Crystallization Rate Research Articles

Revealing the Effect of the Molecular Weight Distribution on the Chain Diffusion and Crystallization Process under a Branched Trimodal Polyethylene System.

With the increasing demand for high-end materials, trimodal polyethylene (PE) has become a research hotspot in recent years due to its superior performance compared with bimodal PE. By means of molecular dynamics (MD) simulations, we aim to expound the effect of the molecular weight distribution (MWD) on the mechanism of nucleation and crystallization of trimodal PE. The crystallization rate is faster when short-chain branching is distributed on a single backbone compared to that on two backbones. In addition, as the content of high molecular weight backbone decreases, the time required for nucleation decreases, but the crystallization rate slows down. This is because low molecular weight backbones undergo intra-chain nucleation and crystallize earlier due to the high diffusion capacity, which leads to entanglement that prevents the movement of medium or high molecular weight backbones. Furthermore, crystallized short backbones hinder the movement and crystallization of other backbones. What is more, a small increase in the high molecular weight branched backbone of trimodal PE can make the crystallinity greater than that of bimodal PE, but when the content of high molecular weight backbone is too high, the crystallinity decreases instead, because the contribution of short and medium backbones to high crystallinity is greater than that of long backbones.

Compliant substrate epitaxial MgZnO films using fluorphlogopite mica approaching homoepitaxy quality

Based on the success of high-quality epitaxial grown ZnO film on the compliant Fluorphlogopite Mica (F-Mica) substrate, the growth of MgZnO films on F-Mica substrate is studied to promote the development of flexible ZnO quantum well structures and devices. These flexible epitaxial MgZnO films show high luminous quality approaching homoepitaxial films. The phenomenon of Mg compositional fluctuations is confirmed by the research on band tail state. The effect of the compositional fluctuations on epitaxial growth dynamical and thermodynamic processes is also revealed by the comprehensively investigation of the crystal quality, optical properties, morphology, and growth rate. The study provides guidance for energy band engineering of ZnO on flexible substrates, and lays the foundation for the bendable optoelectronic devices on F-Mica substrate.

TEAOH-assisted cost-effective preparation of SSZ-13 using L zeolite as Al source

Developing an economical and high-efficiency synthesis pathway of SSZ-13 zeolite is of great significance for the ammonia selective catalytic reduction of nitrogen oxides (NH3-SCR of NOx) reactions. Herein, SSZ-13 zeolite were synthesized using L zeolite as the aluminum source in the presence of a mixed structure directing agent (SDA) composed of N,N,N, trimethtyl-1-adamantammonium hydroxide (TMAdaOH) and tetraethylammonium hydroxide (TEAOH). This synthesis strategy aims to accelerate the crystallization rate through interzeolite transformation, while less expensive TEAOH can play a cooperative structure-directing role, thus reducing the consumption of expensive TMAdaOH template. The results showed that pure SSZ-13 zeolites with high crystallinity can be obtained from L zeolite within 12 h at 160 ℃ under low TMAdaOH/SiO2 ratio of 0.05 (too low to carry out the synthesis on its own in the current synthesis system) in the presence of TEAOH. Moreover, the crystallization mechanism was also investigated by XRD, FT-IR, SEM and TG-DTG techniques. It was proposed that the crystallization of SSZ-13 occurs through the formation of SSZ-13 nuclei under the direction of TMAdaOH and promotion of TEAOH, subsequently TMAdaOH was incorporated in the framework to further induce the crystal growth of SSZ-13. Especially, the zeolite crystal size can be modulated by the amount of TEAOH added. In addition, After Cu2+ exchange, the obtained Cu-SSZ-13 sample exhibits superior catalysis performance in the NH3-SCR of NOx reaction, and the NOx conversion rate remained over 90 % across a broad range from 200 to 600 °C, demonstrating its significant application potentials in NOx removal from diesel vehicle exhausts.

The effect of anisotropic rate dependency on the deformation response of Ti-6242 during dwell fatigue loading

The α phase of titanium alloys is known to exhibit both elastic and plastic anisotropic mechanical behavior during deformation loading. Recent experimental studies indicate that single crystal rate dependency may also be anisotropic, though these studies are limited in scale and scope. Consequently, we present a study in which anisotropic rate dependency is studied on polycrystalline samples via crystal plasticity finite element (CPFE) simulations, which are compared against previously-published data from electron backscatter diffraction/digital image correlation (EBSD-DIC) experiments. Cold dwell fatigue loading is utilized, owing to the propensity for transient behavior during constant-load dwells, which is hypothesized to be sensitive to the relative rate dependencies on different slip families (i.e., basal, prismatic, and pyramidal) in hexagonal close packed crystals. A suite of CPFE simulations is conducted on polycrystalline samples in which the slip family rate dependency values are parameterized. We analyze simulation results by focusing on the slip activity and accumulation of slip on the various slip families as a function of dwell cycles, as well as the transient effect during singular dwell cycles, for hundreds of crystals simultaneously. Results are further discussed through the lens of findings from EBSD-DIC experiments.

Radiocarbon ages of microcrystalline authigenic carbonate in Lake Neusiedl (Austria) suggest millennial‐scale growth of Mg‐calcite and protodolomite

ABSTRACTAuthigenic Mg‐calcite and dolomite are frequently observed in restricted, evaporative environments, such as lagoon or lake systems, but their formation is difficult to capture due to slow growth rates. Lake Neusiedl, an alkaline and subhaline lake with a mean water depth of 0.7 m in Austria, offers a natural system to study the precipitation of Ca‐Mg‐carbonate phases, which occur as fine‐grained, unconsolidated and largely homogenized mud. To elucidate the timing and formation mechanisms of these authigenic carbonate phases, the mineralogical and isotopic composition and radiocarbon age of different sediment grain‐size fractions from <0.2 to >3.0 μm were analysed. X‐ray diffraction analyses show two broad peaks of Mg‐calcite and protodolomite (lacking ordering peaks), suggesting that the carbonates are authigenic rather than detrital in origin. Calibrated carbon‐14 ages range between 200 cal yr bp and 3700 cal yr bp. The linear correlation of age and grain size suggests a very slow growth rate of single crystals of 0.23 to 0.60 μm/ka. These rates suggest an extremely slow sedimentation rate in a shallow lake that existed during most of the Holocene. The higher abundance of protodolomite in older grain fractions, in contrast to the presence of high‐Mg calcite in the youngest fractions, suggests a growth succession where high‐Mg calcite develops first and subsequently transforms into protodolomite. Much higher ages of 6 cal ka bp to 15 cal ka bp are measured in carbonates of lake deposits exposed on land, in a section north‐west of the recent lake, suggesting a growth rate of those carbonate minerals of 0.13 μm/ka. These time constraints further suggest that some carbonate grains could already have nucleated from lake water before or during the last glacial maximum, although under slightly different hydrochemical conditions.

Enhancing the Performance of 2D Tin-Based Pure Red Perovskite Light-Emitting Diodes through the Synergistic Effect of Natural Antioxidants and Cyclic Molecular Additives.

Tin (Sn)-based perovskites are being investigated in many optoelectronic applications given their similar valence electron configuration to that of lead-based perovskites and the potential environmental hazards of lead-based perovskites. However, the formation of high-quality Sn-based perovskite films faces several challenges, mainly due to the easy oxidation of Sn2+ to Sn4+ and the fast crystallization rate. Here, to develop an environmentally friendly process for Sn-based perovskite fabrication, a series of natural antioxidants are studied as additives and ascorbic acid (VitC) is found to have a superior ability to inhibit the oxidation problem. A common cyclic molecule, 18-Crown-6, is further added as a second additive, which synergizes with VitC to significantly reduce the nonradiative recombination pathways in the PEA2SnI4 film. This synergistic effect greatly improves the performance of 2D red Sn-based PeLED, with a maximum external quantum efficiency of 1.87% (≈9 times that of the pristine device), a purer color, and better bias stability. This work demonstrates the potential of the dual-additive approach in enhancing the performance of 2D Sn-based PeLEDs,while the use of these environmentally friendly additives contributes to their future sustainability.

Computational fluid dynamics simulation of a jet crystallizer for continuous crystallization of lovastatin

Continuous crystallization of lovastatin from a lovastatin-methanol solution and water as the anti-solvent in an impinging jet crystallizer is investigated using a computational fluid dynamics model. To capture the important phenomena, the model is coupled with micro-mixing, population balance, and related energy balance equations. It is implemented in OpenFOAM and validated against experimental data, where a fairly good agreement is found. The effects of key process parameters on the crystallization performance are also studied using the validated model. The results show that increasing the inlet jet velocity from 1 to 4 m/s yields a much narrower size distribution and 70% reduction in the mean crystal size. The four-fold increase in the inlet jet velocity also reduces the crystal production rate by one order of magnitude. Also, it is found that increasing the inlet supersaturation ratio from 6.8 to 8.8 nearly doubles the mean crystal size. Moreover, it results in a wider size distribution and a six-fold increase in the crystal production rate. The simulations also confirm that lower solution to anti-solvent mass flow ratios yield a wider size distribution, a larger mean crystal size and a higher crystal production rate. Increasing this ratio from 0.5 to 2 reduces the production rate by two orders of magnitude.

Molecular dynamics simulation and experimental analysis of nucleation and growth mechanism of mixed inorganic salts in supercritical water

Supercritical water gasification (SCWG) technology is one of the more promising approaches for processing oily wastewater. However, there needs to be more research on the sedimentation of mixed inorganic salts in the supercritical water reactor while treating oily wastewater. In this study, the clustering process of mixed inorganic chlorides containing NaCl, KCl, and CaCl2 in supercritical water was simulated through molecular dynamics simulation. Molecular dynamics simulation was mainly conducted for mixed inorganic salts within the parameter range of 673 K-1073 K and 22 MPa-28 MPa. Combined with Yasuoka and Matsumoto's cluster theory, it can be concluded that the nucleation process of mixed inorganic salts in the supercritical water environment is mainly affected by density. Although the ion diffusion coefficient increases with temperature, the nucleation rate of inorganic salts gradually decreases due to the decrease in density. In the temperature range of 673 K-1073 K, the nucleation rate of mixed inorganic salts decreased from 34.96 to 1.65 1036 m−3·s−1. At the same pressure, the crystal growth rate parameter decreased gradually with increasing temperature, reaching about 168.25–60.09 m·s−1. Finally, the simulation results were verified experimentally, confirming that the crystal growth rate decreases with increasing temperature.

Combination of magnetic field and ultraviolet for fouling control in saline wastewater distribution systems

Fouling is a significant challenge for recycling and reusing saline wastewaters for industrial, agricultural or municipal applications. In this study, we propose a novel approach of magnetic field (MaF) and ultraviolet (UV) combined application for fouling mitigation. Results showed, combination of MaF and UV (MaF-UV) significantly decreased the content of biofouling and reduced the complexity of microbial networks, compared to UV and MaF alone treatments. This was due to MaF as pretreatment effectively reduced the water turbidity, improve the influent water quality of UV disinfection and increases UV transmittance, eliminating the adverse impacts of UV scattering and shielding, hence increased the inactivation effectiveness of UV disinfection process. MaF assisted UV also reduced the abundance of UV-resistant bacteria and inhibited the risk of bacterial photoreactivation and dark repair. Meanwhile, MaF-UV drastically reduced the contents of precipitates and particulate fouling by accelerating the transformation rate of CaCO3 crystal from compact calcite to loosen hydrated amorphous CaCO3, and enhancing the flocculation process. These findings demonstrated that MaF-UV is an effective anti-fouling strategy, and provide insights for sustainable application of saline wastewaters.

Modification mechanism, heavy metal coupling and ecological security risk assessment of phosphogypsum utilization in self-leveling mortar

Few researches on high efficiency modified phosphogypsum (MPG) and its resource utilization in bulding materials. This article investigated the effects of different lower temperatures and drying times on the thermodynamic modification mechanism of macroscopic performance and microscopic structure of MPG, and investigates its application in phosphogypsum-based self-leveling mortars (PBSLM). Then, the coupling mechanism of characteristic heavy metals in the modification process (original-modification-hydration) was discussed, and the safety evaluation was conducted on the content of heavy metal elements in the sample. Data from microscopic analysis showed that with the increase of temperature and drying time, the strength of MPG blocks and the decomposition rate of dihydrate gypsum crystal both increased, while the particle size decreased. The degree of crystal decomposition becomes more complete as the temperature rises if the holding time remains constant. As well as, the MPG at 180 °C/7 h, 195 °C/7 h/10 h met the Chinese standard of “Calcined gypsum” (GB/T9776). The heavy metal elements in MPG decreased obviously, caused by the substitution solid solution formed by Ca2+ and Fe3+ and heavy metal ions and the adsorption of calcium sulfate hemihydrate crystals. After hydration of MPG, As and Cd increased slightly because dicalcium phosphate was insoluble in water and soluble in acid, and iron oxide reduced and dissolved Cd. Then, the ecological hazards of heavy metals in hydrated MPG after hydration were evaluated. The results showed that there was no environmental safety problem in the hydrated MPG, but the As and Cr elements in it had an acceptable carcinogenic risk through oral intake. Based on ensuring the safety of MPG, MPG powder was used in PBSLM. The research demonstrates that the basic mechanical properties of the PBSLM produced, when the MPG powder content is 330 g, and cement is 40 g are the best. The heavy metal aqueous solution's leaching amount is lower than China's national standard limit value. (30min fluidity, 24 h-flexural and compressive strength were 154 mm, 5.7 MPa and 10.6 MPa). Finally, based on this research, a set of general evaluation system for safe utilization of solid waste was established according to national standards. This provides theoretical support for the research of heavy metal in PG at low temperature and the ways of harmless and resource utilization.

In Situ Probing the Crystallization Kinetics in Gas‐Quenching‐Assisted Coating of Perovskite Films

AbstractThe pursuit of commercializing perovskite photovoltaics is driving the development of various scalable perovskite crystallization techniques. Among them, gas quenching is a promising crystallization approach for high‐throughput deposition of perovskite films. However, the perovskite films prepared by gas‐quenching assisted blade coating are susceptible to the formation of pinholes and frequently show inferior crystallinity if the interplay between film coating, film drying, and crystallization kinetics is not fully optimized. That arguably requires a thorough understanding of how single processing steps influence the crystallization kinetics of printed perovskite films. Here, in situ optical spectroscopies are integrated into a doctor‐blading setup that allows to real‐time monitor film formation during the gas‐quenching process. It is found that the essential role of gas quenching treatment is in achieving a smooth and compact perovskite film by controlling the nucleation rate. Moreover, with the assistance of phase‐field simulations, the role of excessive methylammonium iodide is revealed to increase grain size by accelerating the crystal growth rate. These results show a tailored control of crystal growth rate is critical to achieving optimal film quality, leading to fully printed solar cells with a champion power conversion efficiency of 19.50% and mini solar modules with 15.28% efficiency are achieved.

Influence of cross-link density on the non-isothermal crystallization kinetics of polybutylene terephthalate

Kinetics of crystallization of the samples of cross-linked polybutylene terephthalate with different cross-link densities was studied experimentally using conventional differential scanning calorimetry (cooling rates 5 to 40 K·min–1) and fast scanning calorimetry (cooling rates 0.5 to 5000 K·s–1). The samples were obtained by copolycondensation of terephthaloyl chloride, 1,4-butanediol, and glycerol. The cross-linking degree was characterized using 1H NMR spectroscopy. An increase of the number of glycerol cross-links in polymer leads to a decrease in the crystallization and melting temperatures and suppression of crystallization process. The critical rate of crystallization decreases monotonically with increasing cross-linking degree from 2700 K·s–1 for linear polybutylene terephthalate to 110 K·s–1 for the sample with 270 mol·m–3 cross-link density. At the cross-link densities higher than 270 mol·m–3, the polymer does not crystallize even at 5 K·min–1 cooling rate. The observed dependence of the cold crystallization enthalpy on the previous cooling rate suggests that the homogeneous nuclei formation process also slows down with an increase in the cross-linking degree.

Sintering and crystallization kinetics of bioactive glass 13–93

This study investigates the sintering and crystallization behavior and kinetic of the bioactive glass (BG) 13–93 with nominal composition (in mol%): 54.6 SiO2 - 1.7 P2O3 - 22.1 CaO - 6.0 Na2O - 7.9 K2O - 7.7 MgO. Sintering and crystallization were investigated non-isothermally for various particle size fractions smaller than 315 µm as well as for bulk samples. Densification was not hindered by the presence of crystalline phases across all particle size fractions. Afterwards, wollastonite was found as the dominant crystal phase at higher temperature which resorb primary surface precipitation-like quartz crystallites. The growth direction shifts into volume when the sample surface is nearly covered. The crystal growth rate of wollastonite was calculated from the crystalline surface layer thickness measured during heating. The findings of this study are relevant for the high temperature processing of BG 13–93.

Ammonium Disrupts Vivianite Crystal Hydration to Enhance Crystallization Rate for Phosphorus Recovery

Ammonium Disrupts Vivianite Crystal Hydration to Enhance Crystallization Rate for Phosphorus Recovery

Improving the thermal stability and operation speed of Sb7Se3 films via carbon nanolayers

The C/Sb7Se3 superlattice-like film was prepared by magnetron sputtering technology, and the effects of carbon nanolayers on the film and device properties were studied. The C/Sb7Se3 superlattice-like films show excellent thermal stability and data retention, especially the [C(3 nm)/Sb7Se3(3 nm)]5 film. The analysis of transmission electron microscopy and x-ray diffraction reveal that the high-quality multilayer structure of [C(3 nm)/Sb7Se3(3 nm)]5 is maintained. The segmentation of phase change material by amorphous carbon layer reduces the size of crystalline region, thus accelerates the crystallization rate. Element mapping indicates that C atoms and Se atoms in the annealed [C(3 nm)/Sb7Se3(3 nm)]5 films show obvious interlayer diffusion. The results of x-ray photoelectron spectroscopy and density functional theory manifest that atomic diffusion results in the formation of strong C-Sb and C-Se bonds in the phase transition layer and C atom prefers to occupying interstitial site in the center of the periodic structural unit of Sb2Se3 phase. Carbon atoms can effectively suppress grain growth and gradually move to the boundary of the grain, refining grain size, thus improving the stability of the amorphous phase. This study indicates that carbon nanolayers play an important role in improving the thermal stability and operation speed, reducing power consumption and resistance drift in Sb7Se3 films.

О геохимической зональности Верхне-Алиинского месторождения золота в Забайкалье (Россия)

The relevance of the study lies in the need to have objective geochemical data to assess the erosion section level of newly discovered manifestations of ore deposits. One of the examples, used to solve this problem, is the results of the mineralogy and geochemistry study of the Verkhnealiinsky gold deposit in Transbaikalia. The purpose of the study is to determine the zonality in the distribution of minerals, gold and associated chemical elements in the deposit space and to evaluate them as criteria for ore zoning. The object of the study is the Verkhnealinsky gold deposit. The subject of the research is the spatial distribution of minerals and chemical elements in the gold ore zones of the deposit. The methodology consists in diagnostics, determination of the chemical elements content and the establishment of regularities in their spatial distribution using modern methods of analysis, namely, electron microscopy, assay analysis and ICP MS, determination of the degree of the crystal structure perfection. The results of the study are as follows: the content of gold and associated chemical elements in the three most industrially important ore-bearing zones of the Western, Latitudinal and Eastern zones, which differ in the depth of formation, have been determined. The least deep Eastern zone is characterized by the intensive development of zinc, lead, antimony, and arsenic minerals and, accordingly, their maximum content in its upper part. For the deepest Western zone, the maximum development of pyrrhotite, chalcopyrite, and cobalt has been revealed, and it is shown that the cobalt-nickel ratio is an important criterion for assessing the level of erosion cut. An important criterion of depth is also the degree of the crystalline structure perfection of vein quartz, which depends both on the crystallization rate, which is determined by the depth from the day surface during the formation of the deposit, and on the amount of isomorphic impurities in it. It is also shown that one of the important criteria for the level of erosion section is the content of rubidium in veined quartz and arsenic in pyrite.

Influence of alloying parameters on the structure and properties of AK-6 aluminium alloy

This work is devoted to the study of the effect of zirconium addition and crystallization rate on the structure and properties of industrial aluminium alloys. Experimental alloying of the AK6 alloy was performed. The required amount of Al-Zr-10 alloy (10 wt. % Zr) was added at a temperature of 900 °C until the zirconium content in the target alloy reached 0.1; 0.3; 0.5 wt. %. According to the results of scanning electron microscopy and X-ray diffraction analysis, the main proportion of zirconium in the initial alloy was represented by intermetallic compounds of predominantly Al3Zr composition and sizes from 5 to 50 μm. Values of microhardness measured after direct alloying of high-purity aluminum with zirconium by the electrolysis of oxide-fluoride melts demonstrate that at a zirconium content of 0.4 wt. %, the microhardness of the alloy increases by 1.5 times and continues to grow as the zirconium content increases. Based on the results of structural analysis, it was found that the average grain size of the aluminium alloy decreased by 4–5 times even at a Zr content of 0.1 wt. %. When studying the properties of the obtained samples, it was found that the addition of zirconium to the AK6 alloy does not affect its hardness, in contrast to high-purity aluminium, which is presumably due to the more pronounced influence of other components and the absence of an additive effect of zirconium on the alloy hardness. Accelerated cooling of the alloy to 103 K/s without zirconium additives has a similar effect of grain reduction, and also increases the microhardness of the alloy by 10 HB according to Brinell. A study of the combined effect of zirconium addition and accelerated cooling shows the additive effect of grinding by more than 25 times, while individual grains do not exceed 5 microns in size. The absence of intermetallic compounds in the obtained samples of the AK6 alloy after modification with the Al-Zr alloy indicates that the phase composition of the initial Al-Zr alloy does not affect the properties of the target alloys.

Copper recovery from treatment of simulated copper-iron wastewater using fluidized-bed homogeneous crystallization technology

Electroless plating wastewater contains highly soluble Cu-EDTA complex which poses challenges for copper recovery using conventional methods. These complexes are destroyed first using Fenton process producing treated solutions with iron concentrations that may interfere copper recovery. The purpose of this study was to confirm the influence of trace amount of iron on copper removal, crystallization, and copper salt recovery using fluidized-bed homogeneous crystallization (FBHC) process. By varying several parameters like pH, initial copper and iron concentrations, and metal and precipitant inlet flowrate and molar ratio, the optimized conditions include pHe of 6.5–7.0, inlet flowrate of 15 mL min−1, and MR of 1.5. The effects of variable copper (3.15–9.44 mM) and iron concentrations (0.36–1.08 mM) were examined. The addition of iron had no significant impact on copper removal mainly due to its minimal presence in the solution, but a trend of decreasing, then increasing, copper crystallization ratio was observed at higher iron concentrations. The study recorded copper removal and crystallization rates from 88% to 96% and 75% to 95%, respectively, with varying iron concentrations. Characterization analyses of precipitates confirmed predominant presence of malachite and azurite. The FBHC's ability to obtain high purity spheroidal solid salts enables resource recovery and catalyzes strategies for circular economy practices.

Lunar Mare Lava Flow Dynamics and Emplacement: Predictions of Non-Newtonian Flow Dynamics, Syn- and Post-emplacement Cooling and Volatile Release Patterns, and Vertical and Lateral Flow Structure Development

We apply basic principles of magma ascent from deep source regions and its eruption into a low-gravity vacuum environment to develop a theoretical treatment of the fluid dynamics and thermodynamics of mare basalt lava flow emplacement and evolution on the Moon. The vacuum conditions influenced the release of volatiles in magma passing through lava fountains, thus controlling the syn- and post-emplacement vesicularity of the resulting deposits. To explain observed lengths and volumes of Mare Imbrium–type flows, high (106–105 m3 s−1) initial magma eruption rates were needed. Combined with low lunar magma viscosity, these caused flows to be initially turbulent. Resulting high radiative heat loss and consequent high crystallization rates caused rapid non-Newtonian rheological evolution and suppression of turbulence at tens of kilometers from vents. Slower cooling rates in the subsequent laminar parts of flows imply distinctive crystal growth rate histories. In a four-phase sequence, (i) initial transient dike-tip gas release followed by (ii) Hawaiian fire fountain activity with efficient volatile loss (iii) transitioned to (iv) Strombolian explosions in a lava lake. Late-stage lava now able to retain volatiles intruded and inflated existing flow deposits after flow front advance ceased. Volatiles forced out of solution by second boiling as lava cooled caused additional inflation. Low gravity and lack of atmospheric pressure commonly produced very vesicular lava. Escape of such lava through cracks in flow crusts is a possible source of ring-moat dome structures; collapse of such lava may explain irregular mare patches.

Large-Scale Preparation of Mechanically High-Performance and Biodegradable PLA/PHBV Melt-Blown Nonwovens with Nanofibers

Biodegradable polylactic acid (PLA) melt-blown nonwovens are attractive candidates to replace non-degradable polypropylene melt-blown nonwovens. However, it is still an extremely challenging task to prepare PLA melt-blown nonwovens with sufficient mechanical properties for practical application. Herein, we report a simple strategy for the large-scale preparation of biodegradable PLA/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) melt-blown nonwovens with high strength and excellent toughness. In this process, a small amount of PHBV is added to PLA to improve the latter’s crystallization rate and crystallinity. In addition, when the PHBV content increases from 0 to 7.5 wt%, the diameters of the PLA/PHBV melt-blown fibers decrease significantly (with the proportion of nanofibers increasing from 7.7% to 42.9%). The resultant PLA/PHBV (5 wt% PHBV) melt-blown nonwovens exhibit the highest mechanical properties. The tensile stress, elongation, and toughness of PLA/PHBV (5 wt% PHBV) melt-blown nonwovens reach 2.5 MPa, 45%, and 1.0 MJ·m−3, respectively. More importantly, PLA/PHBV melt-blown nonwovens can be completely degraded into carbon dioxide and water after four months in the soil, making them environmentally friendly. A general tensile-failure model of melt-blown nonwovens is proposed in this study, which may shed light on mechanical performance enhancement for nonwovens.