Extrusion Parameters Research Articles

Influence of Extruder Plasticizing Systems on the Selected Properties of PLA/Graphite Composite

Abstract Twin-screw extrusion is a crucial method for the direct inserting of carbon micro- and nanomaterials into a polymer matrix using a dry procedure. The study aimed to determine the influence of the parameters of the twin-screw extruder plasticizing system on the dispersion homogeneity and distribution of graphite filler in the polylactide polymer matrix and overall quality of the composite. As a filler, a graphite micropowder with a 5 μm lateral size of platelets was used at concentration of 1 wt.%. Three configurations of screws with different mixing intensity and various types segments were considered in the extrusion experiments. Morphology and chemical structure of the obtained composites were examined using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy – attenuated total reflectance (FTIR-ATR) and Raman spectroscopy. Differential scanning calorimetry (DSC) and melting flow rate measurements (MFR) were used to asses thermal and rheological properties of the composites. Samples of the polylactide/graphite composites were also subjected to mechanical tests. The results show that the selection of the mechanical parameters of twin-screw extruder plasticizing system plays a key role in the preparation of the homogeneous PLA/graphite composites. Incorrect selection of the screw geometry results in poor mixing quality and a significant deterioration of the mechanical and thermal properties of the composites. Optimised mixing and extrusion parameters can be the starting point for the design of efficient twin-screw extruder plasticizing system for fabrication of PLA composites with carbon nanotube and graphene fillers.

Quality prediction for polypropylene extrusion based on neural networks

In the polypropylene (PP) industry, melt index (MI) is considered the most important quality variable. Different grades of PP have their specific range of MI. Accurate prediction of MI is essential for efficient monitoring and off-grade reduction. Neural Networks (NN) modelling is proposed as the technique for MI estimation. It has powerful adaptive capabilities in response to nonlinear behaviours. By training the NN, it can discover the relationship between inputs and outputs and makes it capable of function approximation. The goal of this research is to develop NN model to predict the MI based on PP extrusion parameters. Different types of NN such as artificial neural networks (ANN), stacked neural networks (SNN) and deep neural networks were trained and compared to understand their efficiency in solving the problem. The simulation results show that deep neural networks can perform the highest accuracy prediction with the lowest root mean square error (RMSE), followed by SNN and ANN. All three modelling proved that NN can perform non-linear function approximation for polymer extrusion.

Formation mechanism and optimization strategy of surface back-end defects in miniature complex hollow extruded profile

Back-end defects present a crucial problem in the extrusion of aluminum alloy profiles, particularly in miniature complex hollow profiles. In this study, the formation mechanism and optimization strategy of surface back-end defects in miniature complex hollow extruded profile were revealed for the first time. The flow behavior of the billet skin, back-end defects, and effect of the porthole outer radius were studied via numerical simulation. The microstructure, chemical composition, and mechanical properties of the discarded billet and back-end defects were experimentally investigated. The results showed that the corrosion resistance and mechanical properties of the back-end defects were poor. Unlike regular-sized profiles, a rare forward flow of the billet skin dominates the extrusion of miniature hollow profiles, resulting in the premature formation of severe surface back-end defects. The primary cause of the forward flow is the significant weakening of the radial flow of billet metal under an ultra-large extrusion ratio (e.g., 137). Nevertheless, a small porthole outer radius effectively delays the entry of billet skin into the profile along the forward flow path owing to a larger storage choke zone that increases the blocking effect and storage capacity of billet skin. In summary, a new dimensionless parameter η was formulated to evaluate the ability of the extrusion parameters (e.g., porthole outer radius) in delaying the formation of surface back-end defects in miniature hollow profiles. The larger the value of η, the later the back-end defects form.

Hot-deformation kinetics analysis and extrusion parameter optimization of a dilute rare-earth free magnesium alloy

The fundamental research on thermo-mechanical conditions provides an experimental basis for high-performance Mg-Al-Ca-Mn alloys. However, there is a lack of systematical investigation for this series alloys on the hot-deformation kinetics and extrusion parameter optimization. Here, the flow behavior, constitutive model, dynamic recrystallization (DRX) kinetic model and processing map of a dilute rare-earth free Mg-1.3Al-0.4Ca-0.4Mn (AXM100, wt.%) alloy were studied under different hot-compressive conditions. In addition, the extrusion parameter optimization of this alloy was performed based on the hot-processing map. The results showed that the conventional Arrhenius-type strain-related constitutive model only worked well for the flow curves at high temperatures and low strain rates. In comparison, using the machine learning assisted model (support vector regression, SVR) could effectively improve the accuracy between the predicted and experimental values. The DRX kinetic model was established, and a typical necklace-shaped structure preferentially occurred at the original grain boundaries and the second phases. The DRX nucleation weakened the texture intensity, and the further growth caused the more scattered basal texture. The hot-processing maps at different strains were also measured and the optimal hot-processing range could be confirmed at the deformation temperatures of 600∼723 K and the strain rates of 0.018∼0.563 s−1. Based on the optimum hot-processing range, a suitable extrusion parameter was considered as 603 K and 0.1 mm/s and the as-extruded alloy in this parameter exhibited a good strength-ductility synergy (yield strength of ∼ 232.1 MPa, ultimate strength of ∼ 278.2 MPa and elongation-to-failure of ∼ 20.1%). Finally, the strengthening-plasticizing mechanisms and the relationships between the DRXed grain size, yield strength and extrusion parameters were analyzed.

Manufacturing of a PET Filament from Recycled Material for Material Extrusion (MEX)

Due to its low cost and easy use, the use of material extrusion (MEX) as an additive manufacturing (AM) technology has increased rapidly in recent years. However, this process mainly involves the processing of new plastics. Combining the MEX process with polyethylene terephthalate (PET), which offers a high potential for mechanical and chemical recyclability, opens up a broad spectrum of reutilization possibilities. Turning used PET bottles into printable filament for MEX is not only a recycling option, but also an attractive upcycling scenario that can lead to the production of complex, functional parts. This work analyzes the process of extruding recycled PET bottle flakes into a filament, taking different extrusion screws and extrusion parameters into account. The filament is subsequently processed with MEX into tensile tests. An accompanying thermal, rheological and mechanical characterization of the recycled resin is performed to offer a comparison to the virgin material and a commercially available glycol modified polyethylene terephthalate (PETG) filament. The results show the importance of adequate drying parameters prior to the extrusion and the sensitivity of the material to moisture, leading to degradation. The recycled material is more prone to degradation and presents lower viscosities. Mechanical tests display a higher tensile strength of the recycled and virgin resin in comparison to the PETG. The extrusion of the used PET into a filament and the subsequent printing with the MEX process offers a viable recycling process for the discarded material.

Effect of extrusion parameters on degradation of magnesium alloys for bioimplant applications: A review

Magnesium alloys, as a new generation temporary biomaterial, deserve the desirable biocompatibility and biodegradability, and also contribute to the repair of the damaged bone tissues. However, they do not possess the required corrosion resistance in human body fluid. Hot mechanical workings, such as extrusion, influence both the mechanical properties and bio-corrosion behavior of magnesium alloys. This review aims to gather information on how the extrusion parameters (extrusion ratio and temperature) influence the bio-corrosion performances of magnesium alloys. Their effects are mainly ascribed to the alteration of extruded alloy microstructure, including final grain size and uniformity of grains, texture, and the size, distribution and volume fraction of the second phases. Dynamic recrystallization and grain refinement during extrusion provide a more homogeneous microstructure and cause the formation of basal texture, resulting in improved strength and corrosion resistance of magnesium alloy. Extrusion temperature and extrusion ratio are reported as the influential factors in the degradation. The reports reveal that the increase in extrusion ratio and/or the reduction in extrusion temperature cause a decrease in the final grain size, leading to intensification of basal texture, in parallel side of the samples with extrusion line, and to lower volume fraction and size of precipitates in magnesium alloys. These all lead to improving the bio-corrosion resistance of the magnesium alloy implants.

Predicting Throughput and Melt Temperature in Pharmaceutical Hot Melt Extrusion.

Even though hot melt extrusion (HME) is a commonly applied process in the pharmaceutical area, determination of the optimal process parameters is demanding. The goal of this study was to find a rational approach for predetermining suitable extrusion parameters, with a focus on material temperature and throughput. A two-step optimization procedure, called scale-independent optimization strategy (SIOS), was applied and developed further, including the use of an autogenic extrusion mode. Three different polymers (Plasdone S-630, Soluplus, and Eudragit EPO) were considered, and different optimal process parameters were assessed. The maximum barrel load was dependent on the polymers’ bulk density and the extruder size. The melt temperature was influenced by the screw speed and the rheological behavior of the polymer. The melt viscosity depended mainly on the screw speed and was self-adjusted in the autogenic extrusion. A new approach, called SIOS 2.0, was suggested for calculating the extrusion process parameters (screw speed, melt temperature and throughput) based on the material data and a few extrusion experiments.

Effect of Extrusion on the Functional and Pasting Properties of High-quality Cassava Flour (HQCF)

Cassava is a rich source of starch and is used as a food ingredient and additive. In its natural state, cassava flour or starch cannot meet all functional requirements in food processing. This necessitates the modification of starch to meet specific functional requirements for products and processes. This study investigated the effect of different extrusion conditions, such as moisture content, screw speed, and temperature on the functional and pasting properties of high-quality cassava flour (HQCF). Particle size distribution, functional and pasting properties of the HQCF were determined. Moisture content (MC) had a significant effect on the properties of HQCF. Water absorption capacity (WAC) increased from 245% to 732%, swelling power (SP) increased from 3.4 g/g to 7.2 g/g, and water absorption index (WAI) increased from 3.0% to 3.3% after extrusion at 40% MC. While at lower MC levels, bulk density (BD) increased from 0.7g/ml to 0.8g/ml for the non-extruded and 30% MC; oil absorption capacity (OAC) from 215% to 253% for the non-extruded and 10% MC; water solubility index (WSI) from 6.0% to 56% for the non-extruded and 20% MC respectively. A positive correlation was observed between extrusion parameters and functional properties. The results suggest that manipulation of extrusion conditions can be used to modify HQCF for varied food applications.

Effect of extrusion parameters on microstructure and mechanical properties of Mg-0.12Ca-0.08Ba alloy

By designing several extrusion parameters, the Mg-0.12Ca-0.08Ba (wt%) alloy with dilute alloy content was processed, the microstructure and tensile property of alloys have been reasonably examined by means of electron backscattered diffraction, scanning electron microscopy and X-ray diffraction. The results demonstrate the grains of Mg-0.12Ca-0.08Ba alloys are refined after extrusion, and the alloys form uniform dynamic recrystallized grains. There are two different types of texture components in the extruded alloy, rare earth texture and extruded fiber texture, which crystallographic orientation is < 112>∥ED and <100>∥ED, respectively. This “rare earth texture” component was found to be suppressed at high extrusion temperatures. The extrudants at 380 °C exhibits the best performance, its yield strength (YS) and ultimate tensile strength (UTS) are 197 MPa and 252 MPa, respectively, and the elongation-to-fracture (EL) is 33.1%. The plastic enhancement after extrusion mainly comes from grain refinement and texture weakening in the alloys.

Property Variation of Extruded Mg-Gd Alloys by Mn Addition and Processing

This paper presents how the mechanical properties, the microstructure and the degradation rate of extruded Mn-containing Mg-Gd alloys can be modified during extrusion. Gd as a rare earth element is particularly interesting due to the influence on the texture development in Mg, and is therefore studied as a base alloy system. The contents of Gd were investigated between 2 to 9 wt.%, with Mn additions of 0.5 and 1.0 wt.%. The grain sizes and the corresponding textures were modified by varying the extrusion parameters and the alloy content. It was shown that modification with Mn can lead to further grain refinement, an increase in the degree of recrystallization, as well as a decrease in the degradation rate in the biological medium compared with the binary Mg-Gd system from previous studies. The results suggest that the resulting properties are more robust compared with the binary alloy.

Towards Multi-Scale Modeling of Zirconium Alloys Recrystallization and Application to Thermo-Mechanical Processes Optimization

Zirconium alloys are used in the nuclear industry due to their low neutron capture cross-section and resistance to corrosion, irradiation and creep. The microstructure of the nuclear fuel components evolves during the manufacturing route and can impact the subsequent processes or the final properties. Thus, numerical modeling of thermo-mechanical manufacturing processes is of interest to understand and master these microstructure evolutions.Numerical modeling of thermo-mechanical manufacturing processes with FORGE® NxT software is applied. These models provide the thermo-mechanical history of the material at each integration point of the finite element (FE) mesh, which can be used to assess locally the continuous dynamic and post-dynamic recrystallization during hot extrusion.Mean-field models were developed in Python and integrated into FORGE® NxT software, to quantify the microstructure evolution at the macro-scale of the component. Full-field models (DIGIMU® software1) were also developed for considering microstructural heterogeneities and the influence of initial microstructure at the mesoscopic scale while improving the mean-field equations by homogenization.After validation based on experimental results, these two recrystallization models provide complementary information to optimize the process parameters at the macro-scale and to better understand mesoscopic scale phenomena, such as:• At the macro-scale: influence of hot extrusion parameters on the continuous dynamic and post-dynamic recrystallization of Zircaloy-4.• At the meso-scale: influence of the initial microstructure on the recrystallization phenomena with improved precision. Indeed, the topology of the microstructure is predicted and not only the mean values/distributions of the state variables.

Continuous and adaptable printing path based on transfinite mapping for 3D concrete printing

Three-dimensional (3D) concrete printing is an advanced and promising construction method that shows great development potential in the field of construction engineering owing to its highly flexible and intelligent characteristics. The printing path design that is directly related to the 3D printing process is usually limited by the time-dependent rheological properties of concrete composites and the nozzle opening of the print head. Improper path design is liable to disruption, interfacial defects, self-intersection, and even a certain amount of unfilled areas. This paper proposes a flexible and adaptive transfinite mapping method for the path planning of 3D concrete printing by properly mapping a predetermined continuous-type path to the digital model to be printed. This method combines the morphological features of the digital model and path types to achieve a high-quality and high-continuity adaptive printing path. Meanwhile, the relationship between the extrusion process parameters of cementitious composites is experimentally measured and subsequently incorporated into the path design program to realize zero-gap printing by in-process controlling the extrusion parameters. The advantages of this method in adapting to the diversity of morphological features and path types are verified by a set of free-form structures, and the applicability is experimentally validated.

A study on the effects of internal architecture on the mechanical properties and mixed-mode fracture behavior of 3D printed CaCO3/ABS nanocomposite samples

PurposeThe purpose of this study was to investigate the effects of CaCO3 nanoparticles on the mechanical properties, and mixed-mode fracture behavior of acrylonitrile butadiene styrene 3D printed samples with different internal architectures.Design/methodology/approachThe nanocomposite filaments have been fabricated by a melt-blending technique. The standard tensile, compact tension and special fracture test samples, named Arcan specimens, have been printed at constant extrusion parameters and at four different internal patterns. A special fixture was used to carry out the mixed-mode fracture tests of Arcan samples. Finite element analyses using the J-integral method were performed to calculate the fracture toughness of such samples. The fractographic observations were used to evaluate the mechanism of fracture at different concentrations of nanoparticles.FindingsThe addition of CaCO3 nanoparticles has resulted in a significant increase in the fracture loading of the samples, although this increase was not consistent for all the filling patterns, being more significant for samples with linear and triangular structures. According to the fractographic observations, the creation of uniformly distributed microvoids due to the blunting effect of nanoparticles and 3D stress state at the crack tip in the samples with linear and triangular structures justify the enhancement in the fracture loading by the addition of CaCO3 nanoparticles in the matrix.Originality/valueThere is a significant gap in the knowledge of the effects of different nanoparticles in the polymer samples produced by the fused filament fabrication process. One of such nanoparticles is an inorganic CaCO3 nanoparticle that has been frequently used as nanofillers to improve the thermomechanical properties of thermoplastic polymers. Here, experimental and numerical studies have been conducted to investigate the effects of such nanoadditives on the mechanical and fracture behavior of 3D printed samples.

Role of Extruded Sheet Morphology in Phase Separation and Final Morphology of Superhydrophobic Polypropylene

In this study, we prepared polypropylene sheets with a superhydrophobic surface from extruded sheets with a phase separation method. We investigated the influence of extrusion parameters on the morphological properties of the polypropylene sheet and found that two significantly different structures can be formed in the cross-section of the sheet when the cooling temperature was varied. The effect of the morphology of the extruded material was studied on phase separation and through that on the surface structure that formed. The created morphology of the extruded sheet plays a significant role in the procedure of the phase separation method and less in surface wettability. We also included a polypropylene blend and nucleated polypropylene in this study to investigate their role in surface morphological changes and indirectly on wetting behavior. Surfaces have become superhydrophobic with an increased water contact angle from 102° to 150° and contact angle hysteresis below 10°. For nucleated polypropylene samples, we achieved remarkably good results (a water contact angle of 158°). The morphological and wettability behavior of the surfaces were investigated with a polarized optical microscope and water contact angle measurements, and scanning electron microscopy, respectively.

Experimental and theoretical investigation of extrusion load for AA6063/SiC extruded composite billet

Because of their great strength and stiffness with regard to their weight, extruded sections are commonly utilized as essential parts in many areas. The investigation focuses on experimental and theoretical analysis of cold extruded aluminium composites. Four types of extrusion die configurations, such as 12:8, 2:4, 12:2, and 8:4, were used to obtain the aluminium composite billets. Aluminium with 5 wt% SiC material was used for the fabrication of Ingot. The theoretical models have been used to determine the extrusion load compared with the experimental value. Moreover, the theoretical model is modified to reflect the relative significance of extrusion parameters in the extrusion process and to provide the actual value of the testing process. Also, the modified model was attributed to developing the equation for evaluating the extrusion load in the intermediate process of extrusion for all the types of extrusion die configurations. The experimentally investigated extrusion load has a 0.81% deviation with the modified model and increased with other theoretical models. Surface morphology analysis was carried out for all configurations of extruded billet components and indicated the surface quality of the extruded billet.

Infrared fibers manufacture from single crystals of the AgBr – AgI system

The article is devoted to the manufacture of infrared polycrystalline optical fibers based on crystals of the AgBr–AgI system. The synthesis of a charge with a purity of up to 99.9999 wt % was performed. Single crystals of the AgBr0.96I0.04, AgBr0.92I0.08, AgBr0.87I0.13 compositions were grown. By means of computer simulation, the extrusion parameters of unjacketed optical fibers based on crystals were selected, namely, the temperature was 180 °C, the speed of the plunger movement was 0.2–0.3 mm/min. Using the selected parameters, from the crystals by the extrusion method, fibers with a diameter of 525 μm and a length of 0.55–2.2 m were manufactured, and their optical transmission was measured. The fiber transmission spectra have covered the range from 3 to 25 μm. Optical losses were estimated using the cut-off method. They amounted to 0.3 ± 0.1 dB/m in the region from 10 to 14 μm. The fiber resistance to ionizing β-radiation has been investigated. The transmission parameters were retained when the fibers had been irradiated with doses up to 400 kGy.

Effect of hot extrusion on the microstructure and mechanical properties of SiCNWs/Mg-2Zn-0.1Y composite

This work investigates the effect of adding SiC nanowires (SiCNWs) on the microstructure and mechanical properties of Mg-2Zn-0.1Y matrix composites under different hot extrusion parameters, and the strengthening mechanism was analyzed. The results showed that as the extrusion temperature elevated from 140 °C to 220 °C or the extrusion speed increased from 0.1 mm/s to 1.0 mm/s, both the dynamic recrystallized grain size and the recrystallized volume fraction increased significantly. The changes of precipitate size and volume fraction exhibited the same trend. The finest recrystallized grains (~0.37 μm) were obtained after extrusion at 140 °C and 0.1 mm/s, which also contained nano-sized MgZn2 precipitates and SiC nanowires. As the extrusion temperature increased from 140 °C to 220 °C at a constant extrusion speed of 0.1 mm/s, the strength of the composites decreased while the elongation improved greatly. Similar change in the strength and elongation were obtained in the composite as the extrusion speed increased from 0.1 mm/s to 1.0 mm/s at extrusion temperature of 140 °C. Meanwhile, these composites exhibited a weakened texture, and a mixture of microcracks and dimples was observed in the fracture surfaces of the as-extruded composites, which explained the mix of brittle-ductile fractures of the composites. The composites extruded at 140 °C and 0.1 mm/s exhibited the best performance with yield strength (YS) and ultimate tensile strength (UTS) of ~495.53 MPa and ~514.18 MPa, respectively. Among all strengthening mechanisms, the proportion of grain refinement strengthening is the highest.

Scale-Up of Solvent-Free, Mechanochemical Precursor Synthesis for Nanoporous Carbon Materials via Extrusion.

The mechanochemical synthesis of nitrogen‐rich nanoporous carbon materials has been scaled up using an extruder. Lignin, urea, and K2CO3 were extruded under heat and pressure to yield nanoporous carbons with up to 3500 m2 g−1 specific surface area after pyrolysis. The route was further broadened by applying different nitrogen sources as well as sawdust as a low‐cost renewable feedstock to receive carbons with a C/N ratio of up to 15 depending on nitrogen source and extrusion parameters. The texture of obtained carbons was investigated by scanning electron microscopy as well as argon and nitrogen physisorption, while the chemical structure was analyzed by X‐ray photoelectron spectroscopy. The received carbon was tested as a supercapacitor electrode, showing comparable performance to similar ball‐mill‐synthesized materials. Lastly, the space‐time yield was applied to justify the use of a continuous reactor versus the ball mill.

Modeling a screw extruder for FFF 3D printing

The article presents the development and modeling of a screw extruder for 3D printers operating on the FFF technology, namely, the Fused Filament Fabrication (“production by fusing threads”). Extruders, usually installed on FFF 3D printers, use a thermoplastic polymer filament as a material. There are two filament standards: 1.75mm and 2.85mm. The minimum cost of such a filament starts from $ 11 per kilogram (ABS plastic 1.75 mm). The cost of more expensive filaments can reach several thousand or even tens of thousands per kilogram (depending on the material, filler, the presence of inhibitors, dyes, etc.). The cost of the material is much higher than granulated primary plastics and even more so recycled materials. In addition, the extruder nozzle diameter is typically limited to 1.2mm for 1.75mm filament. Thus, when printing large products, for which the detail and roughness of vertical surfaces are not so important, increase in the diameter of the extruder nozzle will increase significantly the printing speed due to the increase in the thickness of the print layer and the width of the print line.&#x0D; To produce filament, screw filament extruders are used, which work on the principle of injection molding machines. The authors propose a calculation of the parameters of a screw extruder for an FFF 3D printer, which will directly use granulated primary plastics or crushed plastic recyclables as a material. The use of a screw extruder will reduce the cost of the printed product and increase significantly the diameter of the extruder nozzle, which will significantly reduce the production time for large-sized products.&#x0D; When designing a screw extruder, it is necessary to adhere to two main strategies: minimizing the weight and size parameters of the extruder and ensuring the required linear productivity. On the one hand, the extruder must be as light as possible to be able to increase the printing speed, on the other hand, it must provide the necessary linear performance to be able to extrude plastic at printing speeds. Modeling is made for nozzles with a diameter of 1mm and 5mm. According to the calculation results, the screw extruder has a 3-fold and 37-fold margin of linear productivity, respectively.

Precipitation behavior and quenching sensitivity of 2196 Al–Li alloy extrusion profile

Al–Li alloy usually has quenching sensitivity, affecting the mechanical properties of its forming components. This paper investigated the effects of extrusion parameter and quenching cooling rate on precipitation of quench-induced phases, aging phases and quenching sensitivity of extruded 2196 Al–Li alloy profiles. The results showed that a band structure constituted by coarse quench-induced phases including T1 (Al2CuLi) and fine aging phases including σ (Al5Cu6Mg2), θ' (Al2Cu) and T1 was formed as the quenching cooling rate was lower than that of air-quenched. With the increase of quenching cooling rate, the precipitation of quench-induced T1 phases was suppressed, and the size and density of other quench-induced phases, the width of precipitation free zone as well as the quenching sensitivity were significantly reduced. The grains of the profiles in extrusion and solution state both exhibited a fibrous structure, with a strong <112>//ED and <111>//ED orientation. The profile extruded at 370 °C × 1.5 mm/s exhibited abnormal coarse grains and gained a higher proportion of recrystallization after solution. The higher proportion of recrystallization and high angle grain boundaries would increase the hardness quenching sensitivity of 2196 Al–Li alloy. By comparison, extrusion parameters have a stronger impact on the strength quenching sensitivity than on the hardness quenching sensitivity. The effect of extrusion parameters on quenching sensitivity was less than that of quenching cooling rate. The elongation of the profiles increased with the decrease of quenching cooling rate at low extrusion temperature or speed, while it exhibited an opposite trend at high extrusion temperature or speed.