fluid was also illustrated through the on–off test

Magnetic Polymer Composite Particles: Design and Magnetorheology

As a family of smart functional hybrid materials, magnetic polymer composite particles have attracted considerable attention owing to their outstanding magnetism, dispersion stability, and fine biocompatibility. This review covers their magnetorheological properties, namely, flow curve, yield stress, and viscoelastic behavior, along with their synthesis. Preparation methods and characteristics of different types of magnetic composite particles are presented. Apart from the research progress in magnetic polymer composite synthesis, we also discuss prospects of this promising research field

Cellulose-Based Smart Fluids under Applied Electric Fields

Cellulose particles, their derivatives and composites have special environmentally benign features and are abundant in nature with their various applications. This review paper introduces the essential properties of several types of cellulose and their derivatives obtained from various source materials, and their use in electro-responsive electrorheological (ER) suspensions, which are smart fluid systems that are actively responsive under applied electric fields, while, at zero electric field, ER fluids retain a liquid-like state. Given the actively controllable characteristics of cellulose-based smart ER fluids under an applied electric field regarding their rheological and dielectric properties, they can potentially be applied for various industrial devices including dampers and haptic devices

Nanoparticles Functionalized by Conducting Polymers and Their Electrorheological and Magnetorheological Applications

Conducting polymer-coated nanoparticles used in electrorheological (ER) and magnetorheological (MR) fluids are reviewed along with their fabrication methods, morphologies, thermal properties, sedimentation stabilities, dielectric properties, and ER and MR characteristics under applied electric or magnetic fields. After functionalization of the conducting polymers, the nanoparticles exhibited properties suitable for use as ER materials, and materials in which magnetic particles are used as a core could also be applied as MR materials. The conducting polymers covered in this study included polyaniline and its derivatives, poly(3,4-ethylenedioxythiophene), poly(3-octylthiophene), polypyrrole, and poly(diphenylamine). The modified nanoparticles included polystyrene, poly(methyl methacrylate), silica, titanium dioxide, maghemite, magnetite, and nanoclay. This article reviews many core-shell structured conducting polymer-coated nanoparticles used in ER and MR fluids and is expected to contribute to the understanding and development of ER and MR materials

Improved electrochemical properties of linear carbonate-containing electrolytes using fluoroethylene carbonate in Na4Fe3(PO4)2(P2O7)/Na cells

Sodium-ion batteries (NIBs) have attracted considerable attention as promising next-generation rechargeable batteries, especially for large-scale energy storage systems (ESS), because of the natural abundance of Na and the similarities of these batteries to lithium-ion batteries (LIBs). Much effort has been made to improve the electrochemical performances of NIBs through the development of high-performance cathodes, anodes, and electrolytes. One efficient and desirable strategy for practical applications of NIBs is to utilize materials that are adopted in commercialized LIBs. Electrolytes in most studies are composed of polar solvents such as ethylene carbonate (EC) and propylene carbonate (PC). Accordingly, instead of conventional polyethylene (PE) membranes, glass fiber filters (GFF), which easily uptake polar solvents, have been used as separators. However, the too thick, mechanically weak, and porous GFF is not suitable as a separator because it can reduce the volumetric energy density and cannot guarantee the safety of batteries. In this study, for the introduction ofa PE separator into NIBs, the inclusion of linear carbonate as a cosolvent was attempted, motivated by the fact that this material has been widely used owing to its low viscosity and good compatibility with conventional PE separators. However, due to their high reactivity toward Na metal electrodes in half cells, linear carbonate-containing electrolytes are not electrochemically stable at Na4Fe3(PO4)2(P2O7) cathodes during cycling. Undesirable reactions between linear carbonates and Na metal electrodes are examined using 13C nuclear magnetic resonance (NMR) and possible mechanisms for the detrimental effect of byproducts formed by linear carbonate decomposition at the Na metal electrode on the cathode are proposed. To alleviate severe decomposition of linear carbonates at the Na metal electrode, fluoroethylene carbonate (FEC) has been exploited as a functional additive. Our investigation reveals that remarkable enhancement in electrochemical properties of electrolytes with linear carbonates in Na4Fe3(PO4)2(P2O7)/Na half cells is achieved in the presence of FEC additive

The effect of titanium in Li3V2(PO4)3/graphene composites as cathode material for high capacity Li-ion batteries

We report high capacity and rate capability of titanium-added Li3V2(PO4)(3) (LVP) as a cathode material for lithium ion batteries (LIBs). Titanium-added Li3V2-xTix(PO4)(3)/graphene(Ti-added LVP/graphene, x = 0, 0.01, 0.03, and 0.05) composites were synthesized through a sol-gel route by using titanium dioxide (TiO2) and graphene to improve the electrochemical performance. The addition of graphene and titanium significantly enhanced the electric conductivity, resulting in higher kinetic behavior of the LVP. This led to the higher specific capacity of 194 mA h g(-1) at 0.1 C in the potential range of 3.0-4.8 V. The effect of graphene and Ti atoms in Ti-added LVP/graphene was investigated through physical and electrochemical measurements.