Epoxy Emulsion Research Articles

Waterborne novolac epoxy‐based thermal resistant and fire‐retardant thermal insulation coatings

AbstractWaterborne novolac epoxy based thermal resistant and fire‐retardant thermal insulation coatings were developed in this work. Novolac (phenolic) epoxy emulsion (PEE) was prepared by the phase inversion method based on formulation optimization by orthogonal array testing. The prepared emulsions have similar particle size, viscosity, and stability to commercial bisphenol a glycidyl ether epoxy emulsion (PZ). DSC results showed that the varnish film based on PEE had a higher glass transition temperature and initial thermal decomposition temperature compared with PZ cured by the same curing agent. Waterborne thermal insulation coating with PEE and PZ as binders and hollow glass microspheres (HGMs) as thermal insulation fillers were studied. The results indicated that the thermal conductivity of the coating decreased with an increase in HGMs content. Specifically, the thermal conductivity of the PEE coating containing 20 wt% HGMs is as low as 0.093 W/(m·K). It reduces the exterior temperature of the hot tank from approximately 200 °C to approximately 106 °C. Furthermore, the HGMs/PEE waterborne thermal insulation coating exhibits good thermal stability and flame retardance.

Low-viscosity thermal-responsive epoxy emulsion for high-temperature and high-salinity reservoirs: Plugging characteristics and core displacement test

To overcome the temperature and salt resistance challenges faced by unconventional profile control agents in high-temperature and high-salt reservoirs. A novel low viscosity, temperature and salt stimulus response system named TRE was obtained by using emulsified epoxy resin and curing agent. Experimental work covers from core size to microscopic size to explore the effect and mechanism of enhancing oil recovery. A comprehensive analysis was conducted on the rheological properties, apparent viscosity, plugging ability, profile control capability, macroscopic oil displacement efficiency, and microscopic oil displacement mechanism of TRE emulsion. Our results indicated that the TRE exhibits temperature and salt responsiveness, with a salt tolerance of 7 × 104 mg/L and a phase change temperature of approximately 65 °C. Moreover, at a TRE concentration of 8 wt%, TRE showcased a lower injection viscosity of 1.3 mPa s. The microstructure after phase change was studied using SEM, and the irregular elliptical pore network structure enhanced its long-term thermal stability. Core displacement experiments were conducted to evaluate its plugging performance and profile control capability. The optimal plugging effect and injectability conditions were confirmed at an injection rate of 1 mL/min, an injection volume of 0.8 PV, and a TRE concentration of 8 wt%. As a profile control agent, TRE was well-suited for reservoirs with medium to low permeability, formation salinity ranging from 3 to 7 × 104 mg/L, and temperatures above 65 °C, with a permeability limit of 180.2–720.1 mD. When the heterogeneity was below 9, the TRE exhibited a strong profile control effect, achieving a shunt rate of over 66% in low-permeability cores after plugging. Furthermore, macroscopic and microscopic oil displacement experiments indicated that TRE can effectively plug large and medium pores, and increase the coverage area of small pores. TRE has the advantage of plugging high permeability without complete plugging, which can effectively reduce reservoir heterogeneity and provide a uniform displacement. Following plugging, the swept volume by waterflooding increased by 18.46%, and the recovery rate increased by 19.10%. Temperature and salt responsive TRE exhibit excellent plugging ability, profile control capability, and oil displacement efficiency. Overall, this novel self-assembly system has potential for application in the exploitation of high-temperature and high salinity oil reservoirs.

Study on the effect of film-forming agent composition on moisture and heat resistance of basalt fiber composites

Abstract Resistance to hygrothermal aging is the key to the popularization and application of basalt fiber composites in the field of electrical equipment, so it is crucial to develop fiber surface-modified coatings suitable for basalt fibers with excellent hygrothermal resistance. In this study, the performance changes of basalt fiber composite samples treated with four types of surface coatings under artificially accelerated hygrothermal aging test were comparatively analyzed, and the mechanism of different components in the surface coatings was further analyzed. The results showed that the use of epoxy resin emulsion co-mingled with acrylic emulsion as the film-forming agent could significantly improve the mechanical properties of the samples. The use of epoxy resin emulsion co-blended with polyurethane emulsion as the film-forming agent improved the insulating properties and moisture and heat resistance of the samples. Further, the use of 5:1:1 epoxy emulsion, acrylic emulsion, and polyurethane emulsion co-blended as the film-forming agent component can ensure the insulation and hygrothermal resistance of the samples while taking into account the mechanical properties. After 120 hours of wet-heat aging, the breakdown field strength was increased by 22%, leakage current and dielectric loss angle was increased by 10%, and the mechanical properties were also significantly improved compared with the sample with epoxy emulsion as the main film-forming agent. In summary, through the compounding of the film-forming agent emulsion components, the optimization of the moisture and heat resistance of basalt fiber composites can be achieved, and the use of the mass percentage of 5:1:1 for the three types of emulsions blended to prepare the fiber surface coatings is more suitable for the treatment of basalt fibers to prepare the electrician’s equipment.

Epoxy composite microspheres as a versatile platform for enhancement of chlorophyll dispersion and photostability in coatings

Chlorophyll (Chl), as a rich natural pigment, is limited in applications due to poor photostability. The hydrophobic properties of Chl attributed to the tetrapyrrole ring and terminal long-chain hydrocarbons further constrains its dispersion in aqueous coatings. In this work, chlorophyll/epoxy composite microspheres (Chl/EMs) were prepared as candidate pigments via emulsion polymerization to provide a versatile platform for enhanced dispersion and photostability. The optimal reaction temperature of 75 °C for achieving the appropriate particle size distribution of epoxy microspheres (EMs) was first determined. Chl/EMs were then prepared by (1) the combination of Chl and DGEBA in the emulsification process, or by (2) mixing Chl with m-xylylenediamine (MXDA) during curing. The effects of Chl introduction at different steps on the emulsification, curing agent diffusion, and curing process were studied using off-site microscopy observation and aggregation-induced emission technique, to clarify the structure and morphology evolution during emulsion polymerization. The particle size of the microspheres was mainly determined by the emulsification process of the epoxy precursor. Chl participates in emulsification of Chl/EMs in case (1), resulting in a large average particle size and poor particle size distribution. In case (2), the diffusion of MXDA into epoxy emulsion particles is completed within 30 min and does not impede the quicker diffusion process of Chl which was mixed with MXDA. The prepared Chl/EMs with size ranging from 1 to 10 μm create a conducive oxygen blocking environment. Compared to the complete degradation period of untreated Chl coatings, the photostability of Chl/EMs coatings increased nearly 7-fold. Remarkably, Chl/EMs exhibit superior dispersion capability in waterborne polyurethane coatings compared to pure Chl coatings. The EMs with controllable morphology and size can be used as a versatile platform for enhancing dispersion and photostability of other organic or natural dyes and pigments in waterborne coatings.

Construction and properties of graphene oxide hydrogen-blocking coatings

Compared with the composite coating with a single structure, the coating with a multilayer structure may possess better hydrogen barrier performance. Graphene oxide (GO) was chemically modified using polyethylene glycol diglycidyl ether (EGDE) to obtain modified graphene oxide (mGO). The introduction of epoxy groups in mGO would participate in the crosslinking reaction between the epoxy resin (EP) emulsion and the curing agent to improve the dispersion and adhesion of the middle layer in the sandwich structure. An EP/mGO/EP composite coating with a sandwich structure was prepared. The research found that the tightly stacked mGO middle layer in the sandwich structure played a crucial role. The average adhesion of the multilayer composite coating was about 9 MPa. The electrochemical impedance spectroscopy of layer 2-mGO composite coating showed that its modulus was up to 109 Ω cm2. The permeation current density ip and hydrogen content remained at low values of 1.38 μA and 1.34 ppm, respectively. The multilayer composite coating possessed not only excellent adhesion but also excellent corrosion resistance and hydrogen barrier performance.

Facile synthesis of soy protein adhesives with high cold-pressing bonding ability through waterborne epoxy resin and bifunctional branched structure system

Biomass high-temperature soy meal (HSM)-based adhesives are gaining significant attention in the green household industry. However, the low initial adhesion and poor bonding performances have limited their applications in actual production. In this study, a stable waterborne epoxy emulsion (WEU) crosslinker and polyethylenimine (PEI) toughener were synergistically used to modify the HSM matrix owing to their regulated covalent interactions and branched chemistry. The WEU was prepared using a synthetic emulsifier that featured flexible polyether and alternating amine group blocks, providing numerous hydrogen bond sites and a toughened entangled network. PEI, with a unique spatial structure, was introduced to facilitate the noncovalent interactions, and also acted as a curing agent under thermo-curing. The synthesized adhesives exhibited excellent cold-pressing bonding strength at 0.99 MPa, which is sufficient to meet actual needs. Under certain pressure and thermal conditions, covalent bonds facilitated the formation of the crosslinking network. The resulting cured adhesive exhibited improved toughness, which was attributed to the branched and multiple noncovalent energy dissipation network. The HSM15-P7 adhesive exhibited outstanding wet shear strength, which increased by 3675 % compared with that of the unmodified HSM adhesives. This HSM15-P7 adhesive exhibited outstanding results compared with other reported biomass wood adhesives. This study provides a facile and comprehensible method for developing other bioresources for high-value industry products with high performances.

An Experimental Study on the Performance of Materials for Repairing Cracks in Tunnel Linings under Erosive Environments

Addressing the current lining cracking problem in coastal tunnels, this paper independently introduces a novel type of repair material for tunnel lining cracks—the composite repair material consisting of waterborne epoxy resin and ultrafine cement (referred to as EC composite repair material). Through indoor testing, we have analyzed the change rule of the mass change rate, compressive strength, flexural strength, and chloride ion concentration of the repair material samples in erosive environments, with the dosage of each component in the EC composite repair material being varied. We have also investigated the working performance, mechanical properties, and microstructure of the repair material. The results of this study show that when the proportion of each component of ultrafine cement, waterborne epoxy resin, waterborne epoxy curing agent, waterborne polyurethane, defoamer, and water is 100:50:50:2.5:0.5:30, the performance of the EC composite repair material in a chloride ion-rich environment is optimal in all aspects. When the mixing ratio of each component of the EC composite repair material is as stated above, the repair material exhibits the best performance in a chloride ion erosion environment. With this ratio of components in the EC composite repair material, the fluidity, setting time, compressive strength, flexural strength, and bond strength of the repair material in a chloride ion erosion environment can meet the requirements of relevant specifications, and it is highly effective in repairing tunnel lining cracks. The polymeric film formed by the reaction between the waterborne epoxy resin emulsion and the curing agent fills the pores between the hydration products, resulting in a densely packed internal structure of EC composite repair material with enhanced erosion resistance, making it very suitable for repairing cracks in tunnel linings in erosive environments.

Interfacial property enhancement of carbon fiber/epoxy composites via constructing a gradual modulus interphase with a waterborne bio‐based spiro diacetal epoxy emulsion

AbstractIn this article, to explore the utilization of bio‐based epoxy resin in the preparation of sizing agents for carbon fibers (CFs), a bio‐based epoxy emulsion (S‐P‐S) derived from spiro diacetal epoxy (SDE) resin was prepared and compared to the traditional diglycidyl ether of bisphenol A (DGEBA) based emulsion (D‐P‐D) and a mixed emulsion of S‐P‐S and D‐P‐D (S‐P‐S&D‐P‐D). The CF sized with S‐P‐S (CF‐(S‐P‐S)) showed improved surface oxygen content (22.86%) and roughness (40.9 nm), enhancing wettability and interfacial bonding between the fiber and the matrix. Nanoindentation test and AFM results showed the enhanced interfacial stiffness and a gradual modulus interphase with a thickness of 381 nm in CF‐(S‐P‐S) reinforced epoxy resin composite (CF‐(S‐P‐S)/EP). Therefore, the resulting CF‐(S‐P‐S)/EP composite possesses the best mechanical properties, with the transverse fiber bundle tensile (TFBT) strength of 27.3 ± 1.45 MPa and the interfacial shear strength (IFSS) of 85.6 ± 8.26 MPa. These results highlight the potential of the SDE‐based emulsion (S‐P‐S) to enhance the interfacial properties and mechanical performance of CF/EP composite, offering a sustainable alternative to conventional petroleum‐based epoxy resins.Highlights Emulsion (S‐P‐S) was prepared using spiro diacetal epoxy (SDE) for carbon fiber sizing. Properties of S‐P‐S sized CF (CF‐(S‐P‐S)) and its composite were evaluated. Spiro diacetal structure created a gradual modulus interphase in CF‐(S‐P‐S)/EP. The interfacial properties of the CF‐(S‐P‐S)/EP composite were greatly improved. Bio‐based SDE resin showed promise for optimizing carbon fiber composite interphase.

Synthesis of soy-protein adhesives with excellent cohesion and cold-pressing bonding strength through multiple noncovalent crosslinking network of waterborne epoxy resin

In order to achieve the purpose of reducing cost and increasing efficiency of plywood fabrication, development of high-temperature soy meal (HSM)-based adhesives with high cold-pressing bonding strength without compromising its internal cohesion and interfacial adhesion is a meaningful goal in production. However, due to the agglomerated intrinsic structure, weak intermolecular interactions and strong hydrophilicity, the application of HSM adhesive was limited by its poor cohesion and unstable bonding performances. Taking consideration of the abundant hydrogen bonds sites and toughened microphase separation structure, in this work, polyurethane (PU) fragments served to provide bonding strength during prepressing stage. Sulfonate groups were grafted to prepare a stable waterborne epoxy emulsion (WEU) and then used as a crosslinker for HSM adhesives. Besides the introduced carbamate and polyether segments that provided regular hydrogen bonding platforms within HSM matrix, the soft polymer long-chain coils overlapped to increase the initial viscosity of the adhesives. This enhanced cohesive network strengthened the cold-pressing bonding strength of HSM-WPA2–15, reaching 0.76 MPa, which is enough for actual factory requirements. Pressure and thermal condition can stimulate resin penetrating into wood voids and cure it, opening active epoxy groups to covalent bonding within HSM chains. The secondary crosslinking network optimized the water resistance of cured adhesives, achieving 1.00 MPa of the adhesives under wet shear strength testing. This novel and feasible method demonstrates a foundational design, being able to be utilized for developing other plant-based wood adhesives with improved performances.

Interaction between demulsification, curing of waterborne epoxy resin emulsions and cement hydration

Cement-based repair materials modified with waterborne epoxy resin (WER) emulsions has attracted attention owing to their excellent bonding and durability properties. The coalescence of cement and WER emulsion involves complex physical and chemical interactions, especially the effect of cement hydration on the curing of WER emulsion, which needs further study. Herein, the influence of the cement hydration environment on the demulsification and curing of WER emulsion was studied by using cement pastes’ centrifugal liquid. Then, the influence of waterborne epoxy emulsion on cement hydration and microstructure was analyzed. In addition, silica sol is used to compensate for the delayed effect of WER emulsion on the cement hydration. The results show that the high ion concentration environment in the centrifugal liquid of cement pastes reduces the stability of WER emulsion, the reduction of repulsion between colloidal particles could accelerate the demulsification and fusion of emulsion. Therefore, the curing process of WER emulsion was accelerated. The adsorption and complexation of WER emulsions to calcium ions promote cement hydration. When the content of the WER emulsions exceeds 5 %, the polymer film exhibits a more apparent wrapping effect on the cement particles, delaying the cement hydration. The volcanic activity of silica sol can effectively compensate for the delaying effect of WER emulsion on cement hydration. The combination of WER emulsion and silica sol–modified cement forms a uniform interpenetrating network composite structure, considerably improving the properties of cement-based materials.

Investigation on One-Component Waterborne Epoxy Emulsified Asphalt (OWEEA) Used as Bonding Material

Due to the issue of weakened adhesion between ultra-thin surface overlays, higher demands have been placed on bonding layer materials in practical engineering. This study proposed a method for preparing a one-component waterborne epoxy resin-modified emulsified asphalt (OWEEA) and explored the impact of different ratios on its performance. The basic physical and mechanical properties of the OWEEA, as well as its rheological characteristics, were investigated through penetration tests, softening point tests, ductility tests, tensile tests, and dynamic shear rheological tests. Pull-out tests and shear tests considering different substrates were used to evaluate the interfacial bonding performance of the OWEEA as a bonding layer material, and comparative analysis was conducted with conventional waterborne epoxy resin-modified emulsified asphalt. Based on microscopic testing and analysis, the laws of physical and chemical changes and secondary curing characteristics of the one-component waterborne epoxy emulsion (OWE) during the modification of emulsified asphalt were elucidated. The results indicated that the OWE prepared in this study significantly enhanced the tensile strength and bonding properties of emulsified asphalt. The results showed that the tensile strength, bonding strength, and shear strength of the OWEEA increased from 0.15 MPa, 0.36 MPa, and 0.35 MPa to 0.55 MPa, 1.29 MPa, and 2.01 MPa, respectively. The modification effect of the OWEEA surpassed that of conventional waterborne epoxy emulsion, albeit with a certain reduction in elongation at break, reduced from 1551% to 98%. Furthermore, the OWEEA showed a distinct secondary curing phenomenon. The results of the SEM tests showed that high temperatures accelerated the formation of the crosslinked network structure of OWE, promoting its integration with emulsified asphalt and resulting in a more uniform and dense structure, significantly enhancing bonding strength in a short period. In the actual road construction process, laying hot-mix asphalt mixtures on the bonding layer can further enhance its curing effect and improve its bonding performance.

Cellulose nanocrystals-reinforced waterborne epoxy coatings with enhanced corrosion resistance for steel

The practical applications of waterborne epoxy coatings are limited due to their poor barrier properties caused by the formation of numerous micropores and defects during the curing process. Herein, cellulose nanocrystals (CNCs)-reinforced waterborne epoxy coatings were fabricated by the direct addition of 0.2–1.0 wt% CNCs to waterborne epoxy emulsion followed by amine curing agent addition and spray coating. The incorporation of 0.2–0.5 wt% CNCs had no discernible impact on the stability of the waterborne epoxy emulsion. This led to the uniform dispersion of CNCs in the cured coating matrix, as evidenced by differential scanning calorimetry analysis. Because of the good compatibility, 0.2–0.5 wt% CNCs-reinforced epoxy coatings exhibited superior corrosion protection performance for steels. The impedance modulus of these coatings remained at 108 Ω cm2 after being immersed in a 3.5 wt% NaCl solution for 21 d. The hydroxyl groups present on the CNC surface undergo a reaction with the epoxy group, enhancing intermolecular interaction and leading to the formation of a defect-free dense structure that improves coating barrier properties. However, the incorporation of an excessive amount of CNCs (i.e., 0.8 and 1.0 wt%) significantly compromised the corrosion resistance of epoxy coatings due to aggregation-induced coating defects. Overall, this study provides a facile and green strategy for corrosion resistance improvement of waterborne epoxy coatings.

Study on the Performance of Polymer-Modified Conductive Cement-Based Materials

In order to study the synergistic effect of polymer and conductive functional materials on the properties of cement-based materials, polymer conductive cement-based materials were prepared by mixing four polymer lotions of silicon–acrylate emulsion (SG), phenylacrylic emulsion (SR), waterborne epoxy resin emulsion (SH), and acrylic emulsion (SX) with carbon fiber (CF) and carbon black (CB), two conductive functional materials, in a certain proportion. The effects of the different polymer–cement ratios (P/C) of the four polymers on the physical, mechanical, and electrical properties of conductive cement-based materials were studied. The results illustrated that SH improved the fluidity of cement paste, and the four polymers all had a delaying effect, which led to the hardening of the specimens and the extension of the demoulding specimens to varying degrees. SH and SR can increase the ratio of flexural strength to compressive strength (F/C) in cement paste and improve the toughness of materials, and the maximum value is reached when the P/C is 0.15. Except for SX, the other three polymer lotions can reduce the resistivity of cement paste, which is beneficial to the improvement of conductivity. The improvement sequence is SH > SR > SG. Among them, both SH group and SR group achieved the lowest electrical resistivity at the P/C of 0.15. The four kinds of polymer lotion can significantly reduce the water absorption of the specimen and promote the waterproof performance. The improvement effect: SH > SR > SG > SX. Among them, both the SH group and SR group achieved the minimum water absorption at the P/C of 0.15.

Glass fiber/epoxy composites with improved interfacial adhesion by using cross‐linking sizing agent

AbstractGlass fibers (GFs) are frequently employed as reinforcement fibers for polymer resins such as epoxy and polyester. The mechanical behaviors of GFs polymer composites are nevertheless constrained by weak interfacial adhesion between polymer matrix and GFs. Herein, we invented a cross‐linking modified sizing agent using polyethyleneimine and bisphenol A epoxy emulsion, and studied the effect of cross‐linking extent on GF surface characteristics and GF/epoxy interfacial adhesion. The treatment of GFs with cross‐linking modified sizing agent facilitated the formation of interpenetrating polymer networks in composites for strengthening interface interaction. The results show that the modified GFs have a rough surface and improved interfacial adhesion with epoxy matrix. When sizing agents with cross‐linking extent of the 23.0%, the GF/epoxy composites show advanced interfacial shear strength (IFSS) and transverse fiber bundle tension (TFBT) strength. This work demonstrates that the cross‐linking extent of sizing agent could regulate interfacial adhesion, which is a facile and promising strategy in reinforcing glass fiber polymer composites.Highlights Crosslink the sizing agent to enhance GF mechanical properties was reported. GF surface energy was enhanced and thickness of GF/epoxy interphase increased. IFSS and TFBT strength of the GF/resin composites increased by 23.65% and 30.54%, respectively.

Design of low-consumption epoxy resin porous plugging material via emulsification-curing method

Since the higher cost of epoxy resin, its application in reservoir plugging at high temperature and high salinity was seriously restricted. Herein, the expensive epoxy resin was used as the supporting skeleton to provide the mechanical strength required for plugging, while water was introduced via emulsification - curing method in the closed non-connected pores to reduce the material consumption. The curing kinetics of epoxy resin was studied using differential scanning calorimetry (DSC). On this basis, the high temperature stability and dynamic gel time of the epoxy resin emulsion were examined, and the microstructure and mechanical properties of the cured material were tested. Firstly, in the shear rate range of 10–100 s−1, the viscosity of epoxy resin emulsion was less than 1200 mPa·s under the condition of 20 ℃, meanwhile, the viscosity value was less than 100 mPa·s in high temperature environment of the reservoir (120 ℃), which meets the demand of mixing and injection. Secondly, in the W/O emulsion state, the curing reaction rate was accelerated. However, when the curing agent 4,4′-methylenebis[2,6-diethyl]aniline (DTD) is used instead of 3,3′-diethyl-4,4′-diaminodiphenyl methane (DEDDM), utilizing steric effect of double ethyl group, the thickening time is extended from 55 to 60 min to 110–120 min. Finally, after curing the epoxy resin emulsion, although mostly occupied by pore water (fw=50%), the increase in the curing degree made the elastic modulus increase from 0.017 MPa to 3.220 MPa compared with the pure epoxy resin, and the uniaxial compressive strength can reach 25.14 MPa.This design method can reduce the material consumption of epoxy resin by 30–35% while controlling leakage, providing an effective way for the construction of plugging materials in high temperature (120 ℃) and high salinity (21.81 ×104 mg/L) environment.

Research and application of anti - corrosion cement slurry in formation water corrosion environment

Corrosion of cementing cement ring causes the cement ring permeability to increase, resulting in serious casing corrosion. The casing corrosion perforation leads to an increase in water content of oil wells, low driving use of water injection wells, and imbalance of injection and production well patterns. Therefore, on the basis of conventional cementing cement, epoxy resin emulsion non-penetrating agent and corrosion inhibitor composed of rust and antibacterial materials are added to reduce the corrosion and permeability of cementing cement and reduce casing corrosion. The cement sample permeability experiment shows that adding 10% non-permeability agent and 2% corrosion inhibitor to low-density cement reduces the cement stone sample permeability from 0.075mD to 0.021mD, a decrease of 3.57 times. In the conventional density cement, adding 10% non-penetrating agent and 2% corrosion inhibitor, the permeability of the cement stone sample decreased from 0.041mD to 0.0009mD, a decrease of 4.56 times. The evaluation experiment of cement stone anti-corrosion performance shows that adding 10% non-penetrating agent and 2% corrosion inhibitor to cement can increase the corrosion resistance of cement samples by 6 times. At the same time, the thickening time and compressive strength of cement stone samples remain unchanged compared with conventional cement. Optimizing the technological measures of supporting anti-corrosion tools, and summing up a set of anti-corrosion cementing technology through the field application of anti-corrosion cement slurry, which provides strong technical support for the development of cementing technology under the corrosive environment of formation water in the oil field.

Dual hydrogen-bonding network strategy enables fabrication of robust soy protein adhesive capable of excellent bonding at ambient temperature

The application of biobased soy protein adhesives is significantly limited by poor initial adhesion during assembly. This deficiency leads to weak interfacial adhesion and cohesion toughness attributed to insufficient intermolecular interactions. In this study, we propose a dual hydrogen bonding system within a waterborne epoxy emulsion (WEU), in which the 2-ureido-4[1 H]-pyrimidinone (UPy) moiety with quadruple hydrogen bonds is grafted onto an epoxy skeleton, and polyethylene glycol (PEG) blocks with regular weak hydrogen bond sites is used to emulsify the WEU by simple mixing. WEU then acts as a crosslinker to improve the mechanical performances of high-temperature soybean meal (HSM) wood adhesives. The introduction of UPy and PEG blocks contributes to the formation of a dense cohesion crosslinking network and an energy dissipation system via multiple hydrogen bonding with peptide chains, enhancing the cold-pressing bond strength of adhesives with a 140% increase, relative to that of a pure HSM adhesive. Thermocuring facilitates interfacial penetration and covalent links via an epoxy ring-opening reaction in the system, creating a secondary crosslinking platform to optimize the water resistance and toughness of the adhesives. Consequently, the cured HSMW-15 adhesive exhibits an improvement in wet bond strength from 0.11 MPa to 0.90 MPa, with optimal toughness at 2.74 MJ/m3. This effective and feasible design provides valuable insights into modification strategies for preparing biobased wood adhesives with superior performance.

Synthesis of bio‐based modified amphoteric acrylate epoxy emulsion surface sizing agent via RAFT polymerization

AbstractThe synthesis of bio‐based modified amphoteric epoxy modified acrylate sizing emulsion based on reversible addition fragmentation chain transfer (RAFT) polymerization and its application in paper sizing were studied. A macromolecular chain transfer agent for RAFT polymerization was synthesized by the esterification of epoxy resin E‐51 with RAFT agent to eliminate the active groups on RAFT agent. Amphoteric polymer emulsifiers with good emulsification and dispersion effects in acidic and alkaline media were successfully prepared by RAFT polymerization. After neutralization, other monomers were polymerized to access cationic sizing emulsion (acid neutralization) and anionic sizing emulsion (alkali neutralization). The effects of bio‐based monomer content, hydrophilic monomer dimethylaminoethyl methacrylate (DM) content and degree of quaternization on the properties of sizing emulsion and sizing paper were further explored. In addition to the particle size and polymer dispersion index (PDI) of latex particles in different experimental groups, the water resistance, folding resistance, bursting strength, tensile strength and surface roughness of sized paper were analyzed and evaluated. Based on these results, a better sizing emulsion formulation was established. It was confirmed that the addition of bio‐based monomers can improve the sizing performance of paper.

Thermoelectric performance of basalt fiber with nanocomposite sizing

Thermoelectric fiber is widely used in the fabrication of power generator that could convert waste heat into useful electricity. It is assumed that the excellent thermoelectric performance of the material is highly dependent on thermal stability and conductivity at the same time. In this study, conductive basalt fibers (BFs) were developed by dip-coating with functional sizing consisting of epoxy emulsion and carbon nanotubes (CNT)/reduced graphene oxide (RGO). Various techniques were employed to characterize the obtained materials. It was found that both CNT/BF and RGO/BF exhibited remarkable thermoelectric performance. The tensile strength of single fibers also increased due to the introduction of carbon materials. Subsequently, conductive BFs were incorporated into the epoxy substrate to fabricate BF-reinforced polymers (BFRPs). The increased interfacial strength of BFRPs suggested the beneficial effect of nanocomposite coating, which was closely associated with their microstructure. The results verified the novel concept for the construction of fiber-based thermoelectric generator with high performance.

Preparation and Properties of Waterborne Epoxy-Resin-Emulsified Asphalt Modified by Oxidized Extraction Oil

Waterborne epoxy-resin-emulsified asphalt (WEREA) has excellent adhesion and can be used as a good waterproofing tack coat; however, there are some problems such as the poor compatibility between the waterborne epoxy and the emulsified asphalt, and the brittleness of the cured material. In the present work, oxidized furfural extract oil was used as a compatibilizer to prepare the waterborne epoxy emulsion and waterborne epoxy-resin-emulsified asphalt, and their modification effects were studied. The extraction oil was oxidized with potassium permanganate. The effects of oxidized extraction oil on the waterborne epoxy-resin-emulsified asphalt performance were investigated through experiments on viscosity, mechanical properties, and aging resistance. Combined with infrared spectroscopy and fluorescence microscopy, the compatibility and microstructure of the oxidized extraction oil modified WEREA were observed and analyzed. The result showed that the carboxyl group was introduced into the chemical structure of the extraction oil after oxidation. Oxidized extraction oil (OEO) and waterborne epoxy resin (WER) had good compatibility. When the content of OEO in the WER is 21%, the elongation at break of the WER can reach up to a maximum of 91.5%, and has a significant increase of 33.2%. OEO can significantly improve the elongation at the break and aging resistance of WEREA, especially when the mix ratio of oxidized extraction oil and epoxy resin was 6:5, when the breaking elongation of WEREA can be increased by 69%, and the compatibility between the epoxy resin and emulsified asphalt was the best. Moreover, the loss in elongation at the break of aged WEREA decreased from 13.7% to 4.9%.