Strategic Design and Insights into Lanthanum and Strontium Perovskite Oxides for Oxygen Reduction and Oxygen Evolution Reactions.

Perovskite oxides exhibit bifunctional activity for both oxygen reduction (ORR) and oxygen evolution reactions (OER), making them prime candidates for energy conversion in applications like fuel cells and metal-air batteries. Their intrinsic catalytic prowess, combined with low-cost, abundance, and diversity, positions them as compelling alternatives to noble metal and metal oxides catalysts. This review encapsulates the nuances of perovskite oxide structures and synthesis techniques, providing insight into pivotal active sites that underscore their bifunctional behavior. The focus centers on the breakthroughs surrounding lanthanum (La) and strontium (Sr)-based perovskite oxides, specifically their roles in zinc-air batteries (ZABs). An introduction to the mechanisms of ORR and OER is provided. Moreover, the light is shed on strategies and determinants central to optimizing the bifunctional performance of La and Sr-based perovskite oxides.

Bioaugmentation with a defined bacterial consortium: A key to degrade high molecular weight polylactic acid during traditional composting.

Polylactic acid (PLA) is commercialized as a compostable bio-thermoplastic. PLA degrades under industrial composting conditions where elevated temperatures are maintained for a long timeframe. However, these conditions cannot be achieved in a non-industrial compost pile. Therefore, this study aims to degrade high molecular weight PLA films by adding a PLA-degrading bacterial consortium (EAc) comprised of Nocardioides zeae EA12, Stenotrophomonas pavanii EA33, Gordonia desulfuricans EA63, and Chitinophaga jiangningensis EA02 during traditional composting. With EAc-bioaugmentation, PLA films (5-30% w/w) had complete disintegration (35 d), 77-82% molecular weight reduction (16 d), and higher CO2 liberation and mineralization than non-bioaugmented composting. Bacterial community analyses showed that EAc-bioaugmentation increased the relative abundance of Schlegelella, a known polymer degrader, and interacted positively with beneficial indigenous microbes like Bacillus, Schlegelella and Thermopolyspora. The bioaugmentation also decreased compost phytotoxicity. Hence, consortium EAc shows potential in PLA-waste treatment applications, such as backyard and small-scale composting.

Compressed composite carbon felt as a negative electrode for a zinc-iron flow battery.

Flow batteries possess several attractive features including long cycle life, flexible design, ease of scaling up, and high safety. They are considered an excellent choice for large-scale energy storage. Carbon felt (CF) electrodes are commonly used as porous electrodes in flow batteries. In vanadium flow batteries, both active materials and discharge products are in a liquid phase, thus leaving no trace on the electrode surface. However, zinc-based flow batteries involve zinc deposition/dissolution, structure and configuration of the electrode significantly determine stability and performance of the battery. Herein, fabrication of a compressed composite using CF with polyvinylidene fluoride (PVDF) is investigated in a Zn-Fe flow battery (ZFB). Graphene (G) is successfully introduced in order to improve its electrochemical activity towards zinc reactions on the negative side of the ZFB. A compressed composite CF electrode offers more uniform electric field and lower nucleation overpotential (NOP) of zinc than a pristine CF, resulting in higher zinc plating/stripping efficiency. Batteries with modified electrodes are seen to provide lower overpotential. Particularly, the G-PVDF-CF electrode demonstrates maximum discharge capacity of 39.6 mAh cm-2 with coulombic efficiency and energy efficiency over 96% and 61%, respectively. Finally, results lead to increased efficiency and cycling stability for flow batteries.

Asphalt Incorporation with Ethylene Vinyl Acetate (EVA) Copolymer and Natural Rubber (NR) Thermoplastic Vulcanizates (TPVs): Effects of TPV Gel Content on Physical and Rheological Properties.

Plastic waste has been incorporated with asphalt to improve the physical properties of asphalt and alleviate the increasing trend of plastic waste being introduced into the environment. However, plastic waste comes in different types such as thermoplastic or thermoset, which results in varied properties of polymer modified asphalt (PMA). In this work, four thermoplastic vulcanizates (TPVs) were prepared using different peroxide concentrations to produce four formulations of gel content (with varying extent of crosslinked part) in order to imitate the variation of plastic waste. All four TPVs were then mixed with asphalt at 5 wt% thus producing four formulations of PMA, which went through physical, rheological, and storage stability assessments. PMA with higher gel content possessed lower penetration and higher softening temperature, indicating physically harder appearance of PMA. Superpave parameters remained unchanged among different gel content PMA at temperatures of 64, 70, and 76 °C. PMA with any level of gel content had lower Brookfield viscosity than PMA without gel content at a temperature of 135 °C. Higher gel content resulted in shorter storage stability measured with greater different softening temperatures between top and bottom layers of PMA after 5 days of 163 °C storage. This study shows that asphalt with thermoset plastic waste is harder and easier to pave, thus making the non-recycling thermoset plastic waste more useful and friendly to the environment.

Carboxymethyl cellulose-based polyelectrolyte as cationic exchange membrane for zinc-iodine batteries.

The aim of this research is an evaluation of polyelectrolytes. In the application of zinc-iodine batteries (ZIBs), polyelectrolytes have high stability, good cationic exchange properties and high ionic conductivity. Polyelectrolytes are also cost-effective. Important component of ZIBs are cation exchange membranes (CEMs). CEMs prevent the crossover of iodine and polyiodide from zinc (Zn) electrodes. However, available CEMs are costly and have limited ionic conductivity at room temperature. CEMs are low-cost, have high stability and good cationic exchange properties. Herein, polyelectrolyte membranes prepared from carboxymethyl cellulose (CMC) and polyvinyl alcohol (PVA) are examined. It is seen that an increase in the ratio of PVA leads to enhanced ionic conductivity as well as increased iodine and polyiodide crossover. ZIBs using polyelectrolytes having 75:25 wt.% CMC/PVA and 50:50 wt.% CMC/PVA show decent performance and cycling stability. Due to their low-cost and other salient features, CMC/PVA polyelectrolytes prove they have the capacity for use as cation exchange separators in ZIBs.

Curing Behavior, Rheological, and Thermal Properties of DGEBA Modified with Synthesized BPA/PEG Hyperbranched Epoxy after Their Photo-Initiated Cationic Polymerization.

This paper investigates the photo-initiated cationic polymerization of diglycidyl ether of bisphenol A (DGEBA) modified with bisphenol A (BPA)/polyethylene glycol (PEG) hyperbranched epoxy resin. The relationship between curing behavior, rheological, and thermal properties of the modified DGEBA is investigated using photo-differential scanning calorimetry (DSC) and photo-rheometer techniques. It is seen that the addition of the hyperbranched epoxy resin can increase UV conversion (αUV) and reduce gelation time (tgel). After photo-initiation polymerization (dark reaction) occurred, a second exothermic peak in the DSC thermogram takes place: namely, the occurrence of curing reaction owing to the activated monomer (AM) mechanism. Consequently, the glass transition temperature decreased, and at the same time, UV intensity increased which was due to the molecular weight between crosslinking points (Mc). Furthermore, the radius of gyration (Rg) of the network segment is determined via small-angle X-ray scattering (SAXS). It is noted that the higher the Mc, the larger the radius of gyration proves to be, resulting in low glass transition temperature.

Effect of Mixing Method on Properties of Ethylene Vinyl Acetate Copolymer/Natural Rubber Thermoplastic Vulcanizates.

Thermoplastic vulcanizate (TPV) has excellent elastomeric properties and can be reprocessed multiple times. TPV is typically produced by using the dynamic vulcanization (DV) method in which rubber is crosslinked simultaneously with thermoplastics. Peroxide-crosslinked TPV can increase the compatibility between rubber and thermoplastics but loses its reprocessability due to excess crosslinking in the latter. In this work, we overcome this obstacle by using a two-step mixing method to prepare fully crosslinked elastomers of ethylene vinyl acetate copolymer (EVA) and natural rubber (NR). Each sample formulation was prepared with three different mixing methods for comparison: NR-DV, Split-DV, and All-DV. For NR-DV, NR was crosslinked prior to the addition of EVA together with the thermal stabilizer (TS). For Split-DV, a small amount of EVA and NR was crosslinked prior to the addition of EVA and TS. In the All-DV method, EVA and NR were crosslinked, and then TS was added. The appearance and processability of the samples were affected by the degree of crosslinking. NR-DV showed a non-homogeneous texture. Although the samples of the All-DV method appeared homogeneous, their mechanical and rheological properties were inferior to those of the Split-DV method. The mechanical properties of the Split-DV samples were not significantly changed after reprocessing 10 times. Therefore, Split-DV is the preferred method for TPV production.

Discharge profile of a zinc-air flow battery at various electrolyte flow rates and discharge currents.

Nowadays, due to global warming stemming from excessive use of fossil fuel, there is considerable interest in promoting renewable energy sources. However, because of the intermittent nature of these energy sources, efficient energy storage systems are needed. In this regard, zinc-air flow batteries (ZAFBs) are seen as having the capability to fulfill this function. In flow batteries, the electrolyte is stored in external tanks and circulated through the cell. This study provides the requisite experimental data for parameter estimation as well as model validation of ZAFBs. Each data set includes: current (mA), voltage (V), capacity (mAh), specific capacity (mAh/g), energy (Wh), specific energy (mWh/g) and discharge time (h:min:s.ms). Discharge data involved forty experiments with discharge current in the range of 100-200 mA, and electrolyte flow rates in the range of 0-140 ml/min. Such data are crucial for the modelling and theoretical/experimental analysis of ZAFBs.

Binder-Free α-MnO2 Nanowires on Carbon Cloth as Cathode Material for Zinc-ion Batteries.

Recently, rechargeable zinc-ion batteries (ZIBs) have gained a considerable amount of attention due to their high safety, low toxicity, abundance, and low cost. Traditionally, a composite manganese oxide (MnO2) and a conductive carbon having a polymeric binder are used as a positive electrode. In general, a binder is employed to bond all materials together and to prevent detachment and dissolution of the active materials. Herein, the synthesis of α-MnO2 nanowires on carbon cloth via a simple one-step hydrothermal process and its electrochemical performance, as a binder-free cathode in aqueous and nonaqueous-based ZIBs, is duly reported. Morphological and elemental analyses reveal a single crystal α-MnO2 having homogeneous nanowire morphology with preferential growth along {001}. It is significant that analysis of the electrochemical performance of the α-MnO2 nanowires demonstrates more stable capacity and superior cyclability in a dimethyl sulfoxide (DMSO) electrolyte ZIB than in an aqueous electrolyte system. This is because DMSO can prevent irreversible proton insertion as well as unfavorable dendritic zinc deposition. The application of the binder-free α-MnO2 nanowires cathode in DMSO can promote follow-up research on the high cyclability of ZIBs.

Correction: Abbasi, A. et al. Poly(2,6-dimethyl-1,4-phenylene oxide)-Based Hydroxide Exchange Separator Membranes for Zinc-Air Battery. Int. J. Mol. Sci. 2019, 20, 3678.

The authors would like to make the following corrections to their paper published in the International Journal of Molecular Science [...].

Synthesis, Thermal Properties and Curing Kinetics of Hyperbranched BPA/PEG Epoxy Resin.

The hyperbranched epoxy resins (HBE) composed of bisphenol A (BPA) and polyethylene glycol (PEG) as reactants and pentaerythritol as branching point were successfully synthesized via A2 + B4 polycondensation reaction at various BPA/PEG ratios. The 13C NMR spectra revealed that the synthesized HBE mainly had a dendritic structure as confirmed by the high degree of branching (DB). The addition of PEG in the resin enhanced degree of branching (DB) (from 0.82 to 0.90), epoxy equivalent weight (EEW) (from 697 g eq-1 to 468 g eq-1) as well as curing reaction. Adding 5-10 wt.% PEG in the resin decreased the onset and peak curing temperatures and glass transition temperature; however, adding 15 wt.% PEG in the resin have increased these thermal properties due to the lowest EEW. The curing kinetics were evaluated by fitting the experimental data of the curing behavior of all resins with the Sesták-Berggren equation. The activation energy increased with the increase of PEG in the resins due to HBE's steric hindrance, whereas the activation energy of HBE15P decreased due to a large amount of equivalent active epoxy group per mass sample. The curing behavior and thermal properties of obtained hyperbranched BPA/PEG epoxy resin would be suitable for using in electronics application.

Poly(2,6-Dimethyl-1,4-Phenylene Oxide)-Based Hydroxide Exchange Separator Membranes for Zinc-Air Battery.

Rechargeable zinc-air batteries are deemed as the most feasible alternative to replace lithium-ion batteries in various applications. Among battery components, separators play a crucial role in the commercial realization of rechargeable zinc-air batteries, especially from the viewpoint of preventing zincate (Zn(OH)42-) ion crossover from the zinc anode to the air cathode. In this study, a new hydroxide exchange membrane for zinc-air batteries was synthesized using poly (2,6-dimethyl-1,4-phenylene oxide) (PPO) as the base polymer. PPO was quaternized using three tertiary amines, including trimethylamine (TMA), 1-methylpyrolidine (MPY), and 1-methylimidazole (MIM), and casted into separator films. The successful synthesis process was confirmed by proton nuclear magnetic resonance and Fourier-transform infrared spectroscopy, while their thermal stability was examined using thermogravimetric analysis. Besides, their water/electrolyte absorption capacity and dimensional change, induced by the electrolyte uptake, were studied. Ionic conductivity of PPO-TMA, PPO-MPY, and PPO-MIM was determined using electrochemical impedance spectroscopy to be 0.17, 0.16, and 0.003 mS/cm, respectively. Zincate crossover evaluation tests revealed very low zincate diffusion coefficient of 1.13 × 10-8, and 0.28 × 10-8 cm2/min for PPO-TMA, and PPO-MPY, respectively. Moreover, galvanostatic discharge performance of the primary batteries assembled using PPO-TMA and PPO-MPY as initial battery tests showed a high specific discharge capacity and specific power of ~800 mAh/gZn and 1000 mWh/gZn, respectively. Low zincate crossover and high discharge capacity of these separator membranes makes them potential materials to be used in zinc-air batteries.

Storage stability of packaged baby formula in poly(lactide)-whey protein isolate laminated pouch.

BACKGROUND: The use of biodegradable polymeric materials has been proposed as an environmentally-friendly alternative to petroleum-based packaging. To extend the shelf life of food products, these bioplastics must possess appropriate barrier properties and food-package stability. In the present study, shelf life analysis of packaged baby formula in biopolymeric, multilayer film, fabricated from poly(lactide) (PLA) and whey protein isolate (WPI), PLA/WPI/PLA and PLA pouches was performed at 4-35 o C and 50-59% relative humidity. RESULTS: Despite the possible sorption of food components into contact PLA surfaces, the results demonstated that the transparency and barrier properties of PLA-based pouches were insignificantly changed over time (P > 0.05), although the films showed a slow rate of color change. The baby formula packaged in PLA/WPI/PLA had a delayed lipid oxidation compared to the sample in the PLA pouch, especially at a higher temperature. The application of WPI in the multilayer structure shifted the shelf life determination factor from lipid oxidation to moisture gain. CONCLUSION: The results indicate that the PLA/WPI/PLA pouch has good storage stability. The film could be used to package dry food properly at 4-35 o C and 50-59% relative humidity for an extended period of time. © 2016 Society of Chemical Industry.

Development of non-water soluble, ductile mung bean starch based edible film with oxygen barrier and heat sealability.

This research determined the effects of starch concentration (3.5-5.0%w/w), and plasticizer [glycerol (0-30%w/w) or sorbitol (0-60%w/w)] on properties of mung bean starch (MBS) films. The result showed that increasing plasticizer concentration tended to decrease tensile strength (TS), elastic modulus (EM) and oxygen permeability (OP); but increase elongation (%E), solubility, water vapor permeability (WVP) and seal strength. The extent of those changes also depended on starch concentration. Glycerol provided better plasticizer efficiency than sorbitol. A bimodal melting endotherm of retrograded structure was evident in non-plasticized film. However, only a low temperature endotherm was observed in polyol-plasticized films, indicating a plasticizer-induced structural modification. The developed ductile MBS films, (TS of 7.14±0.95 to 46.30±3.09MPa, %E of 2.46±0.21 to 56.95±4.34% and EM of 16.29±3.40 to 1428.45±148.72MPa) with an OP of 0.2397±0.0365 to 1.1520±0.1782 ccmm/m2daykPa and seal strength up to 422.36±7.93N/m, demonstrated in this study indicate the potential for food packaging applications.

Properties and storage stability of whey protein edible film with spice powders.

The impact of spice powders on physical, mechanical, thermal and barrier properties, and on storage stability, of whey protein isolate (WPI)-based films was determined. Films with added spices were prepared from casting solution containing 10 % (w/w) heat-denatured WPI, glycerol (WPI:glycerol of 3:2 w/w), sodium chloride (0.4 g/100 g solution), garlic and pepper powders (≤3 g each/100 g solution). Water activity (aw) of all films was 0.53-0.57. Addition of spice powders increased thickness, darkness and yellowness of the WPI films. Films with added spices had lower tensile strength (TS), percent elongation (%E), and melting enthalpy of WPI matrices, but possessed higher water vapor permeability (WVP) than WPI film without sodium chloride and spices. The WPI film containing highest amount of garlic powder and lowest amount of pepper powder was selected for storage tests at 25-45 °C. Storage for up to 49 days resulted in reduced aw and %E, increased TS, and color changes at 35 and 45 °C, with few changes at 25 °C. However, film WVP and OP were not affected by storage conditions after 7 days storage. Active ingredients decreased over time with up to 81 % allicin and 37 % piperine retained in the film matrix after 47 days storage.

Properties of poly(lactide)-whey protein isolate laminated films.

BACKGROUND: This study aims to examine the feasibility of a novel multi-layer barrier film made entirely from biopolymers, which can be disposed after use in an economically and ecologically acceptable way, by employing mechanical strength and moisture barrier of poly(lactide) (PLA) films and oxygen barrier enhancement of whey protein isolate (WPI) films. The effect of glycerol was also determined. The three-layer films, PLA/WPI/PLA, were compared with those made of linear low-density polyethylene films (LLDPE/WPI/LLDPE). Composite structures of three-layer films obtained by a simple casting method using denatured WPI solution plasticised with glycerol (GLY) at three different ratios of GLY:WPI (1:4, 1:2.5 and 1:1.5). The WPI solution was applied between two base layers of corona-treated PLA or LLDPE films. RESULT: The multi-layer films showed good appearance with no noticeably visible change and good adhesion of layers. PLA enhanced tensile strength of the composite structure. Oxygen permeability of the multi-layer films was significantly lower than the base films. The water vapour permeability of the structure relied mainly on the base films. The plasticiser content did not significantly affect the properties of the multi-layer structures. CONCLUSION: Results suggested that WPI could work successfully as an alternative oxygen barrier layer of multi-layer structures.

Cocrystal formation during cogrinding and storage is mediated by amorphous phase.

PURPOSE: The purpose of this work was to investigate the mechanisms of cocrystal formation during cogrinding and storage of solid reactants, and to establish the effects of water by cogrinding with hydrated form of reactants and varying RH conditions during storage. METHODS: The hydrogen bonded 1:1 carbamazepine-saccharin cocrystal (CBZ-SAC) was used as a model compound. Cogrinding of solid reactants was studied under ambient and cryogenic conditions. The anhydrous, CBZ (III), and dihydrate forms of CBZ were studied. Coground samples were stored at room temperature at 0% and 75% RH. Samples were analyzed by XRPD, FTIR and DSC. RESULTS: Cocrystals prepared by cogrinding and during storage were similar to those prepared by solvent methods. The rate of cocrystallization was increased by cogrinding the hydrated form of CBZ and by increasing RH during storage. Cryogenic cogrinding led to higher levels of amorphization than room temperature cogrinding. The amorphous phase exhibited a T (g) around 41 degrees C and transformed to cocrystal during storage. CONCLUSIONS: Amorphous phases generated by pharmaceutical processes lead to cocrystal formation under conditions where there is increased molecular mobility and complementarity. Water, a potent plasticizer, enhances the rate of cocrystallization. This has powerful implications to control process induced transformations.