Aqueous carbon black dispersions stabilized by sodium lignosulfonates

Palm oil based stretchable piezoresistive strain sensors

The advancement of wearable devices and soft robots requires soft and stretchable sensors to detect their movements. This article proposes palm oil as an organic solvent for a stretchable piezoresistive strain sensor made from a composite consisting of elastomer (Ecoflex 00-30) filled with carbon black. The high content of palmitic acid in the palm oil increases the dispersity of carbon black in the composite, hence effectively improving the conductivity of the sensors. Furthermore, using palm oil as a natural plasticizer can lower the degree of crosslinking of the matrix, reducing the modulus elasticity but still producing a stretchable sensor with 500 % elongation at break. The presence of palm oil in the sensor also increases the gauge factor, showing a value of 2.43-4.75 and better repeatability during loading. These gauge factors are associated with two linear strain regions of the sensors (R2 > 0.99), which are 20-200 % and 0-20 % strain, respectively. The stretchable sensor also shows high durability that can withstand >1500 cycles at 60 % strain. The as-fabricated sensor can be deployed to detect the movement of the human body, such as for measuring a finger's joint angle and in soft robotics applications.

Preparation and characterization of self-dispersive and reactive carbon black and its application in cotton fabric

This study aims to develop a self-dispersive and reactive carbon black (DRCB) to improve its application in cotton fabric. CB was functionalized with γ-aminopropyl triethoxysilane (KH550) and then grafted with as-synthesized compound to obtain aqueous phase DRCB. FTIR analysis confirmed the successful grafting of as-synthesized compound onto KH550-modified CB surface. The weight grafting of DRCB on DRCB-15 % dyed cotton fabric was approximately 15.18 %, with a half weight grafting time of around 17 min. TEM observation demonstrated that DRCB had a core-shell structure with the mean sizes of 36.02 ± 4.30 nm. Particle size analysis revealed that DRCB had smaller average aggregate size of 110.3 nm and higher zeta potential of -33.7 mV than CB, indicating that DRCB had much better dispersion in aqueous media than CB. Cotton fabric was effectively dyed with DRCB, providing excellent color depth of 60 (K/S value) with dry rubbing and wet rubbing/washing color fastness of Grade 4 and Grade 3, respectively. DRCB dyed cotton fabric exhibited outstanding anti-UV and anti-static properties, with no significant difference in softness and tensile property before and after dyeing. This research proposed a new method to solve nanoparticle agglomeration and prepare textile dyes with excellent self-dispersivity and reactivity.

Lignin self-assembly phenomena and valorization strategies for pulping, biorefining, and materials development: Part 1. The physical chemistry of lignin self-assembly

Physical chemistry aspects are emphasized in this comprehensive review of self-assembly phenomena involving lignin in various forms. Attention to this topic is justified by the very high availability, low cost, and renewable nature of lignin, together with opportunities to manufacture diverse products, for instance, polymers/resins, bioplastics, carbon fibers, bio-asphalt, sunscreen components, hydrophobic layers, and microcapsules. The colloidal lignin material, nanoparticles, and microstructures that can be formed as a result of changes in solvent properties, pH, or other adjustments to a suspending medium have been shown to depend on many factors. Such factors are examined in this work based on the concepts of self-assembly, which can be defined as an organizing principle dependent on specific attributes of the starting entities themselves. As a means to promote such concepts and to facilitate further development of nano-scale lignin products, this article draws upon evidence from a wide range of studies. These include investigations of many different plant sources of lignin, processes of delignification, solvent systems, anti-solvent systems or other means of achieving phase separation, and diverse means of achieving colloidal stability (if desired) of resulting self-assembled lignin structures. Knowledge of the self-organization behavior of lignin can provide significant structural information to optimize the use of lignin in value-added applications. Examples include chemical conditions and preparation procedures in which lignin-related compounds of particles organize themselves as spheres, hollow spheres, surface-bound layers, and a variety of other structures. Published articles show that such processes can be influenced by the selection of lignin type, pulping or extraction processes, functional groups such as phenolic, carboxyl, and sulfonate, chemical derivatization reactions, solvent applications, aqueous conditions, and physical processes, such as agitation. Precipitation from non-aqueous solutions represents a key focus of lignin self-assembly research. The review also considers stabilization mechanisms of self-assembled lignin-related structures.

Electrofluids with Tailored Rheoelectrical Properties: Liquid Composites with Tunable Network Structures as Stretchable Conductors

Flexible and stretchable electronics require both sensing elements and stretching-insensitive electrical connections. Conductive polymer composites and liquid metals are highly deformable but change their conductivity upon elongation and/or contain rare metals. Solid conductive composites are limited in mechanoelectrical properties and are often combined with macroscopic Kirigami structures, but their use is limited by geometrical restraints. Here, we introduce "Electrofluids", concentrated conductive particle suspensions with transient particle contacts that flow under shear that bridge the gap between classic solid composites and liquid metals. We show how Carbon Black (CB) forms large agglomerates when using incompatible solvents that reduce the electrical percolation threshold by 1 order of magnitude compared to more compatible solvents, where CB is well-dispersed. We analyze the correlation between stiffness and electrical conductivity to create a figure of merit of first electrofluids. Sealed elastomeric tubes containing different types of electrofluids were characterized under uniaxial tensile strain, and their electrical resistance was monitored. We found a dependency of the piezoresistivity with the solvent compatibility. Electrofluids enable the rational design of sustainable soft electronics components by simple solvent choice and can be used both as sensor and electrode materials, as we demonstrate.

Optimized Design of Material Preparation for Cotton Linters-Based Carbon Black Dispersion Stabilizers Based on Response Surface Methodology

Carbon black particles possess dimensions on the nanometer or sub-nanometer scale. When utilized, these particles have a tendency to aggregate, which compromises their stability under storage conditions. To address this issue, a dispersant was prepared using cotton short fibers as raw materials through etherification and graft polymerization with acrylamide (AM) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) as raw materials. The dispersant was then used to disperse carbon black to test its dispersing performance. A response surface optimization test was utilized to ascertain the influence of AMPS monomer mass, AM monomer mass, and potassium persulfate (KPS) initiator mass on the dispersibility of carbon black during dispersant preparation, and a set of optimal preparation conditions were obtained. The dispersion stability of carbon black in water was assessed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), elemental analysis (EA), thermogravimetric analysis (TG), zeta potential analysis, high magnification scanning electron microscopy (SEM), and contact angle measurements. Results revealed that the optimum mass ratio of carboxymethyl cellulose (CMC) to AMPS to AM was 1:0.69:1.67, with the KPS initiator comprising 1.56% of the total monomer mass. By incorporating the dispersant at a concentration of 37.50%, the particle size of carbon black particles was observed to decrease from 5.350 μm to 0.255 μm, and no agglomeration of carbon black particles occurred even after 3 weeks of storage.

Surface Phenomena with the Participation of Sulfite Lignin under Pressure Leaching of Sulfide Materials

Searching for surfactants which can eliminate the occluding effect of molten elemental sulfur formed in the process of leaching sulfide ores under pressure (autoclave leaching) is relevant. However, the choice and use of surfactants are complicated by the harsh conditions of the autoclave process, as well as the insufficient knowledge of surface phenomena in their presence. This paper presents a comprehensive study of interfacial phenomena (adsorption, wetting, and dispersion) involving surfactants (using lignosulfonates as an example) and zinc sulfide/concentrate/elemental sulfur under conditions simulating sulfuric acid leaching of ores under pressure. The influence of concentration (C_LS 0.1-1.28 g/dm³), features of the molecular weight (M̅_w, 9.250-46.300 Da) composition of lignosulfates, temperature (10-80 °C), addition of sulfuric acid (CH₂SO₄ 0.2-10.0 g/dm³), and properties of solid-phase objects (surface charge, specific surface area, presence and diameter of pores) on surface phenomena at the liquid-gas and liquid-solid interfaces was revealed. It was found that with an increase in molecular weight and a decrease in the degree of sulfonation, the surface activity of lignosulfonates at the liquid-gas interface, as well as their wetting and dispersing activity with respect to zinc sulfide/concentrate increases. It has been found that an increase in temperature contributes to the compaction of the macromolecule of lignosulfonates, as a result of which their adsorption at the liquid-gas and liquid-solid interface in neutral media rises. It has been shown that the introduction of sulfuric acid into aqueous solutions increases the wetting, adsorption, and dispersing activity of lignosulfonates with respect to zinc sulfide. The latter is accompanied by a decrease in the contact angle θ (by 10 and 40°) and an increase in both the specific number of zinc sulfide particles (not less than 1.3-1.8 times) and the content of fractions with a size of -3.5 μm. It has been established that the functional effect of lignosulfonates under conditions simulating sulfuric acid autoclave leaching of ores is implemented through the adsorption-wedging mechanism.

Functional surfaces, films, and coatings with lignin - a critical review

Lignin is the most abundant polyaromatic biopolymer. Due to its rich and versatile chemistry, many applications have been proposed, which include the formulation of functional coatings and films. In addition to replacing fossil-based polymers, the lignin biopolymer can be part of new material solutions. Functionalities may be added, such as UV-blocking, oxygen scavenging, antimicrobial, and barrier properties, which draw on lignin's intrinsic and unique features. As a result, various applications have been proposed, including polymer coatings, adsorbents, paper-sizing additives, wood veneers, food packaging, biomaterials, fertilizers, corrosion inhibitors, and antifouling membranes. Today, technical lignin is produced in large volumes in the pulp and paper industry, whereas even more diverse products are prospected to be available from future biorefineries. Developing new applications for lignin is hence paramount - both from a technological and economic point of view. This review article is therefore summarizing and discussing the current research-state of functional surfaces, films, and coatings with lignin, where emphasis is put on the formulation and application of such solutions.

Surfactant induced catastrophic collapse of carbon black suspensions used in flow battery application

HYPOTHESIS

Carbon black particles act as electronically conductive additives in the slurry electrodes used in electrochemical redox flow batteries. Modifying the carbon black slurry formulation with the addition of a nonionic surfactant could impart improved particle dispersion, gravitational stability, and flowability leading to better battery performance.

EXPERIMENTS

Carbon black particles were dispersed in 1 M H₂SO₄ with volume fractions Φ = 0.01 to 0.06 and a nonionic surfactant (Triton X-100) concentration of c_surf. = 0, 0.05, and 0.1 M. Particle size was characterized using microscopy and surfactant adsorption using UV-vis spectroscopy. Sedimentation kinetics was measured using a custom camera set-up that tracks the height of the settling particle bed. Rheology experiments were conducted to measure linear viscoelasticity and shear flow behavior.

FINDINGS

The sedimentation dynamics of the slurry resembled that of a gel collapse. At short times we observed fast sedimentation associated with structural gel collapse and at long times very slow sedimentation associated with compaction of the sediment. Rheological investigations revealed that the slurry indeed behaved like colloidal gels. Addition of nonionic surfactant at α (= (c_surf./c_CB)) < 0.75 improved particle dispersion and increased gel elasticity. However, α> 0.75 led to a weaker gel that exhibits a fast 'catastrophic collapse' under gravity.