Cryomilling Research Articles

Mixed-Material Feedstocks for Cold Spray Additive Manufacturing of Metal–Polymer Composites

High-performance polymers such as poly(ether ether ketone) (PEEK) are appealing as composite components for a wide variety of industrial and medical applications due to their excellent thermomechanical properties. However, conventional PEEK metallization methods can often lead to poor quality control, low deposition rate, and high cost. Cold spray is a promising potential alternative to produce polymer–metal composites rapidly and inexpensively due to its relatively mild operating conditions and high throughput. In this study, we investigated the deposition characteristics of metal–polymer composite feedstock, composed of PEEK powder and copper flake in varying ratios, onto a PEEK substrate. Copper-PEEK powder blends were prepared by both hand-mixing and cryogenic milling (cryomilling), which predominantly creates composite particles with micron-scale copper domains coating PEEK particle surfaces. This process non-monotonically affects the relative dominance and length scales of the multiple contributing deposition mechanisms present in mixed-material cold spray. In low-pressure cold spray, deposits showed significant changes in deposition efficiency and composition as a result of milling, with improvements in these characteristics most dramatic at lower Cu fractions. Deposits of a cryomilled blend of nominally 30 vol.% copper in PEEK exhibited minimal porosity under scanning electron microscopy, complete retention of powder composition, and the highest deposition efficiency among all samples tested. Notably, neither neat PEEK nor neat Cu meaningfully deposited at the same mild conditions as this 30 vol.% Cu blend, indicating a synergistic departure from linear mixing rules driven by the relative balance of local deposition interactions (e.g., hard–soft, soft–soft, etc.). Intentional powder and process design toward optimizing this balance may facilitate cold spray metallization applications.

Advance processing of cluster-free CNT reinforced 6082 Al matrix nanocomposites: influence of mechanical milling and cryomilling

ABSTRACT In the present study, lightweight high-strength carbon nanotubes (CNTs) reinforced aluminium-based composite was fabricated through powder metallurgical processing. The effect of planetary milling and cryogenic assisted milling on the structure, morphology, mechanical properties, phase composition, and thermal stability of CNTs reinforced Al6082 Al nanocomposites powders was investigated using X-ray diffraction (XRD), scanning electron microscope (SEM)- Energy dispersive spectroscopy (EDS), transmission electron microscope (TEM), and indentation techniques. The CNTs in the Aluminium (AL) matrix were distributed uniformly after 50 h of milling. Further, the cryomilling of 50 h milled Aluminium matrix composites (AMC) decreases agglomeration even more and was successful in cleaving the nanotubes as well as minimising entanglements. The broadening of diffraction peaks suggests a reduction in the crystallite size (from ~36 to ~20 nm) and an increase in induced strain. Milled powders were consolidated through the hot-press and spark plasma sintering technique. The mechanical properties of these AMCs were evaluated through indentation for hardness (>250 HV) and compressive testing techniques. SPSed samples reported better properties in comparison to hot-pressed samples. It is discovered that post-CM of Mechanical Milling (MM) powder aids in overcoming issues related to the agglomeration of Al/CNT composites, and the goal to fabricate tangle-free CNT reinforced composite was achieved. Moreover, it showed enhanced mechanical properties with a maximum yield strength of 210 MPa and good synergy between strength and ductility.

Comparative Study of Pre-Extraction Treatments and Buffer Modifications for Macroalgal Lectin Extraction

Getting an efficient extraction approach is a crucial step in bioactive protein research, particularly lectin. This research aimed to examine the efficiency of cryogenic-grinding (CG) and freeze-dried-grinding (FG) pre-extraction treatments, and also the incorporation of phenylmethylsulphonyl fluoride (PMSF), Tween 80, polyvinylpolypyrrolidone (PVPP), 70% Ethanol (EtOH), or combination of the chemicals in the 20 mM phosphate buffered saline pH 7 (PBS) for extracting lectin from Ulva lactuca, Sargassum polycystum, and Hydropuntia edulis. The lectin content of the extracts was determined using the hemagglutination activity (HA) assay. The phenolic content was measured to determine its impact on the lectins’ HA. Lectin extraction efficiency was determined by analyzing the extracts’ minimum agglutination concentration (MAC) and total hemagglutination activity (THA). CG pre-extraction treatment produced slightly higher THA than FG, making it slightly more efficient. The EtOH treatment efficiently extracted lectin from U. lactuca and H. edulis by substantially reducing the polyphenol (PPs) content, lowering the MAC, and increasing the THA. The EtOH treatment significantly decreased the PPs and HA of the S. polycystum, suggesting that the HA is most likely produced by the PPs rather than the lectin content. Tween 80 raised the THA of U. lactuca by 17-fold with native rabbit erythrocyte compared to the control but did not affect the THA of H. edulis and S. polycystum. Several different effects of chemicals incorporated in the extraction buffers suggested that the optimum macroalgal lectin extraction strategy is species-dependent.

Influence of Crystal Disorder on the Forced Oxidative Degradation of Vortioxetine HBr

The present study investigates the impact of the solid-state disorder of vortioxetine hydrobromide (HBr) on oxidative degradation under accelerated conditions. A range of solid-state disorders was generated via cryogenic ball milling. The solid-state properties were evaluated by calorimetry, infrared-, and Raman spectroscopies. While salt disproportionation occurred upon milling, no chemical degradation occurred by milling. The amorphous fraction remained physically intact under ambient storage conditions. Subsequently, samples with representative disordered fractions were mixed with a solid oxidative stressor (PVP-H2O2 complex) and were compressed to compacts. The compacts were exposed to 40°C/75% RH for up to 6 h. The sample was periodically withdrawn and analyzed for the physical transformations and degradation. Two oxidative degradation products (DPs) were found to be formed, for which dissimilar relations to the degree of disorder and kinetics of formation were observed. The degradation rate of the major DP formation obtained by fitting the exponential model to the experimental data was found to increase up to a certain degree of disorder and decrease with a further increase in the disordered fraction. In contrast, the minor DP formation kinetics was found to increase monotonically with the increase in the disorder content. For the similar crystallinity level, the degradation trend (rate and extent) differed between the single-phase disorder generated by milling and physically mixed two-phase systems. Overall, the study demonstrates the importance of evaluating the physical and chemical (in)stabilities of the disordered solid state of a salt form of a drug substance, generated through mechano-activation.Graphical

A Review On Electrospun Short Fiber Production

Nanotechnology has become the interest of researchers in recent years for their unique properties of submicron scale materials. Nanotechnology also consists of nanofibers made from natural or synthetic polymers which can be electrospun into ultra-thin continuous fibers. These nanofibers are versatile as it can be found in various applications such as in filtration, affinity membranes, tissue engineering, biosensors, scaffolds, drug delivery and fiber reinforcement. Over the years, many researchers have reported various methods used to produce short electrospun fiber by means of ultrasonication, mechanical cutting, UV cutting, precipitation method, microtome cutting, cryo-microcutting, cryogenic milling, ball milling, and razor blade cutting under liquid nitrogen. The aim of this paper is to provide a review on electrospun short fiber production which elaborates more on the scission methods of the continuous as-spun fibers. The literature shows that several methods have been proposed and utilized, with varying degrees of success. Overall, it can be concluded that further research is needed to fully understand the complexities of this area and to develop a more effective approach.

Mechanochemical synthesis of MnBi/Fe3C@C exchange coupled hard magnetic nanocomposites

Despite the better suitability of rare earth permanent magnets for various applications, the scarcity of rare earths limits their application range. The, low temperature phase of MnBi is sought as a probable gap magnet without any rare earth elements. Further, the nanocomposites (soft/hard magnets) are known to provide better properties. In this study, Mn55Bi45/Fe3C@C nanocomposites with enhanced magnetic properties were prepared using cryogenic ball milling. The feasibility of utilizing Fe3C@C as a soft phase in hard-soft composites was explored. Fe3C@C was synthesized through the solvothermal technique, followed by calcination, resulting in a remarkable saturation magnetization (MS) of 150 emu/g. Different amounts of Fe3C@C (0, 5, 10, 15, and 20 wt.%) were added to Mn55Bi45 powder, and after cryo-milling, it was observed that the addition of 10 wt. % yielded the optimum results, with a 37% enhancement in MS and 58% increase in Mr values. The presence of exchange-coupled nanocomposites was confirmed through x-ray diffraction, transmission electron microscopy, and magnetic studies. This study not only paves the way for increasing the energy product of the MnBi system but also explores the potential of utilizing Fe3C@C as a soft phase—a relatively oxidation-resistant phase—in other hard magnetic systems.

An assessment of methods used for the generation and characterization of cryomilled polystyrene micro- and nanoplastic particles

There is a critical need to generate environmentally relevant microplastics (MPs) and nanoplastics (NPs) to better investigate their behavior in laboratory settings. Environmental MPs are heterogenous in size and shape, unlike monodisperse and uniform microspheres commonly used as surrogates. Cryogenic grinding, or cryomilling, was successfully utilized to transform polystyrene (PS) bulk material into heterogenous micro and nano fragments. Fourier-Transform Infrared (FTIR) spectroscopy confirmed that this approach did not alter polymer surface chemistry. The number of milling cycles (time of milling) and frequency of grinding (intensity of milling) were varied to investigate the role cryomilling parameters had on generated MP characteristics. The resulting particle size distributions of cryomilled samples were measured and compared. Coulter Counter and Nanoparticle Tracking Analysis (NTA) were used to measure the particle size distributions at the micro and nanoparticle size ranges, respectively. Microspheres were used to determine what camera settings yielded more accurate sizing and to reduce bias in the NTA analysis. Increasing milling cycles generally increased the number of smaller particles. The evolution of the measured size distributions indicated that small nanosized fragments broke off from larger MPs during cryomilling, steadily eroding larger MP fragments. The number of milling cycles was observed to more consistently impact the size distributions of fragments compared to the frequency of milling. This study offers both analysis of the cryomilling process and recommendations for generating more realistic PS MP/NPs for examining environmental fate and effects.

Impact of Processing and Physicochemical Parameter on Hibiscus sabdariffa Calyxes Biomolecules and Antioxidant Activity: From Powder Production to Reconstitution.

Hibiscus sabdariffa is a tropical plant with red calyxes whose anthocyanins, phenols, and antioxidant activity make it attractive to consumers both from a nutritional and medicinal standpoint. Its seasonality, perishability, and anthocyanin instability, led to the setup of stabilization methods comprising drying and powdering. However, its properties can often be altered during these stabilization processes. Treatments such as dehumidified-air-drying, infrared drying, and oven-drying, and their combination showed better quality preservation. Moreover, powder production enables superior biomolecule extractability which can be linked to a higher bioaccessibility. However, the required temperatures for powder production increase the bioactive molecules degradation leading to their antioxidant activity loss. To overcome this issue, ambient or cryogenic grinding could be an excellent method to improve the biomolecule bioavailability and accessibility if the processing steps are well mastered. To be sure to benefit from the final nutritional quality of the powder, such as the antioxidant activity of biomolecules, powders have to offer excellent reconstitutability which is linked to powder physicochemical properties and the reconstitution media. Typically, the finest powder granulometry and using an agitated low-temperature reconstitution media allow for improving anthocyanin extractability and stability. In this review, the relevant physicochemical and processing parameters influencing plant powder features from processing transformation to reconstitution will be presented with a focus on bioactive molecules and antioxidant activity preservation.

Hydrodistillation and Steam Distillation of Fennel Seeds Essential Oil: Parameter Optimization and Application of Cryomilling Pretreatment

The aim of this study was to examine the effectiveness of cryomilling (CM) pretreatment on the isolation of fennel seeds essential oil (EO). Therefore, the study included (i) the process optimization and comparison of the efficiencies of hydrodistillation (HD) and steam distillation (SD); (ii) the evaluation of the effect of the CM application prior to the distillation method (selected based on the results obtained in the first part) on the EO yield; (iii) the evaluation of possible quality differences of the EOs obtained with the performed isolation methods. The obtained results showed that HD (at a solid to liquid ratio 1:10 and a distillation time of 120 min) was more efficient in terms of the EO yield compared to SD (at a pressure of 0.83 bar and distillation time of 117 min as optimal conditions). Moreover, an increased EO yield or even reduced distillation time was observed when HD was combined with a 3 min or 5 min CM pretreatment. GC-MS analysis showed no qualitative differences in chemical composition upon any of the applied isolation procedures, although higher amounts of volatiles were found in the cryomilled samples. The results of this study could be of interest to academia and the EO industry, as CM showed a positive aspect in EO isolation that could provide economic benefits in terms of higher yields or energy savings.

Experimental study on defects of needled quartz fiber reinforced phenolic aerogel composites by cryogenic milling

Needled quartz fiber reinforced phenolic aerogel composite (NQF/PA) is a kind of lightweight thermal protection material commonly used in the aerospace field. With the continuous development of aerospace science and technology, the design of various spacecraft is becoming more and more complex. Due to the limitation of the preparation process, thermal protection components are difficult to be directly prepared and formed. It is often necessary to carry out secondary processing in order to bond and assemble into a large-size combined thermal protection system. Because NQF/PA composites have the characteristics of high fiber toughness and easy cracking of the matrix, it is easy to cause processing defects such as burrs, tearing and edge collapse in dry machining. Cryogenic machining can improve the machinability of fiber-reinforced composites. However, there is still a lack of research on the cryogenic machining of NQF/PA composites. In order to analyze the feasibility of cryogenic machining technology for low-damage processing of NQF/PA composites, this paper carried out a comparative experimental study on dry machining and cryogenic machining of NQF/PA composites and analyzed the influence of spindle speed, feed rate and radial cutting depth on surface defects and cutting force. The research showed that under the same processing parameters, compared with dry machining, cryogenic machining can effectively reduce the cutting force and suppress processing defects.

Re-visitation of Two Models for Predicting Mechanically-Induced Disordering after Cryogenic Impact Milling.

To compare the prediction accuracy of two models used to characterize the complete disordering potential of materials after extensive cryogenic milling. Elastic shear moduli (μs) were simulated in silico. Comparison with available literature values confirmed that computations were reasonable. Complete disordering potential was predicted using the critical dislocation density (ρcrit) and bivariate empirical models. To compare the prediction accuracy of the models, each material added for dataset expansion was cryomilled for up to 5 hr. Mechanical disordering after comminution was characterized using PXRD and DSC, and pooled with previously published results. Simulated μs enabled predictions using the ρcrit model for 29 materials. This model mischaracterized the complete disordering behavior for 13/29 materials, giving an overall prediction accuracy of 55%. The originally published bivariate empirical model classification boundary correctly grouped the disordering potential for 31/32 materials from the expanded dataset. Recalibration of this model retained a 94% prediction accuracy, with only 2 misclassifications. Prediction accuracy of the ρcrit model decreased with dataset expansion, relative to previously published results. Overall, the ρcrit model was considerably less accurate relative to the bivariate empirical model, which retained very high prediction accuracy for the expanded dataset. Although the empirical model does not imply a mechanism, model robustness suggests the importance of glass transition temperature (Tg) and molar volume (Mv) on formation and persistence of amorphous materials following extensive cryomilling.

Manufacturing of High Conductivity, High Strength Pure Copper with Ultrafine Grain Structure

Applications of Copper (Cu) range from small scale applications such as microelectronics interconnects to very large high-powered applications such as railguns. In all these applications, Cu conductivity and ampacity play vital roles. In some applications such as railguns, where Cu also plays a structural role, not only is high conductivity needed, but high strength, high ductility, and high wear resistance are also critical. Current technologies have achieved their full potential for producing better materials. New approaches and technologies are needed to develop superior properties. This research examines a new fabrication approach that is expected to produce Cu with superior mechanical strength, enhanced wear resistance, and increased electrical conductivity. Materials with refined grain structures were obtained by breaking down the coarse-grained Cu particles via cryogenic ball milling, followed by the consolidation of powders using cold isostatic pressing (CIP) and subsequent Continuous Equal Channel Angular Pressing (C-ECAP). The mixture of fine and ultrafine grains, with sizes between 200 nm to 2.5 µm and an average of 500 nm, was formed after ball milling at cryogenic temperatures. Further processing via C-ECAP produced nanostructured Cu with average grain sizes below 50 nm and excellent homogenous equiaxed grain shapes and random orientations. The hardness and tensile strength of the final Cu were approximately 158% and 95% higher than the traditional coarse-grained Cu bar, respectively. This material also displayed a good electrical conductivity rate of 74% International Annealed Copper Standard (IACS), which is comparable to the current Cu materials used in railgun applications.

Stability of pesticide residues in citrus fruits during storage

Introduction. Storage of selected samples before transportation to the laboratory and immediately before analysis is an important component in the process of product quality control and evaluation.
 Purpose of the work was to evaluate the degradation of pesticide active substances in real samples of citrus fruit left for long periods of storage in deep freezing conditions.
 Materials and methods. High-performance liquid chromatography with triple quadrupole mass detector (HPLC-MS/MS) was used to identify and quantify pesticide active substances. According to the method of analysis MUK 4.1.3657–20, cryogenic grinding of samples was carried out in a cutter using dry ice. Sample preparation was carried out using the QuEChERS technology. To extract analytes from a homogenized sample acetonitrile was used in the presence of salts containing citrate buffer, followed by purification of the extract by SPE.
 Results. In the studied samples of citrus, the analytes showed stability. Thirty months after storage of samples in deep freezing conditions (temperature not higher than –20 °C), the identified levels of active ingredients of the pesticides imazalil, pyrimethanil and prochloraz did not change by more than 20% compared to the previously detected concentrations. Insignificant amounts of imidacloprid, thiabendazole and pyriproxyfen, as well as traces of azoxystrobin and trifloxystrobin, detected in the study of samples, were also found in samples after long-term storage. 
 Limitation. The study is limited to the study of the stability of individual active substances found in real samples of citrus fruits intended for sale to the consumer.
 Conclusion. Proper storage of samples should ensure the preservation of the levels of active substances in the samples and exclude their change due to various processes (volatilization, enzymatic and hydrolytic decomposition, etc.), which requires the performance of preliminary experimental studies to assess their stability. The work showed the stability of residual quantities of imazalil, pyrimethanil, prochloraz, imidacloprid, thiabendazole, and pyriproxyfen in citrus fruit matrices under storage conditions in a freezer at not more than –20 °C for 30 months.

Sublethal effects of bio-plastic microparticles and their components on the behaviour of Daphnia magna.

Bioplastics arise as an alternative to plastic production delinked from fossil resources. However, as their demand is increasing, there is a need to investigate their environmental fingerprint. Here we study the toxicity of microplastics (MPLs) of two widely used materials, the polylactic acid (PLA) and the polyhydroxybutyrate (PHB) on the environmental aquatic model species Daphnia magna. The study was focused on sublethal behavioural and feeding endpoints linked to antipredator scape responses and food intake. The study aimed to test that MPLs from single-use household comercial items and among them bioplastics should be more toxic than those obtained from standard plastic polymers and fossil plastic materials due to the greater amount of plastic additives, and that MPLs should be more toxic than plastic extracts due to the contribution of both particle and plastic additive toxicity. MPLs were obtained by cryogenic grinding and sea-sand erosion to obtain irregular particles. MPL included standard polymers and nine comercial items of PLA and PHB and one fossil-based material of high-density polyethylene (HDPE). The additive content in commercial items was characterised by liquid chromatography coupled with high-resolution mass spectrometry. D. magna juveniles were exposed for 24 h to particles and their plastic extracts. Results indicated that the toxicity of bioplastic particles was five times higher than the effects produced by exposure to the content of the additives alone, that bioplastic particles were more toxic than fossil ones and that particles obtained from commercial items were more toxic than those obtained from PLA, PHB or HDPE polymer standards. Predicted toxicity from the measured plastic additives in the studied commercially available household items, however, was poorly related with the observed behavioural and feeding effects. Further research on unknown chemical components together with physical factors is need it to fully understand the mechanisms of toxicity of bioplastic materials.

English

Oleoresins are key flavoring and coloring ingredients in spices and herbs. Among spices turmeric is most commonly used all around the world. Turmeric oleoresins have a promising future in pharmaceutical and food processing industries as functional ingredient. Apart from conventional extraction methods by using modern extraction methods a higher yield of oleoresins can be obtained without losing characteristic integrity. In the present research turmeric oleoresins were extracted by 5 different extraction methods and were compared for extraction efficiency and characterization. Turmeric samples were dried and their moisture content was further adjusted to 12% prior to extraction. Extraction was carried out by (i) conventional solvent extraction (hexane acetone petroleum ether diethyl ether and petroleum ether) (ii) steam distillation (iii) 3-phase partitioning (iv) Supercritical fluid extraction/SCFE and (v) solvent extraction followed by cryogenic grinding. The results revealed that interestingly the highest extraction efficiency was observed in solvent extraction after cryogenic grinding (4.85%). Total phenolics content (TPC) total flavonoids content (TFC) 2 2-diphenyl-1-picrylhydrazyl (DPPH) Ferric reducing antioxidant power (FRAP) and Lipoxygenase (LOX) inhibition assay were determined through UV-vis spectrophotometer functional characterization was carried out by Fourier transformed infrared (FTIR) spectroscopy while fatty acids profiling was carried out by gas chromatography attached with flame ionization detector. Total volatiles and non-volatiles were also determined by oven drying method. Characteristically oleoresins extracted through SCFE were found to be a rich source of TPC (20.57 mg GAE g-1) TFC (109.00 mg QE 100g-1) and total volatiles (2.23%) while highest non volatiles were observed in extracts obtained after cryogenic grinding. Similarly the highest antioxidant activities assessed by DPPH and FRAP were indicated by oleoresins extracted through SCFE as 59.55% and 220.60 ?M Fe2+ g-1 while highest LOX activity (58.33%) was observed in extract obtained by 3-phase partitioning. FTIR spectroscopic analysis of the selected sample indicated the presence of different functional groups with bond type at different wave numbers. GC-FID analysis of selected sample indicated the presence of 13 different fatty acids ranging from 1.9-18.6%. Pentadecane was found in lowest percentage while cis-10 pentadecanoic acid was found in highest concentration. Overall it was concluded that although extraction % of SCF extract was slight lower (4.07%) but it was found best in term of purity and characterization with a strong potential to be used in food and other related industries.

Influence of the incorporation of flexographic photopolymer plate residues on the mechanical properties of epoxy

A thermosetting epoxy polymer composed of diglycidyl ether of bisphenol A and triethylenetetramine (DGEBA/TETA) was modified by incorporating flexographic photopolymer plate residues (rubber microparticles). The photopolymer plate residues were processed in two ways: (a) by grinding and performing particle size classification (where the resulting samples were denoted PP) and (b) by polyester layer separation and grinding the elastomeric fraction by cryogenic grinding (where the resulting samples were denoted ER). Both residual particles were incorporated into the epoxy at concentrations of 2.5, 5 and 7.5 wt%. The main results indicate that PP was not efficient as a modifier of the epoxy system. A reduction in mechanical properties (maximum tensile strength and deformation) was observed in the samples produced with PP in different concentrations. But, when the ER is incorporated, an increase in tensile property and in the deformation capacity, as well as impact resistance was observed in samples produced with ER. Scanning electron microscopy analysis showed a greater presence of voids in formulations produced with PP, which corroborates the decrease in the tensile strength of these samples.

Fracture in elongational flow of two low-density polyethylene melts

Samples of two commercial low-density polyethylene melts were investigated with respect to their fracture behavior in controlled uniaxial extensional flow at constant strain rate in a filament stretching rheometer. In order to assess the possible influence of grain boundaries on fracture, the samples were prepared by three different types of pre-treatment: by compression molding of (1) virgin pellets used as received, (2) pellets homogenized in a twin-screw extruder, and (3) pellets that were milled into powder by cryogenic grinding under liquid nitrogen. The elongational stress growth data were analyzed by the Extended Hierarchical Multi-mode Molecular Stress Function (EHMMSF) model developed by Wagner et al. (Rheol. Acta 61, 281-298 (2022)) for long-chain branched (LCB) polymer melts. The EHMMSF model quantifies the elongational stress growth including the maximum in the elongational viscosity of LDPE melts based solely on the linear-viscoelastic relaxation spectrum and two nonlinear material parameters, the dilution modulus GD and a characteristic stretch parameter {overline{lambda}}_m. Within experimental accuracy, model predictions are in excellent agreement with the elongational stress growth data of the two LDPE melts, independent of the preparation method used. At sufficiently high strain rates, the fracture of the polymer filaments was observed and is in general accordance with the entropic fracture criterion implemented in the EHMMSF model. High-speed videography reveals that fracture is preceded by parabolic crack opening, which is characteristic for elastic fracture and which has been observed earlier in filament stretching of monodisperse polystyrene solutions. Here, for the first time, we demonstrate the appearance of a parabolic crack opening in the fracture process of polydisperse long-chain branched polyethylene melts.

Influence of Cryogenic Grinding on the Nutritional and Antinutritional Components of Rapeseed Cake

We investigated the influence of cryogenic grinding on the quality of rapeseed cake. Rapeseed cake is a good source of valuable proteins (30%) and oil (14%), with a balanced fatty acid composition and a fair amount of sterols, which may reduce the risk of cardiovascular diseases. However, the presence of antinutritive compounds prevents its use as a food source. Grinding under cryogenic conditions is much more efficient than grinding at room temperature in terms of particle size reduction. The additional cryogenic grinding of the cake had little effect on the nutritional components, as phytosterols and soluble dietary fiber increased slightly. It had no effect on insoluble dietary fiber, polyphenols, and tannins. Prolonged grinding time, both at room and subzero temperatures, reduced the total amount of glucosinolates by 34 and 43%, respectively. However, the reduction in undesirable components is not sufficient to use cryogenic grinding as the sole treatment for the cake, but it could be a good pretreatment for chemical or biological treatments.

Ground Tire Rubber Particles as Substitute for Calcium Carbonate in an EPDM Sealing Compound.

Ground tire rubber (GTR) is a product obtained by grinding worn tire treads before retreading them or via the cryogenic or ambient temperature milling of end-of-life tires (ELTs). The aim of this study is to evaluate if calcium carbonate can be substituted by GTR and, if so, to what extent. Different types of ground tire rubber are incorporated in an EPDM (ethylene-propylene-diene-rubber) model compound as partial or complete substitutes of calcium carbonate. The raw compounds and the vulcanizates are characterized to identify the limits. In general, it is apparent that increasing amounts of GTR and larger particles degrade the mechanical properties. The GTR also influences the vulcanization kinetics by reducing the scorch time up to 50% and vulcanization time up to nearly 80%. This is significant for production processes. The compounds with one-third substitution with the smaller-particle-size GTR show mostly similar or even better properties than the reference.

Research on liquid nitrogen cryogenic milling of 11Cr-3Co-3W martensitic heat-resistant steel

PurposeWhen processing 11Cr-3Co-3W martensitic heat-resistant steel, the traditional pouring cooling method often appears large cutting force, high cutting temperature, serious tool wear and poor surface quality. This paper aims to use new cooling methods for processing this problem.Design/methodology/approachDifferent performance indicators such as cutting force, tool wear and surface quality were measured and analysed under different continuous milling times. The relationship between liquid nitrogen flow and cutting force and surface roughness was analysed and measured.FindingsThe results show that with the increase of liquid nitrogen flow, the cutting force decreases, especially the Fx component, which decreases by 10%. When the liquid nitrogen flow reaches 8 L/min, the effect of increasing the liquid nitrogen flow on reducing the cutting force becomes smaller. The cutting force reduced by up to 15%, and the tool life increased up to 20% using liquid nitrogen cryogenic cooling than in cutting liquids cooling. When minimal quantities of lubricant (MQL) was added, the cutting force was reduced by 23%, and the tool life increased by 25%. When the cutting speed increases from 100 m/min to 250 m/min, the cutting force with cutting liquid cooling does not change significantly while the cutting force with liquid nitrogen cooling decreases with the cutting speed increasing. It shows that liquid nitrogen cooling is more suitable for high-speed machining. After the cutting length reaches 66 m, the surface roughness of the workpiece using liquid nitrogen cooling method larger than that of the cutting liquid cooling method. When MQL is added into liquid nitrogen, the lubrication performance is improved, and the surface roughness of the workpiece is reduced about 8%.Originality/valueMany studies had focused on the improvement of tool life and surface quality by different cooling methods, or on the injection process and chip mechanism. However, there are few relevant studies on the variation of cooling and lubrication properties with the change of cutting length in liquid nitrogen cryogenic processing. In this research, different performance indicators such as cutting force, tool wear and surface quality were measured and analysed under different continuous milling times. The relationship between liquid nitrogen flow and cutting force and surface roughness was analysed and measured.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2023-0053/