Synthesis and Thermal Performance of Polyurea Microcapsulated Phase Change Materials by Interfacial Polymerization

Microencapsulated phase change materials with paraffin as the core material were synthesized by interfacial polymerization of isophorone diisocyanate with diethylene triamine. The particle size and particle size distribution, morphology, thermal performance and the encapsulation efficiency of the prepared materials were investigated. The results of Fourier transform infrared spectrometer and X-ray photoelectron spectroscopy suggested that the paraffin core was well encapsulated by the polyurea resin. The particle size of the prepared materials decreased and its distribution became narrow with the increase of the emulsification time, stirring speed and emulsifier amount. The thermal gravimetric analysis indicated that the prepared materials exhibited good thermal stability, while the differential scanning calorimetry their high encapsulation efficiency.     

A Comparison of NO Reduction Over Mn–Cu/ZSM5 and Mn–Cu/MWCNTs Catalysts Assisted by Plasma at Ambient Temperature

Manganese–copper bimetal oxide catalysts supported on ZSM5 and acid-treated multi-walled carbon nanotubes (MWCNTs) were produced by incipient wetness impregnation for selective catalytic reduction of NO with dielectric barrier discharge plasma. Plasma can activate molecules even at ambient temperature, generating active oxygen species such as O, O₃, and HO₂ radicals, which can oxidize NO to NO₂ effectively. The SCR activity of Mn–Cu/MWCNTs was studied and compared to that of the Mn–Cu/ZSM5. The obtained samples were characterized by XRD, SEM, TEM, ICP, H₂-TPR, Raman spectroscopy, and XPS. The results show that Mn–Cu/MWCNTs catalyst possesses NO removal activity superior to that of the Mn–Cu/ZSM5 catalyst. MWCNTs-based catalyst attains NO removal efficiency of 88% at 480 J/L, while the ZSM5-supported catalyst achieves NO removal efficiency of 82% at the same energy density. The oxygen content increased from 3.33 to 19.07% on the nanotube surface after introducing Mn and Cu, which almost remained unchanged on ZSM5. The oxygen-containing functionalities are important for NO_x adsorption and removal. Moreover, the characterization revealed that CuO is the main phase of copper oxide, but copper dispersion decreases on Mn–Cu/ZSM5 surface because of the formation of copper dimer species. The manganese is well-dispersed on the catalysts, MnO₂ and Mn₂O₃ contents of Mn–Cu/MWCNTs are larger than that of Mn–Cu/ZSM5, MnO₂ is the predominant phase of manganese oxide.     

Recent Progress of Synthesis and Application in Au@MOFs Hybrid Materials

The combination of gold nanoparticles and metal–organic frameworks is one of the new directions of current research. It has applications in many aspects, especially as a catalyst for a variety of reactions. Therefore, this paper describes recent progress of synthesis and application in Au@MOFs hybrid materials.     

Applicability of anthracite filtration‒micro electrolysis‒sand filtration for the treatment of surface waters containing high turbidity

The effect of combined filtration efficiency on the performance of anthracite filtration?micro electrolysis?sand filtration (AMS) was investigated. Impact of different operating parameters, such as iron?carbon ratio of micro electrolytic units, filtration velocity of AMS, were studied. It was found that when iron?carbon ratio was 6: 4, the AMS’s average turbidity removal rate was 96.75% at the filtration velocity of 3 m h^?1. The results showed that when the filtration rate was 3?9 m h^?1 and iron?carbon ratio was 6: 4, the turbidity removal efficiency was over 94%, and the turbidity of the effluent was less than 1 NTU in effective filtration cycle. The effective filtration cycle can last for more than 5 h or longer. Meanwhile, the removal rate of UV₂₅₄ was above 33%, and the concentration of iron ions in the effluent is less than 0.15 mg L^?1. Turbidity and iron indicators have reached the national drinking water standards. It was also found the mechanism of iron?carbon micro electrolytic enhanced filtration by infrared spectroscopy and scanning electron microscopy. And It was also speculated the reasons for the reaction passivation.     

Heat capacity measurements on BaTa<Subscript>2</Subscript>O<Subscript>6</Subscript> and derivation of its thermodynamic functions

Heat capacity measurements of barium tantalate (BaTa₂O₆) were carried out by using a differential scanning calorimeter at temperatures between 323 and 1323 K. From the heat capacity values of BaTa₂O₆, other thermodynamic functions (enthalpy and entropy increments) were derived between 298.15 and 1323 K. The C _p,m (298.15) value of BaTa₂O₆ was computed as 184.857 J mol^?1 K^?1. Moreover, fitted heat capacities exhibited good agreement with Neumann–Kopp rule at the temperatures between 298.15 and 1300 K.     

The effect of organoclay and graphene on the crystallization of PP in ABS/PP blends

In the present research, the isothermal and non-isothermal crystallization of polypropylene (PP) phase in PP-rich poly(acrylonitrile–butadiene–styrene)/polypropylene (ABS/PP) blends was studied. The effect of nanofillers’ incorporation and specialty of organically modified montmorillonite (OMMT) and graphene, into the prepared blends on the isothermal and non-isothermal crystallization of PP phase, were investigated. Moreover, kinetic study of their isothermal crystallization process was carried out, by applying the Avrami equation. The addition of ABS to the PP matrix increased the crystallization rate of PP at 130 °C. The incorporation of OMMT in pure PP accelerated slightly the crystallization process, whereas in ABS/PP blends, it seemed to retard crystallization, due to interactions between ABS phase and organoclay. The incorporation of graphene in pure PP accelerated impressively its isothermal crystallization, while the addition of ABS in graphene/PP nanocomposite slowed down the crystallization rate of PP. The effect of ABS and nanofillers, separately or in combination, on the crystallization of PP phase was reflected on the kinetic parameters of the Avrami equation. Regarding the non-isothermal crystallization, ABS/PP blends presented higher crystallization temperature (T _c) compared to pure PP. The organoclay reinforcement did not have any obvious effect on this temperature, whereas graphene caused significant increase, acting as nucleating agent. The presence of ABS to PP increased the concentration of the β-crystalline phase, reaching its maximum value at 30 mass% ABS content. The organoclay decreased the β-PP in ABS/PP blends, whereas graphene eliminated it.     

Calorimetric study of Sb-modified Ge–Se–Te glassy alloys

The glassy compositions of Ge ₁₆ Se ₅₂ Te _32?x Sb _x system, obtained using rapid melt quenching technique, have been characterized by calorimetric study at different heating rates in this study. A systematic investigation of the crystallization kinetics is carried out for these compositions. Composition corresponding to atomic % 8 of Sb has good thermal stability. The material exhibits the unique thermal properties, which makes it suitable to use for electrical or memory switching devices. Various thermal parameters, activation energies of glass transition and crystallization are calculated using relevant approaches.     

Electrolyte-cathode interactions in 5-V lithium-ion cells

The electrolyte/electrode interactions on the anode side of a lithium-ion cell and the formation of the solid electrolyte interphase (SEI) have been investigated intensively in the past and are fairly well understood. Present knowledge about the reactions on the cathode side and the resulting cathode electrolyte interphase (CEI) is less detailed. In this study, the electrolyte/electrode interactions on the surface of the high-voltage cathode material LiNi_0.5Mn_1.5O₄ (LNMO), both bare and FePO₄-coated, were investigated. The gases evolving upon first time charging of the system were investigated using a GC/MS combination. The degradation products included THF, dimethyl peroxide, phosphor trifluoride, 1,3-dioxolane and dimethyl difluor silane, formed in the GC’s column as its coating reacts with HF from the experiments. Although these substances and their formation are in themselves interesting, the absence of many degradation products which have been mentioned in the existing literature is of equal interest. Our results clearly indicate that coating a cathode material can have a major influence on the amount and composition of the gaseous decomposition products in the formation phase.     

α-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> thin films by liquid phase deposition: low-cost option for supercapacitor

In the present study, iron oxide (α-Fe₂O₃) thin films with good adhesion on stainless steel substrates are deposited by liquid phase deposition (LPD) technique, which is additive and binder-free. Iron oxyhydroxide (FeOOH) thin films are formed by means of a ligand-exchange equilibrium reaction of metal-fluoro complex ions and an F^?ions consuming reaction by using boric acid (H₃BO₃) as a scavenging agent. These films are annealed at 500 °C to get α-Fe₂O₃ thin films. The transformation from hydrophobic to hydrophilic nature of the films is observed due to annealing. The films are characterized by different techniques. The α-Fe₂O₃ film is checked for electrochemical supercapacitive performance in Na₂SO₃ solutions of various concentrations. Specific capacitance is calculated from cyclic voltammetry at numerous scan rates (5–200) mV s^?1. The highest obtained value of specific capacitance is 582 F g^?1 at 5 mV s^?1 for 0.5 M Na₂SO₃ electrolyte. The maximum values of specific power and specific energy are 6.9 and 53.4 Wh kg^?1 from the charge-discharge curve at the current density 2 mA cm^?2 in 0.5 M Na₂SO₃ electrolyte.     

A sustainable synthesis of biomass carbon sheets as excellent performance sodium ion batteries anode

Biomass-derived carbon (BMC) materials have attracted much attention due to their high performance and properties of abundant source. Herein, biomass carbon sheets (BMCS) from wheat straws had been successfully synthesized via a facile high temperature carbonization and expansion processes. The morphology of BMCS keeps the natural honeycomb-like shape of the cross section and the hollow tubular array structure of the vertical section with rich pores, which provides low-resistant ion channels to support fast diffusion. The (002) crystal plane reveals that the intercalation distance of carbon sheets is 0.383 nm larger than that graphite (0.335 nm), which benefits the larger sodium ion de/intercalation. By comparing different carbonization temperatures, wheat straws carbonized at 1200 °C (BMCS-1200) with well graphite microcrystallites show more excellent sodium ion storage performance than that of 900 °C (BMC-900). BMCS-1200 shows a stable reversible capacity of 221 mAh g^?1 after 200 cycles at 0.05 A g^?1, while BMC-900 is 162 mAh g^?1 after 100 cycles. And it also exhibits better rate capability (220, 109 mAh g^?1) than that of BMC-900 (125, 77 mAh g^?1) at 0.2 and 1 A g^?1, respectively. Finally, it delivers 89 mAh g^?1 stable capacity after 1400 cycles at 1 A g^?1 to prove its excellent long-term cycling stability.

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Graphical abstract High temperature carbon sheets with well graphite microcrystallites synthesized from wheat straw forexcellent sodium ion storage performance