Search Results (151)

Drilling fluid losses into formation voids are among the major issues that lead to increases in the costs and nonproductive time of operations. Lost circulation materials have been widely used to stop or mitigate losses. In most cases, the size of the loss zone is not known, making conventional lost circulation materials unsuitable for plugging the loss zone. In this study, novel temperature-sensitive LCM (TS-LCM) particles composed of diglycidyl ether of bisphenol A (DGEBA) and 4,4′-diaminodiphenyl methane were prepared. It is a thermal-response shape-memory polymer. The molecular structure was analyzed by Fourier transform infrared spectroscopy. The glass transition temperature (T_g) was tested by Different scanning calorimetry (DSC). The shape-memory properties were evaluated by a bend-recovery test instrument. The expansion and mechanical properties of particles were investigated under high temperature and high pressure. Fracture sealing testing apparatus was used to evaluate sealing performance. The mechanism of sealing fracture was discussed. Research results indicated that the T_g of the TS-LCM was 70.24 °C. The shape fixation ratio was more than 99% at room temperature, and the shape recovery ratio was 100% above the T_g. The particle was flaky before activation. It expanded to a cube shape, and the thickness increased when activated. The rate of particle size increase for D90 was more than 60% under 120 °C and 20 MPa. The activated TS-LCM particles had high crush strength. The expansion of the TS-LCM particles could self-adaptively bridge and seal the fracture without knowing the width. The addition of TS-LCM particles could seal the tapered slot with entrance widths of 2 mm, 3 mm and 4 mm without changing the lost circulation material formulation. The developed TS-LCM has good compatibility with local saltwater-based drilling fluid. In field tests in the Yan’an area of the Ordos Basin, 15 shale oil horizontal wells were plugged with excellent results. The equivalent circulating density of drilling fluid leakage increased by an average of 0.35 g/cm³, and the success rate of plugging malignant leakage increased from 32% to 82.5%. The drilling cycle was shortened by an average of 14.3%, and the effect of enhancing the pressure-bearing capacity of the well wall was significant. The prepared TS-LCM could cure fluid loss in a fractured formation efficiently. It has good prospects for promotion. Full article

Self-healing coatings can replace conventional coatings and are capable of self-healing and continuing to protect the substrate after coating damage. In this study, two types of self-healing resins were synthesized as coatings: Type-A via Diels–Alder crosslinking of furfuryl-modified diglycidyl ether bisphenol A with bismaleimide, and Type-B through epoxy blending/curing to form a semi-interpenetrating network. FTIR and Raman spectroscopy confirmed the formation of Diels–Alder (DA) bonds, while GPC tests indicated incomplete monomer conversion. Both resins were applied to glass and wood substrates, with performance evaluated through TGA, colorimetry (ΔE), gloss analysis, and scratch-healing tests (120 °C/30 min). The results showed that Type-A resins had a higher healing efficiency (about 80% on glass substrates and 60% on wood substrates), while Type-B resins had a lower healing rate (about 65% on glass substrates and 55% on wood substrates). However, Type-B is more heat-resistant, has a slower decomposition rate between 300 and 400 °C, higher gloss retention, and less color difference (ΔE) between wood and glass substrates. The visible light transmission of Type-B (74.14%) is also significantly higher. Full article

Epoxy adhesives derived from bisphenol A diglycidyl ether (BADGE) are widely utilized in segmental construction—particularly in precast concrete structures—and in building structural strengthening, owing to their outstanding adhesion properties and long-term durability. These materials constitute a significant class of polymeric adhesives in structural engineering applications. However, BADGE-based epoxy adhesives are susceptible to aging under service conditions, primarily due to environmental stressors such as thermal cycling, oxygen exposure, moisture ingress, ultraviolet radiation, and interaction with corrosive media. These aging processes lead to irreversible physicochemical changes, manifested as degradation of microstructure, mechanical properties, and dynamic mechanical properties to varying degrees, with performance deterioration becoming increasingly significant over time. Notably, for the mechanical properties of concern, the decline can exceed 40% in accelerated aging tests. A comprehensive understanding of the aging behavior of BADGE-based epoxy resin under realistic environmental conditions is essential for predicting long-term performance and ensuring structural safety. This paper provides a critical review of existing studies on the aging behavior of BADGE-based epoxy resins. This paper summarizes the findings of various aging tests involving different influencing factors, identifies the main degradation mechanisms, and evaluates current methods for predicting long-term durability (such as the Arrhenius method, Eyring model, etc.). Furthermore, this review provides recommendations for future research, including investigating multifactorial aging, conducting natural exposure tests, and establishing correlations between laboratory-based accelerated aging and field-exposed conditions. These recommendations aim to advance the understanding of long-term aging mechanisms and enhance the reliability of BADGE-based epoxy resins in structural applications. Full article

Thermally conductive polymer composites are essential for effective heat dissipation in electronic packaging, where both thermal management and mechanical reliability are critical. Although diglycidyl ether of bisphenol-A (DGEBA)-based epoxies exhibit favorable properties, their intrinsically low thermal conductivity limits broader applications. Incorporating conductive fillers, such as expanded graphite (EG) and metal powders, enhances heat transport but often compromises mechanical strength due to poor filler–matrix compatibility. In this study, we address this trade-off by employing a titanate coupling agent to surface-modify aluminum (Al) fillers, thereby improving interfacial adhesion and dispersion within the DGEBA matrix. Our results show that incorporating 10 wt% untreated Al increases thermal conductivity from 7.35 to 9.60 W/m·K; however, this gain comes at the cost of flexural strength, which drops to 18.29 MPa. In contrast, titanate-modified Al (Ti@Al) not only preserves high thermal conductivity but also restores mechanical performance, achieving a flexural strength of 35.31 MPa (at 5 wt% Ti@Al) and increasing impact strength from 0.60 to 1.01 kJ/m². These findings demonstrate that interfacial engineering via titanate coupling offers a compelling strategy to overcome the thermal–mechanical trade-off in hybrid composites, enabling the development of high-performance materials for advanced thermal interface and structural applications. Full article

In this study, a novel starch-based adhesive (SBA) was proposed, which mainly involved the synthesis of a carboxyl-terminated hyperbranched polymer using bisphenol A diglycidyl ether (DGEBA) and citric acid as raw materials. Subsequently, starch was modified through hyperbranching to enhance the shear strength and water resistance of the SBA. For this purpose, the feasibility of the reaction between DGEBA and citric acid was analyzed using quantum mechanical simulations. Subsequently, both substances were simulated to synthesize carboxyl-terminated hyperbranched polymers with different ratios. Starch was modified through hyperbranching to establish various models of SBAs, and their properties were estimated using molecular dynamics simulations. Theoretical analysis indicates that a DGEBA-to-citric acid ratio of 3:7 yields a SBA with relatively optimal properties. The solubility parameter of this adhesive is 19.05 (J/cm³)¹/², suggesting strong intermolecular interactions between the hyperbranched polymer and starch. The synthesized adhesive exhibits high cohesive strength, with an estimated water contact angle of up to 138°, indicating good hydrophobicity. Furthermore, the system demonstrates favorable mechanical performance, with a shear modulus of 4.34 GPa and a bulk modulus of 8.80 GPa. Additionally, at this ratio, the SBA exhibits a relatively high interaction energy of −408.01 kcal/mol with the cellulose substrate, suggesting that the adhesive possesses favorable shear strength. Full article

Bio-based polydithioacetal nanocomposites were synthesized to address the critical need for materials that simultaneously achieve enhanced thermomechanical properties and excellent reprocessing capabilities. Using vanillin and cellulose nanocrystals (CNCs) as starting materials, linear polydithioacetals (PDTAs) were prepared via acid-catalyzed polycondensation of vanillin with various dithiols including 1,6-hexanedithiol, 1,10-decanedithiol, 3,6-dioxa-1,8-octanedithiol and 2,2′-thiodiethanethiol. These PDTAs were then crosslinked with a diepoxide (i.e., diglycidyl ether of bisphenol A, DGEBA) via the reaction of phenolic hydroxyl groups of PDTAs with epoxide groups of DGEBA. To create the nanocomposites, cellulose nanocrystals (CNCs) were surface-functionalized with thiol groups and then incorporated as the reinforcing nanofillers of the networks. The results of morphological observation showed that the fine dispersion of CNCs in the polymer matrix was attained. Owing to the incorporation of CNCs, the nanocomposites displayed improved thermomechanical properties. Compared to the network without CNCs, the nanocomposite containing 20 wt% CNCs exhibited an increase of more than tenfold in modulus and threefold in tensile strength. In addition, the nanocomposites exhibited excellent reprocessing properties, attributable to the dynamic exchange of dithioacetal bonds. This work presents a promising strategy for developing bio-based nanocomposites that have not only improved thermomechanical properties but also excellent reprocessing (or recycling) properties. Full article

Liquid hydrogen (LH₂) storage using carbon-fiber-reinforced composite pressure vessels is facing increasing demands in aerospace engineering. However, hydrogen permeation in epoxy resin matrixes seriously jeopardizes the function and safety of the cryogenic vessels, and the micro-behavior of hydrogen permeation in epoxy resins remains mysterious. This study performed molecular dynamics (MD) simulations to investigate the hydrogen molecule permeation behaviors in two types of epoxy resin systems, with similar epoxy reins of bisphenol A diglycidyl ether (DGEBA) and different curing agents, i.e., 4,4′-diaminodiphenylmethane (DDM) and polypropylene glycol bis(2-aminopropyl ether) (PEA). The influencing factors, including the cross-linking degrees and temperatures, on hydrogen permeation were analyzed. It was revealed that increased cross-linking degrees enhance the tortuosity of hydrogen diffusion pathways, thereby inhibiting permeation. The adsorption characteristics demonstrated high sensitivity to temperature variations, leading to intensified hydrogen permeation at low temperatures. By triggering defects in the epoxy resin systems by uniaxial tensile simulation, high consistency between the simulation results and the results from helium permeability experiments can be achieved due to the micro-defects in the simulation model that are more realistic in practical materials. The findings provide theoretical insights into micro-scale permeation behavior and facilitate the development of high-performance epoxy resins in liquid hydrogen storage. Full article

Epoxy-based composite materials, widely used in various industries such as coatings, adhesives, aerospace, electronics, and biomedical engineering, remain a topic of global interest due to their varying characteristics based on the base resin and curing agents used. This paper employs molecular dynamics simulation to examine the thermal and mechanical properties, as well as molecular behaviors, of epoxy systems cured with diglycidyl ether of bisphenol F as the base resin and aromatic amine curing agents, specifically the meta structure of 3,3′-diaminodiphenyl sulfone (3,3′-DDS) and the para structure of 4,4′-diaminodiphenyl sulfone (4,4′-DDS). The 3,3′-DDS system demonstrated a greater density and Young’s modulus than the 4,4′-DDS system. This tendency was analyzed based on differences in molecular fractional free volume and cohesive energy density (CED). The 4,4′-DDS system exhibits a higher glass transition temperature (T_g) compared to the 3,3′-DDS system, with values of 406.36 K and 431.22 K, respectively. To understand this behavior, we examined atomic-scale displacements at T_g through mean squared displacement analysis, which revealed that the onset of molecular motion occurs at a lower temperature in the 3,3′-DDS system. Molecular-level study reveals how the structural features of each curing agent appear in thermal and mechanical properties, offering important insights for epoxy system development. Full article

Bisphenol A diglycidyl ether (BADGE) is the main component of epoxy resin and is used for the inner coating of canned foods and plastic food containers. BADGE can easily migrate from containers and result in food contamination; the compound is known as an endocrine-disrupting chemical. We previously reported that maternal exposure to bisphenol A bis (2,3-dihydroxypropyl) ether (BADGE·2H₂O), which is the most detected BADGE derivative not only in canned foods but also in human specimens, during gestation and lactation, could accelerate neuronal differentiation in the cortex of fetuses and induce anxiety-like behavior in juvenile mice. In this study, we investigated the effects of low-dose BADGE·2H₂O (1–100 pM) treatment on neurites and the mechanism of neurite outgrowth in cortical neurons. BADGE·2H₂O exposure significantly increased the number of dendrites and neurite length in cortical neurons; these accelerating effects were inhibited by estrogen receptor (ER) antagonist ICI 182,780 and G-protein-coupled estrogen receptor (GPER) antagonist G15. BADGE·2H₂O down-regulated Hes1 expression, which is a transcriptional repressor, and increased levels of neuritogenic factor neurogenin-3 (Ngn3) in the cortical neurons; the changes were significantly blocked by G15. These data suggest that direct BADGE·2H₂O exposure can accelerate neuritogenesis and outgrowth in cortical neurons through down-regulation of Hes1 and by increasing Ngn3 levels through ERs, particularly GPER. Full article

In this study, simultaneous exposure to bisphenols and toxic and potentially toxic elements from the consumption of ready-to-eat foods was assessed. In total, 120 different ready-to-eat foods purchased in different Sicilian supermarkets and online shops were analysed. BPA was detected in most of the analysed foods. Statistical analysis was performed, differentiating the samples according to geographical origin and packaging type. Good separation between European and non-European samples could be observed, with the former being characterised by lower levels of Cd and Pb, while the latter showed the highest concentrations of Pb and Cd, followed by Mn and Fe. The calculated estimated weekly intake (EWI) was well below the intake levels recommended by regulatory agencies, indicating that ready-to-eat foods can be safely consumed at expected dietary levels. However, the recently established tolerable daily intake (TDI) for BPA increases the risk quotient values to >1, indicating a risk to the consumer. Full article

Bisphenol A diglycidyl ether (BADGE) and its related derivatives (BADGEs for short) are reactive epoxides condensed from bisphenol A (BPA) and epichlorohydrin. Nowadays, they are heavily used as additives in the production process of food and beverage contacting materials. However, BADGEs are considered as emerging organic pollutants due to their high toxicity including cytotoxicity, mutagenicity, and genotoxicity. In this work, an online analytical method integrated column-switching technique with supercritical fluid chromatography (SFC) was proposed for the simultaneous determination of bisphenol A diglycidyl ether and its derivatives. In this process, a homemade column was utilized in the first dimension of the column-switching SFC system to preconcentrate the analytes as well as eliminate interferences online. Under the optimal conditions, the obtained calibration curves for BADGEs showed good linearity ranging from 0.02 μg/mL to 10.00 μg/mL, while the values of LOD and LOQ were in the range of 0.0024–0.0035 μg/mL and 0.0080–0.0116 μg/mL, respectively. The optimized method exhibited a good recovery ranging from 85.6% to 105.5% with relative standard deviations less than 11.8%. The developed method provides an eco-friendly and effective way for the rapid and automated analysis of BADGEs at trace levels in canned beverages and can be applied to the high-throughput analysis of other similar matrices. Full article

Conventional epoxy thermosets, with irreversible crosslinking networks, cannot be reprocessed and recycled. Furthermore, the utilization of petroleum-based materials accelerates the depletion of non-renewable resources. The introduction of dynamic covalent bonds and the use of bio-based materials for thermosets can effectively address the above issues. Herein, a series of bio-based epoxy vitrimers with dynamic covalent imine bonds were synthesized via a simple solvent-free, one-pot method using vanillin-derived aldehyde monomers, 4,4-diaminodiphenylsulfone (DDS) and bisphenol F diglycidyl ether (BFDGE) as raw materials. The effect of crosslinking density, crosslinking structure and imine bond content on the resulting bio-based vitrimers was studied, demonstrating their excellent thermal properties, UV shielding and solvent resistance, as well as outstanding mechanical properties compared to those of the previously reported vitrimers. In particular, the cured neat resin of vitrimer had a maximum tensile strength of 109 MPa and Young’s modulus of 6257 MPa, which are higher than those of previously reported imine-based vitrimers. The dynamic imine bonds endow these vitrimers with good reprocessability upon heating (over 70% recovery) and degradation under acidic conditions, enabling recycling by physical routes and gentle degradation by chemical routes. This study demonstrates a simple and effective process to prepare high-performance bio-based and recycled epoxy thermosets. Full article

The problems created by conventional polymers after their end use have driven research into new biodegradable polymeric materials. PLA is a compostable polymer obtained from renewable sources, but its main drawbacks are its fragility and slow crystallization kinetics. These drawbacks limit its use in different applications. In order to overcome fragility, in the current study, different compositions of PLA/PCL blends, rich in PLA content and without and with DGEBA, were prepared and characterized by means of different techniques, such as FTIR, DSC, DMA, and the mechanical properties. Some compositions show a certain improvement in the deformation capacity compared to the neat PLA at a low test speed. However, when the test speed increases, no improvement is observed in terms of deformation capacity. By SEM, the morphology of injection-molded specimens was observed. All blends showed a biphasic morphology where the PCL droplets are dispersed within the continuous PLA matrix. In the current study, an attempt has been made to improve the compatibility and adhesion between the phases by incorporating a diglycidyl bisphenol A compound. The results obtained indicate that the epoxy groups seem to react with the end groups of the PLA chain; however, the interactions that it creates with the PCL phase are weak, which is in agreement with the FTIR and DSC results obtained. Full article

Naphthalene is a fungicide that can also be a phase-change agent owing to its high crystallization enthalpy at about 80 °C. The relatively rapid evaporation of naphthalene as a fungicide and its shape instability after melting are problems solved in this work by its placement into a cured epoxy matrix. The work’s research materials included diglycidyl ether of bisphenol A as an epoxy resin, 4,4′-diaminodiphenyl sulfone as its hardener, and naphthalene as a phase-change agent or a fungicide. Their miscibility was investigated by laser interferometry, the rheological properties of their blends before and during the curing by rotational rheometry, the thermophysical features of the curing process and the resulting phase-change materials by differential scanning calorimetry, and the blends’ morphologies by transmission optical and scanning electron microscopies. Naphthalene and epoxy resin were miscible when heated above 80 °C. This fact allowed obtaining highly concentrated mixtures containing up to 60% naphthalene by high-temperature homogeneous curing with 4,4′-diaminodiphenyl sulfone. The initial solubility of naphthalene was only 19% in uncured epoxy resin but increased strongly upon heating, reducing the viscosity of the reaction mixture, delaying its gelation, and slowing cross-linking. At 20–40% mass fraction of naphthalene, it almost entirely retained its dissolved state after cross-linking as a metastable solution, causing plasticization of the cured epoxy polymer and lowering its glass transition temperature. At 60% naphthalene, about half dissolved within the cured polymer, while the other half formed coarse particles capable of crystallization and thermal energy storage. In summary, the resulting phase-change material stored 42.6 J/g of thermal energy within 62–90 °C and had a glass transition temperature of 46.4 °C at a maximum naphthalene mass fraction of 60% within the epoxy matrix. Full article

Epoxy resins exhibit outstanding curability, durability, and environmental compatibility, rendering them extensively utilized in the realm of engineering curing. Nevertheless, the current curing mechanism of epoxy-based resins in cohesion with sand remains inadequately elucidated, significantly impeding their applicability within the domain of soil curing. This study employed molecular dynamics simulations to investigate the adsorption behavior of three distinct types of epoxy resins on the sand surface: diglycidyl ether of bisphenol-A epoxy resin (DGEBA), diglycidyl ether 4,4′-dihydroxy diphenyl sulfone (DGEDDS), and aliphatic epoxidation of olefin resin (AEOR). The objective was to gain insights into the interactions between the sand surface and the epoxy resin polymers. The results demonstrated that DGEDDS formed a higher number of hydrogen bonds on the sand surface, leading to stronger intermolecular interactions compared to the other two resins. Furthermore, the mechanical properties of the adsorbed models of the three epoxy resins with sand were found to be relatively similar. This similarity can be attributed to their comparable chemical structures. Finally, analysis of the radius of gyration for the adsorbed epoxy resins revealed that AEOR exhibited a rigid structure due to strong molecular interactions, while DGEDDS displayed a flexible structure owing to weaker interactions. Full article