Planetary Mixer Research Articles

Carbon nanotube functionalization supports mechanical, tribological, and biological response of freeze‐dried ultra‐high molecular weight polyethylene‐based bio‐composites

AbstractAcetabular cup liners made of ultra‐high molecular weight polyethylene (UHMWPE), in hip implants fail mostly due to wear debris generation and poor wear resistance. Consequently, strengthening UHMWPE becomes essential. The current work exhibits how the addition of 5 vol% carbon nanotubes (CNT) and functionalized carbon nanotubes (fCNT) in UHMWPE (denoted as U) affects the mechanical properties (hardness, elastic modulus) and tribological properties (wear resistance) of biocomposites. To form a composite, powders were mixed using a planetary centrifugal mixer followed by freeze‐drying to disperse‐CNTs, followed by its compression molding at 220°C for 1 h at 10 MPa. With the addition of CNT and fCNT, ≥95% densification was obtained for all samples resulting an increase in hardness and elastic modulus from 74.96 MPa to 168.11 MPa (124%) and 1.65 GPa to 2.96 GPa (79%), respectively, which led to the reduction in wear rate from 12.5 × 10−5 mm3/Nm (U) to 2.5 × 10−5 mm3/Nm (UfCNT). The amount of apatite formation enhanced from U (58.2%) to UfCNT (65.1%) is confirmed via X‐ray diffraction and X‐ray photoelectron spectroscopy. Cell proliferation studies have validated the cytocompatible efficacy of U‐CNT composites with osteoblast‐like MG‐63 cells, making UfCNT as potential material for acetabular cup liners.

The Influence of Calendering Process on the Graphite Anode

Calendering, or pressing, is the final property-defining process for battery electrode manufacturing to maximize the volumetric capacity of the cell through the compaction of an electrode between two large calender rollers12. On one hand, it can reduce the porosity of battery materials thus increase the conductivity of the materials. On the other hand, it can control the thickness of the electrodes, making sure it is uniform and proper thickness to guarantee the minimal variation in the cell thickness, reaching even stack pressure for module assembly and impacting the thermal management [3]. The calendering process significantly influence the performance of lithium-ion battery (LIB).Graphite anode coating on Cu foil was chosen as our baseline coating for this calendering process investigation. The slurry was mixed in a planetary and dispersive mixer and then coated using reverse comma coating method by a scale-up coater with drying zones of 70 °C. Then the coating was calendered by a calendering machine at various conditions.Calendering, though seemingly a simply process, is influenced by several different parameters significantly. In this study, we systematically investigated the calendering process by carrying-out a Design-of-experiment (DOE). The following calendering parameters were investigated: the parameters of calendering machine gap size, calendering pressure, and the speed of the coating web. The calendered graphite coating was then measured for the morphology by scanning electron microscopy (SEM), the pore size change by BET surface area measurement, and Direct current internal resistance (DCIR) by building half cells and cycling and Electrochemical Impedance Spectroscopy (EIS) at 50% State-of-Charge (SOC).The result showed that pressure is the most critical parameter for calendering and the internal resistance and ionic conductivity changes in response to the calendering parameters. The half-cell with calendering at the pressure of 37 MPa, gap size targeted for 30% porosity, the BET surface area around 0.75 m2/g showed highest cell capacity and lowest internal resistance.

Optimum analysis of inclined angle of mixing blades in planetary mixer based on discrete element method

Optimum analysis of inclined angle of mixing blades in planetary mixer based on discrete element method

Estimation of mean shear rate in a vessel of a planetary centrifugal mixer based on the heat balance equation

A planetary centrifugal mixer can fluidize highly viscous fluids in a vessel by strong centrifugal force. Although high rotation and revolution speeds are effective for particle dispersion, experimental observation and numerical simulation of the fluid flow in a moving vessel with a gas-liquid interface have not been well studied. Therefore, we propose the methodology to estimate a shear rate, which dominates the particle dispersion, by the temperature measurement. We measured the fluid and gas temperatures during mixing and used the heat balance equation to estimate the viscous dissipation rate, providing the mean shear rate. As a result, the effect of the mixing conditions on the mean shear rate has been clarified. Furthermore, the ratio of centrifugal force to viscous force helps identify the viscous dominant region, where not only a considerable rotation speed of the vessel but also a large revolution radius is helpful to increase the shear rate.

Investigation of the mechanical properties of magnesium chloride on magnesium oxide improved kaolin clay

In our study, samples were prepared by mixing 2%, 4%, and 6% MgO doses with the dry weight of kaolin-type low-plastic clay. In each MgO dose, 1% and 2% of the soil weight, respectively, MgCl2 chemicals were added, and all samples were mixed at the optimum water content ratio (16.2%). All components were mixed with a planetary mixer for 10 minutes until homogeneous, and then the mixture was poured to have 25 blows for 5 layers. All samples were cured under room conditions for 3–10 days to be tested on the Unconfined Compression Test. From the results, it was observed that the undrained shear strength of the sample increased as the percentages of MgCl2 and MgO rose. It can be said that the interaction between MgO and MgCl2 contributes to the cementation of the clay, and sorel cement plays a role in the mechanical strengthening of kaolin clay based on its effect on strength development. Extending the curing time also developed the mechanical properties of kaolin clay and improved the hardness of the samples by increasing the elastic modulus. In this way, early failures were attained at early strains, and the ductility of the samples increased. We finally saw that the mixture of MgO and MgCl2 worked well as a building material for kaolin clay. The study also tried to get rid of some of the problems that come up with filling materials used in geotechnical engineering and shoring projects, like swelling, shrinkage, and low mechanical properties.

Enhancing Thermomechanical Strength and Thermal Stability of Poly(dicyclopentadiene) Composites through Cost-Effective Fly Ash Reinforcement for Structural and Impact Applications.

Poly(dicyclopentadiene) (poly-DCPD) is a thermoset with potential for high-performance applications. In this research, epoxy resin was blended with different concentrations of fly ash class F particles at 0.0, 1.0, 10.0, and 50.0 wt.%, aiming to improve its use as a high-volume structural material by decreasing costs and reducing its negative environmental impact through using fly ash particles. A planetary Thinky mixer was used to initially mix the resin with the curing agent, followed by incorporating a Grubbs catalyst. The microstructures were analyzed using scanning electron microscopy (SEM), where particles were found to be homogeneously distributed over the polymer matrix. The thermomechanical behavior was evaluated via curing, compression, dynamic mechanical analysis (DMA), and thermo-gravimetric analysis (TGA). Nanoindentation tests were also conducted. Fly ash was found to decelerate the curing of the resin through the release of calcium ions that enhanced the exothermic reaction.

Scalable processing parameters to fabricate silicon elastomer microparticles using a blade-free planetary mixer with a thixotropic medium

The development of biomedical devices and soft robotics has spurred the utilization of silicone elastomers. Converting these polymers into particulates is increasingly important for their application to advanced materials and processes. However, the highly viscous nature of silicone resins, resulting from their long polymer chains, makes it challenging to fabricate them as particulates. Recently, a blade-free planetary mixer has been used to effectively emulsify viscous resins in a thixotropic medium. However, the particle fabrication process has not yet been examined to gain full control over the produced microparticles. This study presents key processing parameters for the fabrication of silicone elastomer microparticles in a sodium alginate medium using a blade-free planetary mixer. The experimental results show that stirring speed, stirring time, and medium concentration are the determining factors for controlling the particle size distribution. The variation in particle size by parameters exhibits differences depending on the viscous-to-elastic transition of the medium.

EVALUATION OF THE CURING KINETICS OF A POLYMER MATRIX COMPOSITE USING A SENSOR CONTAINING AN ELECTRICALLY CONDUCTIVE FILLER

In this work, the kinetics of the curing of fabric GFRP was carried out by measuring the parameters of its electrical conductivity. A compound of epoxy resin (ED-20), plasticizer (DBF) and hardener (PEPA) with the addition of finely milled graphite (FMG) was used as a matrix. To en-sure high-quality mixing of FMG in epoxy resin, a planetary mixer was used. Plain weave glass tape 0.2 mm thick with two woven wires was impregnated with a matrix compound. This tape was placed onto a beam 4 mm thick made of typical GFRP as an external electrically conductive functional sensor (FS). During curing at room temperature, periodic measurements of the electrical conductivity of the FS and the stiffness of the beam with FS in three-point bending were carried out. The amount of FMG into the matrix compound was below the percolation threshold; there-fore, electrical measurements of FS required alternating current. The dependence of the imped-ance on the current frequency (from 10 Hz to 1 MHz) was recorded. Comparison of the change in FS electrical impedance with the change in the beam stiffness during the curing showed their close correlation. The proposed method of measuring the FS impedance can be used to assess the degree of curing of the polymer matrix in critical large-sized composite products during the manufacturing process.

Framework for choosing energy efficient mixing equipment whatever motions it induces: Example of application for planetary and helical ribbon mixers

Energy savings in industrial processes have become one of the main goals of the current society. This paper aims to propose a systematic approach for the assessment of mixing equipment energy performance for highly viscous fluids. The framework is illustrated and applied by performing a rational comparison of the homogenization efficiency of classical mixing systems (involving an agitator revolving around a vertical axis centred in the tank) with that of planetary mixers when mixing highly viscous fluids. For that purpose, the pioneering framework of Zlokarnik is first reminded and its limitations with regard to non-traditional mixing equipment are discussed. Then, the theoretical background to extend this approach to these latter is presented. Experimental data on power consumption and mixing time are provided to demonstrate the applicability of the present frame. The results illustrated that a planetary mixer can be an economic solution for performing highly viscous fluids homogenization.

Numerical Analysis of Viscous Polymer Resin Mixing Processes in High-Speed Blade-Free Planetary Blender Using Smoothed Particle Hydrodynamics

High-speed planetary mixers can rapidly and efficiently combine rheological liquids, such as polymer resins and paste materials, because of the large centrifugal forces generated by the planetary motion of the mixing vessel. Only a few attempts have been made to computationally model and analyze the intricate mixing patterns of highly viscous substances. This paper presents meshless flow simulations of the planetary mixing of polymeric fluids. This research utilized the smoothed particle hydrodynamics (SPH) approach for numerical calculations. This method has advantages over the finite-volume method, which is a grid-based computational technique, when it comes to modeling interfacial and free surface flow problems. Newtonian rheology and interfacial surface force models were used to calculate the dissipative forces in the partial differential momentum equation of fluid motion. Simulations of the flow of an uncured polyurethane resin were carried out while it was mixed in a planetary mixer, under various operating conditions. Simulations using SPH were able to accurately reproduce the intricate flow and blending pattern, providing insight into mixing mechanics and mixing index evolution characteristics according to operating conditions for the planetary mixing of polymeric fluids. The simulation results showed that the spiral band, which promotes the mixing performance, is densely and distinctively formed under high-speed operation conditions.

Effect of nanosilica on low‐velocity impact and compression after impact properties of continuous carbon fiber‐reinforced epoxy composites manufactured by 3D printing

AbstractTo improve the low‐velocity impact (LVI) and compression after impact (CAI) properties of three‐dimensional (3D)‐printed continuous carbon fiber‐reinforced epoxy composites (CFRC), nanosilica (NS) was incorporated into these composites. NS (0.5 and 1 wt%) was dispersed in a liquid epoxy matrix by ultrasonication and mechanical stirring before mixing in a planetary mixer. The addition of NS up to 1 wt% did not render any processing barrier during the extrusion followed by the automated tape placement (ATP) method, adopted in this study. The resulting “hybrid” laminates showed void content <1% and had minimal internal defects as ensured by nondestructive technique (C‐scan) and scanning electron microscopy. The neat and NS‐loaded CFRPs were subjected to an impact energy of 6 J mm−1. The rebound energy increased by ~36% with the addition of 1 wt% NS as compared to unfilled samples, obtained from the LVI test. The CAI results suggest that with 1 wt% NS the residual compressive strength increased by ~13% in comparison with the neat CFRP laminates. After impact, the damage area was reduced significantly, that is, ~62% with the addition of 1 wt% NS in comparison with the neat CFRP laminates.

Dry liquid metals stabilized by silica particles: Synthesis and application in photothermoelectric power generation

HypothesisGallium-based room-temperature liquid metals (LMs) have unique physicochemical properties; however, their high surface tension, low flowability, and high corrosiveness to other materials limit their advanced processing (including precise shaping) and application. Consequently, LM-rich free-flowing powders, named “dry LMs” that offer the inherent advantages of dry powders, should play a critical role in expanding the application scope of LMs. ExperimentsA general method of preparing silica-nanoparticle-stabilized LMs in the form of LM-rich powders (>95 wt% LM) is developed. FindingsDry LMs can be simply prepared by mixing LMs with silica nanoparticles in a planetary centrifugal mixer in the absence of solvents. As a sustainable dry-process route alternative to wet-process routes, this ecofriendly and simple method of dry LM fabrication has several advantages, e.g., high throughput, scalability, and low toxicity owing to the lack of organic dispersion agents and milling media. Moreover, the unique photothermal properties of dry LMs are used for photothermal electric power generation. Thus, dry LMs not only pave the way for the use of LMs in powder form but also provide a new opportunity for expanding their application scope in energy conversion systems.

Digital evaluation of planetary concrete mixer efficiency

Accurately evaluating the mixing efficiency of a planetary concrete mixer is the linchpin of estimating the rationality of the mixer structure, but it is currently difficult to establish a general and systematic evaluation method. This paper proposed a digital method for evaluating the planetary mixer efficiency based on the kinematic model of the mixing blade. The mixing efficiency of two typical symmetrical and asymmetrical planetary mixers was compared based on the digital data computed using the proposed method. An automated concrete mixing platform was established to experimentally validate the digital evaluation method. The results indicated that the asymmetric planetary mixer had higher mixing efficiency than the symmetric mixer. Additionally, the mixing efficiency of symmetric mixer increased about 18% as the angle between the two planetary arms changed from 90° to 45°, which was due to the difference in the coverage of the mixing blades on the mixing surface.

Applicability of cementitious capsules in concrete production: initial assessment on capsule robustness, mechanical and self-sealing properties of concrete

The use of macrocapsules in self-healing applications offers a potential benefit by carrying a larger amount of healing agent in comparison with microcapsules. However, the application of macrocapsules is still limited to paste and mortar levels on lab-scale. This is due to a concern that most capsules might be broken when mixed with concrete components. In this study, cementitious tubular capsules were used and they were considered as a partial replacement of coarse aggregates (2 vol% gravel). The capsules have a dimension of 54 mm and 9 mm in length and outer diameter, respectively. A water-repellent agent (WRA) was entrapped in the capsules as a proposed agent to seal the crack. Initial results revealed high survivability of capsules during concrete mixing: 100% survival ratio when tested in a drum mixer and 70–95% when tested in a planetary mixer. The mechanical and self-sealing properties of concrete containing embedded capsules were evaluated. With the addition of capsules, around 8% reduction of compressive strength was noticed, but no further effect on splitting tensile strength was detected as compared with concrete without capsules. Ultrasonic pulse velocity (UPV) tests confirmed that the presence of capsules also did not significantly affect the compactness of the hardened concrete. Furthermore, the embedded capsules were able to break when a crack was introduced and it was found that 90% sealing efficiency was achieved by capsule-based concrete as a result of the successful release of sealing agent into the crack.

THE MECHANICAL MIXING EFFICIENCY IMPROVING AT FEED PREPARATION BY MIXERS’ DESIGN PROGRESS

The main directions of mixers’ productivity increasing and shredders-and-feed mixers of continuous and periodic action at small and mediumsized livestock enterprises of APK are considered. One of the ways of feed grinding and mixing’s machines productivity increasing is the working bodies’ design to improve, that includes the working bodies of sharpening angles’ cutting edges so as the gaps between the working bodies optimizing, a constructive possibility of changing the angles at cutting working bodies’ turns inclination creating in the depending on the mixed material resistance. Another direction is the working bodies drive’s improvement -trajectory’s optimization and working bodies’ movement speeds, the hollow shaft’s at drive designs using. As examples of these directions implementation, a vertical screw of shredder-and-mixer feeder designs with a screw working body as an active countercutting element and a planetary screw mixer with a hollow shaft at the working bodies’ drive using, that is the conical gearbox’s body simultaneously, are presented. As a result of the presented machines’ improvement, the energy efficiency and mixing performance by energy losses reducing at the working bodies movement and mixed material’s resistance, as well as the structures’ metal consumption reducing are increased. At the proposed working bodies using, feed mixture quality is also improved by the material mixing’s intensity and uniformity increasing.

헬리컬리본 임펠러를 포함한 유성 믹서유동의 동역학계 구조 분석 및 유동 정량화

본 연구에서는 헬리컬리본 임펠러를 포함한 유성 교반기의 동역학계 구조 분석 및 유동 정량화를 수행하였다. 교반기 내에 형성되는 수직 방향의 유동 단면을 실험을 통해 관찰하고, 유동 시뮬레이션과 비교하여 3차원 동역학계 구조를 분석하였다. 동역학계 구조는 임펠러와 동일한 속도로 회전하는 두 종류의 비교반영역으로 구성된다. 임펠러 반대편 넓은 영역에 위치한 반달 형상 및 임펠러 주변에 형성되는 실린더 형상의 구조가 있다. 수치해석을 통해 공전 속도와 자전 속도의 변화에 따른 총 에너지 소산율을 정량화 하였다. 자전 속도에 비해 공전 속도가 시스템의 에너지 소산율에 더 큰 영향을 미치며, 자전 및 공전 방향이 반대일 때 총 에너지 소산율이 증가함을 검증하였다.

In English

The mechanical mixtures of titanium oxide (TiO2) with carbon nanostructures for 3D printing of CJP technology, which are used as consumables for the manufacturing of electrically conductive composite 3D products, are created in this work. Various carbon nanostructures (single- and multi-walled carbon nanotubes and carbon nanofibers) were used in the creation of composite 3D products (TiO2–СNS) by CJP 3D printing technology. Optimal conditions for processing of mechanical mixtures (TiO2/MWCNT) on a planetary ball mixer for composite 3D products (CJP) were studied and proposed. The dose of the deformation influence on the mechanical mixture under optimal conditions of mechanochemical processing (76 J/g), which allows not to deteriorate the electrical conductivity of the material, is determined. The dependence of the electrical conductivity of composite 3D products (CNS/TiO2, where the CNS content is 3 wt. %) on the type of carbon nanostructures (SWCNT, MWCNT and CNF) contained in ceramics (TiO2), is constructed. The exponential dependence of the specific electrical conductivity (G) of composite 3D products (TiO2–MWCNT) on the mass content of multi-walled carbon nanotubes, is also recorded in the work. In the framework of the study of the electrical conductivity of composite 3D products (CJP), a fuel cell cathode based on a Pt/TiO2–MWCNT composite was created. It was found that the catalyst Pt/TiO2–MWCNT, which contains 5 wt. % of carbon nanotubes, has the best catalytic activity in oxygen recovery. At the same time, the average particle size of platinum (Pt) is 5–10 nm, while the content of Pt in the EDX samples is approximately ~10 wt. %. Also, studies were carried out from the mixing of Pt/TiO2-MWCNT composites with MWCNT content 15 and 50 wt. %. Samples were analyzed by transmission and scanning electron microscopy.

Synthesis of a novel injectable alginate impression material and impression accuracy evaluation.

This work aimed to synthesize a novel injectable alginate impression material and evaluate its accuracy. Certain proportions of sodium alginate, trisodium phosphate dodecahydrate, potassium fluorotitanate, diatomaceous earth, and other ingredients were dissolved in water and mixed evenly with a planetary centrifugal mixer to obtain a certain viscosity base paste. Certain proportions of calcium sulfate hemihydrate, magnesium oxide, glycerin, and polyethylene glycol (PEG) 400 were mixed evenly with a planetary centrifugal mixer to obtain the reactor paste with the same viscosity as the base paste. The base and reactor pastes were poured into a two-cylinder cartridge at a 2∶1 volume ratio. A gun device was used to accomplish mixing by compressing materials into a mixing tip. The samples were divided into three groups: injectable alginate impression materials (IA group) as the experimental group, and Jeltrate alginate impression materials (JA group) and Silagum-putty/light addition silicone rubber impression materials (SI group) as the two control groups. Scanning electron microscopy (SEM) showed that the injectable alginate impression materials had a denser structure and fewer bubbles than the commercial alginate impression material. The accuracy of the three kinds of impression materials was evaluated by 3D image superposition. The deviations between the three test group models and the standard model (trueness) were 49.58 μm±1.453 μm (IA group), 54.75 μm±7.264 μm (JA group), and 30.92 μm±1.013 μm (SI group). The deviations of the models within each test group (precision) were 85.79 μm±8.191 μm (IA group), 97.65 μm±11.060 μm (JA group), and 56.51 μm±4.995 μm (SI group). Significant differences in trueness and precision were found among the three kinds of impression materials (P<0.05). The accuracy of the new injectable alginate impression material was better than that of the traditional powder-type alginate impression material but worse than that of the addition silicone rubber impression materials. The novel injec-table alginate impression material demonstrated good operation performance and impression accuracy, showing broad application prospect.

Scalable Mechanochemical Synthesis of β-Ketoenamine-linked Covalent Organic Frameworks for Methane Storage.

In the current scenario of increased pollution and releasing toxic gases by burning petroleum products, switching to natural gas is more promising for reducing CO2 emissions and air pollutants. Hence, research on Liquefied Natural Gas and Compressed Natural Gas is gaining more value. However, natural gas primarily consists of CH4 , which has less energy density than conventional fuels. Interestingly, since the C-H ratio of CH4 gas is 1 : 4, it is easily combustible, gives less carbon footprint, and reduces unburnt hydrocarbon pollution. Hence, research on storing and transporting CH4 has utmost importance, and porous materials are one of the suitable candidates for storing CH4 . Herein we report the scalable synthesis of highly porous and crystalline covalent organic frameworks for storing CH4 at room temperature and pressure. Two COFs, namely, Tp-Azo and Tp-Azo-BD(Me)2 , synthesized in 1 kg at ∼45 g batch scale using a Planetary mixer, displayed a maximum BET surface area of around 3345 m2 /g, and 2342 m2 /g and CH4 storage of 174.10 cc/cc and 151 cc/cc, respectively. A comparison of the CH4 sorption of Tp-Azo and Tp-Azo-BD(Me)2 COFs synthesized in different batches has a variation of only ±5 cc/cc and shows the consistency in bulk scale synthesis of COFs. The cyclic equilibrium CH4 adsorption studies showed the COFs are stable with consistent CH4 adsorption and desorption cycles. The present study is a step towards the scalable mechanochemical synthesis of COFs for gas storage applications.

Influence of the Mixing and Dispersing Process on the Slurry Properties and the Microstructure and Performance of Ultrathick Cathodes for Lithium‐Ion Batteries

The influence of industrial‐suited mixing and dispersing processes on the processability, structure, and properties of suspensions and electrodes for lithium‐ion batteries is investigated for the case of ultrathick NCM 622 cathodes (50 mg cm−2). Performed with a 10 dm3 planetary mixer, two different process strategies for the preparation of the suspensions are compared in which 1) all powders are mixed initially and the solvent is added stepwise so that the process starts with very high shear stress or 2) the powders are added stepwise to a binder solution so that lower shear stress is exerted. It is shown that the process strategy and within this, the level of solid content throughout the process as a measure of shear stress strongly affects the properties of the suspensions and the microstructure, mechanical quality, and electrochemical performance of the resulting electrodes. Compared with the more unfavorable processes following strategy: 1) the most beneficial process following strategy 2) leads to a strongly enhanced elasticity of ultrathick electrodes making them suitable for roll‐to‐roll processing and furthermore to a drastic increase of their rate capability expanding their range of outperforming state‐of‐the‐art electrodes regarding energy density to higher current densities.