Water-based aerosol is widely used as an effective strategy in electro-optical countermeasure on the battlefield used to the preponderance of high efficiency,low cost and eco-friendly.Unfortunately,the stability of th...Water-based aerosol is widely used as an effective strategy in electro-optical countermeasure on the battlefield used to the preponderance of high efficiency,low cost and eco-friendly.Unfortunately,the stability of the water-based aerosol is always unsatisfactory due to the rapid evaporation and sedimentation of the aerosol droplets.Great efforts have been devoted to improve the stability of water-based aerosol by using additives with different composition and proportion.However,the lack of the criterion and principle for screening the effective additives results in excessive experimental time consumption and cost.And the stabilization time of the aerosol is still only 30 min,which could not meet the requirements of the perdurable interference.Herein,to improve the stability of water-based aerosol and optimize the complex formulation efficiently,a theoretical calculation method based on thermodynamic entropy theory is proposed.All the factors that influence the shielding effect,including polyol,stabilizer,propellant,water and cosolvent,are considered within calculation.An ultra-stable water-based aerosol with long duration over 120 min is obtained with the optimal fogging agent composition,providing enough time for fighting the electro-optic weapon.Theoretical design guideline for choosing the additives with high phase transition temperature and low phase transition enthalpy is also proposed,which greatly improves the total entropy change and reduce the absolute entropy change of the aerosol cooling process,and gives rise to an enhanced stability of the water-based aerosol.The theoretical calculation methodology contributes to an abstemious time and space for sieving the water-based aerosol with desirable performance and stability,and provides the powerful guarantee to the homeland security.展开更多
The environmental hazards and"carbon footprint"of oil and gas drilling can be significantly reduced by replacing traditional petroleum-based chemical additives with natural materials derived from plants and ...The environmental hazards and"carbon footprint"of oil and gas drilling can be significantly reduced by replacing traditional petroleum-based chemical additives with natural materials derived from plants and animals.This paper explored for the first time the interaction mechanism between natural rubber latex(NRL)and bentonite suspensions(BTs)through a series of characterization experiments,as well as the potential applications in water-based drilling fluids(WBDF).The gel viscoelasticity experiments showed that NRL could decrease the consistency coefficient(k)and flow index(n)of BTs,and enhance the shear thinning performance of BTs as pseudo-plastic fluids.In addition,0.5 w/v%NRL not only increased the critical yield stress and strengthened the structural strength between the bentonite particles,but also facilitated the compatibility of pressure loss and flow efficiency.The evaluation of colloidal stability and WBDF performance indicated that NRL particles could promote the hydration and charge stability on the surface of BTs particles,and optimize the particle size distribution and flow resistance of WBDF under the"intercalation-exfoliation-encapsulation"synergistic interaction.Moreover,NRL can improve the rheological properties of WBDF at high temperatures(<150.C),and form a dense blocking layer by bridging and sealing the pores and cracks of the filter cake,which ultimately reduces the permeability of the cake and the filtration loss of WBDF.展开更多
Wellbore instability,especially drilling with water-based drilling fluids(WBDFs)in complex shale for-mations,is a critical challenge for oil and gas development.The purpose of this paper is to study the feasibility of...Wellbore instability,especially drilling with water-based drilling fluids(WBDFs)in complex shale for-mations,is a critical challenge for oil and gas development.The purpose of this paper is to study the feasibility of using hydrophobically modified silica nanoparticle(HMN)to enhance the comprehensive performance of WBDFs in the Xinjiang Oilfield,especially the anti-collapse performance.The effect of HMN on the overall performance of WBDFs in the Xinjiang Oilfield,including inhibition,plugging,lu-bricity,rheology,and filtration loss,was studied with a series of experiments.The mechanism of HMN action was studied by analyzing the changes of shale surface structure and chemical groups,wettability,and capillary force.The experimental results showed that HMN could improve the performance of WBDFs in the Xinjiang Oilfeld to inhibit the hydration swelling and dispersion of shale.The plugging and lubrication performance of the WBDFs in the Xinjiang Oilfield were also enhanced with HMN based on the experimental results.HMN had less impact on the rheological and filtration performance of the WBDFs in the Xinjiang Oilfield.In addition,HMN significantly prevented the decrease of shale strength.The potential mechanism of HMN was as follows.The chemical composition and structure of the shale surface were altered due to the adsorption of HMN driven by electrostatic attraction.Changes of the shale surface resulted in significant wettability transition.The capillary force of the shale was converted from a driving force of water into the interior to a resistance.In summary,hydrophobic nanoparticles presented afavorable application potential for WBDFs.展开更多
Water-based drilling fluids can cause hydration of the wellbore rocks,thereby leading to instability.This study aimed to synthesize a hydrophobic small-molecule polymer(HLMP)as an inhibitor to suppress mud shale hydra...Water-based drilling fluids can cause hydration of the wellbore rocks,thereby leading to instability.This study aimed to synthesize a hydrophobic small-molecule polymer(HLMP)as an inhibitor to suppress mud shale hydration.An infrared spectral method and a thermogravimetric technique were used to characterize the chemical composition of the HLMP and evaluate its heat stability.Experiments were conducted to measure the linear swelling,rolling recovery rate,and bentonite inhibition rate and evaluate accordingly the inhibition performance of the HLMP.Moreover,the HLMP was characterized through measurements of the zeta potential,particle size distribution,contact angles,and interlayer space testing.As confirmed by the results,the HLMP could successfully be synthesized with a favorable heat stability.Furthermore,favorable results were found for the inhibitory processes of the HLMP on swelling and dispersed hydration during mud shale hydration.The positively charged HLMP could be electrically neutralized with clay particles,thereby inhibiting diffusion in the double electron clay layers.The hydrophobic group in the HLMP molecular structure resulted in the formation of a hydrophobic membrane on the rock surface,enhancing the hydrophobicity of the rock.In addition,the small molecules of the HLMP could plug the spaces between the layers of bentonite crystals,thereby reducing the entry of water molecules and inhibiting shale hydration.展开更多
This work investigated the pyrolysis reaction of waste resin in a fluidized bed reactor.It was found that the pyrolysis-generated ash would adhere to the surface of ceramic particles,causing particle agglomeration and...This work investigated the pyrolysis reaction of waste resin in a fluidized bed reactor.It was found that the pyrolysis-generated ash would adhere to the surface of ceramic particles,causing particle agglomeration and defluidization.Adding kaolin could effectively inhibit the particle agglomeration during the fluidized pyrolysis reaction through physical isolation and chemical reaction.On the one hand,kaolin could form a coating layer on the surface of ceramic particles to prevent the adhesion of organic ash generated by the pyrolysis of resin.On the other hand,when a sufficient amount of kaolin(-0.2%(mass))was added,the activated kaolin could fully contact with the Na+ ions generated by the pyrolysis of resin and react to form a high-melting aluminosilicate mineral(nepheline),which could reduce the formation of low-melting-point sodium sulfate and thereby avoid the agglomeration of ceramic particles.展开更多
The combination of nano sizes,large pore sizes and green synthesis is recognized as one of the most crucial and challenging problems in constructing metal-organic frameworks(MOFs).Herein,a water-based strategy is prop...The combination of nano sizes,large pore sizes and green synthesis is recognized as one of the most crucial and challenging problems in constructing metal-organic frameworks(MOFs).Herein,a water-based strategy is proposed for the synthesis of nanoscale hierarchical MOFs(NH-MOFs)with high crystallinity and excellent stability.This approach allows the morphology and porosity of MOFs to be fine tuned,thereby enabling the nanoscale crystal generation and a well-defined hierarchical system.The aqueous solution facilitates rapid nucleation kinetics,and the introduced modulator acts as a deprotonation agent to accelerate the deprotonation of the organic ligand as well as a structure-directing agent(SDA)to guide the formation of hierarchical networks.The assynthesized NH-MOFs(NH-ZIF-67)were assessed as efficient adsorbents and heterogeneous catalysts to facilitate the diffusion of guest molecules,outperforming the parent microZIF-67.This study focuses on understanding the NH-MOF growth rules,which could allow tailor-designing NH-MOFs for various functions.展开更多
Difenoconazole(DIF)is a representative variety of broad-spectrum triazole fungicides and liposoluble pesticides.However,the water solubility of DIF is so poor that its application is limited in plant protection.In add...Difenoconazole(DIF)is a representative variety of broad-spectrum triazole fungicides and liposoluble pesticides.However,the water solubility of DIF is so poor that its application is limited in plant protection.In addition,the conventional formulations of DIF always contain abundant organic solvents,which may cause pollution of the environment.In this study,two DIF/cyclodextrins(CDs)inclusion complexes(ICs)were successfully prepared,which were DIF/β-CD IC and DIF/hydroxypropyl-β-CD IC(DIF/HP-β-CD IC).The effect of cyclodextrins on the water solubility and the antifungal effect of liposoluble DIF pesticide were investigated.According to the phase solubility test,the molar ratio and apparent stability constant of ICs were obtained.Fourier transform infrared spectroscopy,thermal gravity analysis,X-ray diffraction and scanning electron microscopy were used systematically to characterize the formation and characteristics of ICs.The results noted that DIF successfully entered the cavities of two CDs.In addition,the antifungal effect test proved the better performance of DIF/HP-β-CD IC,which exceeded that of DIF emulsifiable concentrate.Therefore,our study provides informative direction for the intelligent use of liposoluble pesticides with cyclodextrins to develop water-based environmentally friendly formulations.展开更多
Despite the great potential of cellulose wood pulp and cellulose nanofibrils as reinforcing filler in thermoplastics,its use is limited due to its tendency to form agglomerates and due to its high hydrophilic characte...Despite the great potential of cellulose wood pulp and cellulose nanofibrils as reinforcing filler in thermoplastics,its use is limited due to its tendency to form agglomerates and due to its high hydrophilic character.Here we describe fiberboard composites with high contents of wood pulp or cellulose nanofibrils,and a resin of poly(styrene-methyl-methacrylate-acrylic acid)used as water-based emulsion.Cellulose wood pulp and cellulose nanofibrils were used directly in the form of water suspensions.The method is based on the flocculation of the polymer emulsion followed by agglomeration of a mixture of the polymer emulsion and cellulose suspension,leading to the co-precipitation of the composite material,which can be easily separated from the water phase.Composites with acrylic polymer/cellulose fibers in the proportions of 75:25,50:50 and 25:75 wt%were prepared.Composites were characterized by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR),thermogravimetric analysis(TGA),dynamic mechanical analysis(DMA)and water absorption tests.SEM analysis revealed a very good dispersion of the fibers without evidence of agglomeration,which led to superior mechanical properties.These results showed the effectiveness of the methodology and the potential of cellulose wood pulp and CNF as reinforcement fillers in fiberboard composites and any other high fiber-content materials.展开更多
Benzoxazine resin,being a new type of phenolic resin deve-loped to overcome the shortcomings of traditional phenolic resins,has been synthesized from phenol,formaldehyde and amine,and does not require solvent eliminat...Benzoxazine resin,being a new type of phenolic resin deve-loped to overcome the shortcomings of traditional phenolic resins,has been synthesized from phenol,formaldehyde and amine,and does not require solvent elimination or monomer purification to obtain a relatively clean precursor.It has potential application in the field of aerospace due to its low expansion coefficient,high weather resistance,high carbon yield,good mechanical strength,and excellent ablation resistance[1].It can be mixed with various other resins or polymers to produce new resins with a broad range of applications[2-3].展开更多
A toughener that can effectively improve the interlaminar toughness in carbon fiber composites is crucial for various applications.We investigated,the toughening effects of phenolphthalein-based cardo poly(ether sulfo...A toughener that can effectively improve the interlaminar toughness in carbon fiber composites is crucial for various applications.We investigated,the toughening effects of phenolphthalein-based cardo poly(ether sulfone)(PES-C)on E51/DETDA epoxy and its carbon fiber composites(CFCs).Scanning electron microscopy showed that the phase structures of PES-C/epoxy blends change from island(of dispersed phase)structures to bi-continuous structures(of the matrix)as the PES-C content increased,which is associated with reaction-induced phase separation.After adding 15 phr PES-C,the glass transition temperature(T_(g))of the blends increased by 51.5℃,and the flexural strength,impact strength and fracture toughness of the blends were improved by 41.1%,186.2%and 42.7%,respectively.These improvements could be attributed to the phase separation structure of the PES-C/epoxy sys-tem.A PES-C film was used to improve the mode-II fracture toughness(G_(IIC))of CFCs.The G_(IIC) value of the 7μm PES-C film toughened laminate was improved by 80.3%compared to that of the control laminate.The increase in G_(IIC) was attributed to cohesive failure and plastic deformation in the interleaving region.展开更多
To promote the recycling of reclaimed asphalt pavement(RAP),epoxy resin was used to prepare the epoxy-recycled asphalt mixtures.The effect of epoxy resin on the properties of aged asphalt binder was investigated based...To promote the recycling of reclaimed asphalt pavement(RAP),epoxy resin was used to prepare the epoxy-recycled asphalt mixtures.The effect of epoxy resin on the properties of aged asphalt binder was investigated based on the tensile test,flexural creep test,and laser scanning confocal microscopy.The curing characteristics and the mechanical performance of recycled asphalt with different epoxy contents were explored.The results show that the low-temperature performance,ductility,and strength of the aged asphalt binder were significantly improved when the epoxy content reached 40%.The curing time of epoxy-recycled asphalt should be at least 4 d to ensure the formation of good internal spatial network structure.展开更多
An efficient utilization strategy of ethylene tar(ET),the main by-product of the ethylene cracking unit,is urgently required to meet demands for modern petrochemical industry.On the other hand,condensed polynuclear ar...An efficient utilization strategy of ethylene tar(ET),the main by-product of the ethylene cracking unit,is urgently required to meet demands for modern petrochemical industry.On the other hand,condensed polynuclear aromatic resin of moderate condensation degree(B-COPNA)is a widely used carbon material due to its superb processability,the production of which is,however,seriously limited by the high cost of raw materials.Under such context,an interesting strategy was proposed in this study for producing B-COPNA resin using crosslinked light fractions of ethylene tar(ETLF,boiling point<260℃)facilitated by molecular simulation.1,4-Benzenedimethanol(PXG)was first selected as the crosslinking agent according to the findings of molecular simulation.The effects of operating conditions,including reactions temperature,crosslinking agent,and catalyst content on the softening point and yield of B-COPNA resin products were then investigated to optimize the process.The reaction mechanism of resin production was studied by analyzing the molecular structure and transition state of ETLF and crosslinking agents.It was shown that PXG exhibited a superior capacity of withdrawing electrons and a higher electrophilic reactivity than other crosslinking agents.In addition to the highest yield and greatest heat properties,PXG-prepared resin contained the most condensed aromatics.The corresponding optimized conditions of resin preparation were 180℃,1:1.9(PXG:ETLF),and 3%(mass)of catalyst content with a resin yield of 78.57%.It was the electrophilic substitution reaction that occurred between the ETLF and crosslinking agent molecules that were responsible for the resin formation,according to the experimental characterization and molecular simulation.Hence,it was confirmed that the proposed strategy and demonstrated process can achieve a clean and high value-added utilization of ETLF via B-COPNA resin preparation,bringing huge economic value to the current petrochemical industry.展开更多
Liquid-phase acrylic acid hydration over solid-phase catalysts is a key reaction for the industrial productionof 3-hydroxypropionic acid. However, the relevant literature primarily focuses on the experimental aspects ...Liquid-phase acrylic acid hydration over solid-phase catalysts is a key reaction for the industrial productionof 3-hydroxypropionic acid. However, the relevant literature primarily focuses on the experimental aspects of catalystscreening and exploring reaction conditions, with few accurate descriptions of the reaction kinetics and determination ofthe reaction mechanism. Here, we combined kinetics experiments and theoretical calculations to elucidate the kinetics andmechanism of acrylic acid hydration on a resin catalyst. The pseudo-homogeneous model, and Langmuir-Hinshelwood-Haugen-Watson and Elie-Riedel (ER) heterogeneous models were used to explain the experimental kinetics data. TheER model can explain the experimental data very well, suggesting strong adsorption of acrylic acid on the surface of theresin catalyst. Furthermore, density functional theory calculations show that the hydration follows a stepwise, rather than aconcerted, reaction pathway. The present study provides theoretical insights into the reaction mechanism and kinetics, fillingthe gap in our understanding of the reaction on a fundamental level.展开更多
The use of fillers to enhance the corrosion protection of epoxy resins has been widely applied.In this work,cerium dioxide(CeO_(2))and benzotriazole(BTA)were introduced into an epoxy resin to enhance the corrosion res...The use of fillers to enhance the corrosion protection of epoxy resins has been widely applied.In this work,cerium dioxide(CeO_(2))and benzotriazole(BTA)were introduced into an epoxy resin to enhance the corrosion resistance of Q235 carbon steel.Scanning electron microscopy results indicated that the CeO_(2) grains were rod-like and ellipsoidal in shape,and the distribution pattern of BTA was analyzed by energy dispersive spectroscope.The dynamic potential polarization curve proved the excellent corrosion resistance of the composite epoxy resin with CeO_(2) and BTA co-addition,and electrochemical impedance spectroscopy test analysis indicated the significantly enhanced long-term corrosion protection performance of the composite coating.And the optimal protective performance was provided by the coating containing 0.3%(mass)CeO_(2) and 20%(mass)BTA,which was attributed to the barrier performance of CeO_(2) particles and the chemical barrier effect of BTA.The formation of corrosion products was analyzed using X-ray diffraction.In addition,the corrosion resistance mechanism of the coating was also discussed in detail.展开更多
Using non-toxic,low-volatile glyoxal to completely replace formaldehyde for preparing urea-glyoxal(UG)resin adhesive is a hot research topic that could be of great interest for the wood industry.However,urea-glyoxal(U...Using non-toxic,low-volatile glyoxal to completely replace formaldehyde for preparing urea-glyoxal(UG)resin adhesive is a hot research topic that could be of great interest for the wood industry.However,urea-glyoxal(UG)resins prepared by just using glyoxal instead of formaldehyde usually yields a lower degree of polymerization.This results in a poorer bonding performance and water resistance of UG resins.A good solution is to pre-react urea to preform polyurea molecules presenting already a certain degree of polymerization,and then to condense these with glyoxal to obtain a novel UG resin.Therefore,in this present work,the urea was reacted with hexamethylene diamine to form a polyurea named HU,and then this was used to react it with different amounts of glyoxal to synthesize hexamethylenediamine-urea-glyoxal(HUG)polycondensation resins,and to use this for bonding plywood.The results show that the glyoxal can well react with HU polyuria via addition and schiff base reaction,and also the HUG resin exhibits excellent bonding strength and water resistance.The shear strength of the plywood bonded with this HUG at 160°C hot press temperature as high as 1.93 MPa,2.16 MPa and 1.61 MPa,respectively,which meets the requirement of the China national standard GB/T 9846-2015(≥0.7 MPa),and can be a good choice as a wood adhesive for industrial application.展开更多
Fibre reinforced polymer composites have become a new generation of structural materials due to their unique advantages such as high specific strength,designability,good dimensional stability and ease of large-area mo...Fibre reinforced polymer composites have become a new generation of structural materials due to their unique advantages such as high specific strength,designability,good dimensional stability and ease of large-area monolithic forming.However,the problem of interfacial bonding between the resin matrix and the fibres limits the direct use of reinforcing fibres and has become a central difficulty in the development of basalt fibre-epoxy composites.This paper proposes a solution for enhancing the strength of the fibre-resin interface using maize starch nanocrystals,which are highly yield and eco-friendly.Firstly,in this paper,corn starch nanocrystals(SNC)were prepared by hydrolysis,and were deposited on the surface of basalt fibers by electrostatic adsorption.After that,in order to maximize the modification effect of nano-starch crystals on the interface,the basalt fiber-epoxy resin composite samples were prepared by mixing in a pressureless molding method.The test results shown that the addition of basalt fibers alone led to a reduction in the strength of the sample.Deposition of 0.1 wt%SNC on the surface of basalt fibers can make the strength consistent with pure epoxy resin.When the adsorption amount of SNC reached 0.5 wt%,the tensile strength of the samples was 23.7%higher than that of pure epoxy resin.This is due to the formation of ether bond homopolymers between the SNC at the fibre-epoxy interface and the epoxy resin,which distorts the originally smooth interface,leading to increased stress concentration and the development of cracks.This enhances the binding of basalt fibers.The conclusions of this paper can provide an effective,simple,low-cost and non-polluting method of interfacial enhancement modification.展开更多
Silicon-containing aryl acetylene resin(PSA)is a new type of high-temperature resistant resin with excellent oxidation resistance,whereas antioxidant reaction mechanism of PSA resin under ultra-high temperatures still...Silicon-containing aryl acetylene resin(PSA)is a new type of high-temperature resistant resin with excellent oxidation resistance,whereas antioxidant reaction mechanism of PSA resin under ultra-high temperatures still remains unclear.Herein,the oxidation behavior and mechanisms of PSA resin are systematically investigated combining kinetic analysis and Reax FF molecular dynamics(MD)simulations.Thermogravimetric analysis indicates that the oxidation process of PSA resin undergoes two main steps:oxidative mass gain and oxidative degradation.The distributed activation energy model(DAEM)is employed for describing oxidation processes and the best-fit one is obtained using genetic algorithms and differential evolution.DAEM model demonstrates that the oxidative weight gain stage is dominated by two virtual reactants and the oxidative degradation stage consists of three virtual reactants.Correspondingly,the observation of MD reaction pathways indicates that oxygen oxidation of unsaturated structures occurs in the initial stage,which results in the formation of PSA resin oxides.Furthermore,cracked pieces react with O_(2)to generate CO and other chemicals in the second step.The resin matrix's great antioxidation resilience is illustrated by the formation of SiO_(2).The analysis based on MD simulations exhibits an efficient computational proof with the experiments and DAEM methods.Based on the results,a two-stage reaction mechanism is proposed,which provides important theoretical support for the subsequent study of the oxidation behavior of silica-based resins.展开更多
Super absorbent resin(SAR)is prepared by aqueous high temperature polymerization using hydroxypropyl methylcellulose(HPMC)as monomer backbone material,acrylic acid(AA)and acrylamide(AM)as the graft copolymer monomer,p...Super absorbent resin(SAR)is prepared by aqueous high temperature polymerization using hydroxypropyl methylcellulose(HPMC)as monomer backbone material,acrylic acid(AA)and acrylamide(AM)as the graft copolymer monomer,potassium persulfate(KPS)as the initiator to generate free radicals,and N,N`-methylenebisacrylamide(MBA)as cross-linking agent for cross-linking reaction.Simutaneously,the influence of individual factors on the water absorption is investigated,and these factors are mainly AA,AM,KPS,MBA,HPMC,and reaction temperature.The optimized conditions are obtained by the experiment repeating for several times.The water absorption multiplicity and salt absorption multiplicity under the conditions are 782.4 and 132.5 g/g,respectivity.Furthermore,the effects of different temperatures and salt concentrations on its water absorption,as well as the swelling kinetics of SAR are studied.It is indicated the water-absorbing swelling process is mainly caused by the difference in water osmotic pressure and Na+concentration inside and outside the cross-linked molecular structure of the resin,which is not only consistent with the quasi-secondary kinetic model,but also with the Fick diffusion model.展开更多
Sustained casing pressure(SCP)is a crucial issue in the oil and gas production lifecycle.Epoxy resins,exhibiting exceptional compressive strength,ductility,and shear bonding strength,have the potential to form reliabl...Sustained casing pressure(SCP)is a crucial issue in the oil and gas production lifecycle.Epoxy resins,exhibiting exceptional compressive strength,ductility,and shear bonding strength,have the potential to form reliable barriers.The injectivity and sealing capacity of the epoxy resin is crucial parameters for the success of shallow remediation operations.This study aimed to develop and assess a novel solid-free resin sealant as an alternative to Portland cement for mitigating fluid leakage.The investigation evaluated the viscosity,compressive strength,and brittleness index of the epoxy resin sealant,as well as its tangential and normal shear strengths in conjunction with casing steel.The flow characteristics and sealing abilities of conventional cement and epoxy resin were comparatively analyzed in cracks.The results showed that the application of a viscosity reducer facilitated control over the curing time of the epoxy resin,ranging from 1.5 to 6 h,and reduced the initial viscosity from 865.53 to 118.71 m Pa,s.The mechanical properties of the epoxy resin initially increased with a rise in curing agent content before experiencing a minor decrease.The epoxy resin containing 30%curing agent exhibited optimal mechanical properties.After a 14-day curing period,the epoxy resin's compressive strength reached81.37 MPa,2.12 times higher than that of cement,whereas the elastic modulus of cement was 2.99 times greater than that of the epoxy resin.The brittleness index of epoxy resin is only 3.42,demonstrating high flexibility and toughness.The tangential and normal shear strengths of the epoxy resin exceeded those of cement by 3.17 and 2.82 times,respectively.In a 0.5 mm-wide crack,the injection pressure of the epoxy resin remained below 0.075 MPa,indicating superior injection and flow capabilities.Conversely,the injection pressure of cement surged dramatically to 2.61 MPa within 5 min.The breakthrough pressure of0.5 PV epoxy resin reached 7.53 MPa,decreasing the crack's permeability to 0.02 D,a mere 9.49%of the permeability observed following cement plugging.Upon sealing a 2 mm-wide crack using epoxy resin,the maximum breakthrough pressure attained 5.47 MPa,3.48 times of cement.These results suggest that epoxy resin sealant can be employed safely and effectively to seal cracks in the cement.展开更多
Tannin foam is a new functional material.It can be widely applied to the automobile industry,construction industry,and packaging industry due to its wide range of raw materials,renewable,easily degraded,low cost and a...Tannin foam is a new functional material.It can be widely applied to the automobile industry,construction industry,and packaging industry due to its wide range of raw materials,renewable,easily degraded,low cost and almost no pollution.Preparing tannin foam is a very complex process that includes high temperature,two phases,mechanical agitation,and phase change.To investigate the influence of the stirring velocity and paddle shape,simulation was calculated by making use of the volume of fluid(VOF)method and multiple reference frame(MRF)method in a three-dimensional flow field of tannin-based foaming precursor resin.The gas holdup and velocity magnitude were analysed with various conditions of mechanical velocities and paddle shape in the stirring flow field.The result shows the higher the velocity,the greater the disturbance and paddle shape between the eggbeater and the Rushton turbine,obviously the paddle shape of the eggbeater with a wider range of agitation,which can entrap more air into the tannin-based foaming precursor resin in a short time.Especially when the speed is 1500 rpm,the flow field of the Rushton turbine comes out of a ditch,which decreases the efficiency of mass transfer;there is less air to mix into the tannin-based foaming precursor resin,which causes unevenness.At the same time,the eggbeater shows the marvelous capability of hybrid as it has two vortexes and multiple cycles that make a difference from the Rushton turbine,which has only one vortex and two upper and lower loops;the structure makes the flow field more stable allowed evenness of flow field tannin-based foaming precursor resin.The results reveal that it is beneficial for tannin-based foaming precursor resin to use an eggbeater with a speed of 1500 rpm to reduce the consumption of resources while obtaining a uniform flow field.展开更多
基金supported by the Preparation and Characterization of Fogging Agents,Cooperative Project of China(Grant No.1900030040)Preparation and Test of Fogging Agents,Cooperative Project of China(Grant No.2200030085)。
文摘Water-based aerosol is widely used as an effective strategy in electro-optical countermeasure on the battlefield used to the preponderance of high efficiency,low cost and eco-friendly.Unfortunately,the stability of the water-based aerosol is always unsatisfactory due to the rapid evaporation and sedimentation of the aerosol droplets.Great efforts have been devoted to improve the stability of water-based aerosol by using additives with different composition and proportion.However,the lack of the criterion and principle for screening the effective additives results in excessive experimental time consumption and cost.And the stabilization time of the aerosol is still only 30 min,which could not meet the requirements of the perdurable interference.Herein,to improve the stability of water-based aerosol and optimize the complex formulation efficiently,a theoretical calculation method based on thermodynamic entropy theory is proposed.All the factors that influence the shielding effect,including polyol,stabilizer,propellant,water and cosolvent,are considered within calculation.An ultra-stable water-based aerosol with long duration over 120 min is obtained with the optimal fogging agent composition,providing enough time for fighting the electro-optic weapon.Theoretical design guideline for choosing the additives with high phase transition temperature and low phase transition enthalpy is also proposed,which greatly improves the total entropy change and reduce the absolute entropy change of the aerosol cooling process,and gives rise to an enhanced stability of the water-based aerosol.The theoretical calculation methodology contributes to an abstemious time and space for sieving the water-based aerosol with desirable performance and stability,and provides the powerful guarantee to the homeland security.
基金supported by the National Natural Science Foundation of China (Grant No.51991361 and Grant No.51874329)。
文摘The environmental hazards and"carbon footprint"of oil and gas drilling can be significantly reduced by replacing traditional petroleum-based chemical additives with natural materials derived from plants and animals.This paper explored for the first time the interaction mechanism between natural rubber latex(NRL)and bentonite suspensions(BTs)through a series of characterization experiments,as well as the potential applications in water-based drilling fluids(WBDF).The gel viscoelasticity experiments showed that NRL could decrease the consistency coefficient(k)and flow index(n)of BTs,and enhance the shear thinning performance of BTs as pseudo-plastic fluids.In addition,0.5 w/v%NRL not only increased the critical yield stress and strengthened the structural strength between the bentonite particles,but also facilitated the compatibility of pressure loss and flow efficiency.The evaluation of colloidal stability and WBDF performance indicated that NRL particles could promote the hydration and charge stability on the surface of BTs particles,and optimize the particle size distribution and flow resistance of WBDF under the"intercalation-exfoliation-encapsulation"synergistic interaction.Moreover,NRL can improve the rheological properties of WBDF at high temperatures(<150.C),and form a dense blocking layer by bridging and sealing the pores and cracks of the filter cake,which ultimately reduces the permeability of the cake and the filtration loss of WBDF.
基金the National Natural Science Foundation of China(51904329,52174014)the Major Scientific and Technological Projects of CNPC(ZD 2019-183-005)Key R&D Program of Shandong Province(No.2020ZLYS07).
文摘Wellbore instability,especially drilling with water-based drilling fluids(WBDFs)in complex shale for-mations,is a critical challenge for oil and gas development.The purpose of this paper is to study the feasibility of using hydrophobically modified silica nanoparticle(HMN)to enhance the comprehensive performance of WBDFs in the Xinjiang Oilfield,especially the anti-collapse performance.The effect of HMN on the overall performance of WBDFs in the Xinjiang Oilfield,including inhibition,plugging,lu-bricity,rheology,and filtration loss,was studied with a series of experiments.The mechanism of HMN action was studied by analyzing the changes of shale surface structure and chemical groups,wettability,and capillary force.The experimental results showed that HMN could improve the performance of WBDFs in the Xinjiang Oilfeld to inhibit the hydration swelling and dispersion of shale.The plugging and lubrication performance of the WBDFs in the Xinjiang Oilfield were also enhanced with HMN based on the experimental results.HMN had less impact on the rheological and filtration performance of the WBDFs in the Xinjiang Oilfield.In addition,HMN significantly prevented the decrease of shale strength.The potential mechanism of HMN was as follows.The chemical composition and structure of the shale surface were altered due to the adsorption of HMN driven by electrostatic attraction.Changes of the shale surface resulted in significant wettability transition.The capillary force of the shale was converted from a driving force of water into the interior to a resistance.In summary,hydrophobic nanoparticles presented afavorable application potential for WBDFs.
基金The work is supported by the Integration and Testing of Safe and Fast Drilling and Completion Technologies for Complex Ultra-Deep Wells(2020F-46)Major Technology Field Test of Joint-Stock Company(Drilling and Production Engineering).Xuyang received the grant.
文摘Water-based drilling fluids can cause hydration of the wellbore rocks,thereby leading to instability.This study aimed to synthesize a hydrophobic small-molecule polymer(HLMP)as an inhibitor to suppress mud shale hydration.An infrared spectral method and a thermogravimetric technique were used to characterize the chemical composition of the HLMP and evaluate its heat stability.Experiments were conducted to measure the linear swelling,rolling recovery rate,and bentonite inhibition rate and evaluate accordingly the inhibition performance of the HLMP.Moreover,the HLMP was characterized through measurements of the zeta potential,particle size distribution,contact angles,and interlayer space testing.As confirmed by the results,the HLMP could successfully be synthesized with a favorable heat stability.Furthermore,favorable results were found for the inhibitory processes of the HLMP on swelling and dispersed hydration during mud shale hydration.The positively charged HLMP could be electrically neutralized with clay particles,thereby inhibiting diffusion in the double electron clay layers.The hydrophobic group in the HLMP molecular structure resulted in the formation of a hydrophobic membrane on the rock surface,enhancing the hydrophobicity of the rock.In addition,the small molecules of the HLMP could plug the spaces between the layers of bentonite crystals,thereby reducing the entry of water molecules and inhibiting shale hydration.
基金support and encouragement of the Joint Funds of the National Natural Science Foundation of China(No.U21B2095)the Major Research Project of National Natural Science Foundation of China(No.91834303).
文摘This work investigated the pyrolysis reaction of waste resin in a fluidized bed reactor.It was found that the pyrolysis-generated ash would adhere to the surface of ceramic particles,causing particle agglomeration and defluidization.Adding kaolin could effectively inhibit the particle agglomeration during the fluidized pyrolysis reaction through physical isolation and chemical reaction.On the one hand,kaolin could form a coating layer on the surface of ceramic particles to prevent the adhesion of organic ash generated by the pyrolysis of resin.On the other hand,when a sufficient amount of kaolin(-0.2%(mass))was added,the activated kaolin could fully contact with the Na+ ions generated by the pyrolysis of resin and react to form a high-melting aluminosilicate mineral(nepheline),which could reduce the formation of low-melting-point sodium sulfate and thereby avoid the agglomeration of ceramic particles.
基金the National Key Research and Development Program(2019YFC1805804)the National Natural Science Foundation of China(22008032)+3 种基金the Guangdong Natural Science Foundation(2022A1515011192)the Guangdong Basic and Applied Basic Research Foundation(2019A1515110706)the Guangdong Provincial Key Lab of Green Chemical Product Technology(GC202111)the China Postdoctoral Science Foundation(2021M691059).
文摘The combination of nano sizes,large pore sizes and green synthesis is recognized as one of the most crucial and challenging problems in constructing metal-organic frameworks(MOFs).Herein,a water-based strategy is proposed for the synthesis of nanoscale hierarchical MOFs(NH-MOFs)with high crystallinity and excellent stability.This approach allows the morphology and porosity of MOFs to be fine tuned,thereby enabling the nanoscale crystal generation and a well-defined hierarchical system.The aqueous solution facilitates rapid nucleation kinetics,and the introduced modulator acts as a deprotonation agent to accelerate the deprotonation of the organic ligand as well as a structure-directing agent(SDA)to guide the formation of hierarchical networks.The assynthesized NH-MOFs(NH-ZIF-67)were assessed as efficient adsorbents and heterogeneous catalysts to facilitate the diffusion of guest molecules,outperforming the parent microZIF-67.This study focuses on understanding the NH-MOF growth rules,which could allow tailor-designing NH-MOFs for various functions.
文摘Difenoconazole(DIF)is a representative variety of broad-spectrum triazole fungicides and liposoluble pesticides.However,the water solubility of DIF is so poor that its application is limited in plant protection.In addition,the conventional formulations of DIF always contain abundant organic solvents,which may cause pollution of the environment.In this study,two DIF/cyclodextrins(CDs)inclusion complexes(ICs)were successfully prepared,which were DIF/β-CD IC and DIF/hydroxypropyl-β-CD IC(DIF/HP-β-CD IC).The effect of cyclodextrins on the water solubility and the antifungal effect of liposoluble DIF pesticide were investigated.According to the phase solubility test,the molar ratio and apparent stability constant of ICs were obtained.Fourier transform infrared spectroscopy,thermal gravity analysis,X-ray diffraction and scanning electron microscopy were used systematically to characterize the formation and characteristics of ICs.The results noted that DIF successfully entered the cavities of two CDs.In addition,the antifungal effect test proved the better performance of DIF/HP-β-CD IC,which exceeded that of DIF emulsifiable concentrate.Therefore,our study provides informative direction for the intelligent use of liposoluble pesticides with cyclodextrins to develop water-based environmentally friendly formulations.
文摘Despite the great potential of cellulose wood pulp and cellulose nanofibrils as reinforcing filler in thermoplastics,its use is limited due to its tendency to form agglomerates and due to its high hydrophilic character.Here we describe fiberboard composites with high contents of wood pulp or cellulose nanofibrils,and a resin of poly(styrene-methyl-methacrylate-acrylic acid)used as water-based emulsion.Cellulose wood pulp and cellulose nanofibrils were used directly in the form of water suspensions.The method is based on the flocculation of the polymer emulsion followed by agglomeration of a mixture of the polymer emulsion and cellulose suspension,leading to the co-precipitation of the composite material,which can be easily separated from the water phase.Composites with acrylic polymer/cellulose fibers in the proportions of 75:25,50:50 and 25:75 wt%were prepared.Composites were characterized by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR),thermogravimetric analysis(TGA),dynamic mechanical analysis(DMA)and water absorption tests.SEM analysis revealed a very good dispersion of the fibers without evidence of agglomeration,which led to superior mechanical properties.These results showed the effectiveness of the methodology and the potential of cellulose wood pulp and CNF as reinforcement fillers in fiberboard composites and any other high fiber-content materials.
基金Supported by Shanghai Aerospace Science and Technology Innovation Fund Project (SAST 2022-097)。
文摘Benzoxazine resin,being a new type of phenolic resin deve-loped to overcome the shortcomings of traditional phenolic resins,has been synthesized from phenol,formaldehyde and amine,and does not require solvent elimination or monomer purification to obtain a relatively clean precursor.It has potential application in the field of aerospace due to its low expansion coefficient,high weather resistance,high carbon yield,good mechanical strength,and excellent ablation resistance[1].It can be mixed with various other resins or polymers to produce new resins with a broad range of applications[2-3].
文摘A toughener that can effectively improve the interlaminar toughness in carbon fiber composites is crucial for various applications.We investigated,the toughening effects of phenolphthalein-based cardo poly(ether sulfone)(PES-C)on E51/DETDA epoxy and its carbon fiber composites(CFCs).Scanning electron microscopy showed that the phase structures of PES-C/epoxy blends change from island(of dispersed phase)structures to bi-continuous structures(of the matrix)as the PES-C content increased,which is associated with reaction-induced phase separation.After adding 15 phr PES-C,the glass transition temperature(T_(g))of the blends increased by 51.5℃,and the flexural strength,impact strength and fracture toughness of the blends were improved by 41.1%,186.2%and 42.7%,respectively.These improvements could be attributed to the phase separation structure of the PES-C/epoxy sys-tem.A PES-C film was used to improve the mode-II fracture toughness(G_(IIC))of CFCs.The G_(IIC) value of the 7μm PES-C film toughened laminate was improved by 80.3%compared to that of the control laminate.The increase in G_(IIC) was attributed to cohesive failure and plastic deformation in the interleaving region.
基金Funded by the National Natural Science Foundation of China(No.52378444)。
文摘To promote the recycling of reclaimed asphalt pavement(RAP),epoxy resin was used to prepare the epoxy-recycled asphalt mixtures.The effect of epoxy resin on the properties of aged asphalt binder was investigated based on the tensile test,flexural creep test,and laser scanning confocal microscopy.The curing characteristics and the mechanical performance of recycled asphalt with different epoxy contents were explored.The results show that the low-temperature performance,ductility,and strength of the aged asphalt binder were significantly improved when the epoxy content reached 40%.The curing time of epoxy-recycled asphalt should be at least 4 d to ensure the formation of good internal spatial network structure.
基金support of National Natural Science Foundation of P.R.China(22308104).
文摘An efficient utilization strategy of ethylene tar(ET),the main by-product of the ethylene cracking unit,is urgently required to meet demands for modern petrochemical industry.On the other hand,condensed polynuclear aromatic resin of moderate condensation degree(B-COPNA)is a widely used carbon material due to its superb processability,the production of which is,however,seriously limited by the high cost of raw materials.Under such context,an interesting strategy was proposed in this study for producing B-COPNA resin using crosslinked light fractions of ethylene tar(ETLF,boiling point<260℃)facilitated by molecular simulation.1,4-Benzenedimethanol(PXG)was first selected as the crosslinking agent according to the findings of molecular simulation.The effects of operating conditions,including reactions temperature,crosslinking agent,and catalyst content on the softening point and yield of B-COPNA resin products were then investigated to optimize the process.The reaction mechanism of resin production was studied by analyzing the molecular structure and transition state of ETLF and crosslinking agents.It was shown that PXG exhibited a superior capacity of withdrawing electrons and a higher electrophilic reactivity than other crosslinking agents.In addition to the highest yield and greatest heat properties,PXG-prepared resin contained the most condensed aromatics.The corresponding optimized conditions of resin preparation were 180℃,1:1.9(PXG:ETLF),and 3%(mass)of catalyst content with a resin yield of 78.57%.It was the electrophilic substitution reaction that occurred between the ETLF and crosslinking agent molecules that were responsible for the resin formation,according to the experimental characterization and molecular simulation.Hence,it was confirmed that the proposed strategy and demonstrated process can achieve a clean and high value-added utilization of ETLF via B-COPNA resin preparation,bringing huge economic value to the current petrochemical industry.
文摘Liquid-phase acrylic acid hydration over solid-phase catalysts is a key reaction for the industrial productionof 3-hydroxypropionic acid. However, the relevant literature primarily focuses on the experimental aspects of catalystscreening and exploring reaction conditions, with few accurate descriptions of the reaction kinetics and determination ofthe reaction mechanism. Here, we combined kinetics experiments and theoretical calculations to elucidate the kinetics andmechanism of acrylic acid hydration on a resin catalyst. The pseudo-homogeneous model, and Langmuir-Hinshelwood-Haugen-Watson and Elie-Riedel (ER) heterogeneous models were used to explain the experimental kinetics data. TheER model can explain the experimental data very well, suggesting strong adsorption of acrylic acid on the surface of theresin catalyst. Furthermore, density functional theory calculations show that the hydration follows a stepwise, rather than aconcerted, reaction pathway. The present study provides theoretical insights into the reaction mechanism and kinetics, fillingthe gap in our understanding of the reaction on a fundamental level.
基金financially supported by the National Natural Science Foundation of China(22178242)the Shanxi Provincial Key Research and Development Project(202102040201009).
文摘The use of fillers to enhance the corrosion protection of epoxy resins has been widely applied.In this work,cerium dioxide(CeO_(2))and benzotriazole(BTA)were introduced into an epoxy resin to enhance the corrosion resistance of Q235 carbon steel.Scanning electron microscopy results indicated that the CeO_(2) grains were rod-like and ellipsoidal in shape,and the distribution pattern of BTA was analyzed by energy dispersive spectroscope.The dynamic potential polarization curve proved the excellent corrosion resistance of the composite epoxy resin with CeO_(2) and BTA co-addition,and electrochemical impedance spectroscopy test analysis indicated the significantly enhanced long-term corrosion protection performance of the composite coating.And the optimal protective performance was provided by the coating containing 0.3%(mass)CeO_(2) and 20%(mass)BTA,which was attributed to the barrier performance of CeO_(2) particles and the chemical barrier effect of BTA.The formation of corrosion products was analyzed using X-ray diffraction.In addition,the corrosion resistance mechanism of the coating was also discussed in detail.
基金supported by the Yunnan Provincial Natural Science Foundation (202201AU070222,202201AT070045,202101BD070001-074)Scientific Research Fund Project of Yunnan Provincial Department of Education (2022J0490)financed by the 111 Project (D21027).
文摘Using non-toxic,low-volatile glyoxal to completely replace formaldehyde for preparing urea-glyoxal(UG)resin adhesive is a hot research topic that could be of great interest for the wood industry.However,urea-glyoxal(UG)resins prepared by just using glyoxal instead of formaldehyde usually yields a lower degree of polymerization.This results in a poorer bonding performance and water resistance of UG resins.A good solution is to pre-react urea to preform polyurea molecules presenting already a certain degree of polymerization,and then to condense these with glyoxal to obtain a novel UG resin.Therefore,in this present work,the urea was reacted with hexamethylene diamine to form a polyurea named HU,and then this was used to react it with different amounts of glyoxal to synthesize hexamethylenediamine-urea-glyoxal(HUG)polycondensation resins,and to use this for bonding plywood.The results show that the glyoxal can well react with HU polyuria via addition and schiff base reaction,and also the HUG resin exhibits excellent bonding strength and water resistance.The shear strength of the plywood bonded with this HUG at 160°C hot press temperature as high as 1.93 MPa,2.16 MPa and 1.61 MPa,respectively,which meets the requirement of the China national standard GB/T 9846-2015(≥0.7 MPa),and can be a good choice as a wood adhesive for industrial application.
基金Supported by National Key Research and Development Project of China (Grant Nos.2018YFA0703300,52105300)National Natural Science Foundation of China (Grant No.52075215)+2 种基金Science and Technology Development Plan Project of Jilin Province of China (Grant No.20200201061JC)Science and Technology Research Project of Jilin Provincial Education Department of China (Grant No.JJKH20221021KJ)Changchun Municipal Key Research and Development Program of China (Grant No.21ZGN22)。
文摘Fibre reinforced polymer composites have become a new generation of structural materials due to their unique advantages such as high specific strength,designability,good dimensional stability and ease of large-area monolithic forming.However,the problem of interfacial bonding between the resin matrix and the fibres limits the direct use of reinforcing fibres and has become a central difficulty in the development of basalt fibre-epoxy composites.This paper proposes a solution for enhancing the strength of the fibre-resin interface using maize starch nanocrystals,which are highly yield and eco-friendly.Firstly,in this paper,corn starch nanocrystals(SNC)were prepared by hydrolysis,and were deposited on the surface of basalt fibers by electrostatic adsorption.After that,in order to maximize the modification effect of nano-starch crystals on the interface,the basalt fiber-epoxy resin composite samples were prepared by mixing in a pressureless molding method.The test results shown that the addition of basalt fibers alone led to a reduction in the strength of the sample.Deposition of 0.1 wt%SNC on the surface of basalt fibers can make the strength consistent with pure epoxy resin.When the adsorption amount of SNC reached 0.5 wt%,the tensile strength of the samples was 23.7%higher than that of pure epoxy resin.This is due to the formation of ether bond homopolymers between the SNC at the fibre-epoxy interface and the epoxy resin,which distorts the originally smooth interface,leading to increased stress concentration and the development of cracks.This enhances the binding of basalt fibers.The conclusions of this paper can provide an effective,simple,low-cost and non-polluting method of interfacial enhancement modification.
基金financially supported by National Natural Science Foundation of China(22008073,22078100,21878091)Shanghai Sailing Program(20YF1410600)。
文摘Silicon-containing aryl acetylene resin(PSA)is a new type of high-temperature resistant resin with excellent oxidation resistance,whereas antioxidant reaction mechanism of PSA resin under ultra-high temperatures still remains unclear.Herein,the oxidation behavior and mechanisms of PSA resin are systematically investigated combining kinetic analysis and Reax FF molecular dynamics(MD)simulations.Thermogravimetric analysis indicates that the oxidation process of PSA resin undergoes two main steps:oxidative mass gain and oxidative degradation.The distributed activation energy model(DAEM)is employed for describing oxidation processes and the best-fit one is obtained using genetic algorithms and differential evolution.DAEM model demonstrates that the oxidative weight gain stage is dominated by two virtual reactants and the oxidative degradation stage consists of three virtual reactants.Correspondingly,the observation of MD reaction pathways indicates that oxygen oxidation of unsaturated structures occurs in the initial stage,which results in the formation of PSA resin oxides.Furthermore,cracked pieces react with O_(2)to generate CO and other chemicals in the second step.The resin matrix's great antioxidation resilience is illustrated by the formation of SiO_(2).The analysis based on MD simulations exhibits an efficient computational proof with the experiments and DAEM methods.Based on the results,a two-stage reaction mechanism is proposed,which provides important theoretical support for the subsequent study of the oxidation behavior of silica-based resins.
基金Funded by National Natural Science Foundation of China(No.52174206)Shaanxi Provincial Department of Education Youth Innovation Team Construction Scientific Research Plan Project(No.21JP074)Shaanxi Provincial Department of Education Youth Innovation Team Scientific Research Plan Project(No.22JP047)。
文摘Super absorbent resin(SAR)is prepared by aqueous high temperature polymerization using hydroxypropyl methylcellulose(HPMC)as monomer backbone material,acrylic acid(AA)and acrylamide(AM)as the graft copolymer monomer,potassium persulfate(KPS)as the initiator to generate free radicals,and N,N`-methylenebisacrylamide(MBA)as cross-linking agent for cross-linking reaction.Simutaneously,the influence of individual factors on the water absorption is investigated,and these factors are mainly AA,AM,KPS,MBA,HPMC,and reaction temperature.The optimized conditions are obtained by the experiment repeating for several times.The water absorption multiplicity and salt absorption multiplicity under the conditions are 782.4 and 132.5 g/g,respectivity.Furthermore,the effects of different temperatures and salt concentrations on its water absorption,as well as the swelling kinetics of SAR are studied.It is indicated the water-absorbing swelling process is mainly caused by the difference in water osmotic pressure and Na+concentration inside and outside the cross-linked molecular structure of the resin,which is not only consistent with the quasi-secondary kinetic model,but also with the Fick diffusion model.
基金funded by the National Natural Science(Grant No.52274015)。
文摘Sustained casing pressure(SCP)is a crucial issue in the oil and gas production lifecycle.Epoxy resins,exhibiting exceptional compressive strength,ductility,and shear bonding strength,have the potential to form reliable barriers.The injectivity and sealing capacity of the epoxy resin is crucial parameters for the success of shallow remediation operations.This study aimed to develop and assess a novel solid-free resin sealant as an alternative to Portland cement for mitigating fluid leakage.The investigation evaluated the viscosity,compressive strength,and brittleness index of the epoxy resin sealant,as well as its tangential and normal shear strengths in conjunction with casing steel.The flow characteristics and sealing abilities of conventional cement and epoxy resin were comparatively analyzed in cracks.The results showed that the application of a viscosity reducer facilitated control over the curing time of the epoxy resin,ranging from 1.5 to 6 h,and reduced the initial viscosity from 865.53 to 118.71 m Pa,s.The mechanical properties of the epoxy resin initially increased with a rise in curing agent content before experiencing a minor decrease.The epoxy resin containing 30%curing agent exhibited optimal mechanical properties.After a 14-day curing period,the epoxy resin's compressive strength reached81.37 MPa,2.12 times higher than that of cement,whereas the elastic modulus of cement was 2.99 times greater than that of the epoxy resin.The brittleness index of epoxy resin is only 3.42,demonstrating high flexibility and toughness.The tangential and normal shear strengths of the epoxy resin exceeded those of cement by 3.17 and 2.82 times,respectively.In a 0.5 mm-wide crack,the injection pressure of the epoxy resin remained below 0.075 MPa,indicating superior injection and flow capabilities.Conversely,the injection pressure of cement surged dramatically to 2.61 MPa within 5 min.The breakthrough pressure of0.5 PV epoxy resin reached 7.53 MPa,decreasing the crack's permeability to 0.02 D,a mere 9.49%of the permeability observed following cement plugging.Upon sealing a 2 mm-wide crack using epoxy resin,the maximum breakthrough pressure attained 5.47 MPa,3.48 times of cement.These results suggest that epoxy resin sealant can be employed safely and effectively to seal cracks in the cement.
基金supported by the Key Program of Applied and Basic Research in Yunnan Province(Grant No.202101AS070008)the National Natural Science Foundation of China(NSFC 31760187)+4 种基金supported by the 111 Project(D21027)the Yunnan Provincial Academician Workstation(YSZJGZZ-2020052)the Foreign Expert Workstation(202305AF150006)supported by the Scientific Research Foundation of Education Department of Yunnan Province(Grant Nos.2023J0696,2023Y0699)Foreign Talent Introduction Program of Science and Technology Department of Yunnan Province(Grant No.202305AO350002).
文摘Tannin foam is a new functional material.It can be widely applied to the automobile industry,construction industry,and packaging industry due to its wide range of raw materials,renewable,easily degraded,low cost and almost no pollution.Preparing tannin foam is a very complex process that includes high temperature,two phases,mechanical agitation,and phase change.To investigate the influence of the stirring velocity and paddle shape,simulation was calculated by making use of the volume of fluid(VOF)method and multiple reference frame(MRF)method in a three-dimensional flow field of tannin-based foaming precursor resin.The gas holdup and velocity magnitude were analysed with various conditions of mechanical velocities and paddle shape in the stirring flow field.The result shows the higher the velocity,the greater the disturbance and paddle shape between the eggbeater and the Rushton turbine,obviously the paddle shape of the eggbeater with a wider range of agitation,which can entrap more air into the tannin-based foaming precursor resin in a short time.Especially when the speed is 1500 rpm,the flow field of the Rushton turbine comes out of a ditch,which decreases the efficiency of mass transfer;there is less air to mix into the tannin-based foaming precursor resin,which causes unevenness.At the same time,the eggbeater shows the marvelous capability of hybrid as it has two vortexes and multiple cycles that make a difference from the Rushton turbine,which has only one vortex and two upper and lower loops;the structure makes the flow field more stable allowed evenness of flow field tannin-based foaming precursor resin.The results reveal that it is beneficial for tannin-based foaming precursor resin to use an eggbeater with a speed of 1500 rpm to reduce the consumption of resources while obtaining a uniform flow field.