The generalized rheological tests on sandstone were conducted under both dynamic stress and seepage fields.The results demonstrate that the rheological strain of the specimen under increased stress conditions is great...The generalized rheological tests on sandstone were conducted under both dynamic stress and seepage fields.The results demonstrate that the rheological strain of the specimen under increased stress conditions is greater than that under creep conditions,indicating that the dynamic stress field significantly influences the rheological behaviours of sandstone.Following the rheological tests,the number of small pores in the sandstone decreased,while the number of medium-sized pores increased,forming new seepage channels.The high initial rheological stress accelerated fracture compression and the closure of seepage channels,resulting in reduction in the permeability of sandstone.Based on the principles of generalized rheology and the experimental findings,a novel rock rheological constitutive model incorporating both the dynamic stress field and seepage properties has been developed.Numerical simulations of surrounding rock deformation in geotechnical engineering were carried out using a secondary development version of this model,which confirmed the applicability of the generalized rheological numerical simulation method.These results provide theoretical support for the long-term stability evaluation of engineering rock masses and for predicting the deformation of surrounding rock.展开更多
Graphene oxide nanomaterials are increasingly used in various fields due to their superior properties.In order to study the influence of graphene oxide additives on the performance of modified asphalt,in this study,gr...Graphene oxide nanomaterials are increasingly used in various fields due to their superior properties.In order to study the influence of graphene oxide additives on the performance of modified asphalt,in this study,graphene oxide modified asphalt was prepared and characteristics was studied including the high deformation resistance performance and the self-healing property of modified asphalt.Functional groups and morphology of graphene oxide modified asphalt were described by Fourier transform infrared spectroscopy.The high deformation resistance performance and self-healing effect of asphalt samples were obtained through dynamic slear rheometer(DSR)test.Results shows that graphene oxide dispersions improve the performance of asphalt relatively well compared to graphene oxide powder.There is no chemical reaction between graphene oxide and asphalt,but physical connection.The addition of graphene oxide improved the high deformation resistance of modified asphalt and expedited the self-healing ability of asphalt under fatigue load.展开更多
The rheological properties of an innovative coal-based colloidal composite binder(3Co-Binder)prepared via alkaline–oxygen excitation and mechanochemical synthesis are revealed.Derived from low-rank coal,3Co–Binder i...The rheological properties of an innovative coal-based colloidal composite binder(3Co-Binder)prepared via alkaline–oxygen excitation and mechanochemical synthesis are revealed.Derived from low-rank coal,3Co–Binder is applied in iron ore pelletization as a replacement for traditional bentonite,with the aim of improving the iron grades of the pellets.Cryoscanning electron microscopy revealed that 3Co-Binder exhibits a densely populated,porous network structure.It was determined to be a pseudo-plastic fluid with yield stress and shear-thinning characteristics.The stability of 3Co-Binder was influenced by the humic acid extraction rate,temperature,and static placing time.An extraction rate of humic acids above 96%was found to prevent sedimentation of 3Co-Binder,while lower temperatures and prolonged static placing time increased its apparent viscosity.A storage duration of less than 2 weeks and a temperature range of 25–35℃ were found to be optimal for maintaining the stability of 3Co-Binder.The viscous flow activation energy of 3Co-Binder remained stable at approximately 60 kJ mol^(-1) as the shear rate increased from 0.5 to 5 s^(-1).However,at higher shear rates,up to 100 s^(-1),the viscous flow activation energy decreased to 46.48 kJ mol^(–1).To ensure stability and dispersibility during storage,the rheological parameters of 3Co-Binder must meet the following criteria:yield stress below 10 Pa,consistency coefficient below 1.5 Pa s,non-Newtonian index below 1,and apparent viscosity below 10,000 mPa s at a shear rate of 1 s^(–1).展开更多
Millets,nutrient-rich grains packed with complex carbohydrates,dietary fiber,essential proteins,lipids,and antioxidant phytochemicals,are gaining recognition as valuable dietary components.Various processing technique...Millets,nutrient-rich grains packed with complex carbohydrates,dietary fiber,essential proteins,lipids,and antioxidant phytochemicals,are gaining recognition as valuable dietary components.Various processing techniques,including roasting,extrusion,germination,and hydrothermal treatment,have been employed to enhance nutritional bioavailability and consumer appeal.These processing,which involves the application of heat and moisture,induces specific transformations in millet components.Starch undergoes gelatinization,a process in which its crystalline structure is disrupted,leading to increased digestibility and viscosity.Proteins undergo denaturation,altering their structure and potentially improving their digestibility and functionality.Lipids may also undergo modifications,impacting their stability and interactions with other food components.These changes facilitate the release of bioactive compounds such as phenolics,flavonoids,and tannins.These processes effectively reduce anti-nutritional factors,further boosting nutrient availability.This review provides a comprehensive analysis of various hydrothermal methods,including steaming and heat-moisture treatment,and critically evaluates their impact on the physicochemical properties,nutritional profile,and potential health benefits of millet.Steaming,a gentler method involves cooking millet in a steamer basket above boiling water,preserving its delicate texture and nutty flavor while still promoting starch gelatinization and nutrient retention.Heat-moisture treatment,a more specialized technique,involves exposing millet to elevated temperatures and controlled moisture levels,inducing specific changes in starch properties without causing complete gelatinization.This review examines how hydrothermal methods affect the nutritional and functional properties of millet to inspire the development of innovative,nutritious millet-based food products.展开更多
During the production of natural gas hydrates,micron-sized sand particles coexist with hydrate within the transportation pipeline,posing a significant threat to the safety of pipeline flow.However,the influence of san...During the production of natural gas hydrates,micron-sized sand particles coexist with hydrate within the transportation pipeline,posing a significant threat to the safety of pipeline flow.However,the influence of sand particles on hydrate formation mechanisms and rheological properties remains poorly understood.Consequently,using a high-pressure reactor system,the phase equilibrium conditions,hydrate formation characteristics,hydrate concentration,and the slurry viscosity in micron-sized sand system are investigated in this work.Furthermore,the effects of sand particle size,sand concentration,and initial pressure on these properties are analyzed.The results indicate that a high concentration of micron-sized sand particles enhances the formation of methane hydrates.When the volume fraction of sand particles exceeds or equals 3%,the phase equilibrium conditions of the methane hydrate shift to the left relative to that of the pure water system(lower temperature,higher pressure).This shift becomes more pronounced with smaller particle sizes.Besides,under these sand concentration conditions,methane hydrates exhibit secondary or even multiple formation events,though the formation rate decreases.Additionally,the torque increases significantly and fluctuates considerably.The Roscoe-Brinkman model yields the most accurate slurry viscosity calculations,and as sand concentration increases,both hydrate concentration and slurry viscosity also increase.展开更多
The viscosity of anti-irradiated glass was quantitatively characterized using beam bending viscometry(BBV),parallel plate viscometry(PPV),and rotational viscometry(RV).The Vogel-Fulcher-Tammann(VFT)equation was determ...The viscosity of anti-irradiated glass was quantitatively characterized using beam bending viscometry(BBV),parallel plate viscometry(PPV),and rotational viscometry(RV).The Vogel-Fulcher-Tammann(VFT)equation was determined to be the most suitable for representing the viscosity-temperature characteristics of anti-irradiation glass by comparing the fitting effects and accuracy of different equations within different test ranges.The fragility index m of anti-irradiation glass was 47.5,as calculated using an Angell plot,and the cause of the appropriate fit of the VFT equation was analyzed.The effects of different heating temperatures and loading rates on the tensile properties of glass were studied using a universal testing machine.The results indicated that,at a tensile rate of 10 mm/s,the heating temperature increased from 903 to 1023 K,and the deformation process of anti-irradiation glass transitioned from unstable to stable.When the tensile rate increased from 10 to 30 mm/s at 1023 K,the deformation process of the glass was extremely unstable.This work provides theoretical guidance for the large-size preparation of flexible anti-irradiation glass.展开更多
Modified ethylene-vinyl acetate copolymer(EVAM)and amino-functionalized nano-silica(NSiO_(2))par-ticles were employed as the base materials for the synthesis of the nanocomposite pour point depressant designated as EV...Modified ethylene-vinyl acetate copolymer(EVAM)and amino-functionalized nano-silica(NSiO_(2))par-ticles were employed as the base materials for the synthesis of the nanocomposite pour point depressant designated as EVAM-g-NSiO_(2).This synthesis involved a chemical grafting process within a solution system,followed by a structural characterization.Moreover,combining macro-rheological performance with microscopic structure observation,the influence of the nanocomposite pour point depressant on the rheological properties of the model waxy oil system was investigated.The results indicate that when the mass ratio of NSiO_(2) to EVAM is 1:100,the prepared EVAM-g-NSiO_(2) nanocomposite pour point depressant exhibits excellent pour point reduction and viscosity reduction properties.Moreover,the nanocomposite pour point depressant obtained through a chemical grafting reaction demonstrates structural stability(the bonding between the polymer and nanoparticles is stable).The pour points of model waxy oils doped with 500 mg/kg ethylene-vinyl acetate copolymer(EVA),EVAM,and EVAM/SiO_(2) were reduced from 34℃ to 23,20,and 21℃,respectively.After adding the same dosage of EVAM-g-NSiO_(2) nanocomposite pour point depressant,the pour point of the model wax oil decreased to 12℃ and the viscosity at 32℃ decreased from 2399 to 2396.9 mPa·s,achieving an impressive viscosity reduction rate of 99.9%.Its performance surpassed that of EVA,EVAM,and EVAM/SiO_(2).The EVAM-g-NSiO_(2) dispersed in the oil phase acts as the crystallization nucleus for wax crystals,resulting in a dense structure of wax crystals.The compact wax crystal blocks are difficult to overlap with each other,pre-venting the formation of a three-dimensional network structure,thereby improving the low-temperature flowability of the model waxy oil.展开更多
The toughness of thermoplastic polymers such as polypropylene(PP)can be improved by adding elastomers-based toughening agents,and the phase morphology of these toughening agents is very important for the strength and ...The toughness of thermoplastic polymers such as polypropylene(PP)can be improved by adding elastomers-based toughening agents,and the phase morphology of these toughening agents is very important for the strength and toughness of PP.The low-temperature toughness of PP was improved by inserting high-density polyethylene(HDPE)between PP and polystyrene-b-ethylene-co-propyleneb-polystyrene(SEPS)to form an unusual SEPS@HDPE core–shell structure,with SEPS as the core and HDPE as the shell.Based on the microtopography and rheological behavior characterization,HDPE in PP/SEPS/HDPE composites was found to serve as an emulsifier,decrease the size of SEPS particles,and promote the homogeneous dispersion of dispersed phase particles in the matrix.An increase in the HDPE content shifted the toughening mechanism of PP composites from cavitation to matrix shear yielding.The reduction in the distance between the dispersed core–shell structure particles promoted shear yielding in the PP composites,leading to increased toughness.The creation of an intermediate HDPE layer with a moderate modulus was crucial for dispersing stress concentrations and significantly improving toughness without compromising the tensile strength.These findings will facilitate the fabrication of high-toughness PP products at low temperatures.展开更多
Understanding the rheology of bentonite suspensions is crucial for ensuring the safety of engineering practices.However,the rheological mechanisms of bentonite remain unclear due to the limitations of conventional exp...Understanding the rheology of bentonite suspensions is crucial for ensuring the safety of engineering practices.However,the rheological mechanisms of bentonite remain unclear due to the limitations of conventional experimental techniques,particularly in assessing the microscopic interactions between clay particles and their impact on rheological properties.In this paper,the rheological behaviors of Namontmorillonite were studied with a focus on interparticle interactions.Both equilibrium molecular dynamics(MD)and non-equilibrium MD simulations were conducted to understand the physical properties of Na-montmorillonite under zero shear and various shear rates,respectively.The interaction between two parallel clay particles was determined in simulations,indicating that the classical Darjaguin-Landau-Verwey-Overbeek(DLVO)theory underestimates the interactions for a small separation distance.Na-montmorillonite exhibits a typical shear thinning behavior under shearing.However,as water content increases,it begins to behave more like liquid water.The yield stress of montmorillonite,as determined by the Bingham model,was found to be linearly related to the interaction pressures between clay particles.Besides MD simulations,the microstructure of clay suspension was further quantified using the separation distance and incline angle between non-parallel clay particles.Based on MD results and the quantified clay structure,a model was developed to estimate the yield stress of montmorillonite considering various influence factors,including electrolyte concentration,temperature,and solid fraction.Finally,from a comparison with calculated and experimental data,the results confirm the good performance of the proposed model.These findings provide significant insights for understanding the rheological soil behaviors and evaluating the yield stress of bentonite suspensions.展开更多
To reveal the effects of environmental and loading conditions, as well as asphalt properties on the nonlinear rheological behavior of asphalt, the large amplitude oscillation shear(LAOS) test was introduced, and the F...To reveal the effects of environmental and loading conditions, as well as asphalt properties on the nonlinear rheological behavior of asphalt, the large amplitude oscillation shear(LAOS) test was introduced, and the Fourier transform rheology, Lissajous curve method, and the LAOS fatigue test have been applied to investigate the nonlinear rheological behavior of asphalt binders. The research results indicate that a decrease in temperature, an increase in shear frequency and strain level, the introduction of polymer modifiers, and the aging effect of asphalt can significantly increase the nonlinearity of asphalt, manifested by the higher relative magnitude of the third harmonic and zero-strain nonlinear coefficient. For the two polymer modifiers selected in this study, the 4%polyurethane modifier exhibits a higher nonlinear lifting effect than the 4% styrene-butadiene-styrene(SBS). The impact of long-term aging on nonlinear viscoelasticity is observably greater than that of short-term aging. The zero-strain nonlinear coefficient estimated based on the average value method can accurately characterize the nonlinear viscoelasticity of asphalt, which can serve as an effective supplement to the relative magnitude of the third harmonic. All asphalts exhibit shear thinning behavior under the test temperature of 24℃, and the decrease in test temperature, the increase in shear rate and strain level, the introduction of modifiers, and the aging effect of asphalt all exacerbate the shear thinning behavior of asphalt. In addition, the fatigue failure process of asphalt materials is accompanied by an increasing degree of nonlinearity.展开更多
Based on thermodynamic calculations and continuous rheological extrusion(CRE)technology,Al-Ti-V-B master alloys were designed and prepared.The morphology and the distribution of the refined phases in the master alloys...Based on thermodynamic calculations and continuous rheological extrusion(CRE)technology,Al-Ti-V-B master alloys were designed and prepared.The morphology and the distribution of the refined phases in the master alloys were analyzed by XRD,SEM,and TEM.The effects of master alloy addition and holding time on the microstructure and mechanical properties of A356 alloy were investigated.Under the optimum refiner addition of 0.3wt.%and the holding time of 20 min,the average grain size of the refined A356 alloy is 151.8±9.11μm,89.62%lower than that of original A356 alloy.The tensile strength and elongation of as-cast A356refined alloy are 196.11 MPa and 5.75%,respectively.After T6 treatment,the tensile strength and elongation of A356 refined alloy are 290.1 MPa and 3.09%,respectively.The fracture morphology is characterized by a predominance of along-crystal fracture with a small amount of through-crystal fracture,attributed to the refined grains.Finer grains promote crack path deflection and localized plastic deformation,enhancing energy dissipation and reducing the tendency for brittle fracture.This study provides a novel approach to improving the mechanical properties of A356 alloy through grain refinement using CRE Al-Ti-V-B master alloy.展开更多
High-performance devices usually have curved surfaces, requiring high accuracy of shape and low surface roughness. It is a challenge to achieve high accuracies for form and position on a device with low surface roughn...High-performance devices usually have curved surfaces, requiring high accuracy of shape and low surface roughness. It is a challenge to achieve high accuracies for form and position on a device with low surface roughness. However, due to the unique nonlinear rheology, magnetorheological fluids with hard abrasives are widely applied in ultra-precision surface finishing. Compared with conventional mechanical finishing, magnetorheological finishing displays obviously advantages, such as high precision shape of machined surface, low surface roughness and subsurface damage, and easy control for finishing processes. However, finishing performance depends on various factors, e.g. volume fraction and distribution of magnetic particles, types of hard abrasives and additives, strength of magnetic field, finishing forms. Therefore, a comprehensive review on related works is essential to understand the state-of-the-art of magnetorheological finishing and beneficial to inspire researchers to develop lower cost, higher machining accuracy and efficient approaches and setups, which demonstrates a significant guidance for development of high-performance parts in fields of aerospace, navigation and clinical medicine etc. This review starts from the rheological property of magnetorheological fluids, summarizing dynamically nonlinear rheological properties and stable finishing approaches. Then, the effect of components in magnetorheological fluids is discussed on finishing performance, consisting of magnetic particles, carrier fluid, additives and abrasives. Reasonable configuration of magnetorheological fluids, and different magnetorheological finishing methods are presented for variously curved surfaces. In addition, the current finishing forms and future directions are also addressed in this review.展开更多
To achieve higher strength and better durability,ultra-high performance concrete(UHPC)typically employs a relatively small water-binder ratio.However,this generally leads to an undesired increase in the paste viscosit...To achieve higher strength and better durability,ultra-high performance concrete(UHPC)typically employs a relatively small water-binder ratio.However,this generally leads to an undesired increase in the paste viscosity.In this study,the effects of liquid and powder polycarboxylate superplasticizers(PCE)on UHPC are compared and critically discussed.Moreover,the following influential factors are considered:air-entraining agents(AE),slump retaining agents(SA),and defoaming agents(DF)and the resulting flow characteristics,mechanical properties,and hydration properties are evaluated assuming UHPC containing 8‰powder PCE(PCE-based UHPC).It is found that the spread diameter of powder PCE is 5%higher than that of liquid PCE.Among the chemical admixtures studied,AEs have the best effect on improving UHPC workability,while DFs have the worst effect.When the addition of AE and SA is 1.25‰and 14.7%of PCE,paste viscosity reduces by 35%and 19%,respectively compared to the paste with only 8‰PCE.A low AE dosage(1.25‰)decreases compressive strength by 4.1%,while SA(8.1%)increases UHPC compressive strength by 9.1%.Both AE and SA significantly delay the UHPC hydration process,reducing the hydration heat release peaks by 76%and 27%,respectively.展开更多
Traditional asphalt rejuvenators,like aromatic oil(AO),are known to be effective in improving the low-temperature properties and fatigue performances of aged SBS(styrene-butadiene-styrene)modified asphalt(SBSMA)binder...Traditional asphalt rejuvenators,like aromatic oil(AO),are known to be effective in improving the low-temperature properties and fatigue performances of aged SBS(styrene-butadiene-styrene)modified asphalt(SBSMA)binders and mixtures.However,these rejuvenators inevitably compromise their high-temperature properties and deformation resistances because they dilute asphalt binder but do not fix the damaged structures of aged SBS.In this study,a highly-active chemical called polymerized 4,4-diphenylmethane diisocyanate(PMDI)was used to assist the traditional AO asphalt rejuvenator.The physical and rheological characteristics of rejuvenated SBSMA binders and the moisture-induced damage and rut deformation performances of corresponding mixtures were comparatively evaluated.The results showed that the increasing proportion of AO compromises the hightemperature property and hardness of aged SBSMA binder,and an appropriate amount of PMDI works to compensate such losses;3%rejuvenator at mass ratio of AO:PMDI=70:30 can have a rejuvenated SBSMA binder with a high-temperature performance similar to that of fresh binder,approximately at 71.4°C;the use of AO can help reduce the viscosity of PMDI rejuvenated SBSMA binder for improving its workability;PMDI can help improve the resistance of AO rejuvenated SBSMA binder to deformation,especially at elevated temperatures,through its chemical reactions with aged SBS;moisture induction can enhance the resistance to damage of rejuvenated mixtures containing AO/PMDI or only PMDI;and the rejuvenator with a mass ratio of AO:PMDI=70:30 can lead the rejuvenated mixture to meet the application requirement,with a rut depth of only 2.973 mm,although more PMDI can result in a higher resistance of rejuvenated mixtures to high-temperature deformation.展开更多
In order to settle the issues of poor rheology for drilling fluids in Antarctica,it is important to develop an agent that can availably address these challenges.For this reason,a rheological regulator(HSCN)of drilling...In order to settle the issues of poor rheology for drilling fluids in Antarctica,it is important to develop an agent that can availably address these challenges.For this reason,a rheological regulator(HSCN)of drilling fluid was synthesized by modifying montmorillonite with composite modifiers(DODMAC and CPL).The structure of HSCN was characterized by X-ray diffraction,contact angle,infrared spectroscopy and scanning electron microscopy.And HSCN properties were also evaluated by experiments such as colloidal rate,rheology,viscosity-temperature characteristics and corrosion test.Finally,the mechanism of HSCN was investigated.2%HSCN can enhance the improvement rate of yield point for drilling fluid at-55℃by 167%,and the colloidal rate of drilling fluid is 90.4%after 24 h.The corrosion of the three rubbers is weak,with a maximum mass increase of only 0.014 g and a maximum outside diameter increase of 0.04 cm.The mechanism study shows that the staggered lapping between HSCN lamellar units forms an infinitely extended reticular structure.The structure is mainly formed by the electrostatic attraction between HSCN particles,hydrogen bonding,physical adsorption and entanglement between the long carbon chains in HSCN.The formation of this structure can effectively enhance the rheology properties of drilling fluids.This research gives a direction for the investigation of drilling fluids suitable for Antarctic conditions,which is greatly sense for accelerating the efficient exploitation of oil and gas in Antarctica.展开更多
To elucidate the high temperature rheological capability of graphene modified rubber asphalt,three contents of graphene and crumb rubber were prepared by a combination of mechanical agitation and high speed shearing m...To elucidate the high temperature rheological capability of graphene modified rubber asphalt,three contents of graphene and crumb rubber were prepared by a combination of mechanical agitation and high speed shearing machine,then used dynamic shear rheological test(DSR)and multiple stress creep recovery(MSCR)tests to evaluate.The hardness and softening point with rotational viscosity of samples raised with the addition of graphene,especially the addition of 0.04%.Dynamic shear rheological test revealedthat the dynamic shear modulus G*,rutting factor G*/Sin δ,and zero shear viscosity(ZSV)of graphene-modified rubber asphalt were greatly influenced along with graphene-increased,on the contrary,phase angle δ which characterize the viscoelastic ratio of asphalt decreased.Multiple stress creep recovery(MSCR)tests showed that the graphene-enhanced rubber asphalt had high-temperature stability through non-recoverable creep compliance(Jnr).Based on these findings,graphene-modified rubber asphalt binders with the addition of 0.04% graphene had good viscoelastic properties as well as high temperature rutting resistance performance.In the meantime,G*/Sin δ,ZSV,and Jnr100,Jnr3200 have good correlation,which can reveal the excellent high-temperature stability performance of asphalt.展开更多
For evaluation of the rheological and mechanical properties of highly filled wood plastic composites （WPCs）, polypropylene/polyethylene （PP/PE） blends were grafted with maleic anhydride （MAH） to enhance the inte...For evaluation of the rheological and mechanical properties of highly filled wood plastic composites （WPCs）, polypropylene/polyethylene （PP/PE） blends were grafted with maleic anhydride （MAH） to enhance the interfacial adhesion between wood fiber and matrix. WPCs were prepared from wood fiber up to 60 wt.% and modified PP/PE was blended by extrusion. The rheological properties were studied by using dynamic measurement. According to the strain sweep test, the linear viscoelastic region of composites in the melt was determined. The result showed that the storage modulus was independent of the strain at low strain region （〈0.1%）. The frequency sweep resuits indicated that all composites exhibited shear thinning behavior, and both the storage modulus and complex viscosity of MAH modified composites were decreased comparing to those unmodified. Flexural properties and impact strength of the prepared WPCs were measured according to the relevant standard specifications. The flexural and impact strength of the manufactured composites significantly increased and reached a maximum when MAH dosage was 1.0 wt%, whereas the flexural modulus after an initial decreased, also increased with MAH dosage. The increase in mechanical properties indicated that the presence of anhydride groups enhanced the interracial adhesion between wood fiber and PP/PE blends.展开更多
By the methods of uniaxial single-stage loading and graded incremental cyclic loading, the creep experiments were performed on the deep saturated rock from Dongguashan Mine, and the creep curves of saturated rock unde...By the methods of uniaxial single-stage loading and graded incremental cyclic loading, the creep experiments were performed on the deep saturated rock from Dongguashan Mine, and the creep curves of saturated rock under different loading stresses were obtained. By comparing with the creep rule of dry rock in the same location, the creep rule of deep saturated rock was analyzed. Based on the united rheological mechanical model, the rheological model of deep saturated rock was recognized, and the parameters of the model were determined. The results show that the creep curves are very smooth under low stress, but the phenomena of wave and catastrophe turn up under high stress, and the bearing capacity of rock is weakening over time. The rheological properties of saturated and dry rocks are very different under tlie condition of deep high stress, especially when unloading, degradation and damage of rock quality is more serious, and the effect of water cannot be neglected. The H--HIN--NJS model （Schofield-Scott-Blair model） was selected to represent the rheology rule of deep saturated rock, and the fitting curves of model agree well with the experiment data, so the selected model is reasonable.展开更多
Ti-6Al-4V alloy powder was taken as raw material. 60%（mass fraction） paraffin, 35%low density polyethylene and 5%stearic acid were employed as binders to prepare injection feedstocks. Capillary rheometer was adopted...Ti-6Al-4V alloy powder was taken as raw material. 60%（mass fraction） paraffin, 35%low density polyethylene and 5%stearic acid were employed as binders to prepare injection feedstocks. Capillary rheometer was adopted to determine the rheological parameters and to analyze the rheological properties of the feedstocks at different milling time, powder loading and temperature. It is indicated through the results that the viscosity increases and the value of n decreases with the increase of milling time. The more the powder loading is, the higher the viscosity is. The empirical formula on the relationship between the viscosity and the powder loading is： ηr=η/ηb=A（1-Ф/Фmax）/^- m . The value m is calculated as 0.33. The flow activation energy Ea decreases with the increase of shear rate.展开更多
The rheological behavior of low consistency thermomechanical pulp of Chinese fir harvested by intermediate thinning was analyzed. The results show that the apparent viscosity of pulp changed along with the beating deg...The rheological behavior of low consistency thermomechanical pulp of Chinese fir harvested by intermediate thinning was analyzed. The results show that the apparent viscosity of pulp changed along with the beating degree, pulp consistency and shearing velocity. With the increasing of pulp consistency, the apparent viscosity of pulp increased gradually. Beating degree of pulp had an effect on microstructure of pulp. The apparent viscosity of pulp declined as beating degree of pulp increased, and the apparent viscosity of pulp fell along with the shearing velocity increasing. Based on the results, the rheological models are set up. The models showed that the fluid types of the low consistency pulp could be described as pseudoplastics fluids （non-Newtonian fluids）.展开更多
基金supported and financed by Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology (No.2024yjrc96)Anhui Provincial University Excellent Research and Innovation Team Support Project (No.2022AH010053)+2 种基金National Key Research and Development Program of China (Nos.2023YFC2907602 and 2022YFF1303302)Anhui Provincial Major Science and Technology Project (No.202203a07020011)Open Foundation of Joint National-Local Engineering Research Centre for Safe and Precise Coal Mining (No.EC2023020)。
文摘The generalized rheological tests on sandstone were conducted under both dynamic stress and seepage fields.The results demonstrate that the rheological strain of the specimen under increased stress conditions is greater than that under creep conditions,indicating that the dynamic stress field significantly influences the rheological behaviours of sandstone.Following the rheological tests,the number of small pores in the sandstone decreased,while the number of medium-sized pores increased,forming new seepage channels.The high initial rheological stress accelerated fracture compression and the closure of seepage channels,resulting in reduction in the permeability of sandstone.Based on the principles of generalized rheology and the experimental findings,a novel rock rheological constitutive model incorporating both the dynamic stress field and seepage properties has been developed.Numerical simulations of surrounding rock deformation in geotechnical engineering were carried out using a secondary development version of this model,which confirmed the applicability of the generalized rheological numerical simulation method.These results provide theoretical support for the long-term stability evaluation of engineering rock masses and for predicting the deformation of surrounding rock.
基金supported by Gansu Provincial Science and Technology Plan(23CXGA0195)Longnan Science and Technology Plan(2024CX03)。
文摘Graphene oxide nanomaterials are increasingly used in various fields due to their superior properties.In order to study the influence of graphene oxide additives on the performance of modified asphalt,in this study,graphene oxide modified asphalt was prepared and characteristics was studied including the high deformation resistance performance and the self-healing property of modified asphalt.Functional groups and morphology of graphene oxide modified asphalt were described by Fourier transform infrared spectroscopy.The high deformation resistance performance and self-healing effect of asphalt samples were obtained through dynamic slear rheometer(DSR)test.Results shows that graphene oxide dispersions improve the performance of asphalt relatively well compared to graphene oxide powder.There is no chemical reaction between graphene oxide and asphalt,but physical connection.The addition of graphene oxide improved the high deformation resistance of modified asphalt and expedited the self-healing ability of asphalt under fatigue load.
基金supported by National Natural Science Foundation of China(No.52204302)Young Elite Scientist Sponsorship Program by CAST(No.YESS20220533)+1 种基金China Postdoctoral Science Foundation(No.2022M713519)Graduate Research Innovation Project of Central South University(No.1053320210230).
文摘The rheological properties of an innovative coal-based colloidal composite binder(3Co-Binder)prepared via alkaline–oxygen excitation and mechanochemical synthesis are revealed.Derived from low-rank coal,3Co–Binder is applied in iron ore pelletization as a replacement for traditional bentonite,with the aim of improving the iron grades of the pellets.Cryoscanning electron microscopy revealed that 3Co-Binder exhibits a densely populated,porous network structure.It was determined to be a pseudo-plastic fluid with yield stress and shear-thinning characteristics.The stability of 3Co-Binder was influenced by the humic acid extraction rate,temperature,and static placing time.An extraction rate of humic acids above 96%was found to prevent sedimentation of 3Co-Binder,while lower temperatures and prolonged static placing time increased its apparent viscosity.A storage duration of less than 2 weeks and a temperature range of 25–35℃ were found to be optimal for maintaining the stability of 3Co-Binder.The viscous flow activation energy of 3Co-Binder remained stable at approximately 60 kJ mol^(-1) as the shear rate increased from 0.5 to 5 s^(-1).However,at higher shear rates,up to 100 s^(-1),the viscous flow activation energy decreased to 46.48 kJ mol^(–1).To ensure stability and dispersibility during storage,the rheological parameters of 3Co-Binder must meet the following criteria:yield stress below 10 Pa,consistency coefficient below 1.5 Pa s,non-Newtonian index below 1,and apparent viscosity below 10,000 mPa s at a shear rate of 1 s^(–1).
基金the Indian Council of Agriculture Research,All India Coordinated Research Project on Postharvest Engineering and Technology(ICAR-AICRP on PHET)Chaudhary Charan Singh Haryana Agricultural University,Hisar,for providing technical and financial support for the research.
文摘Millets,nutrient-rich grains packed with complex carbohydrates,dietary fiber,essential proteins,lipids,and antioxidant phytochemicals,are gaining recognition as valuable dietary components.Various processing techniques,including roasting,extrusion,germination,and hydrothermal treatment,have been employed to enhance nutritional bioavailability and consumer appeal.These processing,which involves the application of heat and moisture,induces specific transformations in millet components.Starch undergoes gelatinization,a process in which its crystalline structure is disrupted,leading to increased digestibility and viscosity.Proteins undergo denaturation,altering their structure and potentially improving their digestibility and functionality.Lipids may also undergo modifications,impacting their stability and interactions with other food components.These changes facilitate the release of bioactive compounds such as phenolics,flavonoids,and tannins.These processes effectively reduce anti-nutritional factors,further boosting nutrient availability.This review provides a comprehensive analysis of various hydrothermal methods,including steaming and heat-moisture treatment,and critically evaluates their impact on the physicochemical properties,nutritional profile,and potential health benefits of millet.Steaming,a gentler method involves cooking millet in a steamer basket above boiling water,preserving its delicate texture and nutty flavor while still promoting starch gelatinization and nutrient retention.Heat-moisture treatment,a more specialized technique,involves exposing millet to elevated temperatures and controlled moisture levels,inducing specific changes in starch properties without causing complete gelatinization.This review examines how hydrothermal methods affect the nutritional and functional properties of millet to inspire the development of innovative,nutritious millet-based food products.
基金supported by the Natural Science Starting Project of Sichuan Provincial Youth Foundation Project(2025ZNSFSC1356)Southwest Petroleum University,China(2023QHZ019)+1 种基金General Project of the Sichuan Provincial Natural Science Foundation,China(24NSFSC1295)Open fund of Dazhou Industrial Technology Institute of Intelligent Manufacturing,China(ZNZZ2215).
文摘During the production of natural gas hydrates,micron-sized sand particles coexist with hydrate within the transportation pipeline,posing a significant threat to the safety of pipeline flow.However,the influence of sand particles on hydrate formation mechanisms and rheological properties remains poorly understood.Consequently,using a high-pressure reactor system,the phase equilibrium conditions,hydrate formation characteristics,hydrate concentration,and the slurry viscosity in micron-sized sand system are investigated in this work.Furthermore,the effects of sand particle size,sand concentration,and initial pressure on these properties are analyzed.The results indicate that a high concentration of micron-sized sand particles enhances the formation of methane hydrates.When the volume fraction of sand particles exceeds or equals 3%,the phase equilibrium conditions of the methane hydrate shift to the left relative to that of the pure water system(lower temperature,higher pressure).This shift becomes more pronounced with smaller particle sizes.Besides,under these sand concentration conditions,methane hydrates exhibit secondary or even multiple formation events,though the formation rate decreases.Additionally,the torque increases significantly and fluctuates considerably.The Roscoe-Brinkman model yields the most accurate slurry viscosity calculations,and as sand concentration increases,both hydrate concentration and slurry viscosity also increase.
基金Funded by the China Building Material Federation Projects(Nos.20221JBGS06-19,2023JBGS02-01)the National Natural Science Foundation of China(No.U2241236)。
文摘The viscosity of anti-irradiated glass was quantitatively characterized using beam bending viscometry(BBV),parallel plate viscometry(PPV),and rotational viscometry(RV).The Vogel-Fulcher-Tammann(VFT)equation was determined to be the most suitable for representing the viscosity-temperature characteristics of anti-irradiation glass by comparing the fitting effects and accuracy of different equations within different test ranges.The fragility index m of anti-irradiation glass was 47.5,as calculated using an Angell plot,and the cause of the appropriate fit of the VFT equation was analyzed.The effects of different heating temperatures and loading rates on the tensile properties of glass were studied using a universal testing machine.The results indicated that,at a tensile rate of 10 mm/s,the heating temperature increased from 903 to 1023 K,and the deformation process of anti-irradiation glass transitioned from unstable to stable.When the tensile rate increased from 10 to 30 mm/s at 1023 K,the deformation process of the glass was extremely unstable.This work provides theoretical guidance for the large-size preparation of flexible anti-irradiation glass.
基金supported by the National Natural Science Foundation of China(No.52076036)supported by the National Natural Science Foundation of China(No.52174020).
文摘Modified ethylene-vinyl acetate copolymer(EVAM)and amino-functionalized nano-silica(NSiO_(2))par-ticles were employed as the base materials for the synthesis of the nanocomposite pour point depressant designated as EVAM-g-NSiO_(2).This synthesis involved a chemical grafting process within a solution system,followed by a structural characterization.Moreover,combining macro-rheological performance with microscopic structure observation,the influence of the nanocomposite pour point depressant on the rheological properties of the model waxy oil system was investigated.The results indicate that when the mass ratio of NSiO_(2) to EVAM is 1:100,the prepared EVAM-g-NSiO_(2) nanocomposite pour point depressant exhibits excellent pour point reduction and viscosity reduction properties.Moreover,the nanocomposite pour point depressant obtained through a chemical grafting reaction demonstrates structural stability(the bonding between the polymer and nanoparticles is stable).The pour points of model waxy oils doped with 500 mg/kg ethylene-vinyl acetate copolymer(EVA),EVAM,and EVAM/SiO_(2) were reduced from 34℃ to 23,20,and 21℃,respectively.After adding the same dosage of EVAM-g-NSiO_(2) nanocomposite pour point depressant,the pour point of the model wax oil decreased to 12℃ and the viscosity at 32℃ decreased from 2399 to 2396.9 mPa·s,achieving an impressive viscosity reduction rate of 99.9%.Its performance surpassed that of EVA,EVAM,and EVAM/SiO_(2).The EVAM-g-NSiO_(2) dispersed in the oil phase acts as the crystallization nucleus for wax crystals,resulting in a dense structure of wax crystals.The compact wax crystal blocks are difficult to overlap with each other,pre-venting the formation of a three-dimensional network structure,thereby improving the low-temperature flowability of the model waxy oil.
基金supported by the Taiyuan Major Science and Technology Project Fund in 2021,Fund for Shanxi“1331 Project,”Key Research and Development Program of Shanxi Province(202102040201011)the Zhanjiang Marine Equipment and Marine Biological Industry Unveiled the Talent Team Project(2021E05034).
文摘The toughness of thermoplastic polymers such as polypropylene(PP)can be improved by adding elastomers-based toughening agents,and the phase morphology of these toughening agents is very important for the strength and toughness of PP.The low-temperature toughness of PP was improved by inserting high-density polyethylene(HDPE)between PP and polystyrene-b-ethylene-co-propyleneb-polystyrene(SEPS)to form an unusual SEPS@HDPE core–shell structure,with SEPS as the core and HDPE as the shell.Based on the microtopography and rheological behavior characterization,HDPE in PP/SEPS/HDPE composites was found to serve as an emulsifier,decrease the size of SEPS particles,and promote the homogeneous dispersion of dispersed phase particles in the matrix.An increase in the HDPE content shifted the toughening mechanism of PP composites from cavitation to matrix shear yielding.The reduction in the distance between the dispersed core–shell structure particles promoted shear yielding in the PP composites,leading to increased toughness.The creation of an intermediate HDPE layer with a moderate modulus was crucial for dispersing stress concentrations and significantly improving toughness without compromising the tensile strength.These findings will facilitate the fabrication of high-toughness PP products at low temperatures.
基金the financial support provided by the National Science Fund for Distinguished Young Scholars of China(Grant No.42225702)the National Natural Science Fund of China for Excellent Young Scholars Fund(Overseas)+2 种基金Applied Basic Research Programme of Liaoning Province(2023JH2/101300139)Opening fund of State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(Chengdu University of Technology,SKLGP2024K020)Key Laboratory of Earth Fissures Geological Disaster,Ministry of Natural Resources.
文摘Understanding the rheology of bentonite suspensions is crucial for ensuring the safety of engineering practices.However,the rheological mechanisms of bentonite remain unclear due to the limitations of conventional experimental techniques,particularly in assessing the microscopic interactions between clay particles and their impact on rheological properties.In this paper,the rheological behaviors of Namontmorillonite were studied with a focus on interparticle interactions.Both equilibrium molecular dynamics(MD)and non-equilibrium MD simulations were conducted to understand the physical properties of Na-montmorillonite under zero shear and various shear rates,respectively.The interaction between two parallel clay particles was determined in simulations,indicating that the classical Darjaguin-Landau-Verwey-Overbeek(DLVO)theory underestimates the interactions for a small separation distance.Na-montmorillonite exhibits a typical shear thinning behavior under shearing.However,as water content increases,it begins to behave more like liquid water.The yield stress of montmorillonite,as determined by the Bingham model,was found to be linearly related to the interaction pressures between clay particles.Besides MD simulations,the microstructure of clay suspension was further quantified using the separation distance and incline angle between non-parallel clay particles.Based on MD results and the quantified clay structure,a model was developed to estimate the yield stress of montmorillonite considering various influence factors,including electrolyte concentration,temperature,and solid fraction.Finally,from a comparison with calculated and experimental data,the results confirm the good performance of the proposed model.These findings provide significant insights for understanding the rheological soil behaviors and evaluating the yield stress of bentonite suspensions.
基金supported by the National Key Research and Development Program of China(2023YFB2603500).
文摘To reveal the effects of environmental and loading conditions, as well as asphalt properties on the nonlinear rheological behavior of asphalt, the large amplitude oscillation shear(LAOS) test was introduced, and the Fourier transform rheology, Lissajous curve method, and the LAOS fatigue test have been applied to investigate the nonlinear rheological behavior of asphalt binders. The research results indicate that a decrease in temperature, an increase in shear frequency and strain level, the introduction of polymer modifiers, and the aging effect of asphalt can significantly increase the nonlinearity of asphalt, manifested by the higher relative magnitude of the third harmonic and zero-strain nonlinear coefficient. For the two polymer modifiers selected in this study, the 4%polyurethane modifier exhibits a higher nonlinear lifting effect than the 4% styrene-butadiene-styrene(SBS). The impact of long-term aging on nonlinear viscoelasticity is observably greater than that of short-term aging. The zero-strain nonlinear coefficient estimated based on the average value method can accurately characterize the nonlinear viscoelasticity of asphalt, which can serve as an effective supplement to the relative magnitude of the third harmonic. All asphalts exhibit shear thinning behavior under the test temperature of 24℃, and the decrease in test temperature, the increase in shear rate and strain level, the introduction of modifiers, and the aging effect of asphalt all exacerbate the shear thinning behavior of asphalt. In addition, the fatigue failure process of asphalt materials is accompanied by an increasing degree of nonlinearity.
基金supported by the National Key Research and Development Program of China (Grant No.2022YFB3706801)the National Natural Science Foundation of China (Grant Nos.U2341253,52371019,U2241232)+2 种基金the Dalian High-level Talents Innovation Support Program (Grant No.2021RD06)the Applied Basic Research Program of Liaoning Province (Grant No.2022JH2/101300003)the Natural Science Foundation of Liaoning Province (Grant Nos.2022-BS-262,JYTMS20230031)。
文摘Based on thermodynamic calculations and continuous rheological extrusion(CRE)technology,Al-Ti-V-B master alloys were designed and prepared.The morphology and the distribution of the refined phases in the master alloys were analyzed by XRD,SEM,and TEM.The effects of master alloy addition and holding time on the microstructure and mechanical properties of A356 alloy were investigated.Under the optimum refiner addition of 0.3wt.%and the holding time of 20 min,the average grain size of the refined A356 alloy is 151.8±9.11μm,89.62%lower than that of original A356 alloy.The tensile strength and elongation of as-cast A356refined alloy are 196.11 MPa and 5.75%,respectively.After T6 treatment,the tensile strength and elongation of A356 refined alloy are 290.1 MPa and 3.09%,respectively.The fracture morphology is characterized by a predominance of along-crystal fracture with a small amount of through-crystal fracture,attributed to the refined grains.Finer grains promote crack path deflection and localized plastic deformation,enhancing energy dissipation and reducing the tendency for brittle fracture.This study provides a novel approach to improving the mechanical properties of A356 alloy through grain refinement using CRE Al-Ti-V-B master alloy.
基金funded by the National Key Research and Development Program of China (2018YFA0703400)the Young Scientists Fund of the National Natural Science Foundation of China (52205447)+2 种基金Changjiang Scholars Program of Chinese Ministry of Educationthe Xinghai Science Funds for Distinguished Young Scholars at Dalian University of Technologythe Collaborative Innovation Center of Major Machine Manufacturing in Liaoning。
文摘High-performance devices usually have curved surfaces, requiring high accuracy of shape and low surface roughness. It is a challenge to achieve high accuracies for form and position on a device with low surface roughness. However, due to the unique nonlinear rheology, magnetorheological fluids with hard abrasives are widely applied in ultra-precision surface finishing. Compared with conventional mechanical finishing, magnetorheological finishing displays obviously advantages, such as high precision shape of machined surface, low surface roughness and subsurface damage, and easy control for finishing processes. However, finishing performance depends on various factors, e.g. volume fraction and distribution of magnetic particles, types of hard abrasives and additives, strength of magnetic field, finishing forms. Therefore, a comprehensive review on related works is essential to understand the state-of-the-art of magnetorheological finishing and beneficial to inspire researchers to develop lower cost, higher machining accuracy and efficient approaches and setups, which demonstrates a significant guidance for development of high-performance parts in fields of aerospace, navigation and clinical medicine etc. This review starts from the rheological property of magnetorheological fluids, summarizing dynamically nonlinear rheological properties and stable finishing approaches. Then, the effect of components in magnetorheological fluids is discussed on finishing performance, consisting of magnetic particles, carrier fluid, additives and abrasives. Reasonable configuration of magnetorheological fluids, and different magnetorheological finishing methods are presented for variously curved surfaces. In addition, the current finishing forms and future directions are also addressed in this review.
基金Key Research and Development Program of Hubei Province(2022BCA082 and 2022BCA077).
文摘To achieve higher strength and better durability,ultra-high performance concrete(UHPC)typically employs a relatively small water-binder ratio.However,this generally leads to an undesired increase in the paste viscosity.In this study,the effects of liquid and powder polycarboxylate superplasticizers(PCE)on UHPC are compared and critically discussed.Moreover,the following influential factors are considered:air-entraining agents(AE),slump retaining agents(SA),and defoaming agents(DF)and the resulting flow characteristics,mechanical properties,and hydration properties are evaluated assuming UHPC containing 8‰powder PCE(PCE-based UHPC).It is found that the spread diameter of powder PCE is 5%higher than that of liquid PCE.Among the chemical admixtures studied,AEs have the best effect on improving UHPC workability,while DFs have the worst effect.When the addition of AE and SA is 1.25‰and 14.7%of PCE,paste viscosity reduces by 35%and 19%,respectively compared to the paste with only 8‰PCE.A low AE dosage(1.25‰)decreases compressive strength by 4.1%,while SA(8.1%)increases UHPC compressive strength by 9.1%.Both AE and SA significantly delay the UHPC hydration process,reducing the hydration heat release peaks by 76%and 27%,respectively.
基金supported by the Scientific Technology R&D Project of CCCC Asset Management Co.,Ltd.(RP2022015294).
文摘Traditional asphalt rejuvenators,like aromatic oil(AO),are known to be effective in improving the low-temperature properties and fatigue performances of aged SBS(styrene-butadiene-styrene)modified asphalt(SBSMA)binders and mixtures.However,these rejuvenators inevitably compromise their high-temperature properties and deformation resistances because they dilute asphalt binder but do not fix the damaged structures of aged SBS.In this study,a highly-active chemical called polymerized 4,4-diphenylmethane diisocyanate(PMDI)was used to assist the traditional AO asphalt rejuvenator.The physical and rheological characteristics of rejuvenated SBSMA binders and the moisture-induced damage and rut deformation performances of corresponding mixtures were comparatively evaluated.The results showed that the increasing proportion of AO compromises the hightemperature property and hardness of aged SBSMA binder,and an appropriate amount of PMDI works to compensate such losses;3%rejuvenator at mass ratio of AO:PMDI=70:30 can have a rejuvenated SBSMA binder with a high-temperature performance similar to that of fresh binder,approximately at 71.4°C;the use of AO can help reduce the viscosity of PMDI rejuvenated SBSMA binder for improving its workability;PMDI can help improve the resistance of AO rejuvenated SBSMA binder to deformation,especially at elevated temperatures,through its chemical reactions with aged SBS;moisture induction can enhance the resistance to damage of rejuvenated mixtures containing AO/PMDI or only PMDI;and the rejuvenator with a mass ratio of AO:PMDI=70:30 can lead the rejuvenated mixture to meet the application requirement,with a rut depth of only 2.973 mm,although more PMDI can result in a higher resistance of rejuvenated mixtures to high-temperature deformation.
基金financially supported by the National Natural Science Foundation of China(No.52274021)the National Key Research and Development Program of China(No.2021YFA0719102)。
文摘In order to settle the issues of poor rheology for drilling fluids in Antarctica,it is important to develop an agent that can availably address these challenges.For this reason,a rheological regulator(HSCN)of drilling fluid was synthesized by modifying montmorillonite with composite modifiers(DODMAC and CPL).The structure of HSCN was characterized by X-ray diffraction,contact angle,infrared spectroscopy and scanning electron microscopy.And HSCN properties were also evaluated by experiments such as colloidal rate,rheology,viscosity-temperature characteristics and corrosion test.Finally,the mechanism of HSCN was investigated.2%HSCN can enhance the improvement rate of yield point for drilling fluid at-55℃by 167%,and the colloidal rate of drilling fluid is 90.4%after 24 h.The corrosion of the three rubbers is weak,with a maximum mass increase of only 0.014 g and a maximum outside diameter increase of 0.04 cm.The mechanism study shows that the staggered lapping between HSCN lamellar units forms an infinitely extended reticular structure.The structure is mainly formed by the electrostatic attraction between HSCN particles,hydrogen bonding,physical adsorption and entanglement between the long carbon chains in HSCN.The formation of this structure can effectively enhance the rheology properties of drilling fluids.This research gives a direction for the investigation of drilling fluids suitable for Antarctic conditions,which is greatly sense for accelerating the efficient exploitation of oil and gas in Antarctica.
文摘To elucidate the high temperature rheological capability of graphene modified rubber asphalt,three contents of graphene and crumb rubber were prepared by a combination of mechanical agitation and high speed shearing machine,then used dynamic shear rheological test(DSR)and multiple stress creep recovery(MSCR)tests to evaluate.The hardness and softening point with rotational viscosity of samples raised with the addition of graphene,especially the addition of 0.04%.Dynamic shear rheological test revealedthat the dynamic shear modulus G*,rutting factor G*/Sin δ,and zero shear viscosity(ZSV)of graphene-modified rubber asphalt were greatly influenced along with graphene-increased,on the contrary,phase angle δ which characterize the viscoelastic ratio of asphalt decreased.Multiple stress creep recovery(MSCR)tests showed that the graphene-enhanced rubber asphalt had high-temperature stability through non-recoverable creep compliance(Jnr).Based on these findings,graphene-modified rubber asphalt binders with the addition of 0.04% graphene had good viscoelastic properties as well as high temperature rutting resistance performance.In the meantime,G*/Sin δ,ZSV,and Jnr100,Jnr3200 have good correlation,which can reveal the excellent high-temperature stability performance of asphalt.
文摘For evaluation of the rheological and mechanical properties of highly filled wood plastic composites （WPCs）, polypropylene/polyethylene （PP/PE） blends were grafted with maleic anhydride （MAH） to enhance the interfacial adhesion between wood fiber and matrix. WPCs were prepared from wood fiber up to 60 wt.% and modified PP/PE was blended by extrusion. The rheological properties were studied by using dynamic measurement. According to the strain sweep test, the linear viscoelastic region of composites in the melt was determined. The result showed that the storage modulus was independent of the strain at low strain region （〈0.1%）. The frequency sweep resuits indicated that all composites exhibited shear thinning behavior, and both the storage modulus and complex viscosity of MAH modified composites were decreased comparing to those unmodified. Flexural properties and impact strength of the prepared WPCs were measured according to the relevant standard specifications. The flexural and impact strength of the manufactured composites significantly increased and reached a maximum when MAH dosage was 1.0 wt%, whereas the flexural modulus after an initial decreased, also increased with MAH dosage. The increase in mechanical properties indicated that the presence of anhydride groups enhanced the interracial adhesion between wood fiber and PP/PE blends.
基金Project (50774095) supported by the National Natural Science Foundation of ChinaProject (200449) supported by China National Outstanding Doctoral Dissertations Special Funds
文摘By the methods of uniaxial single-stage loading and graded incremental cyclic loading, the creep experiments were performed on the deep saturated rock from Dongguashan Mine, and the creep curves of saturated rock under different loading stresses were obtained. By comparing with the creep rule of dry rock in the same location, the creep rule of deep saturated rock was analyzed. Based on the united rheological mechanical model, the rheological model of deep saturated rock was recognized, and the parameters of the model were determined. The results show that the creep curves are very smooth under low stress, but the phenomena of wave and catastrophe turn up under high stress, and the bearing capacity of rock is weakening over time. The rheological properties of saturated and dry rocks are very different under tlie condition of deep high stress, especially when unloading, degradation and damage of rock quality is more serious, and the effect of water cannot be neglected. The H--HIN--NJS model （Schofield-Scott-Blair model） was selected to represent the rheology rule of deep saturated rock, and the fitting curves of model agree well with the experiment data, so the selected model is reasonable.
文摘Ti-6Al-4V alloy powder was taken as raw material. 60%（mass fraction） paraffin, 35%low density polyethylene and 5%stearic acid were employed as binders to prepare injection feedstocks. Capillary rheometer was adopted to determine the rheological parameters and to analyze the rheological properties of the feedstocks at different milling time, powder loading and temperature. It is indicated through the results that the viscosity increases and the value of n decreases with the increase of milling time. The more the powder loading is, the higher the viscosity is. The empirical formula on the relationship between the viscosity and the powder loading is： ηr=η/ηb=A（1-Ф/Фmax）/^- m . The value m is calculated as 0.33. The flow activation energy Ea decreases with the increase of shear rate.
基金This study was sponsored by the Research Funding for Outstanding Young University Faculty of China Ministry of Education (No. 2001-39), Fujian Provincial Innovation Fundation for Young Science and Technology Talents (No. 2004J012), and the National Natural Science Funda-tion of China (No. 30571461)
文摘The rheological behavior of low consistency thermomechanical pulp of Chinese fir harvested by intermediate thinning was analyzed. The results show that the apparent viscosity of pulp changed along with the beating degree, pulp consistency and shearing velocity. With the increasing of pulp consistency, the apparent viscosity of pulp increased gradually. Beating degree of pulp had an effect on microstructure of pulp. The apparent viscosity of pulp declined as beating degree of pulp increased, and the apparent viscosity of pulp fell along with the shearing velocity increasing. Based on the results, the rheological models are set up. The models showed that the fluid types of the low consistency pulp could be described as pseudoplastics fluids （non-Newtonian fluids）.
