Vibratory Ball Mill Research Articles

Preparation and Characterization of Solid Dispersions Composed of Curcumin, Hydroxypropyl Cellulose and/or Sodium Dodecyl Sulfate by Grinding with Vibrational Ball Milling.

Solubility is an important physicochemical property affecting drug bioavailability. One approach to improve drug solubility is using amorphous formulations, which can improve solubility by up to a 1000-fold. Herein, amorphous curcumin (CUR) and amorphous solid dispersions (SDs) consisting of CUR, hydroxypropyl cellulose (HPC) and/or sodium dodecyl sulfate (SDS) were developed using vibrational ball milling. The resulting ground mixtures (GMs) were characterized using powder X-ray diffractometry, Fourier transform infrared spectroscopy, differential scanning calorimetry and a dissolution test. The 60-min GM containing 90% HPC significantly increased the drug solubility. Presence of SDS in the GMs containing 90% HPC reduced the grinding duration from 60 min to 30 min in forming a ground SD that significantly increased the CUR dissolution rate. This amorphous state was stable for 30 days when stored at 40 °C/RH 75%.

Enhancing the electrochemical performances of Li7P3S11 electrolyte through P2O5 substitution for all-solid-state lithium battery

Li7P3S11 (70Li2S·30P2S5) sulfide is a promising electrolyte candidate for all-solid-state lithium batteries (ASSLBs) owing to its high ionic conducivity and wide electrochemical stability window. However, the sensitivity to moisture and the poor interfacial compatibility with electrodes limit the conventional application of Li7P3S11. Herein, we present a substitution strategy to produce a O-incorporated 70Li2S·(30-x)P2S5·xP2O5 (mol%) sulfide electrolyte to address above issues. The elaborately designed electrolyte is prepared via wet vibration ball milling technique with P2O5 substitution content of 1, 3 and 5. As a result, the 70Li2S·27P2S5·3P2O5 electrolyte displays the highest ionic conductivity of 2.61× 10−3 S cm−1 which outperforms than that of pristine Li7P3S11 (ionic conductivity of 1.35 × 10−3 S cm−1) and the assembled LiCoO2@LiNbO3/70Li2S·27P2S5·3P2O5/Li-In ASSLB exhibits the superior capacity retention of 93.2% after 100 cycles at 0.5C. The reason for the developed electrochemical performance lies in the substitution of the non-bridging sulfur atom with bridging oxygen atom, from which the interaction between electrolyte and lithium ions is weakened, thereby the rapid transfer of lithium ions is facilitated. Furthermore, Raman and XRD results indicate that the adverse interfacial reactions are suppressed through P2O5 substitution. This work suggests that P2O5 substitution is an effective strategy for sulfide electrolyte toward high energy all-solid-state lithium batteries.

B4C particulate-reinforced Al-8.5 wt% Si-3.5 wt% Cu matrix composites: Powder metallurgical fabrication, age hardening, and characterization

The present work investigates microstructural and mechanical properties of B4C particulate-reinforced Al-8.5 wt% Si-3.5 wt% Cu matrix composites prepared by a successive process of mechanical alloying (MA), cold pressing, and pressureless sintering. The effects of B4C amount, milling duration, and heat treatment were investigated. The MA (for 0, 3, 5, and 7 h) in a high-energy vibratory ball mill was applied to elemental powder blends, in which 0, 5, 7.5, and 10 wt % B4C was incorporated as reinforcing particles. Mechanically alloyed (MAed) powders were uniaxially pressed and sintered for 2 h at 550 °C then subjected to an aging heat treatment to improve the mechanical properties. Based on XRD, SEM, and TEM microstructural investigations, compared to the as-blended case, the MAed powders possessed a semi-equiaxed morphology and homogenous structure, with higher lattice strain and smaller crystallite size. In addition, the Al-8.5 wt% Si-3.5 wt% Cu-xB4C (x = 0, 5, 7.5, and 10 wt%) composites consolidated from the MAed powders exhibited improved mechanical properties, including microhardness, wear resistance, and compressive strength. The hardness of the 5 h-MAed Al-8.5 wt% Si-3.5 wt% Cu–10B4C composite was 167 H V, and yield and compressive strength were 362 MPa and 454 MPa, respectively. This sample also exhibited one of the lowest wear rates, 5.82 × 10−5 mm3/m.N, roughly 17 and 10 times lower than that of the 5 h-MAed Al-8.5 wt% Si-3.5 wt% Cu sample and its as-blended counterpart, respectively. Furthermore, the hardness and compressive strength of 5 h-MAed Al-8.5 wt% Si-3.5 wt% Cu–10B4C composite increased to 231 H V and 475 MPa, respectively, after the age-hardening treatment.

In-situ reaction monitoring of a mechanochemical ball mill reaction with solid state NMR

We present an approach towards the in situ solid state NMR monitoring of mechanochemical reactions in a ball mill. A miniaturized vibration ball mill is integrated into the measuring coil of a home-built solid state NMR probe, allowing for static solid state NMR measurements during the mechanochemical reaction within the vessel. The setup allows to quantitatively follow the product evolution of a prototypical mechanochemical reaction, the formation of zinc phenylphosphonate from zinc acetate and phenylphosphonic acid. MAS NMR investigations on the final reaction mixture confirmed a reaction yield of 89% in a typical example. Thus, NMR spectroscopy may in the future provide complementary information about reaction mechanisms of mechanochemical reactions and team up with other analytical methods which have been employed to follow reactions in situ, such as Raman spectroscopy or X-ray diffraction.

Functionalised calcium carbonate as a coformer to stabilize amorphous drugs by mechanochemical activation

The aim of this study was to investigate the amorphization, physical stability and drug release of a model drug, carvedilol (CAR), when loaded onto functionalised calcium carbonate (FCC) using mechanochemical activation (vibrational ball milling). The solid-state characteristics and physical stability of CAR–FCC samples, prepared at different weight ratios and for different milling times, were determined using differential scanning calorimetry and X-ray powder diffraction. Upon milling CAR–FCC samples containing 50% CAR, amorphization of CAR was observed after 10 min. For CAR–FCC samples milled for either 30 or 90 min, it was found that CAR was amorphised at all ratios (10–90% CAR), but FCC remained crystalline. The glass transition temperature (Tgα) of the various CAR–FCC samples milled for 90 min was found to be similar (38 °C) for all ratios containing 20% CAR and above. The similar Tgαs for the different drug ratios indicate deposition of amorphous CAR onto the surface of FCC. For CAR–FCC samples containing 10% CAR, a Tgα of 49 °C was found, which is 11 °C higher compared with other CAR–FCC samples. This may indicate restricted molecular mobility resulting from CAR molecules that are in close contact with the FCC surface. The physical stability, under both stress (100 °C) and non-stress conditions (25 °C at dry conditions), showed that drug concentrations up to 30% CAR can be stabilized in the amorphous form for at least 19 weeks under non-stress conditions when deposited onto FCC, compared to less than a week physical stability of neat amorphous CAR. In vitro drug release showed that CAR–FCC samples containing 60% CAR and below can improve the drug release and generate supersaturated systems compared to neat amorphous and crystalline CAR. Samples with lower drug concentrations (40% CAR and below) can maintain supersaturation during 360 min of dissolution testing. This study indicates that the crystalline inorganic material, FCC, can facilitate amorphization of drugs, provide stabilization against drug crystallization, and improve dissolution properties of amorphous drugs upon mechanochemical activation.

Co-grinding with surfactants as a new approach to enhance in vitro dissolution of praziquantel

This paper evaluates the process of co-grinding with a surfactant as a new approach to enhance physicochemical and biopharmaceutical properties of praziquantel (PZQ), a poorly soluble drug that is essential for the treatment of schistosomiasis, a neglected tropical disease. Surfactants used in this study were poloxamer F-127 and sucrose stearate (C-1816), selected based on their well-documented biocompatibility and solubilizing activity. A series of products were prepared by mechanochemical activation using vibrational ball-mill at different drug to surfactant ratio and milling times. The obtained products were characterised in terms of drug recovery, solubility and in vitro dissolution rates. The obtained results were correlated to solid-state properties of the products analysed by differential scanning calorimetry, powder X-ray diffraction and particle size analysis. Results of UPLC-MS analysis and 1H-NMR spectroscopy showed that the used surfactants and applied grinding procedures caused no chemical degradation of the PZQ. The physicochemical properties, solubility and the in vitro dissolution enhancement of the co-ground products were related to the drug to surfactant ratio and the grinding protocol applied. The highest enhancement of the in vitro dissolution rate was achieved at the drug to surfactant ratio of 10:3 and 10:2 for F-127 and C-1816, respectively with the milling time of 30 min. The MTT assay on Caco-2 cell line demonstrated the biocompatibility of both co-ground products. Furthermore, the surfactants used did not change intrinsically high intestinal permeability of PZQ (Papp ∼ 4.00 × 10−5 cm s−1). The presented results confirmed that the co-grinding with surfactant is a promising new approach in enhancing in vitro dissolution of poorly soluble drugs like PZQ.

Promoted crystallisation and cationic ordering in thermoelectric Cu26V2Sn6S32 colusite by eccentric vibratory ball milling.

A pristine colusite Cu26V2Sn6S32 was successfully synthesised on a 100 g scale via a mechanochemical reaction in an industrial eccentric vibratory ball mill followed by spark plasma sintering (SPS) at 873 K. The milling of elemental precursors from 1 up to 12 hours was performed and the prepared samples were investigated in detail by X-ray powder diffraction, Mössbauer spectroscopy, scanning electron microscopy, and thermoelectric property measurements. The results point to the formation of a high purity and high crystallinity non-exsoluted colusite phase after the SPS process (P4[combining macron]3n, a = 10.7614(1) Å) in the case of a 12 h milled sample. In comparison, samples milled for 1-6 h displayed small quantities of binary Cu-S phases and vanadium core-shell inclusions, leading to a V-poor/Sn-rich colusite with a higher degree of structural disorder. These samples exhibit lower electrical conductivity and Seebeck coefficient while an increase in the total thermal conductivity is observed. This phenomenon is explained by a higher reactivity and grain size reduction upon prolonged milling and by a weak evolution of the chemical composition from a partly disordered V-poor/Sn-rich colusite phase to a well-ordered stoichiometric Cu26V2Sn6S32 colusite, which leads to a decrease in carrier concentration. For all samples, the calculated PF values, around 0.7-0.8 mW m-1 K-2 at 700 K, are comparable to the values previously achieved for mechanochemically synthesised Cu26V2Sn6S32 in laboratory mills. This approach thus serves as an example of scaling-up possibility for sulphur-based TE materials and supports their future large-scale deployment.

A Combined Mechanochemical and Calcination Route to Mixed Cobalt Oxides for the Selective Catalytic Reduction of Nitrophenols.

Para-, or 4-nitrophenol, and related nitroaromatics are broadly used compounds in industrial processes and as a result are among the most common anthropogenic pollutants in aqueous industrial effluent; this requires development of practical remediation strategies. Their catalytic reduction to the less toxic and synthetically desirable aminophenols is one strategy. However, to date, the majority of work focuses on catalysts based on precisely tailored, and often noble metal-based nanoparticles. The cost of such systems hampers practical, larger scale application. We report a facile route to bulk cobalt oxide-based materials, via a combined mechanochemical and calcination approach. Vibratory ball milling of CoCl2(H2O)6 with KOH, and subsequent calcination afforded three cobalt oxide-based materials with different combinations of CoO(OH), Co(OH)2, and Co3O4 with different crystallite domains/sizes and surface areas; Co@100, Co@350 and Co@600 (Co@###; # = calcination temp). All three prove active for the catalytic reduction of 4-nitrophenol and related aminonitrophenols. In the case of 4-nitrophenol, Co@350 proved to be the most active catalyst, therein its retention of activity over prolonged exposure to air, moisture, and reducing environments, and applicability in flow processes is demonstrated.

EFFECT OF MILL FEED SIZE DISTRIBUTION AND GRINDING MEDIA SIZE ON SIZE REDUCTION PERFORMANCE OF AN INDUSTRIAL SCALE VIBRATING BALL MILL (VBM) IN CEMENT CLINKER GRINDING

In this study, open circuit single and two stage industrial scale vibrating ball mill (VBM) grinding performance of raw (uncrushed) cement clinker was investigated using different mill feed size distributions and grinding ball size configurations. The mill was modelled for the test cases using perfect mixing mathematical modelling approach. Different ball size configurations were applied in the grinding tests to estimate the effect of ball size configuration on grinding performance. Proposed coarse ball size configuration (30-20-15mm) was determined to increase the size reduction performance of single stage VBM grinding when coarse mill feed material was fed to the VBM (F50=185μm) as compared to the finer mill feed case (F50=24μm). VBM grinding performance was determined to increase with finer mill feed material (F50=24μm) and application of finer ball size configuration (10-8-6mm) in single stage grinding case as compared to the two stage grinding case.

Solid-State Synthesis of Lithium-Substituted Spinels Mg1 – xLixMnO3 – δ

Solid solutions based on MgMnO3 – δ in which magnesium is partially substituted for by lithium were produced by solid-phase synthesis by air annealing of mechanocomposites obtained by mechanical activation (in a vibration ball mill) of mixtures of high-purity grade precursors: oxides MgO, Mn2O3, and MnO2, and also Li2CO3 and LiOH · H2O. It was shown that using lithium hydroxide monohydrate increases the degree of substitution of lithium for magnesium with simultaneous decrease in the synthesis temperature in comparison with using lithium carbonate.

Production and properties of Co-based metallic-glass-reinforced aluminum matrix composites

Cobalt (Co)-based metallic-glass-particulate-reinforced aluminum (Al) matrix composites were prepared by microwave sintering under air atmosphere conditions at a proper temperature that avoids crystallization of reinforcing particles. Composite powders containing 5–20 vol.% metallic-glass reinforcements were prepared by using a high-speed vibrating ball mill, and green compacts were sintered through the microwave-heating method at 500°C for 30 min. Microstructural features were investigated by X-ray diffraction and scanning electron microscopy. Furthermore, the mechanical properties of the samples were evaluated through compression tests and Vickers hardness measurements. Sintering studies showed that the metallic-glass particles interacted with the microwaves during the microwave-heating process over a certain temperature (>500°C) apart from the susceptor heating element and caused excessive heating, which led to overheating of the composite sample in an uncontrollable manner. Therefore, the sintering temperature of the samples was selected to be 500°C. Investigations of the microstructure of the samples with well-distributed reinforcements revealed that there was no brittle intermetallic phase formation between the reinforcement and matrix interfaces. The results showed that the composite samples milled for 2 h exhibited significantly higher compressive strength and hardness values compared with pure aluminum.

Kinetic analysis of the complete mechanochemical synthesis of a palladium(II) carbene complex

Benzimidazoline-2-ylidene complexes of palladium(II) were synthesized mechanochemically in a vibratory ball mill. Complete syntheses began with preparation of benzimidiazolium halides from commercially available starting materials. These “greener chemistry” syntheses proceed in high yield and require minimal purification using environmentally benign solvents. Kinetic analysis shows that liquid assisted grinding impedes the production to benzimidazolium halides while enhancing the production of the palladium-carbene complex.

One-Pot, One-Step Precatalysts through Mechanochemistry

The development and implementation of transition-metal-based precatalysts have played crucial roles in modern organic synthesis. However, while the use of such species greatly improves sustainability, their preparative routes often rely on multiple time-, energy-, and solvent-intensive steps. By leveraging solvent-free mechanochemical synthesis through vibratory ball milling, we report the one-pot, one-step synthesis of a range of first-row transition-metal bis(imino)pyridine complexes, where both the ligand and coordination complex are assembled in situ. Bis(imino)pyridine complexes of the first-row transition metals have an extensive history of application as precatalysts for numerous bond-forming transformations. The method reported herein facilitates access to such species in a time-, solvent-, and space-saving manner which can easily be adapted to any laboratory setting regardless of prior experience with coordination complex synthesis.

Impact of Particle-Size Reduction on the Solubility and Antidiabetic Activity of Extracts of Leaves of Vinca rosea.

The present study aimed to enhance the aqueous solubility of methanol extract of leaves of Vinca rosea (family: Apocynaceae) by particle-size reduction using milling and to evaluate its antidiabetic activity. The methanol extract (ME) was micronized using a vibratory ball mill, operated at a vibratory speed of 15 Hz for 60 min at room temperature, and the resulting extract micronized ME (MME) was investigated to determine particle size, solubility, UV/visible profile, and in vitro antidiabetic activity. The average particle size of MME was 0.753±0.227 μm, which was less than half of that of the ME (2.007±0.965 μm). The solubility of MME was greater than that of the ME. MME exhibited 65.63%, 18.0%, and 96.87% higher antidiabetic activity in the glucose uptake by the yeast cells method, hemoglobin glycosylation assay, and the alpha amylase inhibition assay, respectively (p<0.05). The results of the present study indicate that micronization effectively enhanced the aqueous solubility and antidiabetic activity of methanol extract of leaves of Vinca rosea.

Preparation of nanocellulose and lignin-carbohydrate complex composite biological carriers and culture of heart coronary artery endothelial cells

Lignin-carbohydrate complexes, i.e. LCC-48 and LCC-72 were isolated with vibrational ball milling for 48 h and 72 h, respectively. Composite tubular carriers were prepared by casting film formation and crimping with the LCCs and cellulose nanofibrils (CNFs) as raw materials. The structures and chemical properties of different milling time LCCs were analyzed. The carriers were used to culture human coronary artery endothelial cells (HCAEC), and the activities of these cells were examined in vitro. The FT-IR and chemical composition results showed that the biocarriers were composed of lignin moieties and polysaccharides. The SEM and inverted microscope studies revealed that a large number of cells adhered to the porous carriers. HCAEC grown on the LCC-72/CNF carriers outperformed the LCC-48/CNF and control groups in every observed category, including cell proliferation rate and metabolic activity. In summary, tubular carriers prepared from LCC/CNF composite had high biocompatibility and have potential applications in heart tissue engineering.

Mechanically Activated Solid-Phase Reaction of Copper(I) Chloride with Sodium β-Diketonates: Formation of Metallic Copper Nanoparticles

Solid-phase reaction of copper(I) chloride with sodium β-diketonates under mechanical activation in a vibration ball mill involves disproportionation of CuCl with the formation of the corresponding copper(II) β-diketonate and highly reactive X-ray amorphous metallic copper nanoparticles. The effect of reaction conditions on the process and some properties of the activated mixtures have been studied.

Effects of different milling conditions on the properties of lanthanum hexaboride nanoparticles and their sintered bodies

In this study, the preparation and consolidation of nanocrystalline LaB 6 powders originating from powder blends of La 2 O 3 , B 2 O 3 and Mg were reported. A consecutive route of mechanochemical synthesis (MCS) and purification was utilized for the achievement of nano-sized LaB 6 powders. As-synthesized powders were leached out from intermediate reaction products or impurities. Then, a sequential step of cold pressing (uniaxial pressure at 800 MPa) and pressureless sintering (at 1700 °C for 5 h under Ar gas flow) were utilized for the consolidation of the purified LaB 6 powders. The type of mill (vibratory and planetary high-energy ball mills) was employed as a MCS parameter to reveal its effect on the physical, microstructural and mechanical properties of the LaB 6 powders, and their bulk structures. Compositional, physical and microstructural properties of the products after powder processing were determined via X-ray diffractometer (XRD), particle size analyzer (PSA), differential scanning calorimeter (DSC), stereomicroscope (SM), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive spectrometer (EDS) coupled with both SEM and TEM, and vibrating sample magnetometer (VSM). The bulk properties of the LaB 6 consolidated from nanocrystalline powders with a minimum 99.99% purity, and ∼62 nm (for vibratory ball mill) or ∼74 nm (for planetary ball mill) average particle size were compared according to various properties. LaB 6 powders were synthesized in planetary mill at an approximately six times longer duration than that of in vibratory mill. According to the results, density, surface area and mean particle size values of the vibratory ball-milled samples (containing paramagnetic powders) are better than those of planetary ball-milled (containing diamagnetic powders) ones. However, mechanical properties such as hardness, surface roughness, wear rate, friction coefficient, and also electrical conductivity were improved in the planetary ball-milled LaB 6 bulks.

Effects of ZrC content and mechanical alloying on the microstructural and mechanical properties of hypoeutectic Al-7 wt.% Si composites prepared by spark plasma sintering

This paper reports on the preparation of ZrC particulate-reinforced Al-7 wt.% Si composites by using a consecutive method of mechanical alloying (MA) and spark plasma sintering (SPS). Al, Si (7 wt.%), and ZrC (0, 2, 5, and 10 wt.%) powders were blended and mechanically alloyed (MA'd) for 4 h in a high-energy vibratory ball mill. Subsequently, SPS (at 450 °C for 210 s) was carried out on non-MA'd and MA'd powders. Dissimilar to the inhomogeneous microstructure of the non-MA'd powders, the 4 h MA'd powders exhibited a homogeneous morphology with semi-equiaxed particles that revealed a lower average crystallite size and higher average lattice strain. Furthermore, microstructural, physical, and mechanical characterizations were performed on the spark plasma sintered (SPS'd) composites. The mechanical characterizations showed that MA'd/SPS'd Al-7 wt.% Si-5 wt.% ZrC composite displayed the highest hardness and strength values among all the fabricated composites. It exhibited a hardness of 1.52 ± 0.16 GPa, yield strength of 327.56 ± 7.16 MPa, and compressive strength of 406.42 ± 2.82 MPa. Besides, the MA'd/SPS'd Al-7 wt.% Si-10 wt.% ZrC composite exhibited the lowest wear rate of 0.0022 mm 3 /N.m, which was approximately 46% of that of the unreinforced composite (0.0048 mm 3 /N.m). It can be stated that the addition of ZrC and application of MA effectively improved the microstructural and mechanical properties of the composites.

The Impact of Anatomical Characteristics on the Structural Integrity of Wood

The structural integrity of wood is closely related to its brittleness and thus to its suitability for numerous applications where dynamic loads, wear and abrasion occur. The structural integrity of wood is only vaguely correlated with its density, but affected by different chemical, physico-structural and anatomical characteristics, which are difficult to encompass as a whole. This study aimed to analyze the results from High-Energy Multiple Impact (HEMI) tests of a wide range of softwood and hardwood species with an average oven-dry wood density in a range between 0.25 and 0.99 g/cm³ and multifaceted anatomical features. Therefore, small clear specimens from a total of 40 different soft- and hardwood species were crushed in a heavy vibratory ball mill. The obtained particles were fractionated and used to calculate the ‘Resistance to Impact Milling (RIM)’ as a measure of the wood structural integrity. The differences in structural integrity and thus in brittleness were predominantly affected by anatomical characteristics. The size, density and distribution of vessels as well as the ray density of wood were found to have a significant impact on the structural integrity of hardwoods. The structural integrity of softwood was rather affected by the number of growth ring borders and the occurrence of resin canals. The density affected the Resistance to Impact Milling (RIM) of neither the softwoods nor the hardwoods.

Surface modification of Fe3O4 nanoparticles with dextran via a coupling reaction between naked Fe3O4 mechano-cation and naked dextran mechano-anion: A new mechanism of covalent bond formation

A surface modified Fe3O4 nanoparticle with dextran, possessing a core-shell structure, was synthesized by vibration ball-milling of Fe3O4 with dextran in the solid state under vacuum. A combination of experimental results and density functional theory calculations demonstrate that the surface modified Fe3O4 nanoparticle with dextran was performed via a coupling reaction between a “naked” Fe+ atom of Fe3O4 mechano-cation and a “naked” O− atom of dextran mechano-anion, viz., a “Fe:O” bond-formation. The naked Fe+ atom of Fe3O4 mechano-cation was produced by ionic scission of FeO bond of Fe3O4 and lost an “electron pair” under the ionic scission. The naked :O− atom of dextran mechano-anion was produced by ionic scission of CO bond comprising the α-1,6 glycosidic linkage of the dextran and gained the electron pair under the ionic scission. The Fe:O bond formation, viz., a novel type covalent bond formation, was achieved via an electron pair donation from the naked :O− atom and its acceptance by the naked Fe+ atom. Consequently, a shared “electron pair” comprising the Fe:O bond was only donated from the naked :O− atom. Our work demonstrates a novel method to form covalent bond formation between metal oxides and organic polymers, and provides a novel functionalized nanoparticle.