Screw Speed Research Articles

Currently, ca. 30 million m3 of Pinus radiata are harvested annually in New Zealand to produce timber, pulp and paper, with by-products such as bark and sawdust generated during processing. The most common use for sawdust is as a solid fuel for process heat. However, it is a feedstock that can be processed into platform biochemicals. Although conversion processes focusing on biochemical production from wood are scarce, they are becoming more commercially established. Here, reactive extrusion was explored as a continuous, fast method to depolymerise sawdust into soluble biochemicals with residence times of less than two minutes. This is substantially shorter than other biotechnology routes or conventional batch processing and highlights the potential for integration of reactive extrusion into biorefinery operations. While conventional wood extrusion focused on the solid fraction, this work extensively investigated the liquid biochemical profile. The effects of temperature, moisture content, screw speed, and screw design on the biochemical yield from sawdust were studied. The results indicated that kneading elements in the screw design were key to achieving good processing of the sawdust. A high moisture content of 50% (by weight) was instrumental in the isolation of biochemicals. Moreover, the screw speed had little to no effect on the biochemical composition obtained from the reactive extrusion process. Finally, a maximum of 6.5-7.5% of biochemicals were recovered from sawdust in the liquid phase when processed between 325 °C and 375°C. The biochemical analyses of the liquor showed a high amount of acetic acid (up to 7913mg/L) and methanol (up to 2277mg/L). Furthermore, the furanic content increased with an increase in temperature between 275 °C and 375°C, while an inverse trend was observed for aromatic phenols. The analyses also revealed that lignin and hemicellulose were depolymerised to produce oligomeric and monomeric breakdown products, while cellulose was untouched. This study successfully demonstrated the successful use of a twin-screw reactive extruder to continuously produce a biochemical-rich liquor from sawdust.

Impact of extrusion-induced protein molecular rearrangement on cooking qualities, in vitro digestibility and gluten allergenicity of durum wheat pasta.

This study explores the use of a homemade mung bean protein extract solution (MP) as the moisture source in high-moisture extrusion to produce pea–mung bean composite textured protein (PMP). Single-factor experiments assessed the effects of MP addition amount (30–70%), screw speed (140–220 rpm), and extrusion temperature (140–180 °C) on the textural, physicochemical, and structural properties, followed by optimization using response surface methodology (RSM). MP addition amounts between 50% and 60% promoted higher surface hydrophobicity, a higher disulfide bond content, more ordered secondary structures, and a higher intrinsic fluorescence, accompanied by improved water- and oil-holding capacities, bulk density, and texturization degree (p < 0.05). Screw speeds of 160–180 rpm enhanced texturization and texture via increased shear and reduced residence time, whereas higher extrusion temperatures darkened the color (Maillard browning) and reduced texturization and the bulk density. RSM found that the optimal conditions were 53% MP, 160 rpm, and 150 °C, yielding a theoretical maximum texturization degree of 1.55, which was experimentally validated (1.53 ± 0.02). These findings support MP as an effective green moisture source to tailor the structure and functionality of pea-based high-moisture extrudates. Future work will integrate calibrated SME, sensory evaluation, and application testing in meat-analog formats.

ABSTRACT This study investigates the effect of processing parameters on the dispersion quality of carbon nanotube (CNT) within poly(butylene adipate‐co‐terephthalate) (PBAT) matrix and the corresponding rheological behavior, electrical conductivity, dielectric properties, and electromagnetic interference shielding effectiveness (EMI‐SE). Neat PBAT and nanocomposites containing 1, 3, and 5 wt% CNT were prepared using an internal melt mixer with varying processing temperatures and screw speeds. Small amplitude oscillatory shear rheological analysis revealed that an increase in processing temperature resulted in a more significant increase in complex viscosity and storage modulus at low frequencies reflecting a better CNT dispersion and the formation of a stronger network. Higher mixing speeds also facilitated CNT dispersion more effectively; although further increases could cause the mechanical degradation of PBAT molecules and CNTs breakage. Scanning electron microscopy analysis confirmed the better and more uniform CNT dispersion when the nanocomposites were processed at higher temperatures and mixing speeds. The changes in electrical conductivity, dielectric permittivity, and EMI‐SE of the nanocomposites were consistent with the melt rheological results confirming a symbiotic correlation between these characteristics. Nanocomposites with 5 wt% CNT revealed DC conductivity and EMI‐SE values of about 10 −7 S/cm and 35–38 dB, respectively, when processed at 150°C and 100 rpm. These values, however, reached about 10 −3 S/cm and 44–50 dB, respectively, when nanocomposites were prepared at 190°C and 200 rpm. Under this preparation condition, the onset of rheological and electrical conductivity percolation thresholds was estimated at CNT contents of about 0.18 and 0.45 wt%, respectively. A higher processing temperature (190°C) and increased mixing speed (200 rpm) were found to be critical in achieving uniform CNT dispersion and enhancing the multifunctional properties of the nanocomposites.

Pasta made from broken rice and sake kasu is safe for people with celiac disease, as it is gluten-free by nature (due to the composition of its ingredients). The aim of this study was to study the effect of extrusion process on properties of gluten-free pastas made from broken rice and sake kasu to obtain optimal processing conditions. Effects of extrusion temperature (ET, 85-125°C), screw speed (SS, 75-125 rpm) and sake kasu flour conten (SKF, 25-75), on properties of pasta was evaluated, using a rotatable composite central design and the response surface methodology for the statistical analysis of the data. The protein content increases with the SKF increased. The cooking solids loss increased proportionally with SKF at high ET and high SS, demonstrating that at these extrusion conditions there is greater process severity. Total phenolic compounds content increased proportionally with SKF. The highest total antioxidant capacity (ABTS) was found at high SKF, medium ET, and high SS. The overall sensory acceptability response variable increased as ET and SS increased and decreased as SKF increased at low processing conditions. The optimum conditions were SKF = 60.83%, ET = 116.89 °C and SS = 107.93 rpm. The values of response variables under optimal conditions were: protein content of 13.18 ± 0.28%, cooking loss of 6.89 ± 0.36%, total phenolic compounds of 376.11 ± 18.55 mg GAE/100 g d.b., antioxidant activity (ABTS) of 8691.89 ± 381.13 µmol TE/100 g d.b. and general acceptability of 57.47 ± 1.80. Optimal paste obtained a higher protein content compared to commercial controls. Due to its composition and high sensory acceptability, sake kasu pasta prepared in present study has a potential beneficial effect on health. In addition, it can work as an alternative for people who cannot consume gluten and also look for products with a high protein content.

The fabrication of support-free structures in pellet additive manufacturing (PAM) is severely limited by gravity-induced sagging, a phenomenon lacking predictive, physics-based models. This study introduces and validates a numerical model for the thermofluid dynamics of sagging, aiming to correlate process parameters with filament deflection. A predictive finite element (FE) model incorporating temperature-dependent non-Newtonian material properties and heat transfer dynamics has been developed. This was validated via a systematic experimental study on a desktop-scale PAM 3D printer investigating nozzle temperature, printhead speed, screw speed and fan cooling, using polylactic acid (PLA) as a printing material. Findings show that process parameter optimization can reduce bridge deflection by 64.91%, with active fan cooling being the most dominant factor due to accelerated solidification. Increased printhead speed reduced sagging, whereas higher screw speeds and extrusion temperature showed the opposite effect. The FE model accurately replicated these results and further revealed that sagging ceases once the filament cools below its minimum flow temperature (approximately 150–160 °C for PLA). This validated model provides a robust foundation for tuning process parameters, unlocking effective support-free 3D printing in PAM.

Puffed snacks have gained attention due to their light texture and appealing taste. However, refined grain flour-based products generally provide little nutritional content, especially protein and dietary fiber. In an effort to improve their nutritional quality, extruded snacks were developed by blending corn flour with cowpea, chickpea, and mung bean flours at substitution levels of 25–50%. Extrusion was carried out using a twin-screw extruder at a barrel temperature of 150 °C, screw speed of 85 rpm, and die diameter ratios ranging from 2 to 2.50. The products were then dried at 60 ± 0.5 °C. Five formulations were developed: E0 (100% corn flour); E1 (50% corn and 50% cowpea); E2 (50% corn and 50% chickpea); E3 (50% corn and 50% mung bean); and E4 (25% each of corn, cowpea, chickpea, and mung bean flours). The snacks developed from E4 showed the highest protein (23.34 ± 1.27%), dietary fiber (2.32 ± 0.22%), FRAP activity on a dry weight basis (48.70 ± 0.30 µmol Fe²⁺/g), and DPPH radical scavenging activity (12.50 ± 0.23%). SEM analysis revealed an enhanced protein matrix continuity along with improved cellular structure. Overall, incorporating pulses into extruded snacks significantly enhanced their nutritional and functional properties, offering a healthier alternative to conventional refined-grain snacks.

This study investigated the drying–grinding–extrusion processing of camel compound feeds enriched with locally available botanicals. A 2 × 2 × 3 full factorial design was applied to evaluate the effects of infrared drying temperature (two levels), grinding time (two levels), and extrusion screw speed (three levels) on process efficiency and product quality. Moisture calibration was performed using gravimetric reference values. Drying kinetics were modeled with Page and Midilli equations, while specific energy consumption (SEC) and specific moisture extraction rate (SMER) were calculated. Particle-size distribution, extrusion parameters, and extrudate properties (expansion ratio, bulk density, water absorption index (WAI), water solubility index (WSI), hardness, and color) were analyzed. Infrared drying resulted in faster moisture removal and greater energy efficiency compared with convective drying. The Midilli model provided the best fit to drying kinetics data. The results indicate that optimized combinations of drying, grinding, and extrusion conditions can enhance the technological and nutritional potential of camel compound feeds; however, biological validation is required. Limitations: These findings are limited to processing and compositional outcomes; biological validation in camels (in vivo or in vitro) remains necessary to confirm effects on digestibility, health, or performance.

ABSTRACTThis study investigates the effect of processing conditions on the structural, mechanical, and degradation behavior of poly(butylene succinate) (PBS), a promising biodegradable polyester. PBS was processed using a micro‐compounder by varying screw speeds (20 and 60 rpm) and residence times (2 and 5 min). Considering that the processing conditions for biopolymers in a microcompounder are typically around 60 rpm with a residence time of approximately 5 min, this work attempts to minimize the thermo‐mechanical degradation undergone during the PBS processing by reducing the screw speed by about three times (from 60 to 20 rpm) and the processing times by about 2.5 times (from 5 to 2 min). Characterization was performed by using thermal, mechanical, and rheological analyses. A lower screw speed (20 rpm) resulted in a higher degree of crystallinity (~62%), about 5% greater than that of samples processed at 60 rpm. The mechanical properties at break (e.g., tensile strength and elongation at break) and the rheological properties remained unchanged when the processing conditions were changed. It is worth noting that at 60 rpm, increasing residence time led to a 12.7% increase in elastic modulus. Degradation behavior was evaluated under photo‐oxidative and hydrolytic conditions. After 96 h of UV exposure, samples processed at a lower speed (20 rpm) showed lower hydroxyl, carbonyl, and vinyl indices, indicating better resistance to photo‐oxidation due to their higher crystallinity. Hydrolytic degradation was carried out at high and low environmental temperatures. Hydrolysis of all PBS samples at low temperature (25°C) occurred more slowly than at high temperature (70°C). These results highlight the critical role of processing parameters in tuning PBS crystallinity and stiffness, as well as degradation behavior. The PBS processed at low speed (20 rpm) for a short time (2 min) has been successfully processed, consuming lower energy and resulting in improved properties and reduced thermo‐mechanical degradation. Overall, prolonged processing of PBS (at 5 min) appears to result in materials with poorer properties and lower degradation resistance, particularly at high screw speeds. These are key aspects of its application in sustainable materials and biodegradable packaging.

From print settings to printlet performance: a study on critical quality attributes in pellet-based direct extrusion additive manufacturing.

Extruded whole flours from blends of cereals and pulses have great potential to be key ingredients in the development of more innovative gluten-free products, both from a technological and nutritional perspective. The objective of this work was to obtain pre-cooked flours from four formulations based on blends of whole cereals (PR: parboiled brown rice; PM: pearl millet) and pulses (CP: chickpea; CB: common bean). CB was fixed at 10%, and the other components (PR-PM-CP) were set at 60-15-15 (F1), 15-60-15 (F2), 15-15-60 (F3), and 30-30-30 (F4), which were extruded at two combined conditions of feed moisture and screw speed: mild E1 (30% and 300 rpm) and severe E2 (18% and 600 rpm). The temperature profile was kept constant from 25 to 130 °C (from feed to output). The protein, dietary fiber, and ash contents in the raw formulations varied from 11.2 to 17.4%, 9.8 to 15.0%, and 2.2 to 3.3%, respectively, according to the low or high pulse content in the blend. As more mechanical energy was delivered to the raw formulations (W·h/kg, 63.7 for E1 and 179.4 for E2), the extruded particles had increased water absorption (g/g) from 1.7 to 4.5 (E1) or 3.8 (E2), increased water solubility due to E2 from 10.9 to 20.9%, and decreased oil absorption (g/g) from 1.5 to 0.9 (E1 and E2). The peak viscosity (PV, cP) was noticeable only in the raw formulation F2 (355), which decreased 10.3% due to E1. In the other formulations, PV appeared due to E1 in F1 (528), F3 (420), and F4 (371), while it disappeared due to E2 in all formulations. However, at the E2 condition, they did show cold viscosity in the initial stage (222 to 394 cP). The final viscosity (FV, cP) decreased from 795 to 390 (E1) or 123 (E2). In F2, the contents of phenolic compounds (285 µg GAE/g) and ABTS+ (13.2 μmol TE/g) were more than twice that in the other formulations, and their respective degradations were low due to E1 (4.2 and 12%) and high due to E2 (16 and 17%). Extrusion cooking did not cause significant changes in the luminosity (81) and redness (0.9) of particles, while yellowness increased from 15.7 to 18.2 (E1) or 18.7 (E2). Based on these findings, it is concluded that both extrusion conditions improved the technological and functional properties. Regarding the formulations, F2 stood out for being rich in antioxidant capacity, which poorly degraded under the conditions studied. Further work is needed to contribute to understanding the optimization of formulas and processes that would improve the nutritional, sensorial, and functional properties while still preserving the bioactive value of the final products.

The growing demand for personalization in e-commerce, coupled with rising sustainability concerns, is reshaping the future of polymer manufacturing. This study investigates the integration of artificial intelligence (AI) into polymer production to optimize material performance, enhance consumer-driven personalization, and align with circular economy goals. Using machine learning, deep learning, and reinforcement learning models, polymer processing parameters such as extrusion temperature, screw speed, and additive ratios were optimized to improve tensile strength, durability, and defect reduction. Consumer preference data were analyzed to identify five distinct market segments, each exhibiting unique priorities in customization, sustainability, and durability. Experimental trials validated AI predictions, while statistical analyses, including MANOVA, PCA, regression models, and cluster validation, confirmed the robustness of the results. AI-optimized polymers demonstrated significant reductions in carbon footprint, energy use, and waste generation while improving recyclability and biodegradability. The findings underscore AI’s capacity to transform polymer manufacturing into a demand-responsive, sustainable, and consumer-centric process, offering practical implications for industries seeking to adapt to rapidly evolving e-commerce markets.

Codonopsis pilosula, a valuable traditional herb, is rich in bioactive compounds like polysaccharides and phenolics. However, conventional processing methods may limit its functional properties and application in modern food industries. Extrusion processing, as an efficient and versatile technology, offers a promising approach to enhancing the bioactivity and utilization of botanical materials. In this study, Codonopsis pilosula was enhanced through extrusion processing. The results demonstrated that extrusion under the optimal conditions (screw speed of 250 rpm, moisture content of 20%, and barrel temperature of 131 °C) significantly enhanced the properties of Codonopsis pilosula. Specifically, the polysaccharide content increased from 244.41 to 271.00 mg/g, and the water solubility index rose markedly from 12.99% to 40.79%. Concurrently, a significant improvement in antioxidant activity was observed, with the hydroxyl radical scavenging rate increasing from 52.89% to 69.27% and the DPPH radical scavenging rate from 60.43% to 67.35%. Based on the optimized extrusion conditions, a Codonopsis oat flour was developed. Through orthogonal experiments, the optimal formulation ratio was identified, resulting in a flour product with moderate color and viscosity, a distinctive aroma, and a maximum sensory score of 88.7. These results demonstrate that extrusion is a viable approach for enhancing the functional properties of Codonopsis pilosula, providing a theoretical basis for its application in food processing lines and the development of functional foods.

Twin-screw melt granulation of Eudragit® FS100: optimization of coating-free delayed-release matrix tablets with HPMC K4M modulation.

The study of particle size is particularly important, as it influences the functional, textural, and physical properties of food products. This work evaluated the effect of milling extruded nixtamalized blue corn on anthocyanin content and tortilla texture. Blue corn was milled, conditioned with 0.3% lime at 25% moisture, and extruded at 90°C with a screw speed of 145 rpm. Extrudates were dried and milled using different mesh sizes (0.5, 0.8, 1.0, and 2.0 mm) to produce flours with fine and coarse particle sizes. Tortillas were machine-made and stored at room temperature for 48 h. The results showed that milling mesh size significantly affected the properties of masa and tortillas. Coarser flours (2.0 mm) led to improved tortilla texture, rollability, and higher anthocyanin retention during storage. These findings highlight the importance of milling and particle size selection in the manufacture of non-traditional tortillas to enhance their functional and textural quality.

This study evaluated the effects of various factors on breakfast cereals containing β-glucan-enriched flour fraction (BEFF). A central composite design (CCD) was used to examine the effects of BEFF level, screw speed, and die temperature on the physical, textural, microstructural, and nutritional properties of the cereals. The addition of BEFF initially increased the L* value by 5.1%, followed by a decrease at higher levels. Porosity increased linearly, whereas starch digestibility decreased. Screw speed was the most significant independent variable affecting the physical and structural properties of the cereals, followed by die temperature. The optimum processing conditions were 5.1% BEFF, 435 rpm screw speed, and 170 °C die temperature (with the other barrel zones maintained at 40, 50, 70, 90, and 100 °C), yielding β-glucan content of 14.3 g kg-1 and starch digestibility of 196.46 mg maltose g-1. β-Glucan loss was limited to 42% at most when compared with the unextruded blend. Extrusion increased starch digestibility and reduced β-glucan content, and the enthalpy of starch gelatinization tended to decrease with BEFF incorporation into the control sample. All breakfast cereal products in this study met Food and Drug Administration (FDA) requirements, containing at least 0.75 g of β-glucan per serving portion. © 2025 Society of Chemical Industry.

ABSTRACT Polylactic acid (processed by fused filament fabrication) and 17-4 precipitate-hardened stainless steel (processed by direct metal laser sintering) have wide scaffolding applications. However, little has been reported on recycling biocompatible polylactic acid-based waste and 17-4 precipitate-hardened stainless steel-based waste powder (collected from the direct metal laser sintering setup) for scaffolding applications such as splints. This study highlights the development of polylactic acid-17-4 precipitate hardened stainless steel matrix-based composite to fabricate splints/external fixators. The mechanical, thermal, and morphological properties of polylactic acid-17-4 precipitate-hardened stainless steel filament composites were investigated using varying heat treatment types, extrusion speed, and temperature. The best setting for maximising the peak strain and break strain was predicted with the combination of post-heat treatment, 7 rpm screw speed, and 210℃ extrusion temperature. Further, the morphological, thermal, and bond characteristics (based on differential scanning calorimetry, Fourier transmission infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy and X-ray diffraction analysis) also support the study. The proposed composite prepared by the extrusion has shown acceptable properties as splints/external fixators.

Physicochemical effects of succination in aqueous medium and reactive extrusion on achira (Canna indica L.) starch intended for food industry applications.

ABSTRACTExtrusion is an innovative technology for improving the techno‐functional and nutritional properties of pulse flours. This study aimed to optimize extrusion conditions for broad bean and mung bean flours and to assess their potential in bread making. Die temperature (135°C–165°C) and screw speed (200–300 rpm) were optimized using response surface methodology, with water absorption index (WAI), phytic acid (PA), and insoluble dietary fiber (ISDF) as response variables. Optimal conditions were found to be a 165°C die temperature and a 200 rpm screw speed for both pulses. Die temperature and screw speed had a significant effect on WAI, PA, and ISDF values. Flours obtained under optimum conditions showed the following changes: in mung bean, WAI increased by 50%, whereas PA and ISDF decreased by 59.5% and 30.9%, respectively; in faba bean, WAI increased by 33.69%, whereas PA and ISDF decreased by 45.27% and 29.68%, respectively. Extrusion disrupted starch crystallinity and changed protein‐carbohydrate structures as observed by XRD, FTIR, and DSC analyses. Incorporation of pulse flours affected the rheological properties of the bread dough, causing a decrease in viscous and elastic responses. In bread making trials, wheat flour was substituted with pulse flours at 12.5% and 25%. Both substitution levels reduced bread volume and increased crumb hardness. In conclusion, it is shown that extrusion is an effective method for modifying the functional properties of pulse flours, and the use of optimized extrusion as a tool to develop novel functional pulse‐based ingredients.

ABSTRACTThe rich information from the input electrical signal of the injection molding machine can independently reflect the characteristics of the whole state of the equipment, which is an ideal signal for analyzing the manufacturing process. In this study, a method of analyzing the injection molding process by input electrical signal is presented, and the related applications of this method are discussed. Eight kinds of electrical signals during the molding process are measured for this method. The principal components analysis (PCA), optimum segmentation method, and continuous wavelet transform (CWT) are introduced to build the multivariate ordered time series segmentation method. After segmenting the processes, a mathematical model is established to investigate the relationship between the electrical power consumption and screw speed. The injection energy is divided into kinetic energy and internal energy, which is equal to the electrical energy. The results show that the accuracy of this segmentation method can reach 92.6% under appropriate parameters. Moreover, the results of the model show that the error between the calculated results and the measured results is less than 10% in the initial stage of injection. The methods provide a new way of analyzing the injection molding process for improving molding quality stability.