Excellent Dispersion Performance Research Articles

A Novel Slickwater System with Strong-Polarity Fibers for High-Efficiency Proppant Flowback Mitigation

To avoid or mitigate proppant flowback after a massive hydraulic fracturing of tight formations and to reduce its impairment to well productivity, this study developed a new type of fiber material with strong polarity based on polyester fiber. This fiber material is modified by introducing a strong-polar functional monomer into the molecular structure and adopting the means of surface grafting. On the basis of this fiber material, a fiber slip-water system with excellent dispersion performance can be established to prevent proppant backflow. Laboratory experiments were performed to analyze the specific function of the fibers with strong polarity and its working mechanisms. The results indicate that strong-polarity fibers have excellent dispersion performance. The fibers and resistance-reducing agents form an interwoven structure that can carry proppants, resulting in the enhancement of the sand-carrying capacity of the fracturing fluid system and the overall strength of the sand bank. In terms of the sand-carrying capacity and mitigation of proppant flowback, strong-polar fibers have significantly improved compared to unmodified fibers. In a 5 mm simulated crack, strong-polar fibers can increase the static settling time of 70/140 mesh quartz sand proppant by 26.5%. Meanwhile, the placement height of the sand embankment increased by 23.4% after the settlement of the proppant. In proppant transport experiments, strong-polar fibers with a mass fraction of 0.4% can increase the transport distance of proppants by more than 50%. Within the closed stress range of 2–10 MPa, the concentration of 0.5% strong-polar fibers increases the critical sand flow rate of the proppant by more than twice. The strong-polarity fiber system introduced in this study can be used to develop a fiber slickwater fracturing fluid system suitable for the massive hydraulic fracturing of tight reservoirs and has broad application prospects in the field of proppant flowback mitigation in tight reservoirs.

Hierarchical MXene@PBA nanohybrids towards high-efficiency flame retardancy and smoke suppression of robust yet tough polymer nanocomposites at ultra-low additions

Developing efficient flame-retardant MXene-based polymeric materials with enhanced mechanical properties has been a huge challenge. Herein, Prussian blue analogues (PBAs) were used to modify the surface of MXene nanosheets via an electrostatic self-assembly method to construct hierarchical MXene-based nanohybrids (MXene@PBA). Then, MXene@PBA was incorporated into the epoxy matrix to fabricate high-performance epoxy nanocomposites (EP-MXene@PBA). The study indicates that hierarchical MXene@PBA exhibits excellent dispersion performance in the epoxy matrix. Notably, MXene@PBA results in high-efficiency flame retardancy and smoke suppression for epoxy nanocomposites at ultra-low additions. What is very surprising is that only 1.0 wt% MXene@PBA can easily enhance the UL-94 rating of EP-1.0%MXene@PBA to V0. Meanwhile, the peak heat release rate (pHRR), total smoke production (TSP), and peak CO production rate (pCO) are remarkably reduced by 36.70%, 34.28%, and 43.48%, compared to those of the pristine epoxy resin, respectively. Furthermore, the 1.0 wt% MXene@PBA nanohybrids can enhance the flexural and impact strengths of EP-1.0%MXene@PBA. This work provides a feasible strategy for the creation of multifunctional MXene derivatives and their polymeric nanocomposites and holds great promise for many industrial applications.

Research progress on synthetic methods and application performances of polycarboxylic acids with different sequence structures

AbstractPolycarboxylic acids are being widely used in concrete mixtures and coal‐water slurry industries due to their high‐water reduction rate and excellent dispersion performance at low dosage. In this article, several typical sequence‐structured polycarboxylic acids, including random, blocked and gradient‐type products, their synthesis methods, mechanism of action and the comparison of the advantages and disadvantages of the relevant application performance in concrete industry and coal‐water slurry are described. Finally, the future development trend of various sequence structure polycarboxylic acids is given.

Structure-property study of novel star-shaped block polycarboxylate superplasticizers prepared via ATRP in Portland cement

Star-shaped superplasticizers exhibited excellent dispersion performance on cement paste, but the molecular structure remained poorly controlled. This study develops three star-shaped block superplasticizers via atom transfer radical polymerization to investigate their effects on fluidity and early hydration in the Portland cement system. The three star-shaped block superplasticizers with acid to ether monomer ratio of 28, 36 and 100, are marked as SPCE-1, SPCE-2 and SPCE-3 respectively. Fluidity test shows that SPCE-1 and SPCE-3 with higher hydrodynamic radius exhibit better initial fluidizing effect than SPCE-2. Besides, there is competitive adsorption of SPCEs between the clinker phase and nano-ettringite in pore solution. SPCE-1 behaves best in fluidity retention due to the increase of adsorption amount over hydration time. A dispersion mechanism based on the extended-DLVO theory was proposed that SPCEs reduce hydrophobic interaction between cement grains and prevent agglomeration between cement grains and air bubbles.

Synthesis and performance of a novel bio-oil-based dispersant as coal water slurry

With pyrolytic bio-oil as raw material, an efficient bio-oil-based dispersant (BOBD) applied to coal water slurry (CWS) has been synthesized successfully by grafting polymerization of the organic fractions from the bio-oil and acrylic acid (AA) in the mild condition. As a comparison, two commercial dispersants, namely poly (styrene sulfonic acid) sodium (PSS) and sodium lignosulfonate (SL) were employed. The structures and properties of the synthesized BOBD were characterized by using FTIR, 1H NMR, GC/MS, GPC, zeta potential, contact angle, and surface tension. The results showed the molecular weight of the BOBD was concentrated at 832 g/mol and 1954 g/mol. The surface tension and contact angle of BOBD aqueous solution were 47.71mN/m−1 and 60.8° respectively. The zeta potential of the suspension prepared from BOBD-water-coal was −67.1 mV. Using BOBD as a dispersant, the apparent viscosity of CWS loading 66 wt% coal dropped to 288 mPa·s at 0.3 wt% BOBD, and the maximum coal content reached 72 wt%. BOBD exhibited better viscosity reduction and stability enhancement capabilities than PSS and SL. The excellent dispersion performance of BOBD was due to the large electrostatic repulsion and steric hindrance derived from the grafted acrylic polymer, which effectively dispersed the coal particles uniformly. The rheological behavior of CWS with BOBD belonged to pseudoplastic fluid. The synthesized BOBD not only had an excellent dispersion performance but also could overcome the shortcomings of secondary pollution caused by PSS and SL containing element sulfur as dispersants in combustion. In addition, the synthetic route possessed simple, environmentally friendly and sustainable characteristics. The research opened up a new way for the utilization of bio-oil.

Surface activity, micellization, and application of nano-surfactants—amphiphilic carbon dots

For nano-surfactants, a new class of surfactants, the unique surface properties, micellization, and application of amphiphilic carbon dots (CDs) have been investigated carefully. Amphiphilic CDs (C12-CDs and C12-SCDs) were synthesized under mild reaction conditions. These CDs exhibit higher surface activity than conventional surfactants (APG12 and SDBS), whereas hydrophilic CDs have negligible surface activity. Above the critical micelle concentration, C12-CDs aggregate into an irregular spherical structure like micelle with an average diameter of about 100 nm, whereas C12-SCDs do not form aggregates. The surface tension of C12-CDs and C12-SCDs reaches the minimum at pH = 3, which is close to the isoelectric point of CDs. As pH increases, the water solubility of CDs increases, and thus the surface tension increases. C12-CDs can still maintain high activity at cNaCl = 250 g/L, but their resistance to CaCl2 is poor. The addition of the sulfonate groups enhances the tolerance of CDs to both NaCl and CaCl2. At cNaCl = 360 g/L and cCaCl2 = 750 g/L, C12-SCDs still have high surface activity.The removal efficiency of oil film and contact angle experiments show that compared to the traditional surfactant SDBS, C12-CDs and C12-SCDs have an excellent wettability alternation due to their abundant hydroxyl, carboxyl, amine, and sulfonate groups. Among them, the wettability alternation of C12-SCDs is better than that of C12-CDs due to their hydrophilic sulfonate groups. Furthermore, the Pickering emulsions stabilized by C12-SCDs have rapid pH and CO2 response performance. In addition, compared to the traditional surfactants SDBS and APG12, CDs have an excellent dispersion performance to MWCNTs. Different from the dispersion mechanism of cationic surfactant CPC (strong electrostatic attraction), CDs are adsorbed on the surface of MWCNTs through their hydrophobic effect and π-π stacking effect to achieve effective dispersion. Among them, because the sulfonate groups have high steric resistance and electrostatic repulsion, the dispersion performance of C12-SCDs is better than that of C12-CDs.

A cross-comparison of biosurfactants as marine oil spill dispersants: Governing factors, synergetic effects and fates

Biosurfactant-based dispersants (BBDs) may be more effective, cost-efficient and environmentally friendly than dispersants currently used for oil spill response. An improved understanding of BBD performance is needed to advance their development and commercial use. In this study, the ability of four BBDs, i.e. sufactins, trehalose lipids, rhamnolipids and exmulsins, alone and as various combinations to disperse Arabian light crude oil and weathered Alaska North Slope crude oil was compared to a widely used commercial oil dispersant (Corexit 9500A). Surfactin and trehalose lipids, which have balanced surface activity/emulsification ability, showed dispersion efficacy comparable to Corexit 9500A. Rhamnolipids (primarily a surface-active agent) and exmulsins (primarily an emulsifier) when used alone had significantly lower efficacy. However, blends of these surfactants had excellent dispersion performance because of synergistic effects. Balanced surface activity and emulsification ability may be key to formulate effective BBDs. Of the BBDs evaluated, surfactins with an effective dispersant-to-oil ratio as low as 1:62.3 and trehalose lipids with high oil affinity, biodegradation rate, and low toxicity characteristics show the most promise for commercial development.

Synthesis of waterborne hydroxyl acrylate resins and its application in VOC-free waterborne coatings

Purpose A kind of the Z-6020/E-44 modified waterborne hydroxyl acrylate resin (Z-WEA) and its application in volatile organic compound-free waterborne coatings were prepared. Design/methodology/approach The Z-6020/E-44 modified waterborne hydroxyl acrylate resin (Z-WEA) was obtained dropwise by adding a mixed solution of methyl methacrylate, n-butyl acrylate, hydroxyethyl methacrylate, acrylic acid and an initiator into a pre-prepared solution of isopropyl alcohol and E-44 and by semi-continuous solution polymerization, and this chain was further extended with organosiloxane (Z-6020) through graft copolymer, which was then neutralized with organic base and dispersed with water, with waterborne amino resin curing agent to form a film, and the properties were tested. Findings The results showed that when the dosage of initiator was 2.5% accounts for the total acrylic monomer, the hydroxyl content was 10%; the dosage of E-44 was 16%; the dosage of Z-6020 was 6%; the mass ratio of hard and soft monomer was 2.0:1; the neutralization was 100%; Z-6020/E-44 modified waterborne hydroxyl acrylate resin (Z-WEA) had excellent dispersion performance in water and storage stability; water absorption of cured film was 7.8%; pencil hardness reached 5H; adhesive force was 1 level; and the film was uniform and endowed with remarkable heat resistance, high gloss and good fullness. Practical implications This paper established a method to synthesize Z-6020/E-44 modified waterborne hydroxyl acrylate resin (Z-WEA) with green surfactants that can be used in the coatings, adhesives, finishing agents and so on. Originality/value This paper provides a method of preparing Z-6020/E-44 modified waterborne hydroxyl acrylate resin (Z-WEA) and with waterborne amino resin curing agent to form a film, and the film is uniform and endowed with remarkable heat resistance, high gloss and good fullness and meets the requirements of high-grade paint.

Amphoteric polycarboxylate superplasticizers with enhanced clay tolerance: Preparation, performance and mechanism

From the point view of molecular structure design, three different kinds of amphoteric polycarboxylate superplasticizers (APC) by introducing a cationic monomer such as [2-(methacryloyloxy)ethyl]trimethylammonium chloride (DMC), 3-[2-(methacryloyloxy)ethyl]dimethylammonio-propane-1-sulfonate (DMAPS) and acrylamide (AM) were synthesized by free radical polymerization. The functional groups, molecular weights and molecular weight distributions of these superplasticziers were characterized by Fourier transform infrared spectra (FT-IR) and gel permeation chromatography (GPC). The dispersion performance of as-prepared APC were evaluated by the fluidity of cement paste and cement mortar. The results showed that the fluidities of samples mixed with APC were higher than that of the conventional polycarboxylate ether (PCE) superplasticizers, indicating excellent dispersion performance and dispersion retention. The strengths of concrete with APC or PCE were greatly improved compared with that of the standard concrete, and the strengths of samples with APC were superior to that with PCE. By substituting cement with 1 wt% sodium bentonite, the fluidity of the cement pastes with APC was higher than that with PCE1, which can be ascribed to the enhanced clay tolerance of APC. Total organic carbon (TOC), X-ray diffraction (XRD) and thermo gravimetric analysis (TGA) were conducted to study the adaptability of superplasticizers to cement and clay. Adsorption capacity measurement revealed that APC and PCE exhibit selective adsorption on cement and clay and APC exhibited better adaptability to clay than PCE. The interlayer spacing of sodium bentonite increased by 0.2 nm after the adsorption of superplasticizer, without significant difference between APC and PCE. A possible mechanism was proposed that the cationic groups can insert into the interlayer of clay by cation exchange, and the intercalation of PEO side chains was inhibited, which is different from that of PCE.

Dispersing and doping carbon nanotubes by poly(p-styrene-sulfonic acid) for high-performance and stable transparent conductive films

Carbon nanotubes (CNTs) have been integrated into many electronic and energy devices due to their high conductivity and flexibility. Here, we report the discovery of poly (p-styrene-sulfonic acid) (PSS) as an efficient dispersant and stable dopant for CNTs. PSS showed an excellent dispersion performance; CNTs were partially dispersed by just stirring and well dispersed by sonication for only 3 min in PSS aqueous solution. PSS also showed an excellent doping performance; the as-filtrated CNT films, which had CNT bundles wrapped with a few nm-thick PSS layer, showed low sheet resistances of 115 and 49 Ω/sq at optical transmittances of 90% and 79%, respectively. Moreover, the CNT films showed long-term stability (>1000 h) and high-temperature stability (250 °C) in ambient air without any passivation layer. The simple dispersion and stable doping for CNTs is a promising way to achieve superior transparent conductive films for fundamental and industrial applications.

Amphiphilic Super-Wetting Ionic-Liquid-Based Lower Critical Solution Temperature System: Preparation, Characterization, and Excellent Dispersion Performance for Nanostructured Materials

Lower critical solution temperature (LCST) behavior is a well-known thermo-response and materials with LCST behavior are attractive in nanostructured material applications. However, traditional LCS...

Effects of polycarboxylates with different adsorption groups on the rheological properties of cement paste

The adsorption of polycarboxylate (PCE) superplasticizer is the key step in the dispersing of cement particles, which is closely associated with problems in practice (e.g. compatibility). The adsorption process could be finely tuned by the modification of adsorption groups. However, the fundamental effect of different adsorption groups on the rheological properties of cement pastes was still not so clear. In this paper, a series of PCEs with different types (carboxyl group, sulfonate group and phosphate group) and proportions (1/3 and 2/3 substitution ratio) of adsorption groups have been synthesized and characterized via gel permeation chromatography (GPC), Fourier-transform infrared (FTIR) spectroscopy and 1H nuclear magnetic resonance (1H NMR). The effects of PCEs with different adsorption groups on the solution conformation and adsorption conformation, adsorption amount, dispersion and rheological properties have been systematically explored to reveal the mechanism. The results show that for PCEs with sulfonate groups, both the lowest adsorption amount and poorest affinity toward negatively-charged surfaces lead to poorest dispersion performance. For PCEs with phosphate groups, the excellent dispersion performance and relative low yield stress is attributed to the strong electrostatic effect and Ca2+ complexity at high dosage. Differences between the PCEs containing phosphate groups relied on the difference of adsorption affinity and conformation. Meanwhile, the dispersing performance at low PCE dosage is quite different with expectation owing to the “bridging” effect. In summary, the above findings will be useful for the development of high-performance superplasticizers.

Synthesis of nonylphenol polyoxyethylene oligomer and application as an effective dispersant in pyraclostrobin suspension concentrate

ABSTRACTA versatile dispersant plays a critical role in suspension stability of pesticide aqueous suspension concentrate (SC), thus it is extremely important to design and synthesize an effective dispersant for SC. Herein, nonionic trimeric nonylphenol polyoxyethylene (10) (TNP10) was successfully synthesized using nonylphenol polyoxyethylene(10) ethers (NP10) as raw materials. The surface activities of TNP10 were evaluated according to critical micelle concentration (CMC), and the surface tension at CMC (γCMC). TNP10 showed higher surface activity due to its lower CMC value compared with that of NP10. In addition, the dispersing and stabilizing properties of TNP10 in 25 wt.% pyraclostrobin SC system were investigated. The results showed that TNP10 as a dispersant exhibited more excellent dispersion performance than NP10. Meanwhile, the obtained SC system exhibits shear thinning behavior under high-speed shearing showing typical features of pseudo-plastic non-Newtonian fluids, which conforms to the Herschel-Buckley model. The nonionic trimeric nonylphenol polyoxyethylene (10 can effectively improve the surface activities and the suspension rate and stability of SC compared with its monomer NP10.

Facile preparation of fluorescent layered double hydroxide polymeric composites through the photo-induced surface-initiated controlled living polymerization

(Zn/Al) layered double hydroxide (LDH) based fluorescence probes have been facilely fabricated via photo-induced surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization, which demonstrated green fluorescence, good biocompatibility and excellent dispersion performance in aqueous solution. The as prepared (Zn/Al)LDH polymeric composites were modified with 2-methacryloyloxyethyl phosphorylcholine (MPC), acrylic acid (AA) and diacroloyl-fluorescein (Ac-Fl). Among them, the comonomers MPC and AA were used to endow their water dispersibility, biocompatibility and potential drug carriers, while the Ac-Fl was served both as the fluorescence signal and photocatalyst for RAFT polymerization. A series of characterization methods, including 1H nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, transmission electronic microscopy, thermogravimetric analyses, X-ray photoelectron spectroscopy were employed to conform the successful of surface modification of LDH through photo-induced surface-initiated RAFT polymerization. Besides, UV-vis absorption spectra and fluorescence spectra were adopted to evaluate the optical characteristics of as prepared (Zn/Al)LDH-co-Poly(MPC-AA-Fl) composites, which exhibited high intense green fluorescence. Furthermore, the endocytosis behavior indicates that (Zn/Al)LDH-co-Poly(MPC-AA-Fl) composites could be potentially used in cell imaging and even drug delivery application for their excellent biocompatibility and all advantages described above.

Synthesis and performance evaluation of a novel biodegradable dispersant for offshore cementing

We developed a novel biodegradable oil-well dispersant, gelatin grafted acetone formaldehyde sulphonates (GAFS). This dispersant was prepared based on the chemical modification of naturally biodegradable products: gelatin. GAFS was synthesized through aldehyde ketone addition, hydroxyl condensation and Mannich amine methylation reaction. Functional groups and molecular structure of GAFS were characterized by FTIR (Fourier Transform Infrared Spectroscopy) and NMR (Nuclear Magnetic Resonance). Lab tests were conducted to determine the biodegradation rate, rheological properties, thickening time, compressive strength and dispersing property of GAFS in Class-G cement slurry. It is found that GAFS exhibits no retarding by-effect on oil well cement and can be considered biodegradable based on the biodegradation test results. The measured adsorption capacity and zeta potential of GAFS in Class-G well cement slurry show that: GAFS can be adsorbed greatly onto the surface of cement particles, resulting in strong electrostatic repulsion between cement particles and consequently generating an excellent dispersion performance.

Dispersion performance and mechanism of polycarboxylates bearing side chains of moderate length in coal-water slurries

The side chain structures of polycarboxylates are of great importance for their dispersion performance. The impacts of side chain length (length of polyethyleneglycol PEG, m ranging from 8 to 23) of the polycarboxylates on their dispersion performances and adsorption behaviors were investigated systematically to clarify the governing dispersing mechanism. The study reveals the length of side chain affects main chain polymerization degree (DPw) of polycarboxylates, density of charge groups and adsorption in coal-water interface. Dispersion performances of polycarboxylates in coal-water slurry depend on their adsorption density and the adsorption layer thickness on the coal. The shorter side chain is beneficial to increase adsorption density. However, the longer side chain is good for increasing adsorption layer thickness. Specifically, the polycarboxylate with side chains of moderate length (m=11) has the thickest adsorption layer and the highest adsorption density to result in its excellent dispersion performance. This information indicates that a balance between main chain length and side chain length should exist. So the polycarboxylate with the moderate length ratio of main chain to side chain can be designed as a highly efficient dispersant for low rank coal-water slurries.

Growing three-dimensional biomorphic graphene powders using naturally abundant diatomite templates towards high solution processability.

Mass production of high-quality graphene with low cost is the footstone for its widespread practical applications. We present herein a self-limited growth approach for producing graphene powders by a small-methane-flow chemical vapour deposition process on naturally abundant and industrially widely used diatomite (biosilica) substrates. Distinct from the chemically exfoliated graphene, thus-produced biomorphic graphene is highly crystallized with atomic layer-thickness controllability, structural designability and less noncarbon impurities. In particular, the individual graphene microarchitectures preserve a three-dimensional naturally curved surface morphology of original diatom frustules, effectively overcoming the interlayer stacking and hence giving excellent dispersion performance in fabricating solution-processible electrodes. The graphene films derived from as-made graphene powders, compatible with either rod-coating, or inkjet and roll-to-roll printing techniques, exhibit much higher electrical conductivity (∼110,700 S m−1 at 80% transmittance) than previously reported solution-based counterparts. This work thus puts forward a practical route for low-cost mass production of various powdery two-dimensional materials.

Dispersion Investigation on Cobalt Blue in Organic Solvent

The performance of the dispersion of cobalt blue in organic solvent is studied. The influence of dispersant (type & dosage), pH value, and other dispersion parameters on the stability of cobalt blue dispersion system is tested which shows good stability and excellent dispersion performance with diethylamide glycol ether the solvent, complex formulation (M (KH550): M (KH560): M (A-842) = 1:1:2) the dispersant and 7 the pH value. The characteristics of dispersion system are evaluated through sedimentation experiment and measurement of article size distribution. The most steady dispersion system is formed through high speed shearing force and the size of cobalt blue in this system is about 300nm.