Emerging low-density polyethylene/paraffin wax/aluminum composite as a form-stable phase change thermal interface material

Thermal interface materials(TIMs) play a vital role in the thermal management of electronic devices and can significantly reduce thermal contact resistance(TCR). The TCR between the solid–liquid contact surface is much smaller than that of the solid–solid contact surface, but conventional solid–liquid phase change materials are likely to cause serious leakage. Therefore, this work has prepared a new formstable phase change thermal interface material. Through the melt blending of paraffin wax(PW) and low-density polyethylene(LDPE), the stability is improved and it has an excellent coating effect on PW. The addition of aluminum(Al) powder improves the low thermal conductivity of PW/LDPE, and the addition of 15wt% Al powder improves the thermal conductivity of the internal structure of the matrix by 67%. In addition, the influence of the addition of Al powder on the internal structure, thermal properties, and phase change behavior of the PW/LDPE matrix was systematically studied. The results confirmed that the addition of Al powder improved the thermal conductivity of the material without a significant impact on other properties, and the thermal conductivity increased with the increase of Al addition. Therefore, morphologically stable PW/LDPE/Al is an important development direction for TIMs.

Properties of Compound Systems of Paraffin Wax Emulsion and Copper Azole and Treated Wood

[Objective]Preservation and waterproof treatment are two crucial parts in wood protection, which can not only extend the service time, but also expand the application range of wood products. [Method] This work combined CA with paraffin wax emulsion to treat wood samples, and basic properties of the compound system, such as stability （storage stability and centrifugal stability）, particle size and pH val-ue, and water repel ency （water absorption, shrinkage and swel ing） of treated sam-ples were investigated. [Result and Conclusion] 1） the compound systems of CA and paraffin latex had a favorable miscibility and stability; 2） compared with untreated wood, CA-treated samples showed poor water repel ing properties, whereas samples treated with the compound systems indicated an obvious reduction in water absorp-tion, and the shrinkage and swel ing of them were improved as wel .

Molten solvent extraction behavior of trivalent La, Sm, Dy, and Yb with tri-n-butyl phosphate into molten paraffin wax at 60 ℃

The extraction behavior of La^3+, Sm^3+, Dy^3+, and Yb^3+ insodium acetate-acetic acid medium was studied with tri-N-butylphosphate (TBP) at 60 deg. C using paraffin wax as a diluent. Theextraction percentage is greater than 85/100 in the pH range of 6 to8. The result of slope analysis method indicates that thecompositions of the extracted species are different between the lightand heavy rare ear this. The formula of the extracted species isfound to be La (TBP) (OH) (Ac)_2 for La^3+ and Yb (TBP) (OH)_3 forYb^3+. The effects of extracting time, the concentration of TBP inthe organic phase and salts on the extraction efficiency were alsodiscussed.

Direct incorporation of paraffin wax as phase change material into mass concrete for temperature control: mechanical and thermal properties

Taking advantage of heat absorbing and releasing capability of phase change material(PCM),Paraffin wax-based concrete was prepared to assess its automatic temperature control performance.The mechanical properties of PCM concrete with eight different Paraffin wax contents were tested by the cube compression test and four-point bending test.The more Paraffin wax incorporated,the greater loss of the compressive strength and bending strength.Based on the mechanical results,four contents of Paraffin wax were chosen for studying PCM concrete's thermal properties,including thermal conductivity,thermal diffusivity,specific heat capacity,thermal expansion coefficient and adiabatic temperature rise.When the Paraffin wax content increases from 10%to 20%,the thermal conductivity and the thermal diffusivity decrease from 7.31 kJ/(m·h·°C)to 7.10 kJ/(m·h·°C)and from 3.03×10−3 m2/h to 2.44×10−3 m2/h,respectively.Meanwhile the specific heat capacity and thermal expansion coefficient rise from 5.38×10−1 kJ/(kg·°C)to 5.76×10−1 kJ/(kg·°C)and from 9.63×10−6/°C to 14.02×10−6/°C,respectively.The adiabatic temperature rise is found to decrease with an increasing Paraffin wax content.Considering both the mechanical and thermal properties,15%of Paraffin wax was elected for the mass concrete model test,and the model test results confirm the effect of Paraffin wax in automatic mass concrete temperature control.

Effects of Preparation Parameters on Paraffin Wax Microemulsion

The paraffin wax microemulsion was prepared from fully refined paraffin wax No.58-60 in the presence of a nonionic surfactant and an anionic surfactant.The influence of manufacturing parameters on the particle diameter of paraffin wax microemulsion included the quantity of the emulsifier,the temperature and emulsification time,the stirring speed,the pH value and the auxiliary ingredient(cosurfactant).The test results showed that the temperature of emulsification had little effect on the particle size of paraffin wax microemulsion in a temperature range of 75-85 ℃.Other manufacturing parameters all had a great effect on the particle size of paraffin wax microemulsion.The optimum preparation conditions included:a w(emulsifier) of 6%,an emulsification temperature of 80 ℃,an emulsification time of 40 min,a pH value of about 8,and a stirring speed of 600 r/min,with n-amyl alcohol serving as the co-surfactant.Under these conditions,a translucent and baby blue paraffin wax emulsion was prepared with its particle size equating to 97 nm.

The Thermodynamic Model on Paraffin Wax Deposition Prediction

In process of crude oil production and transportation, wax and other solid deposition issues have a significant impact on oilfield production. Solid precipitation not only reduces the production efficiency and increases the cost of production. Therefore, there is a need to study the rate of paraffin wax deposition and cloud point temperature in order to guide the oil field control the paraffin wax deposition. In this paper, we use the Flory theory of polymer solution to correct the liquid activity coefficients, and regular solution theory to correct for the non ideality of the solid mixture, and we consider the impact of isoparaffin. Finally, thermodynamic model is established. The actual example calculation shows that the forecast results of this model are more accurate.

Preparation and Characterization of High Content Paraffin Wax Microcapsules and Micro/Nanocapsules with Poly Methyl Methacrylate Shell by Suspension-Like Polymerization

The suspension-like polymerization method is used to obtain poly methyl methacrylate （PMMA）/paraffin wax microcapsules and micro/nanocapsules with high core content. Particle size distribution （PSD） analysis indicates that the average particle size of microcapsules is 94 μm, and the size of micro/nanocapsules ranges in 0.1-19 μm. Differential scanning calorimetry （DSC） and thermalgravimetric analysis （TGA） results show that the fabricated paraffin contents in microcapsules and micro/nanocapsules are as high as 89.5 wt% and 80~2 wt%, respectively with good thermal stability. Thermal cycling tests justify that both the microcapsules and micro/nanocapsules have good thermal reliability with respect to the changes in their thermal properties after 1000 thermal cycling. This work pro- vides a novel method to prepare microcapsules and micro/nanocapsules with high core content which may benefit further study on thermal energy storage.

Synergistic Extraction of Rare Earth Ions by 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone and Trioctylphousphine Oxide in Paraffin Wax

The paraffin wax was used as an organic solvent for 1 phenyl 3 methyl 4 benzoyl 5 pyrazolone (PMBP) and trioctylphousphine oxide (TOPO) in the extraction of rare earth ions (La 3+ , Pr 3+ , Eu 3+ , Yb 3+ and Ho 3+ ) at 70℃. The composition of the extracted specices were given as RE(PMBP) 3(TOPO) 2 by means of slope analysis. The variation of the synergistic extraction equilibrium constant ( K sex ) was studied at 55℃～70℃. The thermodynamic data obtained showed that the synergistic extraction of rare earth ions by PMBP and TOPO in molten paraffin wax is exothermic and the extracted complexes were formed by TOPO bonding to the outer sphere hydration.

An optimized protocol using Steedman’s wax for high-sensitivity RNA in situ hybridization in shoot apical meristems and flower buds of cucumber

In situ mRNA hybridization(ISH)is a powerful tool for examining the spatiotemporal expression of genes in shoot apical meristems and flower buds of cucumber.The most common ISH protocol uses paraffin wax;however,embedding tissue in paraffin wax can take a long time and might result in RNA degradation and decreased signals.Here,we developed an optimized protocol to simplify the process and improve RNA sensitivity.We combined embedding tissue in low melting-point Steedman’s wax with processing tissue sections in solution,as in the whole-mount ISH method in the optimized protocol.Using the optimized protocol,we examined the expression patterns of the CLAVATA3(CLV3)and WUSCHEL(WUS)genes in shoot apical meristems and floral meristems of Cucumis sativus(cucumber)and Arabidopsis thaliana(Arabidopsis).The optimized protocol saved 4–5 days of experimental period compared with the standard ISH protocol using paraffin wax.Moreover,the optimized protocol achieved high signal sensitivity.The optimized protocol was successful for both cucumber and Arabidopsis,which indicates it might have general applicability to most plants.

Characterization and manufacturing of a paraffin wax as fuel for hybrid rockets

The hybrid propulsion performed with paraffin waxes exhibits most attractive capabilities compared to solid or liquid engines,e.g.,throttleability and re-ignition,alongside higher regression rates compared to the conventional hydroxyl terminated polybutadiene(HTPB)hybrid fuel.This is because the paraffin wax forms a thin and hydro-dynamically unstable liquid layer,and then enhances the regression rate with the entrainment of droplets from the liquid-gas interface.Nevertheless,some critical open points on the manufacturing of the paraffin fuel grains still persist,because the paraffin wax exhibits high shrinkage during the solidification phase,leading to the formation of cavities,cracks and internal rips,which may be detrimental to the mechanical properties and the structural integrity of the fuel grain.In this context,this paper deals with a wide calorimetric,thermo-mechanical and physical characterization of the paraffin wax selected to manufacture the hybrid rocket engines(HRE)fuel grain,in order to gain a thorough knowledge of the material necessary to avoid the formation of critical defects.Several manufacturing methods were investigated,and it was found that only laboratory scale processes,based on the use of a heated circular mould-piston apparatus,are able to avoid the formation of critical defects,with the application of both high temperature and pressure.

Investigation of adsorption behaviors of paraffin waxes on iron, iron oxide, and iron Ⅲ oxide pipeline's internal surfaces using adsorption locator model

Wax deposition in pipelines leads to pressure drop,reduced effective cross-sectional area,and blockages.Although mathematical models and experimental loops were used to model wax precipitation on pipeline surfaces,its prediction at molecular levels is not fully recognized.Molecular dynamics is another powerful approach that can predict wax precipitation at the molecular level.This paper uses molecular dynamics simulations with the adsorption locator model found in Material Studio Software to investigate the adsorption behaviors of Icosane-C20H42,Docosane-C22H46,and Tetracosane-C24H50 paraffin waxes on the Fe,FeO,and Fe2O3 pipeline internal surfaces.Modeling is performed by varying temperature values and validated with experimental data.It was found that as the temperature altered,the adsorption energies,probability energy distribution and adsorption density field on the surfaces also changed;on the other hand,the energetic analysis results showed adsorption energies increase with carbon numbers increase due to its larger surface contacting areas and lower aspect ratio,which resulted in stronger interaction with the surfaces.Further,paraffin waxes showed to adsorb easily on Fe surfaces than oxide surfaces.At temperatures below Wax Appearance Temperature(WAT)on both simulations and experiments showed wax deposition.The lower adsorption energy capacity observed on the Fe2O3 pipeline surface confirms it's vitality and suitability for crude oil transportation pipelines surface lining material.

用于加热卷烟的石蜡改性二醋酸纤维素降温滤嘴的制备与表征

以二醋酸纤维素滤棒为载体,以食品级石蜡为相变吸热材料,采用浸渍法制备了石蜡/醋纤降温滤棒,研究了石蜡熔点和负载量对加热卷烟主流烟气温度的影响,并采用热重/差热分析仪(TG/DTA)、傅里叶变换红外光谱仪(FT-IR)、差示扫描量热仪(DSC)和场发射扫描电子显微镜(SEM)等技术对石蜡/醋纤滤棒进行了表征。石蜡/醋纤滤棒是通过醋纤滤棒的吸附作用完成复合,在抽吸过程中具有良好的热稳定性,当52~#石蜡乳化液质量分数为60%时,即石蜡负载量为35 mg时,由石蜡/醋纤滤棒组成的三段式降温滤嘴对主流烟气具有显著的降温效果,可将主流烟气温度从68℃降低到42℃。

不同温度条件下相变石蜡力学性能分析

对3种不同相变温度的石蜡材料(PCM-28、PCM-18和PCM-10)在不同温度下的基本力学性能参数进行了系统的压缩实验,计算出对应的弹性模量和泊松比。结果表明:PCM-18和PCM-10的抗压强度随温度的降低而有所提高,但PCM-28的抗压强度随温度的降低反而呈现出下降趋势。在单轴压缩条件下PCM-28和PCM-18的应力-应变曲线主要经历了压实阶段、弹性变形阶段、裂纹扩展阶段和裂纹后破坏阶段4个明显阶段,最终表现为脆性破坏。PCM-10在经历压实阶段和弹性变形阶段后进入塑性阶段,曲线发展近似水平,且整个过程无明显裂纹出现。

2010年以来国内外石蜡市场分析及展望

近些年欧美市场合成蜡和其他替代产品的发展,压缩了石蜡的消费增长空间。2020年新冠病毒疫情导致全球石蜡需求下降,消费规模退回到2015年的水平。2020—2025年全球石蜡需求将在低基数上稳定增长,但随着合成蜡和环境友好型包装物的使用增加,全球石蜡需求增长空间有限。中国是世界上重要的石蜡生产和出口国,石蜡及其制品的国外市场消纳度已达到70%左右。未来中国石蜡消费量将稳中趋升,预计2025年消费量在90万吨左右;生产企业继续减少,但总生产能力相对稳定。延伸石蜡产业链,提高石蜡制品附加值,做大国内市场,降低对国外市场的依赖程度,是中国石蜡市场未来的发展方向。

含强化肋的PCM相变储热与传热特性数值研究

为了有效提升PCM相变储热器的性能,本文采用多种金属翅片对相变过程进行强化,并采用焓-多孔介质模型对相变储热过程进行了数值模拟,分析了不同金属材料和不同基体孔隙率对相变储热及传热特性的影响.研究结果表明,采用金属泡沫强化翅片能够增强导热和对流效应,优化流场对流涡分布,储热器相变储热时间大大缩短,耗时仅为无翅片工况的16.8%;采用铜金属泡沫翅片的储能效率略优于铝金属泡沫翅片,储热时间缩短3.47%;强化翅片孔隙率对储热性能影响较弱,孔隙率为0.4时最优,孔隙率为0.6时次之,孔隙率为0.8时最差.

石蜡与氨基酸废母液粉配施对烟草重金属Cd吸附的阻控效应

烟草是强富集镉(Cd)的重要经济作物.为降低烟草对Cd的吸收,以矿区污染土壤(Cd含量为0.678 mg·kg^(−1))为种植基质,烟草专用肥(硝态氮)为对照,氨基酸母液粉为新型氮肥(氨基氮),并分别配施作为土壤微生物碳源的食品级石蜡,以期促进土壤微生物种群与数量的持续增加(石蜡降解速度缓慢),通过微生物的生化调控达到降低土壤有效态Cd含量,从而减少烟叶对镉的吸收.结果表明:(1)石蜡和氨基酸废母液粉配施(T4处理)显著(P<0.05)提高土壤微生物丰富度,ACE指数达到4464.47,Chao1指数达到3888.30,氨基酸废母液粉(T3处理)土壤微生物多样性最好,Shannon指数达到6.4066;(2)施加氨基酸废母液粉(T3、T4处理)可显著(P<0.05)提高土壤pH值,3个时期(烟叶旺长期、打顶期、成熟期)最大提高量分别为0.23、0.49和0.35;(3)石蜡和氨基酸废母液粉显著(P<0.05)降低土壤有效态Cd含量,3个时期较烟草专用肥组(T1处理)分别降低了14.8%—20.7%、18.6%—34.5%、20.5%—36.7%;(4)石蜡和氨基酸废母液粉显著(P<0.05)降低烟叶Cd含量,3个时期较烟草专用肥(T1处理)分别降低了0.6%—10.2%、8.2%—26.2%、13.8%—38.9%.因此,石蜡和氨基酸废母液粉配施能够有效提高土壤微生物丰富度和多样性,降低土壤有效态Cd含量,减少烟草对Cd的吸收.

差示扫描量热法测定石蜡熔点的研究

采用差示扫描量热(DSC)技术,模拟石蜡熔点(冷却曲线法)测试过程,测定石蜡的熔点。研究了起始温度、终止温度、吹扫气(氮气)流量、升降温速率、试样质量、恒温时间、样品制备方式、升降温次数等对测试结果的影响,确定了DSC法测定石蜡熔点的适宜条件,考察了DSC法与标准方法(GB/T 2539—2008)的偏倚。结果表明,采用DSC法测定石蜡熔点时的升温速率宜为10℃/min,降温速率宜为5℃/min,试样在高于预估熔点20~30℃下熔融时间不应超过1 h。通过采用6台不同型号的DSC仪器对14个牌号石蜡样品进行测试,计算出DSC法与标准方法的偏倚为-1.14℃。DSC法操作简单、试样用量少、检测速率快、重复性好,可作为控制分析手段,快速准确地测定石蜡的熔点。

Hydrocarbon-Degrading Bacteria and Paraffin from Polluted Seashores 9 Years after the Nakhodka Oil Spill in the Sea of Japan

Pollution of petroleum hydrocarbons, in particular oil spills, has attracted much attention in the past and recent decades. Oil spills influence natural microbial community, and physical and chemical properties of the affected sites. The biodegradation of hydrocarbons by microorganisms is one of the primary ways by which oil spill is eliminated from contaminated sites. One such spill was that of the Russian tanker the Nakhodka that spilled heavy oil into the Sea of Japan on January 2, 1997. The impact of the Nakhodka oil spill resulted in a viscous sticky fluid fouling the shores and affected natural ecosystems. This paper describes the weathering of hydrocarbon-degrading bacteria （genus Pseudomonas） and crystallized organic compounds from the Nakhodka oil spill-polluted seashores after nine years. The Nakhodka oil has hardened and formed crust of crystalline paraffin wax as shown by XRD analysis （0.422, 0.377, and 0.250 nm d-spacing） in association with graphite and calcite after 9 years of bioremediation. Anaerobic reverse side of the oil crust contained numerous coccus typed bacteria associated with halite. The finding of hydrocarbon-degrading bacteria and paraffin wax in the oil crust may have a significant effect on the weathering processes of the Nakhodka oil spill during the 9- year bioremediation.

浸石蜡对碳滑板载流摩擦磨损性能影响研究

为研究在载流条件下浸石蜡对碳滑板摩擦磨损性能的影响,在环-块载流摩擦磨损试验台上试验浸石蜡、未浸石蜡2种纯碳滑板与铜银合金接触线在载流条件下的摩擦磨损性能,并对比碳滑板在不同载荷、滑动速度、电流情况下的表面形貌变化。试验结果显示,浸石蜡对碳滑板载流摩擦磨损性能的影响与电弧烧蚀紧密相关。石蜡及其有机产物加剧电弧烧蚀,石蜡的不完全分解会削弱滑板的载流摩擦磨损性能,通过减小法向载荷、加快滑动速度、增大电流均能显著加剧浸石蜡碳滑板在试验中的电弧烧蚀。浸石蜡碳滑板的摩擦系数的变化规律是:随法向载荷、电流的增大呈现减小的趋势,随滑动速度的增加先增大后减小,60km/h时摩擦系数最大;浸石蜡碳滑板的平均电弧能量、磨耗量随法向载荷的增大呈现减少的趋势,随电流的增大而增加,平均电弧能量随滑动速度的增加而增大,磨耗量随滑动速度的增加先增加后减少,60km/h时磨耗量最大;在低速(40km/h)和高速(80km/h)时浸石蜡增强碳滑板的耐磨性能。