Thermoplastic Extrusion Process Research Articles

Effect of different screw speeds on the structure and properties of starch straws

To illustrate the action mechanism of screw speed on the performance of starch-based straws during the extrusion process, starch-based straws at different screw speeds were prepared using a twin-screw extruder and the structures and characteristics were compared. The results indicated that as screw speeds improved from 3 Hz to 13 Hz, the A chain of amylopectin increased from 25.47 % to 28.87 %, and the B3 chain decreased from 6.34 % to 3.47 %. The absorption peak of hydroxyl group shifted from 3296 cm−1 to 3280 cm−1. The relative crystallinity reduced from 13.49 % to 9.89 % and the gelatinization enthalpy decreased from 3.5 J/g to 0.2 J/g. The performance of starch straws did not increase linearly with increasing screw speeds. The starch straw produced at screw speed of 7 Hz had the largest amylose content, the highest gelatinization temperature, the minimum bending strength, and the lowest water absorption rate in hot water (80 °C). Screw speed had a remarkable impact on the mechanical strength, toughness and hydrophobicity of starch-based straws. This study revealed the mechanism of screw speed on the mechanical strength and water resistance of starch straws in the thermoplastic extrusion process and created the theoretical basis for the industrial production of starch-based straws.

Assessing the Sensitivity of the Heat Transfer Coefficient at the Polymer-Calibrator Interface in Profile Extrusion

One of the major challenges in modeling the cooling stage of the thermoplastic profile extrusion process is defining the heat transfer coefficient at the polymer-calibrator interface (hint), which significantly affects the cooling rate. Accurate values for the hint are essential for improving process efficiency using numerical modeling codes. In the existing literature, values of hint are only available for a limited number of cases, and there are no systematic studies regarding the influence of processing conditions on this parameter. This study focuses on the determination of accurate values for hint and on the influence of processing parameters, namely: cooling fluid temperature, pulling velocity, and vacuum pressure. To accomplish this, a previously developed calibrator prototype, and associated methodology, targeting the measurement of hint for thermoplastic materials, is utilized in a conventional profile extrusion line. The results obtained show hint values in the range of 200–1500 W·m−2·K−1, which is in accordance with the results published in the available literature. The results also reveal that the cooling fluid temperature and the pulling velocity have the most substantial influence on hint, while vacuum pressure has minimal impact within the range of the experiments conducted.

Material Extrusion Additive Manufacturing of the Composite UAV Used for Search-and-Rescue Missions

The additive processes used in the manufacture of components for unmanned aerial vehicles (UAVs), from composite filaments, have an important advantage compared to classical technologies. This study focused on three-dimensional design, preliminary aerodynamic analysis, fabrication and assembly of thermoplastic extruded composite components, flight testing and search-rescue performance of an UAV. The UAV model was designed to have the highest possible structural strength (the fuselage has a structure with stiffening frames and the wing is a tri-spar), but also taking into account the limitations of the thermoplastic extrusion process. From the preliminary aerodynamic analysis of the UAV model, it was found that the maximum lift coefficient of 1.2 and the maximum drag coefficient of 0.06 were obtained at the angle of attack of 12°. After conducting flight tests, it can be stated that the UAV model, with components manufactured by the thermoplastic extrusion process, presented high stability and maneuverability, a wide range of speeds and good aerodynamic characteristics. The lack of this type of aircraft, equipped with electric motors, a traffic management system, and a thermal module designed for search-and-rescue missions, within the additive manufacturing UAV market, validates the uniqueness of the innovation of the UAV model presented in the current paper.

Impact of thermoplastic extrusion process on chemical, nutritional, technological and sensory properties of gluten‐free breakfast cereals from pigmented rice

SummaryThe black rice and red rice varieties cultivated in Brazil are rich in dietary fibres, proteins, and phenolic compounds with great antioxidant potential, being a promising alternative for the production of healthy gluten‐free snacks. In this study, pigmented rice flours and their respective extrudates were characterised for the nutrient profile, phenolic compounds, antioxidant capacity, technological properties and colour aspects, and the results were compared through heat map analysis. Black rice snacks presented better nutrient and phenolic profiles, while the red rice snacks stood out for the expansion and texture properties. Both breakfast cereals were nutritive, gluten‐free, hypoallergenic, naturally coloured (no need to add artificial colorants) and presented good sensory acceptance, with the higher scores for the attributes shape, size, colour and crispness.

Overview on Lithium-Ion Battery 3D-Printing By Means of Material Extrusion

Among the various additive manufacturing processes, material extrusion techniques recently emerged as an encouraging option in order to 3D-print lithium-ion battery components. In this work, an overview of the recent advances and progress on the ink material extrusion, known as liquid deposition modeling (LDM), as well as the thermoplastic material extrusion process, known originally as the trademark Fused Deposition Modeling (FDM), is discussed. Representing a promising route to achieve complete lithium-ion batteries in a single print without the necessity to perform any post-processes, a particular consideration is devoted to the FDM process. Trends, prospects as well as an exhaustive list of the parameters still requiring further investigations are provided, thus paving the way towards the next generation of FDM 3D-printed lithium-ion batteries.

Biocatalytic Degradation of Proteins and Starch of Extruded Whole Chickpea Flours

In this study, the effects of extrusion cooking of whole chickpea flour in preparation for its further hydrolyses with proteases and amylases were evaluated. The thermoplastic extrusion process was carried out varying processing moisture (15.6% or 22.55%), final barrel temperature (143°C or 150 °C), and screw speed (450 rpm, 580 rpm, or 700 rpm) to generate three specific mechanical energy (SME) inputs (127.95 Wh/kg, 161.58 Wh/kg, and 199.13 Wh/kg). After extrusion, flours were hydrolyzed with alcalase and α-amylase in order to maximize soluble compounds after hydration. In general, extrusion did not affect chemical composition but caused structural modifications that influenced functional properties and in vitro protein and starch digestibilities. Extruded chickpea flours presented higher content of soluble proteins and increased starch hydrolysis after alcalase and α-amylase treatment, respectively. It was found that extrusion treatment of chickpea with a SME input of 127.95 Wh/kg produced at 22.5% processing moisture, 150 °C of final temperature, and 580 rpm of screw speed in combination with the later alcalase/α-amylase treatments achieved the highest degree of starch hydrolysis (84%) and the release of both soluble proteins (70%) and total soluble solids (62%). These results suggest that amylolytic and proteolytic digestion combined with the extrusion process could transform the whole chickpea flour into a valuable soluble food ingredient with adequate contents of proteins and starch-derived dextrins and sugars.

Predicting extrusion process parameters in Nigeria cable manufacturing industry using artificial neural network

The extrusion process is a very complex process due to the number of process parameters that are associated with it which are prone to high fluctuations. The main purpose of this work is to determine the realistic extrusion process parameters in the thermoplastic extrusion process in Nigeria cable manufacturing industries with the use of an artificial neural network. Conventionally, the use of trial and error technique which involves full-size experiments is generally used to determine the process parameters in the thermoplastic extrusion process. This conventional technique is expensive and it is also time-consuming. The use of an artificial neural network to predict extrusion process parameters before plant execution will make extrusion process operations more efficient. This technique also bridges the gap that exists between theoretical analysis and real manufacturing system because real manufacturers' data was used. The neural network was developed in a MATLAB environment and was trained with a supervised learning method based on Levenberg Marquardt Algorithm and the developed ANN model is capable of predicting manufacturing process parameters for different grades of PVC thermoplastic material.

Computed tomography evaluation of the porosity and fiber orientation in a short carbon fiber material extrusion filament and part

The computed tomography (CT) evaluation of the material extrusion (MEX) of a short carbon fiber (SCF) Nylon-12 filament and part is presented. CT, a non-destructive testing method, was used to quantify the internal structure of specimens into three phases: pore, Nylon, and SCF. The intensity histograms from the CT data were fit using a mixed skew-Gaussian distribution (MSGD) algorithm to segment the CT image into phases. Thresholded images were used to isolate pores in the CT image to determine pore volume and distribution within both the MEX SCF filament and part. The phase volume percentages of the MEX SCF filament were found to be 1.6% pore, 62.2% Nylon, and 36.2% SCF. The volume of most pores within the filament were found to be under 100 μm3. The highest frequency of pores was located near the outside of the filament, but the large pores were located near the center of the filament. This result indicates that the thermoplastic filament extrusion process likely entraps large bubbles in the center of filament or causes large thermal gradients and residual stresses that induce voids during post-extrusion cooling. MSGD analysis of sections of the MEX SCF part estimated phase volume percentages to be 9.8% pore, 59.6% Nylon, and 30.9% SCF. This analysis showed a more than 8% increase in porosity from the MEX SCF filament to the part. For the MEX SCF part, the average pore area was found to be highest (>250 μm2) at the bottom of the layer and smallest (<100 μm2) at the top of the layer, which could be explained by a large temperature gradient between and contractile thermal stresses inside the layer that cause the thermoplastic to shrink into a smaller volume allowing the voids to grow during deposition. A qualitative analysis of fiber orientation conducted on the SCF filament indicated that the SCFs maintain their orientation from filament to part except in the intersection zone of rasters.

Cereal extrusion with steam recuperation process

The extrusion process advantage of agricultural raw materials processing into food and feed over traditional technologies is the high specific productivity, energy efficiency and versatility of use. The presence of a large number of control factors and influence on the raw materials quality, such as operating parameters and structural elements, make extrusion a difficult reproducible process when scaling or moving from one installation to another. But this aspect is the reason for the maximum flexibility of extrusion systems and the possibility of their continuous improvement. One of the ways for the extrusion technology development is the improvement of equipment and design solutions in the field of energy saving. Investigations of the thermoplastic extrusion process of wheat grinding with the application of the recovery of steam heat generated by a special configuration of screw elements and its degassing with the feeding into the processed material were carried out in the work. The modernized extruder Werner &amp; Phleiderer Continua 37, supplemented by a developed recuperative unit and a steam line, was used to achieve this goal. An assessment of changes in energy consumption during steam recovery was carried out. The physicochemical properties of the experimental and control samples of wheat grain extrudates obtained under various operating conditions were investigated and determined. It was found out that the steam recovery mode is a statistically significant reason for increasing the humidity of the extruded product from 3.8 to 5.0 bulk density - by 15% relative to the mode without recovery. A decrease in the explosion coefficient and the water-holding capacity of the extrudates during operation in the regenerative mode of extrusion was noticed. The presented method with additional thermal effects on the processed raw materials allows us to expand the technological capabilities of the process of thermoplastic extrusion in obtaining products of various functional and technological purposes.

Composites based on HDPE, jute fiber, wood, and thermoplastic starch in tubular pultrusion die: The correlation between mechanical performance and microstructure

AbstractThis paper presents an experimental study on pultrusion of tube‐shaped composites. Green tube‐shaped composites based on jute/thermoplastic starch, jute/HDPE, and jute/HDPE/wood flour were prepared. Jute fibers were impregnated in thermoplastic extrusion process, and a round prepreg was produced in a hot die. The impregnated jute fibers were entered into pultrusion die, and tube‐shaped composites were fabricated. Properties of final samples were investigated by tensile measurement and void faction. It was found that tensile strength of jute/HDPE was higher than jute/starch. It seems that the melt viscosity of polymer plays as an important role determining the mechanical performances. In addition, tensile strength increases with increasing volume fraction of fiber in the composites. Morphological study showed that in jute/starch sample, impregnation was not done perfectly and tubular cross section has inhomogeneity.

A new energy conservation scheme for the numeric study of the heat transfer in profile extrusion calibration

In this work, a new second-order conservative finite volume scheme using the cell-to-vertex interpolation is proposed to solve the heat transfer problem involving discontinuous solution and discontinuous materials properties. We apply the method to a thermoplastic extrusion process where a dry calibration is used to cool down a polymer tape. One of the major difficulties in the modelling is to prescribe the adequate value for the heat transfer coefficient between the polymer and the calibrator. To this end, we define an optimization procedure coupled with the new finite volume method to evaluate the heat transfer coefficient at the polymer–calibrator interface from experimental data.

Effect of long fiber thermoplastic extrusion process on fiber dispersion and mechanical properties of viscose fiber/polypropylene composites

Viscose fiber reinforced polypropylene (PP/VF) composites were manufactured using long fiber thermoplastic (LFT) extrusion techniques with two different methods namely LFT-l and LFT-2. The compatibilizer [maleated polypropylene (MAPP)] and dispersing agent [stearic acid (SA)] were added to the PP/VF in order to improve the fiber dispersion and interfacial adhesion. The PP/VF composites manufactured using LFT-2 showed better fiber dispersion with higher tensile and flexural properties compared to the composites manufactured using LFT-1 method. Similarly, the impact strength and toughness of the LET-2 composites showed an improvement of 36 and 20% than LFT-1 whereas the average fiber length of composites was decreased from 6.9 mm to 4.4 mm because of the increase in shear energy as a result of residence time. Further, the addition of SA and MAPP to LFT-2 process has significantly improved the fiber dispersion and mechanical performance. The fiber dispersion and fracture behavior of the LFT-1 and LFT-2 composites were studied using scanning electron microscopy analysis. The Fourier transformation infrared spectra were also studied to ascertain the existence of type of interfacial bonds. Copyright © 2015 John Wiley & Sons, Ltd.

Determinação da concentração de diferentes sistemas de solventes na solubilização de proteínas de análogo de carne

O uso de solventes específicos para extração de proteínas determina o tipo de reação química que ocorre entre os componentes proteicos, principalmente quando estes foram submetidos a tratamentos térmicos como a extrusão termoplástica, uma tecnologia de alta versatilidade, baixo custo, alta produtividade e que não gera efluentes. No entanto, é necessário o uso de concentrações adequadas dos solventes para maximizar a extração das proteínas. Neste trabalho foi avaliada a solubilização de proteínas de análogo de carne a base de isolado proteico de soja e glúten vital, submetidos ao processo de extrusão termoplástica a baixa (23%) e alta (60%) umidade. Os solventes utilizados foram: tampão fosfato (pH 7,5) de 10, 20, 40, 60, 80 e 100mM, dodecil sulfato de sódio de 1, 2, 3, 4 e 5%, β-mercaptoetanol de 1, 2, 3 e 4%, Triton X-100 de 1, 2, 3 e 4% e ureia de 6, 7, 8, 9 e 10M. Todos os reagentes foram dissolvidos ou solubilizados em tampão fosfato 40mM (pH 7,5). Os resultados mostraram que as maiores extrações proteicas foram obtidas com o uso de 40mM de tampão fosfato, 2% de dodecil sulfato de sódio, 2% de β-mercaptoetanol, 3% de Triton X-100 e 7M de ureia

Ferroelectric KNNT Fibers by Thermoplastic Extrusion Process: Microstructure and Electromechanical Characterization

B-site substitution in KNN with tantalum results in a higher d33 and dielectric constant. This higher value makes KNNT interesting for lead-free actuator applications. KNNT fibers with diameters of 300 and 500 μm have been extruded and sintered at 1200 °C in a KNNT-enriched atmosphere. Subsequently, the influence of fiber diameter on the microstructure (porosity and grain size) was investigated. The measurements revealed that with decreasing fiber diameter, the porosity increases, whereas the grain size decreases. The influence of these microstructural differences on the piezoelectric properties was evaluated using a novel characterization procedure for single fibers. The larger diameter fibers show an increase in the electromechanical properties measured, i.e., d33, tanδ, Pr, Ec and the free longitudinal fiber displacement, when compared to smaller diameter fibers. The lower alkali losses result in a larger grain size, a higher density during sintering and lead to higher electromechanical properties.

Fabrication and performance of a tubular ceria based oxygen transport membrane on a low cost MgO support

A 30μm thin-film tubular CGO (Ce0.9Gd0.1O1.95−δ) membrane with catalytic layers on both sides has been prepared by dip-coating on a low cost, porous magnesium oxide (MgO) support. The MgO support was fabricated through a thermoplastic extrusion process. Support, thin membrane and catalytic layers were sintered in individual steps at temperatures between 1250 and 1300°C to achieve a controlled removal of binder and organic additives and to obtain the desired, defect free microstructure. The prepared asymmetric tubular CGO membrane has been tested at elevated temperatures (up to 900°C) using atmospheric air and N2, H2 for the feed and sweep side respectively. The oxygen permeation was 4Nmlmin−1cm−2 at 850°C using H2 on one side and air on the other side.

Thermoplastic processing, rheology, and extrudate properties of wheat, soy, and pea proteins

Plant protein isolates (wheat gluten, soy, and pea protein) were treated in a thermoplastic extrusion process, yielding protein based bioplastic material. The application of glycerol as plasticizer in amounts of 50–67% of total mass and high temperatures above 140°C led to smooth and homogeneous extrudates. Viscosity measurements of the protein melt under extrusion conditions confirmed the thermoplastic behavior, obeying the power law with power law indices of 0.31-0.4. Chemical changes in the material were qualitatively shown by amino acid analysis and fluorescence measurement. High moisture sensitivity and low mechanical stability of the extrudates, as determined by solubility, water vapor permeability, sorption isotherms, and tensile strength, can be partially ascribed to the high glycerol content. The application of pure protein bioplastics for technical purposes, e.g., as packing material, is discussed on basis of the presented data considering stability, appearance, and long time storage. POLYM. ENG. SCI., 55:1912–1919, 2015. © 2014 Society of Plastics Engineers

Effects of Build Orientations on Tensile Properties of PLA Material Processed by FDM

Fused Deposition Modelling (FDM) of thermoplastic materials is generally a well-known technology among all additive manufacturing (AM) technologies and therefore, it is essential to investigate the mechanical properties of such FDM processed materials. Several open-source and low cost AM machines, known as 3D Printers, have recently been developed using thermoplastic extrusion process based on the original FDM technology. Many of these 3D Printers use Polylactic Acid (PLA) plastic for building parts. The main objective of this paper is to investigate the tensile properties of the PLA thermoplastic material processed by the Cube-2 3D Printer. In this study, the dog-bone sized PLA specimens are printed in different build orientations and a Zwick Z010 tensile testing machine is used to determine the tensile properties of PLA in different build orientation.

Low shear compounding process for thermoplastic fabrication of ferroelectric lead-free fibres

The thermoplastic ceramic extrusion process involves the shaping of a polymer highly filled with inorganic powder, the so-called ceramic–thermoplastic feedstock. The limitation faced with the process is the amount of raw material required to produce the feedstock. Depending on the density and desired volume of the materials used, the typical amount of ceramic powder required is a minimum of ∼100 g. The validation of a low shear feedstock preparation method against a standard high shear mixing method occurred. Microstructure investigation and single electromechanical fibre characterization of low shear produced KNN ( d 33 – 49 pC/N; P r – 3.7 μC/cm 3 ) and PZT ( d 33 – 392 pC/N; P r – 32.4 μC/cm 3 ) fibres, in terms of PE, SE loops and d 33 measurements, demonstrating the reproducibility of the results when compared to a standard ceramic–thermoplastic high shear mixing process. The repeatability of the measurements showed the proposed procedure to be robust, validating the new compounding method for wide-scale use.

Functional extruded snacks with lycopene and soy protein

In this work, the effects of thermoplastic extrusion process parameters (raw material moisture content and temperature) and the addition of functional ingredients (lycopene and soy protein) on quality characteristics of a base-formulation for extruded corn snacks were studied, with the objective of developing an easy-to-eat functional product. A single-screw Labor PQ 30 model Inbramaq extruder was used for extrusion and a central composite rotational design (CCRD) was followed. The independent variables were: i) percentage of soy protein isolate (0-30%); ii) percentage of lycopene preparation (0-0.1%); iii) raw material moisture content (20-30%); and iv) 5th zone temperature (100-150 °C). The expansion index reached maximum values with the lowest raw material moisture content (20%) and intermediate temperatures (approximately 125 °C). Instrumental hardness was higher with high moisture and low temperature; however, increasing the percentage of soy protein was beneficial for the texture of the product, reducing hardness. The red color intensity increased with the increase in lycopene content and moisture, and with the reduction of temperature. Sensory acceptance tests were carried out for two products, with maximum percentages of the functional ingredients, 20% moisture and temperatures of 125 and 137 °C, with greater acceptance for the product extruded at 125 °C.

Effect of Some Extrusion Variables on Residual Quantity of Cyanogenic Compounds in an Organic Breakfast Cereal Containing Passion Fruit Fiber

ABSTRACTOrganic passion fruit fiber is obtained from organic passion fruit rind and is an interesting source of dietary fiber with potential for use in food products such as breakfast cereals. However, various researchers have confirmed the presence of cyanogenic compounds in passion fruit. The objective of this study was to evaluate the effect of the thermoplastic extrusion process on the residual quantity of total cyanogenic compounds (TCC) in extruded organic breakfast cereal produced with corn flour and different levels of passion fruit fiber added to the formulation. For the production of the extrudates, a 23 complete factorial design was followed, that permitted the analysis of the results by response surface methodology. The effects of the quantity of passion fruit fiber (0–30%), feed moisture content (18–28%) and barrel temperature (120–160°C) on the residual quantity of TCC were studied. The raw passion fruit fiber presented 748.3 mg/kg of TCC. The extruded products presented TCC contents of 0–254.1 mg/kg, increasing significantly with the increase of the quantity of passion fruit fiber. The residual quantity of TCC was influenced by feed moisture, while temperature had no significant effect on this response. Nevertheless, only a small reduction of cyanogenic compounds was verified in the breakfast cereals produced by thermoplastic extrusion. Thus, it was concluded that the toxicity of the cereal blends was not improved by the extrusion process.