Fabrication, property characterization and thermal performance of composite phase change material plates based on tetradecanol-myristic acid binary eutectic mixture/expanded perlite and expanded vermiculite for building application

A binary eutectic mixture composed of tetradecanol(TD)and myristic acid(MA)was maximally absorbed into the microstructures of expanded perlite(EP)and expanded vermiculite(EVMT),respectively,through a self-made vacuum adsorption roller to prepare phase change material(PCM)particle(PCP).Then EP and EVMT-based composite PCM plates were respectively fabricated through a mold pressing method.The thermal property,chemical stability,microstructure and durability were characterized by differential scanning calorimeter(DSC),Fourier transform infrared spectroscope(FT-IR),scanning electron microscope(SEM)and thermal cycling tests,respectively.The results show that both PCPs have high latent heats with 110 J/g for EP-based PCP and more than 130 J/g for EVMT-based PCP,compact microstructure without PCM leakage,stable chemical property and good durability.The research results have proved the feasibility for the vacuum adsorption roller used in the composite PCM fabrication.Results of thermal storage performance experiment indicate that the fabricated PCM plates have better thermal inertia than common building materials,and the thermal storage performance of PCM plates has nonlinearly changed with outside air velocity and temperature increase.Therefore,PCM plates show a significant potential for the practical application of building thermal storage.

Optimization of clay material mixture ratio and filling process in gypsum mine goaf

Because there is neither waste rock nor mill tailings in the gypsum mine, and the buildings on the goaf of gypsum mine are needed to be protected, the research proposed the scheme of the clay filling technology. Gypsum, cement, lime and water glass were used as adhesive, and the strength of different material ratios were investigated in this study. The influence factors of clay strength were obtained in the order of cement, gypsum, water glass and lime. The results show that the cement content is the determinant influence factor, and gypsum has positive effects, while the water glass can enhance both clay strength and the fluidity of the filing slurry. Furthermore, combining chaotic optimization method with neural network, the optimal ratio of composite cementing agent was obtained. The results show that the optimal ratio of water glass, cement, lime and clay (in quality) is 1.17:6.74:4.17:87.92 in the process of bottom self-flow filling, while the optimal ratio is 1.78:9.58:4.71:83.93 for roof-contacted filling. A novel filling process to fill in gypsum mine goaf with clay is established. The engineering practice shows that the filling cost is low, thus, notable economic benefit is achieved.

Membrane materials in the pervaporation separation of aromatic/aliphatic hydrocarbon mixtures—A review

The separation of aromatic/aliphatic hydrocarbon mixtures is a significant process in chemical industry, but challenged in some cases. Compared with conventional separation technologies, pervaporation is quite promising in terms of its economical, energy-saving, and eco-friendly advantages. However, this technique has not been used in industry for separating aromatic/aliphatic mixtures yet. One of the main reasons is that the separation performance of existed pervaporation membranes is unsatisfactory. Membrane material is an important factor that affects the separation performance. This review provides an overview on the advances in studying membrane materials for the pervaporation separation of aromatic/aliphatic mixtures over the past decade. Explored pristine polymers and their hybrid materials(as hybrid membranes) are summarized to highlight their nature and separation performance. We anticipate that this review could provide some guidance in the development of new materials for the aromatic/aliphatic pervaporation separation.

Note:Molecular simulation of the adsorption of linear alkane mixtures in pillared layered materials

The adsorption isotherms of mixtures of linear alkanes, involving n-pentane, n-hexane, and n-heptane in pillared layered materials (PLMs) with three different porosities Ψ=0.98, 0.94 and 0.87, and three pore widths H=1.02, 1.70 and 2.38 nm at temperature T=300 K were simulated by using configurational-bias Monte Carlo (CBMC) techniques in grand canonical ensemble.A grid model was employed to calculate the interaction between a fluid molecule and two layered boards here. For alkane mixtures,the n-heptane, the longest chain component in alkane mixtures, is preferentially adsorbed at low pressures, with its adsorption increasing and then decreasing as the pressure increases continuously while the n-pentane, the shortest chain component in alkane mixtures, is still adsorbed at high pressures; the adsorption of the longest chain component of alkane mixtures increases as the pore width and the porosity of PLMs increase.

Performance evaluation of new epoxy resin-based composite phase change materials and their asphalt mixture

In recent years,the temperature-adjusted asphalt pavement has been an extensive concern by scholars in various countries,and this pavement can reduce temperaturerelated diseases.In this study,the shaped composite phase change materials(CPCMs)were successfully synthesized by two processes,which are vacuum impregnation and epoxy curing.Firstly,the applicability of CPCMs in asphalt mixtures was evaluated by microscopic characterization,chemical compatibility,thermal properties,durability,and leakage stability.Secondly,CPCMs were applied to the asphalt mixture to evaluate its temperatureadjusted characteristics and pavement performance.Finally,the performance of the temperature-adjusted asphalt mixture was analyzed by integrating all factors.The research shows that the prepared CPCMs have excellent thermal properties and durability,the phase transition temperature is 48.93℃,and the phase transition enthalpy is 106.5 J/g,which fully meets the requirements for use in pavement.The temperature-adjusted asphalt mixture could alleviate the occurrence of extreme temperature,which was 4.9℃lower than the conventional mixture.The pavement performance of the temperatureadjusted asphalt mixture can meet the specified standards for humid areas.Considering the factors,the recommended amount of CPCMs is 1.5%.The research results provide a basis for the promotion of temperature-adjusted asphalt pavement and effectively support the development of pavement engineering technology.

Development of overlay tester for fracture test of asphalt mixture

To determine the fracture characteristics of asphalt mixture a novel fracture test with modified loading modes loading fixtures and the control system of the conventional overlay tester is implemented by the asphalt material performance tester AMPT .In order to evaluate the validity of the proposed fracture test four different loading rates including 1 2 3 and 4 mm/min are examined in the AMPT. The results indicate that the fracture behavior is similar to creep at a low loading rate and does not show significant marginal tail extension at a high loading rate.It clearly shows the phase of crack initiation crack propagation and fracture at a loading rate of 3 mm/min. Besides eight fracture parameters such as fracture energy tensile strength and tensile modulus are applied to evaluate the fracture characteristics of asphalt mixture.Development of the overlay tester for the fracture test of asphalt mixture can be considered as a new fracture test of asphalt mixture.

Thermal Energy Storage Characteristics of Myristic and Stearic Acids Eutectic Mixture for Low Temperature Heating Applications

Stearic acid (67.83℃) and myristic acid (52.32℃) have high melting temperatures that can limit their use as phase change material (PCM) in low temperature solar heating applications such as solar space and greenhouse heating in regard to climatic requirements. However, their melting temperatures can be adjusted to a suitable value by preparing a eutectic mixture of the myristic acid (MA) and the stearic acid (SA). In the present study, the thermal analysis based on differential scanning calorimetry (DSC) technique shows that the mixture of myristic acid (MA) and stearic acid (SA) in the respective composition (by mass) of 64% and 36% forms a eutectic mixture having melting temperature of 44.13℃ and the latent heat of fusion of 182.4J·g-1. The thermal energy storage characteristics of the MA-SA eutectic mixture filled in the annulus of two concentric pipes were also experimentally established. The heat recovery rate and heat charging/discharging fractions were determined with respect to the change in the mass flow rate and the inlet temperature of heat transfer fluid. Based on the results obtained by DSC analysis and by the heat charg- ing/discharging processes of the PCM, it can be concluded that the MA-SA eutectic mixture is a potential material for low temperature thermal energy storage applications in terms of its thermo-physical and thermal characteristics.

Hydro-mechanical behaviours of highly compacted sand-bentonite mixture

： This paper presents the results of laboratory testing on a heavily compacted sand-bentonite mixture. To measure the soil-water retention curve （SWRC） of the mixture over a large range of suction, a pressure plate apparatus and filter papers were used. The obtained SWRC shows that the measurements via the two methods consistently agree with each other. By using a suction-controlled oedometer for unsaturated soils, a series of one-dimensional compression tests were performed on the unsaturated compacted sand-bentonite mixture at different constant suctions. The testing results indicate that the yield stress increases and compression index decreases with the increase of imposed suction. The results also demonstrate that the mixture wetted to saturation and subsequently dried to a certain suction level has a lower yield stress than that wetted directly to the same suction.

Novel material tailoring method for internally pressurized FG spherical and cylindrical vessels

A new material tailoring method for spherical and cylindrical vessels made of functionally graded materials (FGMs) is presented.It is assumed that the FG material is composed of an A1-SiC metallic-matrix composite.A uniform ratio of inplane shear stress to yield strength [φ(r)] is used as the design criterion to utilize the maximum capacity of the vessel.The aim is to find a distribution of SiC particles in the radial direction,i.e.,f(r),that achieves a uniform index φ(r) =const,through the wall thickness of the internally pressurized spherical or cylindrical vessel.Both the Mori-Tanaka and rule-of-mixtures homogenization schemes are used to express the effective elastic module and Poisson's ratio.Moreover,the strength of the composite is expressed based on the rule of mixtures.Besides,finite element simulation is carried out to verify the accuracy of the analytical solution.The effects of input parameters such as the internal pressure,strength of the SiC particles,ratio of in-plane shear stress to effective yield strength,and choice of homogenization scheme on the tailored distribution of the SiC volume fraction in the radial direction are also investigated.

Dynamics of Drainage of Power-Law Liquid into a Deformable Porous Material

In this study we explore the one-dimensional drainage of a power-law fluid into a deformable porous material. Initially, the fluid is imbibed into the dry undeformed material due to capillary suction which in turn deforms the porous material and forms liquid and solid interfaces. Mixture theory is employed to study the movement of the liquid and solid phases. The zero-gravity model contains the similarity solution that is solved numerically. The stress gradient within the deformable porous material is induced from a pressure gradient that produces an evolving solid fraction and hence deformation. In the absence of gravity effects, the deformation of the solid seems in the same direction of imbibition. This is because of attraction of gravity. Note that these liquid and solid dynamics depend on both the power-law indexes n and μ. We performed the experiments to measure the drainage and deformations of deformable porous materials for two samples of silicon oil (polydimethylsiloxane) in a polyurethane foam. Our experiments show that the silicon with high viscosity drains slower than silicon oil with low viscosity. The theoretical and experimental results show the same qualitative trend.

Melting and Solidification Heat Transfer Characteristics of a Phase-Change Material in a Latent Heat Storage Vessel: Effects of a Perforated Partition Plate and Metal Fiber

Today, latent heat storage technology has advanced to allow reuse of waste heat in the middle-temperature range. This paper describes an approach to develop a latent heat storage system using middle-temperature waste heat (~100oC - 200oC) from factories. Direct contact melting and solidification behavior between a heat-transfer fluid (oil) and a latent heat storage material mixture were observed. The mixture consisted of mannitol and erythritol (Cm = 70 mass %, Ce = 30 mass %) as a phase-change material (PCM). The weight of the PCM was 3.0 kg and the flow rate of the oil, foil, was 1.0, 1.5, or 2.0 kg/min. To decrease the solidified height of the PCM mixture during the solidification process, a perforated partition plate was installed in the PCM region in the heat storage vessel. PCM coated oil droplets were broken by the perforated partition plate, preventing the solidified height of the PCM from increasing. The solidification and melting processes were repeated using metal fiber. It was found that installing the metal fiber was more effective than installing the perforated partition plate to prevent the flow out problem of the PCM.

Material Selection of a Natural Fibre Reinforced Polymer Composites using an Analytical Approach

Material selection has become a critical part of design for engineers,due to availability of diverse choice of materials that have similar properties and meet the product design specification.Implementation of statistical analysis alone makes it difficult to identify the ideal composition of the final composite.An integrated approach between statistical model and micromechanical model is desired.In this paper,resultant natural fibre and polymer matrix from previous study is used to estimate the mechanical properties such as density,Young’s modulus and tensile strength.Four levels of fibre loading are used to compare the optimum natural fibre reinforced polymer composite(NFRPC).The result from this analytical approach revealed that kenaf/polystyrene(PS)with 40%fibre loading is the ideal composite in automotive component application.It was found that the ideal composite score is 1.156 g/cm^(3),24.2 GPa and 413.4 MPa for density,Young’s modulus and tensile strength,respectively.A suggestion to increase the properties on Young’s modulus are also presented.This work proves that the statistical model is well incorporated with the analytical approach to choose the correct composite to use in automotive application.

Effects of Different Material Ratios on the Dissolution of Tongmai Pills

[Objectives]To study the effects of different material ratios on the dissolution of Tongmai pills.[Methods]Based on mixture uniform experiment design,the fiber,starch and grease-resin materials in Tongmai pills were proportioned.The contents of strychnine,brucine,paeoniflorin,calycosin,ferulic acid,hesperidin and salvianolic acid B in the solution were determined by HPLC,and the content of total flavonoids was determined by ultraviolet spectrophotometry.The weight coefficient of index components was determined by analytic hierarchy process,and the SAS software was used to optimize the dissolution model and calculate the dissolution parameter T40.MATLAB was used to establish a mathematical model and realize the data visualization between material ratio and dissolution parameter T40.[Results]The mathematical model between material ratio and dissolution parameter was T40=8.93-5.31X1-5.83X2+17.67X1X3(X1,X2,X3 are fiber,starch and grease-resin materials respectively,r2=0.9706,P=0.01,RMSE=0.5696).[Conclusions]Fiber can effectively promote the dissolution(P<0.05).Starch can promote the dissolution,but the effect is not obvious(P=0.05).The interaction between fiber and grease-resin can inhibit the dissolution,but was not significant(P=0.07).

Moroccan Phosphogypsum Use in Road Engineering:Materials and Structure Optimization

Morocco produces annually large quantities of phosphogypsum(PG),which permanent stacking rises technical and environmental constraints.However,the valorization of this coproduct in civil engineering and especially in roads building,is a promising solution within a circular economy frame.A first experimental one-kilometer-long pilot,incorporating four different PG based formulations with a 7%cement addition,built at Safi in 2017,allowed positive mechanical assessment(by deflector)and environmental one(by leaching test).In order to further evaluate PG use as road material,our experimental approach focuses here on optimizing material mixtures-made of phosphogypsum(maximum content desired)treated with cement(to be minimized so as to reduce the cost)and sand or steel slag as granular corrector-to meet mechanical requirements of a road base material.We first identified and characterized phosphogypsum produced at the Jorf Lasfar plant and other materials used.Design of experiment is used for modeling desired physical and mechanical responses and to establish domains meeting the required criteria for using the mixture material either as road subgrade layer or foundation layer.In addition,through a parametric study,we evaluated the effects of traffic level,soil bearing capacity and mechanical performance of treated phosphogypsum mixtures on pavement design for three different pavement structures(mixed,reverse and structure with treated sub-base)and determined that the best to adopt for maximizing PG recycling is the pavement structure with subbase treated with hydraulic binder.

Analysis of Raw Materials Components of Dry Composite Mixes for Production Food Concentrates

Background:The simplest and most convenient food technology is the using of dry composite mixtures.They have a lot of advantages.Dry composite mixtures,which would completely be the basis for the production of personalized food concentrates,are not represented.The development of such dry composite mixtures is actual and of scientific and practical interest.The purpose of this research is the selection and justification of local import-substituting raw materials components for dry composite mixtures used as the basis for the production of food concentrates.As the objects of research,the raw materials components of the starch,fruit and vegetable,industry were selected.The work uses currently accepted standard research methods for organoleptic and physic-chemical parameters of raw materials components.The research was carried out within of the project“Theoretical Substantiation of Production Technology and the Development of Import-Substituting Food Products of Functional Purpose Based on Dry Composite Mixtures”,funded by the Belarusian Republican Foundation for Basic Research.Based on the researches,it was found out that in the composition of dry composite mixtures for the production of food concentrates it is expedient to use the following raw materials:potato starch,extruded corn starch,dried carrots,dried beets,dried topinambur and dried apples in chopped form.

吸波沥青混合料的制备及微波自愈合特性

吸波材料具有良好的微波传热能力,可用于沥青路面微裂缝自修复。本研究选取了炭黑粉、羰基铁粉和镍锌铁氧体粉3种吸波材料替换部分矿粉制备了SMA-13吸波沥青混合料。通过车辙试验、低温弯曲破坏试验和冻融劈裂试验对比分析了不同吸波沥青混合料的路用性能,并采用半圆弯曲(SCB)试验研究了吸波材料类型、掺量、微波加热时间等因素对吸波沥青混合料表面温度分布和自愈合性能的影响。利用扫描电子显微镜(SEM)和X射线衍射(XRD)分析吸波材料的微观特性。结果表明,随吸波材料掺量从10%增至30%,炭黑粉沥青混合料的动稳定度和冻融劈裂强度比都呈现出逐渐上升趋势,而低温弯曲应变则表现出先增加后减小的特征;羰基铁粉沥青混合料动稳定度和低温弯曲应变均呈现先增加后减小的趋势,而冻融劈裂强度比表现出逐渐减小的特征;镍锌铁氧体粉沥青混合料动稳定度和低温弯曲应变均呈现逐渐减小趋势,而冻融劈裂强度比则与之相反。吸波沥青混合料的表面温度随着吸波材料掺量和微波加热时间的增加而逐渐上升,能够快速达到沥青混合料裂缝面的愈合温度,从而增强沥青混合料的微波自愈合性能。

基于微波加热的沥青混合料自愈合性能研究

微波加热作为一种全新的体积加热形式,因其快速、均匀和节能的加热特性,已广泛应用于食品、陶瓷等行业,但在道路早期养护领域尚处于探索研究阶段。本研究归纳了基于微波加热的沥青混合料自愈合性能研究进展,针对沥青材料自愈合理论、微波加热机理、微波加热材料、微波加热沥青混合料自愈合影响因素等方面研究现状进行了总结。综述分析表明:由于沥青成分、微观结构以及复杂的相互作用,沥青材料的愈合机制尚未完全清楚,但裂缝表面分子扩散理论、裂缝表面能理论和毛细流动理论在一定的限定条件下能够很好地表征沥青材料的自愈合特性;微波加热是一种高效、环保的沥青混合料自愈合热诱导形式,通过掺入钢屑、钢渣、炭黑、铁素体颗粒等微波加热材料,可提高沥青混合料的自愈合性能;沥青混合料的自愈合性能受到微波特性、沥青性能及沥青混合料类型、外部环境等因素的共同影响,外部环境对沥青混合料自愈合性能的影响最为显著,当超过最佳加热时间、含水率过高、损伤程度较大时,沥青混合料的自愈合性能显著下降。最后,从实际工程的角度,分析了微波加热沥青混合料自愈合性能工程应用面临的问题,并展望了其应用前景。

基于混合物理论的饱和孔隙-裂隙岩体本构模型

考虑饱和孔隙-裂隙岩体中固相材料应变与固相材料压力间的关系,完善模型力学参数的取值理论依据,建立新的本构模型.在混合物理论框架内,依据变形特征将固相体应变分解为裂隙骨架体应变、孔隙骨架体应变、岩块材料体应变.假定应变仅取决于能量方程中的共轭应力,基于自由能势函数构建饱和孔隙-裂隙岩体本构模型,根据模型力学含义推导模型力学参数取值方法.结合达西定律建立流固耦合控制方程.一维固结算例分析表明,相比其他方法确定的参数,所提方法确定参数计算的初始超孔压偏低、初始沉降偏大,孔隙超孔压消散滞后于裂隙超孔压.参数敏感性分析表明,增大渗透系数比会显著提高岩体固结速率,增大形状系数对裂隙超孔压消散和岩体沉降影响较小.

BlueScreen HC在食品接触材料多组分迁移物遗传毒性检测中的适用性

目的探讨基于人生长阻滞和DNA损伤诱导45α(GADD45α)基因的遗传毒性高通量筛选体系BlueScreen HC(BSHC)在食品接触材料多组分迁移物遗传毒性检测中的适用性。方法将人GADD45α基因开放阅读框上游2000 bp序列作为启动子,采用分子克隆构建入嘌呤霉素和高斯荧光素酶(Gluc)双标记的慢病毒质粒pEZX-LvPG04中,并用慢病毒感染人淋巴母细胞TK6,获得稳转细胞系TK6-Gluc。以甲基磺酸甲酯(MMS,终浓度0,1.56,3.13,6.25,12.5,25.0和50.0 mg·L^(-1))为非代谢活化条件下的阳性物质,环磷酰胺(CTX,终浓度0,0.78,1.56,3.13,6.25,12.5和25.0 mg·L^(-1))为代谢活化条件下的阳性物质,二甲基亚砜(DMSO,终浓度0,0.35,0.69,1.38,2.75,5.5和11.0 g·L^(-1))为阴性物质,分别在非活化和活化条件下验证构建的BSHC。将改性淀粉/聚对苯二甲酸-己二酸丁二醇酯(MS/PBAT)作为研究对象,采用体积分数4%乙酸及10%,20%,50%和95%乙醇作为食品模拟物,40℃、浸泡24 h获得5份MS/PBAT多组分迁移物,并用DMSO作为溶剂复溶得到5份多组分迁移溶液作为受试物。以终浓度为0,0.38,0.76,1.53,3.05,6.10和12.20 g·L^(-1)的不同受试物在活化和非活化2种条件下处理TK6-Gluc细胞。非活化条件下作用48 h;活化条件下,在添加体积分数1%大鼠肝S9代谢活化系统的同时,作用3 h后更换新鲜培养基,继续培养至48 h。处理结束后,采用CCK-8法检测细胞活性,同时采用Secrete-Pair^(TM)Gaussia Luciferase Assay试剂盒检测培养基中Gluc化学发光强度。另外,采用终浓度为3.05和12.20 g·L^(-1)的不同受试物对鼠伤寒沙门氏菌TA98和TA100进行微量波动Ames试验以及对体外培养的中国仓鼠肺细胞CHL进行体外哺乳细胞染色体畸变试验,检测受试物的致突变和染色体畸变作用,与BSHC遗传毒性结果进行对比分析。结果采用BSHC法,将相对细胞活性80%定义为生长抑制的最低有效浓度阈值,实验组相对细胞活性低于溶剂对照组的80%提示化合物引起细胞生长抑制。将实验组相对细胞活性低于溶剂对照组的30%定义为出现细胞毒性,此时将不考虑遗传毒性。在无细胞毒性前提下,活化条件下实验组Gluc化学发光强度大于溶剂对照组的1.8倍时,非活化条件下实验组Gluc化学发光强度大于溶剂对照组的1.5倍时,判定为遗传毒性阳性;反之认为无遗传毒性。与溶剂对照组相比,阴性物质DMSO所有浓度均未产生遗传毒性。非活化条件下,MMS 12.5,25.0和50.0 mg·L^(-1)产生遗传毒性;活化条件下,CTX 6.25,12.5和25.0 mg·L^(-1)产生遗传毒性。非活化条件下,MS/PBAT的95%乙醇迁移物6.10和12.20 g·L^(-1)和MS/PBAT的50%乙醇迁移物12.20 g·L^(-1)组细胞生长抑制,所有处理组均未观察到相对细胞活性低于30%的细胞毒性,且未观察到Gluc高表达,表明5种MS/PBAT多组分迁移物在非活化条件下均未产生遗传毒性。活化条件下,MS/PBAT的95%乙醇迁移物12.20 g·L^(-1)和MS/PBAT的4%乙酸迁移物6.10,12.20 g·L^(-1)组细胞表现出显著的生长抑制,所有处理组均未观察到相对细胞活性低于30%的细胞毒性,且未观察到Gluc高表达,表明5种MS/PBAT多组分迁移物在活化条件下均未产生遗传毒性。微量波动Ames试验结果表明,在活化和非活化条件下,MS/PBAT的5种多组分迁移物3.05和12.20 g·L^(-1)作用于TA98和TA1002种菌株,致突变阳性孔的数量均不超过溶剂对照组的2倍,即均未产生致突变作用;作用于CHL细胞后的细胞染色体畸变率亦均无显著变化。结论初步建立了基于GADD45α基因的遗传毒性高通量筛选方法BSHC,提示可用于食品接触材料多组分迁移物的体外遗传毒性评价,但仍需进一步探索其最低有效浓度,并应用更多种类混合物进行进一步验证。

循环物料在烧结机的综合利用研究实践

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