Screw Rotation Research Articles

Evolution of the Microstructure of PP-LDHs Nanocomposites during Melt Compounding: A Simulation Approach.

In the context of polymer-based nanocomposites containing layered nanofillers, the achievement of good extents of dispersion and distribution of the embedded nanoparticles and, even more, the obtainment of intercalated and/or exfoliated structures through melt compounding still represents a persistent challenge, especially in the case of anionic layered double hydroxides (LDHs)-containing systems and non-polar polymeric matrices. In this work, a simulation approach is proposed to evaluate the influence of the processing conditions on the morphology of polypropylene (PP)-based nanocomposites containing organomodified LDHs. In particular, the effect of the screw rotation speed and the feed rate on the final microstructure of the materials formulated through melt compounding in a twin-screw extruder was assessed. The rheological and morphological characterizations demonstrated that a more homogeneous morphology was achieved when high levels of both exploited processing parameters are selected. The results coming from the simulation of the processing were used to establish some relationships between the flow parameters and the microstructure of the nanocomposites, demonstrating that low residence times coupled with high local shear rates are required to ensure the achievement of homogenous morphologies, likely involving the occurrence of intercalation phenomena.

Development of Feed Expander

The development's objective is to increase productivity and reduce energy consumption in the execution of the technological process of expanded feed preparation while ensuring the necessary quality and safety of the expandates. The rationale for the construction and technological scheme of the feed expander with an improved shaping nozzle has been provided. This nozzle differs in that it consists of a narrowed area of the cylinder, a concave cone, and a crown nut. When heated plasticized mass is moved into the narrowed area of the shaping nozzle, there is an increase in pressure, followed by a sharp decrease after it passes through. This is achieved by increasing the working volume due to the shape of the concave cone. As a result, the plasticized mass expands and exits through the crown nut, forming expandates. Through numerical modelling, the dynamics and distribution of feed mixture components in the cavity between the cylinder of the shaping nozzle and the cone have been determined based on the force of pressure and the force of contact interaction between feed components. This dependence on the radius of narrowing of the cylinder of the shaping nozzle, the radius of the concave cone, and the distance between the cone and the cylinder have been established. Regression equations for the density of the plasticized feed mixture components at the outlet of the shaping nozzle and the maximum pressure required to extrude the plasticized feed components through the shaping nozzle along their movement direction from the specified research factors have been derived. As a result of experimental studies of the compact feed expander, dependencies of the changes in expander productivity, power consumption, the specific energy consumption of the expansion process, and the density of obtained expatriates have been established to the moisture content of the compound feed, the gap between the cone and the nut, and the screw rotation speed.

A new 2.5‐D twin screw extruder melting model with comparisons to data

AbstractMany polymers are processed and compounded in co‐rotating, fully intermeshing twin screw extruders. A typical compounding process consists of multiple unit operations including feed introduction, solids transport, transitioning from the conveying zone to the kneading block melting zone, melting, a downstream feed zone, a mixing zone, a devolatilization region, and a pressure generating discharge section. This paper will focus on the kneading block melting zone which typically includes a reverse pitch element so the kneaders remain full. Mechanisms for flow and energy input to pellets in kneading elements, including friction heating, pellet compression, energy diffusion, and viscous dissipation to form a melt phase: followed by viscous dissipation in a solid pellet/melt slurry, and heat transfer; are developed and implemented in a novel melting model. The model is validated with extrusion measurements and visualizations using low density polyethylene (LDPE). The predictions of the model are also compared with a classical set of experiments using high density polyethylene (HDPE). This paper describes the physics and engineering concepts that the authors feel are inherent in the melting section of the twin screw extruder where a large pressure peak is calculated using the friction and compression of the polymer pellets. The modeled increase in pellet bulk/surface temperature is due to the inclusion of four energy sources, pellet compression, thermal diffusion, friction energy dissipation, and viscous energy dissipation. This combined thermal dynamics based melting model results in a novel melting protocol. The melting mechanisms are coupled to flow regimes in the kneading blocks as melting progresses. The effects of throughput, Q, and screw rotation speed, N, are also examined.Highlights Novel 2.5D melting model for corotating, intermeshing twin‐screw extruders. Energy for melting; friction, deformation, diffusion, and viscous dissipation. The model helps elucidate mechanisms during melting in a twin‐screw extruder.

Investigation of constructive and technological parameters of an energy-efficient screw oil press

The article presents the investigation of constructive and technological parameters of an energy-efficient screw oil press. It is outlined the principle of operation of an energy-efficient screw oil press. The construction of the oil press is improved by the steam atomizer that is installed in the receiving hopper under the rifled rollers for moisture-thermal treatment with steam, which is completed with the heat exchanger, heating element, expansion tank and hydro group. Also, a steam generator connected to a steam atomizer which is embodied into the receiving hopper. It was analyzed the influence of the optimization criteria (oil yield, energy consumption and press productivity) on the efficiency of the technological process. These optimization criteria depend on the main independent factors: the length of the reception and preparation chamber, the material (sunflower pulp) moisture; the heating temperature, the screw rotation speed, the linear speed of movement of screw shaft turns. The optimal constructive and technological parameters of energy-efficient screw oil press are considered. The energy-efficient screw oil press refers to the equipment of the oil enterprises of small productivity and due to its design, it allows to use a simple technological scheme of oil pressing and to reduce the amount of energy and resources spent on the technological process in the context of use in sustainable food systems.

대두 탈지 처리가 식물조직단백 조직화 특성에 미치는 영향

In this study, the quality characteristics of texturized vegetable proteins (TVP) produced from defatted soy flour (DSF) were analytically compared with those of texturized vegetable proteins produced with isolated soy protein (ISP) and non-defatted soy flour (SF). The base raw material formulation consisted of 50% soy proteins, 30% gluten, and 20% corn starch. A cooling die-equipped extruder was used with a barrel temperature set at 190°C and screw rotation speed of 250 rpm. With respect to the hardness of isolate soy proteins, that of soy flour and defatted soy flour was 22.4% and 68.8%, respectively, and gumminess was 17.6% and 44.3%, respectively. Defatting increased chewiness, shear strength, and springiness. Moisture content was higher in soy flour than in defatted soy flour, while there were no significant differences in terms of water absorption and turbidity. The pH was higher with soy flour than with defatted soy flour. Concerning color, the L and b values were higher with soy flour, while the a value was higher with defatted soy flour. These results suggest that defatting soybeans can improve the quality of plant-based proteins. Further research is needed to address the quality differences from those of isolated soy proteins.

Influence of Grinding Degree and Screw Rotation Speed on Sunflower Oil Pressing Process

Sunflower is a major agricultural oilseed crop, and the Republic of Kazakhstan has been steadily strengthening its position as a producer of oilseeds. In this study, an oil pressing machine with two processes, including grinding sunflower seeds and pressing the obtained cake to separate the oil, is constructed. The experiment investigated the impact of different grinding degrees (hole diameters of plates of 5 mm, 4 mm, 3 mm, and 2 mm) and screw rotation speeds (ranging from 30 rpm to 250 rpm) on oil pressing efficiency. The study used sunflower seeds with an oil content of 45–47% and moisture of 7–9%. The results showed that increasing the grinding degree and screw rotation speed led to higher oil yield. The optimal condition was a grinding degree of 4 mm and a screw rotation speed of 60 rpm, resulting in the highest oil yield of 15.6 g/s. Additionally, the residual oil content of the seed cake decreased significantly as pressure increased during pressing, particularly with 4 mm grinding. Power consumption increased with higher screw rotation speeds and finer grinding degrees, indicating the influence of grinding components on energy demand. The cake density increased with higher screw rotation speeds and finer grinding degrees, highlighting the impact of grinding mechanisms on cake compactness. Moreover, the temperature of the cake rose with increased screw rotation speed and the presence of grinding sieves. These findings provide valuable insights into optimizing the sunflower oil pressing process, highlighting the importance of selecting appropriate grinding degrees and screw rotation speeds to maximize oil yield and pressing efficiency.

Experimental Investigation and Optimization of Blow Molding Process Parameters of HDPE Material

Abstract: Optimization of machining processes is essential for achieving higher productivity and high-quality products in order to remain competitive. The objective of this study is to optimize the process parameter of extrusion blow molding process of high density polyethylene (HDPE). In this paper three process parameters namely barrel temperature, Mandrel Position, Screw Rotation. Taguchi Method is a statistical method to improve the process parameters and improve the quality of components that are manufactured. ANOVA has been carried out to identify importance of the operating parameters on the performance characteristics considered. Further the verification experiment has been carried out to confirm the performance of optimum parameters. The results from this study will be useful for selecting appropriate set of process parameters to epoxy coating has been selected. The analysis of variance (ANOVA) has been used to determine effect of each parameter on wear rate so Finally, the confirmation test has been carried out to compare the predicted value of wear rate with the experimental value.

Damage to seeds by screw working bodies

Seed damage caused by screw working bodies of agricultural machines reduces the seed quality and increases the total cost of crop production. This paper describes the impact interaction of a particle with screw flights when seeds are fed into the transportation zone. There are velocity dependences during the impact and reflection of seeds on the screw surface at the maximum distance of the radius from the screw rotation axis. The potential energy lost by seeds when interacting with screw flights is determined. The paper considers the way transporting the seed material by screw working bodies impacts seed damage. The potential energy accumulated after impact by the reflecting surface and the particle depends on the magnitude and direction of the falling velocity to the screw belt, the auger geometric and kinematic parameters (the screw diameter; the inclination angle of the helix to the screw axis and the angular velocity), as well as the physical and mechanical properties of the particle and the reflecting surface (recovery and friction coefficients). Previous studies have shown that the critical angular velocity of the screw flight depends on the screw casing and the reduction factor of the circumferential velocity. In turn, the reduction factor depends on the transported seed material and the geometric parameters of the screw. It is possible to diminish the destruction of the seed material due to impact interaction with the working surface of the screw by reducing the inclination angle of the screw flight α, the angular speed of the screw rotation ω and its radius R. It also requires direct the seed flow closer to the rotation center. Reducing injury to seeds during transportation in a screw device requires a higher critical angular velocity of the screw. To increase the working angular velocity of the screw without exceeding its threshold of critical angular velocity, it is advisable to use screws with a large pitch and polymer screws with a wider pitch.

The Use of Hot Melt Extrusion to Prepare a Solid Dispersion of Ibuprofen in a Polymer Matrix.

In this work, we report the use of the hot melt extrusion method in harsh extrusion conditions, i.e., screw rotation speed of 250 rpm, temperature above 100 °C, and two mixing zones, in order to obtain an amorphous dispersion of an active pharmaceutical ingredient (API) that is sparingly soluble in water. As a polymer matrix Eudragit EPO (E-EPO) and as an API ibuprofen (IBU) were used in the research. In addition, the plasticizer Compritol 888 ATO (COM) was tested as a factor potentially improving processing parameters and modifying the IBU release profile. In studies, 25% by weight of IBU, 10% of COM and various extrusion temperatures, i.e., 90, 100, 120, 130, and 140 °C, were used. Hot melt extrusion (HME) temperatures were selected based on the glass transition temperature of the polymer matrix (Tg = 42 °C) and the melting points of IBU (Tm = 76 °C) and COM (Tm = 73 °C), which were tested by differential scanning calorimetry (DSC). The thermal stability of the tested compounds, determined on the basis of measurements carried out by thermogravimetric analysis (TGA), was also taken into account. HME resulted in amorphous E-EPO/IBU solid dispersions and solid dispersions containing a partially crystalline plasticizer in the case of E-EPO/IBU/COM extrudates. Interactions between the components of the extrudate were also studied using infrared spectroscopy (FTIR-ATR). The occurrence of such interactions in the studied system, which improve the stability of the obtained solid polymer dispersions, was confirmed. On the basis of DSC thermograms and XRPD diffractograms, it was found that amorphous solid dispersions were obtained. In addition, their stability was confirmed in accelerated conditions (40 °C, 75% RH) for 28 days and 3 months. The release profiles of prepared tablets showed the release of 40% to 63% of IBU from the tablets within 180 min in artificial gastric juice solution, with the best results obtained for tablets with E-EPO/IBU extrudate prepared at a processing temperature of 140 °C.

A Novel In-Line Polymer Melt Viscosity Sensing System of Integrated Soft Sensor and Machine Learning

Real-time monitoring of melt viscosity is one of the many challenges faced in the polymer extrusion process. Viscosity is one of the important metric reflecting material properties during plastic process. However, viscosity is an indicator that can be evaluated by calculating the evaluation value through temperature, pressure, screw rotation speed, etc., but cannot be directly measured by physical sensors. Melt viscosity should be calculated at the exact melt temperature. Temperature sensors cannot accurately measure the temperature of the melt in the barrel. Soft sensing technique is the best solution for estimating material properties. It just needs some physical sensors and physical formulas. The proposed viscosity soft sensor consists of physical sensors, a temperature estimator, and a simulation analysis software for calculating material properties. Four physically temperature signals, one physically pressure signal, and the simulation properties data are used as the dataset for the temperature estimator. An ensemble machine learning model of temperature estimators consisting of Random Forests (RF) and Convolutional Neural Networks (CNN). Melt viscosity, shear stress and shear rate are calculated by physical formulas. Experimental results show that the proposed temperature estimator predicts that the temperature will reduce the MAE from 6.08 to 2.86. Compared with the current work, the prediction error rate of the soft sensor is also reduced from 4% to 1.1%. The proposed soft sensor can be used to better predict polymer melt temperature. Finally, according to the predicting results, the material property scatter chart of viscosity can be precisely plotted under the specific melt temperature. In the past, the melt viscosity could only be measured offline. The proposed method can be added as a plug-in to the existing process to achieve real-time viscosity monitoring.

Functionalized Poly(ethylene-octene)/Linear Low-Density Polyethylene Prepared by Melt Free-radical Grafting Reaction and Its Potential in Toughening Poly(butylene terephthalate) Resins

Glycidyl methacrylate (GMA) and styrene (St) were used as the graft monomer and co-graft monomer, respectively, and grafted onto poly(ethylene-octene) (POE) and linear low-density polyethylene (LLDPE) to prepare a series of GMA-functionalized (POE/LLDPE)-g-(GMA-co-St) graft copolymers. The copolymers were then blended with poly(butylene terephthalate) (PBT) to produce PBT/(POE/LLDPE)-g-(GMA-co-St) blends. The effects of grafting factors and copolymer content on the mechanical properties, thermal properties, rheology, morphology, and deformation mechanism of the blends were studied in detail. The results showed that GMA and St were successfully grafted onto the molecular chains of POE and LLDPE. In the grafting reaction, the best grafting degree and comprehensive performance were achieved when the amounts of dicumyl peroxide and GMA were 0.3 and 5 wt %, respectively, the mass ratio of GMA to St was 1:2, and the screw rotation speed was 60 rpm. By introducing graft copolymers into the PBT matrix, the toughness and thermal stability of the blends were improved. At the same time, the crystallinity and fluidity decreased, and the blends possessed the best mechanical properties when the copolymer content was 20 wt %, with the elongation at break and notched impact strength increasing to 409.98% and 945.90 J/m, respectively. Scanning electron microscopy analysis showed that the copolymers were uniformly dispersed in the PBT matrix. The principal toughening mechanisms were the shear-yielding properties of the PBT matrix and cavitation of (POE/LLDPE)-g-(GMA-co-St) phases.

Optimisation of extrusion process parameters to make ABS-PC filament for 3D printing using Taguchi-GRA technique

ABSTRACT This paper attempts to optimise the single screw extrusion (SSE) process parameters for extruding Acrylonitrile-butadiene-styrene (ABS) and Polycarbonate (PC) blend filament, having improved tensile strength and melt flow rate. The melt flow and mechanical properties of ABS-PC blend filament are highly reliant on the SSE process parameters. Thus, optimising the process parameters to fabricate the blend filaments with high performance has become essential. Grey relational analysis has been integrated with the Taguchi method to optimise the SSE process parameters by evaluating the grey relational grades in terms of the performance index. Experimentation has been carried out according to Taguchi’s L9 orthogonal array (OA), which has been designed considering three SSE process parameters, i.e. screw rotation, blend composition and chamber temperature. The co-continuous structure and compatibility between the phases of the blend obtained at ABS:PC 50:50 by wt%. Micrographs and thermographs support the results. The tensile strength of the 3D printed ABS:PC 50:50 by wt.% composite specimen has improved by 38.02% as compared to virgin ABS.

Dirac-Weyl semimetal in photonic metacrystals.

Dirac-Weyl semimetal is a novel type of topological phase that features the coexistence of Dirac and Weyl points in momentum space. In this study, a photonic Dirac-Weyl semimetal is proposed by introducing screw rotation symmetries into a spatial inversion symmetry-lacking system. A realistic metacrystal structure is designed for experimental consideration. The screw rotation symmetries are crucial for the existence of Dirac points, whose Z2 topology is revealed by the (010) surface states. Meanwhile, two pairs of ideal Weyl points at the same frequency are protected by D2d point group symmetries. The Dirac points and Weyl points reside in a clean frequency interval. The proposed photonic Dirac-Weyl semimetal provides a versatile platform for exploring the interaction between Dirac and Weyl semimetals and exploiting possible photonic topological devices.

True self-reinforced composites enabled by tuning of molecular structure for lightweight structural materials in future mobility

The development of vehicle bodies based on lightweight structural composites is urgently required to upgrade electric cars and to commercialize urban air mobility. Self-reinforced composites (SRCs) are attracting attention due to their advantages in terms of price, lightness, disposal and recycling compared to carbon fiber-reinforced polymers (CFRPs). In this study, a new concept for 100% polypropylene (PP) SRC was proposed to simultaneously improve the adhesive, tensile and impact properties of SRCs without undermining the advantages of SRCs. For this implementation, a facile engineering strategy using quad screw extrusion (QSE) capable of generating high shear stress was employed to modify the melting temperature and impregnation properties of the PP matrix via controlling polymer chain structure. As the screw rotation speed of QSE increased, low molecular weight polymer chains with uniform chain lengths were prepared, which led to a decrease in the melting temperature of the PP matrix and an increase in the flowability and impregnation property of the matrix. Using this strategy, the adhesive strength, tensile strength and impact resistance of the optimized SRC improved by 333%, 228%, and 2700%, respectively. Racing drone flight experiments with the SRC and CFRP frames illustrated the advantages of the SRC frame such as the increase of the flight time due to low density of the SRC, the excellent impact resistant characteristics (which improves user safety), and the superior electrical insulation properties suitable for frequency transmission and reception. Therefore, the proposed SRC can be an ideal choice as a lightweight structural material for future mobility.

Process parameters optimization and mechanical properties of 3D PLA/HA printing scaffold

This research aimed to study the mechanical properties, specifically the compressive strength of Polylactic Acid (PLA)/Hydroxyapatite (HA) cell scaffolds obtained by 3D printing, and to find the relationship of factors used in the synthesis of PLA/HA cell scaffolds obtained by 3D printing. The PLA/HA filaments with glycerol as a binder were formed at an optimal condition of tensile strength by 5 wt% HA and a melting temperature of 170 °C with a screw rotation speed of 25 revolutions per minute. The highest tensile strength of synthetic filaments was 35.12 MPa. Then, the central composite design was designed using three factors, nozzle temperature, printing speed, and the density of the forming specimens. Then, 3D-forming specimens were fabricated to be examined for compressive strength. Effective factors and optimal levels were analyzed by Minitab statistic software. The optimal factor level was refabricated, and the annealed process was also applied to improve its mechanical properties. Annealed and Unannealed specimens’ compressive strengths were compared. The results showed that a nozzle temperature of 215 °C and a part density of 100% had the most affected on maximum compressive strength at 65.62 MPa. The printing speed had no significant effect. Furthermore, a differential scanning calorimeter (DSC) was used to study the properties and the degree of crystallinity of PLA. The result found that the crystallization of a PLA was increased by an annealing treatment that affects heat resistance and also increases compressive strength by 11.60% compared to unannealed specimens.

Mathematical Modeling of Screw Press Configuration for Processing Safflower Oil

This article is devoted to modeling the pressing process of an experimental screw press for safflower oil production in small enterprises of the grain processing industry. The theoretical analysis for developing the process of oil pressing in a screw press is considered. Using methods of mathematical modeling, the problem of squeezing the liquid phase from dispersed material is described and solved. The basic scheme and characteristics of the press equipment and the principle of its work are presented. The proposed method of the theoretical calculation of the pressing process helps to determine the optimal parameters and to press safflower oil using the proposed design of the screw press. During the process of pressing, the highest value of oil yield is reached at the diaphragm gap of δ = 0.1 mm and screw rotation speed of ω = 6.2 rad/s.

Design and dynamic analysis of a scissors hoop-rib truss deployable antenna mechanism

As the support mechanism of space-borne antennas, space deployable antenna mechanism belongs to complex multi-closed-loop coupling mechanism, configuration design and dynamic analysis are more difficult than general parallel mechanism. In this paper, an unequal-length scissors mechanism (ULSM) is proposed by changing the position of the internal rotational joint through a basic scissors mechanism. A scissors hoop-rib truss deployable antenna mechanism (SHRTDAM) is constructed by replacing the parabolic rib with the ULSM. Kinematic analysis of SHRTDAM is conducted, and the degree of freedom (DOF) of the whole antenna mechanism is analyzed based on screw theory, the result showed that it has only one DOF. Velocity and acceleration characteristics of SHRTDAM are obtained by the screw derivative and rotation transformation. Based on Lagrange equation, dynamic model of this mechanism is established, the torque required to drive the mechanism is simulated and verified by Adams and MATLAB software. In addition, a ground experiment prototype of 1.5-m diameter was fabricated and a deployment test is conducted, which demonstrated the mobility and deployment performance of the whole mechanism. The mechanism proposed in this paper can provide a good reference for the design and analysis of large aperture space deployable antennas.

Real-Time Monitoring of Pellet Plastication in a Full-Flight Screw and Kneading Disk Elements of a Co-Rotating Self-Wiping Twin-Screw Extruder by Acoustic Emission (AE) Sensing

The plastication of pellets in a co-rotating twin-screw extruder is a significant concern for product homogeneity and stability in the plastic industry. We developed a sensing technology for pellet plastication in a plastication and melting zone in a self-wiping co-rotating twin-screw extruder. The collapse of the solid part of the pellets emits an elastic wave as an acoustic emission (AE) that is measured on the kneading section of the twin-screw extruder using homo polypropylene pellets. The recorded power of the AE signal was used as an indicator of the molten volume fraction (MVF) in the range of zero (fully solid) to unity (fully melted). MVF decreased with increasing feed rate monotonically in the range of 2-9 kg/h at a screw rotation speed of 150 rotations per minute (rpm) because of the reduction in the residence time of pellets in the extruder. However, the increase in feed rate from 9 to 23 kg/h at 150 rpm resulted in an increase in the MVF as the friction and compaction of pellets caused their melting. The AE sensor could elucidate the pellet's plastication phenomena caused by friction, compaction of pellets, and melt removal in the twin-screw extruder.

Spatial symmetry modulation of planar Hall effect in Weyl semimetals

The planar Hall effect in Weyl semimetals has been proposed as a key feature of chiral anomaly and nontrivial Berry curvature, while the effect of fundamental spatial symmetry remains to be explored. Here, we show with general symmetry analysis and lattice model calculations that the planar Hall effect can be significantly modulated by a certain class of spatial symmetry operations. The odd terms of conductivity with respect to magnetic field, including the linear terms, vanish in the plane perpendicular to the axis of twofold rotation (${C}_{2}$) or the ${C}_{2}$ combined symmetry operations (mirror, twofold screw rotation, glide plane). When applying the magnetic field perpendicular to the glide plane, we find that the planar Hall conductivity in bulk forbidden by glide symmetry becomes nonzero in its quasi-two-dimensional counterpart with broken glide symmetry. It is further clarified that the nonzero planar Hall conductivity comes from surface states. This signature can be used to distinguish bulk and surface transport in Weyl semimetals.

Cavity pressure profile study during foam injection molding and its effect on cell formation of polypropylene/chemical blowing agent foam

AbstractIn the current scenario, many automotive and aerospace industries have exaggerated replacement of most of the metal parts with polymers to achieve the pursuit of lightweight thereby to reduce fuel consumption and carbon emission. Foam injection molding (FIM) is among one of the cost‐effective approaches to produce lightweight polymer products. During FIM, stringent control over various processing parameters is crucial to ensure the precision and reliability of molded parts. This work aims toward the investigation of cavity pressure and its effect on microstructure or cell morphology in chemical blowing agent mixed polypropylene (PP) foams produced by FIM. In particular, effect of varying injection temperature, injection speed and plasticization parameters (screw rotation speed and back pressure) have been examined on the cavity pressure profiles and its conforming influence on cell nucleation and growth have been discussed acutely. The results of this study indicate that various process parameters significantly influence the trajectory of cavity pressure profile during FIM which in turn critically decides structural uniformity of foamed product.