Rheology Modifiers Research Articles

Vitrification of Liquid Metal‐in‐Oil Emulsions Using Nano‐Mineral Oxides

AbstractGa and Ga‐based alloys have recently received significant attention as “liquid metals (LMs)” with the combined advantages of a low toxicity, low melting point, high fluidity, and high conductivity. An important method for modifying LMs for enhanced processabilities and new applications is to tailor them into colloidal microdroplets suspended in a liquid medium. In this study, the unique vitrification behavior of oil‐based colloidal systems is shown with suspended LM microdroplets induced by various mineral oxide (MO) nanoparticles that are added as solid rheology modifiers. MOs exhibit a high affinity for the surfaces of suspended LM droplets in an apolar oil medium due to the polar interaction between the MO surface and the oxide skin of the LM. Thus, even minute amounts of added MOs (ΦMO < 0.01) transform a free‐flowing LM suspension (ΦMO ≈ 0.55) into a highly viscoelastic fluid that enables advanced processing (e.g., 3D printing). At high MO loadings (ΦMO ≥ 0.1), an emulsion with unprecedentedly high rheological strength is obtained, characterized by a yield stress of ≈104 Pa. In highly vitrified emulsions, partial sintering effects are induced by high internal sample stress, which improves the thermophysical properties of emulsions that may be useful for several practical applications.

Hydrophobically Associating Polyacrylamide “Water-in-Water” Emulsion Prepared by Aqueous Dispersion Polymerization: Synthesis, Characterization and Rheological Behavior

The hydrophobically associating polyacrylamide (HAPAM) is an important kind of water-soluble polymer, which is widely used as a rheology modifier in many fields. However, HAPAM products prepared in a traditional method show disadvantages including poor water solubility and the need for hydrocarbon solvents and appropriate surfactants, which lead to environmental pollution and increased costs. To solve these problems, we reported a novel kind of HAPAM "water-in-water" (w/w) emulsion and its solution properties. In this work, a series of cationic hydrophobic monomers with different alkyl chain lengths were synthesized and characterized. Then, HAPAM w/w emulsions were prepared by the aqueous dispersion polymerization of acrylamide, 2-methylacryloylxyethyl trimethyl ammonium chloride and a hydrophobic monomer. All these emulsions can be stored more than 6 months, showing excellent stability. An optical microscopy observation showed that the particle morphology and the particle size of the HAPAM emulsion were more regular and bigger than the emulsion without the hydrophobic monomer. The solubility tests showed that such HAPAM w/w emulsions have excellent solubility, which took no more than 180 s to dilute and achieve a homogeneous and clear solution. The rheology measurements showed that the HAPAM association increases with a hydrophobe concentration or the length of hydrophobic alkyl chains, resulting in better shear and temperature resistances. The total reduced viscosity was 124.42 mPa·s for cw101, 69.81 mPa·s for cw6-1, 55.38 mPa·s for cw8-0.25, 48.95 mPa·s for cw12-0.25 and 28 mPa·s for cw16-0.25 when the temperature increased from 30 °C to 90 °C. The cw8-2.0 that contains a 2 mol% hydrophobe monomer has the lowest value at 19.12 mPa·s due to the best association. Based on the excellent stability, solubility and rheological properties, we believe that these HAPAM w/w emulsions could find widespread applications.

Investigating the structure-to-property of thermo-thickening polymers capped by different structural side chains

This study investigates the structure and comparison of solution properties of a series of acrylamide-based polymers capped by different thermo-sensitive side chains such as N-vinyl caprolactam (NVCL), N,N-dimethylacrylamide (DEAM) and N-isopropylacrylamide (NIPAM) synthesized via continuous initiation free-radical polymerization. Techniques such as Fourier-transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H NMR) afforded the chemical structure, X-ray diffraction (XRD) exhibit the tacticity and environmental scanning electron microscopy (ESEM) displayed the morphology. Turbidimetry, dynamic light scattering (DLS), and DSC techniques examined the responsiveness and hydrodynamic radii of the colloidal particles at their lower critical solution temperature (LCST). The thickening profiles were investigated via rheometric analysis and the relationship between viscoelastic properties and hydrodynamic radii synergistically explained the anomalous viscosity build-up among the different side chains. The polymers exhibited excellent thickening abilities at high temperatures (>70 °C) with relatively rough surface mixed intercalations attributed to the thermo-responsive moieties grafted on acrylamide methylpropane sulfonic acid (AMPS) as thermal resistance backbone. PAMPS/NVCL displayed particularly excellent responses owing to its partial conjugation effect, compared to PAMPS/DEAM and PAMPS/NIPAM in solution at 150 °C. The polymers also displayed strong anti-salt responses, with a drop in viscosity initially observed but quickly subdued due to hydrophobic side chain association, electrostatic shield, and double-layer compression of the hydrated shells. These polymer side chains grafted on acrylamide backbones promote excellent self-assembly properties at varying grafting ratios and are interesting as self-adaptive rheology modifiers and fluid immobilizers for enhanced oil and gas recovery in deep reservoirs.

Structure, rheology, and 3D printing of salt-induced κ-carrageenan gels

κ-carrageenan is a seaweed-derived polysaccharide commonly used in the food and pharmaceutical industry as a thickening agent and rheological modifier. The biopolymer has shown promising potential as a gel-based ink for 3D printing applications. However, its application is limited due to its poor structural stability and mechanical strength. In this work, we propose to overcome the printing limitation by optimizing the ink formulation of salt-induced κ-carrageenan gels. The gelation of 0.25–2% w/v κ-carrageenan with gelling agents of potassium chloride (KCl), calcium chloride (CaCl2), and a combination of KCl and CaCl2 salts was studied using rheological and SANS measurements, and SEM and AFM imaging. A state diagram for the κ-carrageenan-salt samples reveals that the sol-gel transformation shifts to lower κ-carrageenan concentrations with the 25 mM salts. The rheological measurements show a synergistic increase in the storage modulus of κ-carrageenan by the addition of equimolar mixed salts of KCl and CaCl2. The addition of 25 mM KCl or CaCl2 significantly improved the printability of 1% w/v κ-carrageenan to form thin and continuous filaments. However, complex shapes consisting of cylinders, polygons, and multilayer structures could successfully be 3D printed with only the 1% w/v κ-carrageenan with 25 mM KCl gel ink. Live/dead assay of human lung cancer A549 cells seeded on the printed structures show the excellent biocompatibility of these gels.

Clay-free biodiesel-based drilling fluid suitable for high temperature

This paper introduces the formation of a clay-free biodiesel-based drilling fluid system. The system uses the biodiesel derived from the transesterification between soybean oil and methanol as the continuous phase, which is environmentally friendly and has an appropriate flow state. In order to inhibit the hydrolysis of the base oil under high temperatures, a small amount of methanol is retained and Lime addition is minimized. Besides, the system also contains a special polyamine-typed rheological modifier instead of organoclay to provide a fragile gel-structure with lower plastic viscosity and higher yield point, thus good for hole cleaning and solid suspension while keeping a higher rate of penetration (ROP). In order to strengthen the plugging and fluid loss control abilities, superfine calcium carbonate and oxidized asphalt are added and obtain a good outcome. Evaluation results showed that the clay-free biodiesel-based drilling fluid exhibits good properties of rheology, filtration, and emulsion stability, with temperature resistance over 200°C, which is suitable for the exploration of unconventional oil/gas restores.

Sustainable associative thickeners based on hydrophobically modified ethoxylated poly(hydroxy-urethane)s end-capped by long alkyl chains

Hydrophobically modified ethoxylated urethanes (HEURs) are associative polymers applied as thickening additives in various waterborne systems, such as emulsions, coatings and printing inks. Their conventional synthesis, based on diisocyanates, poses environmental and health threats during both manufacture and application. Hence, in this paper we present an approach for the next generation of sustainable and CO2-rich polyurethane rheological modifiers – isocyanate-free HEURs (IFHEURs) obtained through poly(hydroxy-urethane) route. The hydrophilic core of the IFHEURs was prepared by step-growth polyaddition between diamine and poly(ethylene glycol) bis(cyclic carbonate) – synthesized using CO2 as a green source of the carbonate bonds. Such obtained prepolymer with terminal carbonate groups was subsequently modified with hydrophobic amines using reactive extrusion method, which enabled efficient homogenisation of the viscous reaction systems and reaching high end-capping functionality after only 2 h. In contrast to previously reported studies, the synthetic procedure was both solvent- and catalyst-free and allowed to incorporate up to 11 wt% of CO2 into the backbone of the final products. The structural analysis of the obtained IFHEURs using NMR and FT-IR spectroscopy and MALDI-ToF mass spectrometry confirmed obtaining the desired telechelic architecture resembling standard HEUR materials. The associative behavior of the IFHEURs in aqueous solutions was addressed in a rheological study, which revealed typical thickening mechanisms exhibited by rheological additives.

Deep Eutectic Solvents for Enhancing the Rheological Behavior of Polymers and Clays in Polymeric Water-Based Drilling Fluids

Drilling fluids with high suspending capacity without high viscosity are required in drilling operations, such as horizontal wells and highly deviated wells, with the “cutting bed”. Non-viscosifying rheological modifiers that can enhance the rheological properties of polymer drilling fluids are urgently needed. This study reports the application of a choline-chloride-based deep eutectic solvent (Gly-DES) as a rheological modifier for polymeric water-based drilling fluids. The rheological effects of Gly-DES on bentonite/polymer fluids were evaluated by high-temperature rheological testing, rheological model fitting, and rheological parameter (yield point, fluidity index, gel strength, etc.) analysis. The results showed that 2–4 wt % Gly-DES can improve the rheological properties of polymer drilling fluid in the temperature range of 150 °C. The addition of Gly-DES significantly improved the rheological parameters of drilling fluids, such as the yield point, gel strength, low shear rate viscosity, etc. At the same time, the viscosity of drilling fluids was always stable at different temperatures, which means that Gly-DES can help improve the suspension and cutting carrying capacity of drilling fluids without significantly increasing the viscosity of drilling fluids. Mechanistic analysis revealed that Gly-DES was connected to the polymer and bentonite through hydrogen bonds and ionic bonds, which enhanced the cross-linked network structure of the polymer at high temperatures and promoted the formation of weak gels in Na bentonite suspensions. Gly-DES can simultaneously enhance rheology, inhibit clay hydration, and improve filter cake lubricity and has the potential to be a multifunctional drilling fluid treatment agent.

Can superabsorbent polymers be used as rheology modifiers for cementitious materials in the context of 3D concrete printing?

Autogenous shrinkage may be a critical issue concerning the use of limestone-calcined clay-cement (LC3) in high-performance concrete and 3D printable cementitious materials, which have relatively low water to binder (W/B) ratio. Adding an internal curing agent, i.e., superabsorbent polymer (SAP), could be a viable solution in this context. However, employing SAP (without adding additional water) may also influence the fresh properties of LC3 composites by increasing yield stress and viscosity, which may be beneficial for 3D printability. Therefore, this study attempts to use SAP as a rheology modifying admixture with the aim of investigating the impact of SAP on flow behavior, structural build-up, hydration kinetics, compressive strength, and autogenous shrinkage of LC3 pastes with a fixed W/B (0.3). In addition, hydroxypropyl methylcellulose (a typical rheology/viscosity modifier in 3D printable cementitious materials) was also employed in two mixtures to compare their effects. Results show that adding SAP increases the dynamic yield stress and the apparent viscosity, as well as structural build-up and hydration, but decreases the compressive strength at 3, 7 and 28 days. Furthermore, using SAP (especially 0.2 wt% SAP) not only promotes the early-age expansion but also effectively mitigates the autogenous shrinkage of LC3 pastes for up to 7 days. Overall, the obtained results indicated that SAP could act as a promising rheology modifier for the development of 3D printable cementitious materials.

Eco-Oriented Formulation and Stabilization of Oil–Colloidal Biodelivery Systems Based on GC-MS/MS-Profiled Phytochemicals from Wild Tomato for Long-Term Retention and Penetration on Applied Surfaces for Effective Crop Protection

Vegetable oils as hydrophobic reserves in oil dispersions (OD) provide a practical approach to halt bioactive degradation for user and environment-efficient pest management. Using biodegradable soybean oil (57%), castor oil ethoxylate (5%), calcium dodecyl benzenesulfonates as nonionic and an-ionic surfactants, bentonite (2%), and fumed silica as rheology modifiers, we created an oil-colloidal biodelivery sytem (30%) of tomato extract with homogenization. The quality-influencing parameters, such as particle size (4.5 μm), dispersibility (97%), viscosity (61 cps), and thermal stability (2 years), have been optimized in accordance with specifications. Vegetable oil was chosen for its improved bioactive stability, high smoke point (257 °C), coformulant compatibility, and as a green build-in-adjuvant by improving spreadability (20-30%), retention and penetration (20-40%). In in vitro testing, it efficiently controlled aphids with 90.5% mortalities and 68.7-71.2% under field-conditions without producing phytotoxicity. Wild tomato-derived phytochemicals can be a safe and efficient alternative to chemical pesticides when combined wisely with vegetable oils.

Research on rheological properties and modification mechanism of waterborne polyurethane modified bitumen

Polyurethane (PU) based materials are emerging as asphalt modifiers due to their unique molecular structure, but the production of commonly used PU prepolymers and PU elastomers might pose environmental and safety risks. In this work, environment-friendly waterborne polyurethane (WPU) additives were prepared and employed to modify bitumen. The properties of the WPU additive were characterized first. Then, the storage stability, workability, and rheological properties of the modified bitumen containing different dosages of WPU additives were investigated. The modification mechanism of the WPU on virgin bitumen was also analyzed. The Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) experimental results indicate that WPU with two glass transition temperatures (Tg) without toxic terminal groups was successfully prepared. Additionally, the excellent storage stability and workability of the WPU modified bitumen can be observed with the dosages of WPU additives no more than 9 wt%. Dynamic shear rheometer results show that WPU additives enhanced the deformation resistance of bitumen in high-temperature environments. The improvement of the anti-cracking ability of WPU modified bitumen at low-temperature environments was also verified by the bending beam rheometer experiment. However, the fatigue resistance of bitumen was slightly weakened by WPU. FTIR analyses for modified bitumen prove that the incorporation of WPU additives didn’t change the chemical structure of virgin bitumen. The enhanced high-temperature and low-temperature performance of the WPU modified bitumen can be attributed to the two-phase structure of the WPU molecular chain. Overall, the eco-friendly bitumen additive applied in this study has excellent application value and broad market prospects.

Direct ink writing of polyimide/bacterial cellulose composite aerogel for thermal insulation

Polyimide (PI) aerogels are well known for their high porosity, low density, thermal insulation and outstanding mechanical strength, thus expected to be applied in aerospace vehicle, intelligent driving and batteries. However, currently most PI aerogels are fabricated through traditional molding process, seriously restricted their practical applications. Although some researches on 3D printing of PI aerogels have been reported, there are some critical restrictions in present work such as complex support structures, low porosity and high thermal conductivity resulting from high solid content in printed ink. Herein, we choose bacterial cellulose (BC) with high aspect ratio as rheological modifier to construct water-based polyamic acid (PAA)/BC ink with low solid content but high yield stress enough for direct ink writing (DIW). Due to the good printability and formability of PAA/BC ink, the PI/BC aerogel with various macrostructures can be easily printed. Owing to the orientation from printing, the obtained printed PI/BC aerogel shows lower shrinkage, lower thermal conductivity and enhanced mechanical properties compared with molded PI/BC aerogels. Such printed PI/BC aerogel is potentially to be applied as thermal insulators for designated products with specific complex structure in fields of buildings and petrochemical engineering.

Chitosan Based Materials in Cosmetic Applications: A Review

This review provides a report on the properties and recent advances in the application of chitosan and chitosan-based materials in cosmetics. Chitosan is a polysaccharide that can be obtained from chitin via the deacetylation process. Chitin most commonly is extracted from cell walls in fungi and the exoskeletons of arthropods, such as crustaceans and insects. Chitosan has attracted significant academic interest, as well as the attention of the cosmetic industry, due to its interesting properties, which include being a natural humectant and moisturizer for the skin and a rheology modifier. This review paper covers the structure of chitosan, the sources of chitosan used in the cosmetic industry, and the role played by this polysaccharide in cosmetics. Future aspects regarding applications of chitosan-based materials in cosmetics are also mentioned.

Nonplanar 3D Printing of Epoxy Using Freeform Reversible Embedding.

Thermally cured thermoset polymers such as epoxies are widely used in industry and manufacturing due to their thermal, chemical, and electrical resistance, and mechanical strength and toughness. However, it can be challenging to 3D print thermally cured thermosets without rheological modification because they tend to flow and not hold their shape when extruded due to cure times of minutes to hours. 3D printing inside a support bath addresses this by allowing the liquid polymer to be held in place until the thermoset is fully cured and expands the structures that can be printed as extrusion is not limited to layer-by-layer. Here we report the use of Freeform Reversible Embedding (FRE) to 3D print off-the-shelf thermoset epoxy into lattice structures using non-planar extrusion. To do this we investigate how extrusion direction in 3D space impacts epoxy filament morphology and fusion at filament intersections. Further, we show the advantages of this approach by using non-planar printing to produce lattice geometries that show ~4 times greater specific modulus compared to lattice structures printed using other materials and printing techniques.

Structure‐property relationships of waterborne polyurethane (WPU) in aqueous formulations

AbstractThis study provides an overview of the rheological properties of aqueous polyurethanes (WPU), as the main component, or as a thickening additive in aqueous formulations. Waterborne polyurethanes (WPU) have been proposed as an environmentally friendly alternative to conventional solvent‐based solutions in a variety of industrial applications such as coatings, adhesives, inks. In all these fields, the control of rheological properties became an important prerogative to determine the quality of the dispersion and its potential applicability. First, the effect of parameters such as components, particle size and content, temperature, and interactions on dispersion viscosity was reported. Then, the effect of two additives, i.e. thickeners and nanomaterials, on structure–property relationships of WPU‐base systems, was described. Thickeners are rheological modifiers, commonly used to stabilize the dispersion and prevent flocculation and sedimentation of the particles, or to change the flow behavior of dispersions from Newtonian to pseudoplastic. These species can interact with water and polymer particles to create a network structure that alters the flow resistance, and thus viscosity. The use of hyperbranched aqueous polyurethane as thickening agent in WPU formulations was also presented. On the other hand, nanostructured fillers (0D/1D/2D) or a combination thereof in waterborne polyurethane led to the formation of specific microstructures that prevented the penetration of water, oxygen, and corrosive substances, also improved mechanical and thermal properties, allowing the development of high‐performance WPU‐based products.

Emulsion Stabilization Strategies for Tailored Isocyanate Microcapsules.

We report on the stabilization of an oil-in-water (O/W) emulsion to, combined with interfacial polymerization, produce core-shell polyurea microcapsules (MCs) containing isophorone diisocyanate (IPDI). These will act as crosslinkers for mono-component adhesives. The emulsion stabilization was evaluated using three types of stabilizers, a polysaccharide (gum arabic) emulsifier, a silicone surfactant (Dabco®DC193), a rheology modifier (polyvinyl alcohol), and their combinations. Emulsion sedimentation studies, optical microscopy observation, and scanning electron microscopy enabled us to assess the emulsions stability and droplet size distribution and correlate them to the MCs morphology. Fourier transform infrared spectroscopy and thermogravimetric analysis revealed the MCs composition and enabled us to evaluate the encapsulation yield. All stabilizers, except DC193, led to spherical, loose, and core-shelled MCs. The rheology modifier, which increases the continuous phase viscosity, reduces the emulsion droplets sedimentation, keeping their size constant during the MCs' synthesis. This allowed us to obtain good quality MCs, with a smaller average diameter, of approximately 40.9 µm mode, a narrower size distribution and 46 wt% of encapsulated IPDI. We show the importance of the emulsion stability to tune the MCs morphology, size, and size distribution, which are critical for improved homogeneity and performance when used, e.g., in natural and synthetic adhesive formulations industry.

Chloroplast/thylakoid-rich material: A possible alternative to the chemically synthesised flow enhancer polyglycerol polyricinoleate in oil-based systems

Chloroplasts are abundant organelles in a diverse range of plant materials; they are predominantly composed of multicomponent thylakoid membranes which are lipid and protein rich. Intact or unravelled thylakoid membranes should, in principle, have interfacial activity, but little has been published on their activity in oil-in-water systems, and nothing on their performance on an oil continuous system. In this work different physical methods were used to produce a range of chloroplast/thylakoid suspensions with varying degrees of membrane integrity. Transmission electron microscopy revealed that pressure homogenisation led to the greatest extent of membrane and organelle disruption compared to less energy intensive preparation methods The ability of the derived materials to modulate the flow behaviour of a chocolate model system (65% (w/w) sugar/ sunflower oil (natural amphiphiles removed) suspension) was investigated by acquiring rheological parameters. All chloroplast/thylakoid preparations reduced yield stress, apparent viscosity, tangent flow point and cross over point in a concentration-dependent fashion, although not as significantly as polyglycerol polyricinoleate applied at a commercially relevant concentration in the same chocolate model system. Confocal laser scanning microscopy confirmed presence of the alternative flow enhancer material at the sugar surfaces. This research reveals that low-energy processing methods that do not extensively disrupt thylakoid membranes are applicable to generating materials with marked capacity to affect the flow behaviour of a chocolate model system. In conclusion, chloroplast/thylakoid materials hold strong potential as natural alternatives to synthetic rheology modifiers for lipid-based systems such as PGPR.

Cellulose nanofibrils as rheology modifier and fluid loss additive in water-based drilling fluids: Rheological properties, rheological modeling, and filtration mechanisms

This study aims to improve the rheological and filtration properties of water-based drilling fluids (WDFs) by using cellulose nanofibrils (CNFs), which are the critical parameters in drilling operation. Results showed that the incorporation of CNFs in WDFs effectively improved the rheological and filtration properties. The lathy and flexible CNFs was entangled with bentonite (BT) to form the intertwined CNFs-BT network structure in WDFs, leading to an enhanced viscosity, gel behavior, and temperature stability of WDFs. WDFs containing CNFs showed the superior rheological properties, including the yield stress, anti-deformation capacity and structural restructuring capacity, suggesting an increased capacity to transport the cuttings to the surface. The excellent shear-thinning behavior was due to the orientation movement of CNFs along the shear force. Moreover, the nanosized CNFs resulted in the low permeable filter cakes, leading to less fluid loss volume and final filtration rate. We revealed the fundamental insights into the rheological and filtration properties of WDFs containing CNFs, paving the way for the application of new eco-friendly drilling fluid. Data availabilityData will be made available on request.

Corrosion protection for sustainability – watching paint dry

Corrosion protection for sustainability – watching paint dry Stuart Lyon, AkzoNobel Professor of Corrosion Control, looks at corrosion's cost to industrialised economies and the importance of corrosion protection – where car vehicle bodies suffer from rust perforation within a few years of purchase. Now manufacturers offer anti-perforation warranties for up to 12 years. Corrosion – the deterioration and loss of materials and their functional properties by environmental exposure – remains a significant cost to industrialised economies. Therefore the most practical and effective means of protection is to apply a coating, and the most widely used are paint coatings. Corrosion-protective organic coatings are engineered to optimise application (onto challenging surfaces) and lifetime performance. They comprise many ingredients including functional pigments that chemically inhibit the corrosion process, components that provide desired physical properties including hardness, wetting agents, rheology modifiers to enable correct surface flow from spray or brush application, etc. Overall, high-resolution analytical tools to probe the structure and chemistry of coatings and the interfaces between their constituent parts are being explored in the University of Manchester.

Novel thermo-associating polymer/silica nanocomposite as a temperature-resistant rheology modifier for bentonite-free water-based drilling fluids

Thermo-associating polymers have emerged as the promising agent to regulate the rheological properties of bentonite-free drilling fluids (BFDF). However, the application of thermo-associating polymers in high temperature drilling was still limited due to its unsatisfactory thermal stability. In this study, the method of combine the advantages of thermo-associating polymers and nanoparticles into an organic/inorganic hybrid system has been used to further enhance the thermal stability of thermo-associating polymers. In detail, the novel thermo-associating polymer/silica nanocomposite (AMS-CGBA) was prepared by in situ polymerization under optimal synthesis conditions. Different techniques (FT-IR, 1H-NMR, Elemental analysis and TGA) were used to characterize the structure and the thermal stability of AMS-CGBA. Rheological performance of the AMS-CGBA in BFDF was comprehensively studied and compared with that of thermo-associating polymer (CGBA). The TGA results showed that AMS-CGBA had excellent thermal stability probably due to incorporation of amino-grafted nano-silica (AMS) into thermo-associating polymer. Results from rheological tests revealed that AMS-CGBA exhibited much better performance than CGBA in improving the thermal stability of BFDF under high temperature and high salt (HTHS). Especially at the concentration of 1.5 wt% AMS-CGBA, the AMS-CGBA based BFDF showed nearly 16 times higher values of rheological parameters (AV, PV and YP) than that of CGBA-containing fluid after aging at 200 °C. And the dynamic light scattering tests revealed that the stability temperature of AMS-CGBA molecular was higher than 160 °C, while that of the CGBA was lower than 150 °C. Moreover, the AMS-CGBA-containing fluids exhibited a weakened thermo-thickening viscosity over a wide temperature range (80–180 °C), which was favorable for the “flat” rheology characteristic of BFDF. And the thermo-associative mechanism of AMS-CGBA was investigated through differential scanning calorimetry experiments to analyze the rheological stability of AMS-CGBA-containing fluids at high temperatures. The nanocomposite with the characteristic of both thermosensitive polymers and nanoparticles showed potential application in rheological regulation of bentonite-free drilling fluids at high temperatures.

High-performance thermosets for additive manufacturing

Additive manufacturing (AM) has come a long way since its initial inception. Previously considered a fast prototyping method, it offers significant benefits for use as a method of producing user-end parts that are limited in quantity, customizable, and/or complicated geometries. For AM to be considered in high-performance applications, such as automotive and aerospace, we must consider AM technology and the available and compatible printing materials. Typically only thermoset plastic resins are capable of meeting high-performance specifications, such as sufficiently high strength, stiffness, and toughness, as well as excellent chemical and environmental resistance. This review presents a broad overview of the available high-performance thermoset chemistries and formulations, i.e., resin blends. The base resin chemistries that are covered are: vinyl, epoxy, imides, cyanate ester, urethanes, benzoxazine, and click chemistries (e.g., Michael addition). Subsequently, more application-relevant blends of these base resins are discussed. Each section focuses on resin details such as reaction mechanisms, typical monomer structure, mechanical properties, and applications specific to AM. The review is organized as follows. We begin with an introduction on the state-of-the-art, the challenges still faced by the field, and a benchmark definition of “high performance.” This is followed by a discussion of the available AM technologies for thermoset printing, with a focus on their advantages and disadvantages. Next, we cover the details of different resin chemistry, followed by their blends. The following section details the difficulties in developing AM technologies that allow for the incorporation of fillers, such as rheological modifiers and reinforcements. The review ends with a perspective on the future of AM technologies that would bridge the gap between pure resin printing and the much needed composite printing for high-performance applications.