High Decomposition Temperature Research Articles

Thermoformed, thermostable, waterproof and mechanically robust cellulose-based bioplastics enabled by dynamically reversible thia-Michael reaction.

Cellulose is a renewable biodegradable polymer derived from abundant natural resources. Substituting petroleum-based polymers with cellulose-based bioplastics is an effective way to alleviate environmental issues like resource depletion and white pollution. However, challenges such as poor thermostability, difficulty in thermoforming and water sensitivity seriously hinder the fabrication and use of cellulose-based bioplastics. Herein, a thermoformed, thermostable, waterproof and mechanically robust cellulose-based bioplastic (H-HEC) is fabricated by introducing thia-Michael-based reversible crosslinked structure into hydroxyethyl cellulose. This is the first instance of integrating thia-Michael-based crosslinked structure into cellulose derivatives. The resulting H-HEC can be thermoformed and remolded without adding any plasticizers. Besides, the obtained H-HEC exhibit excellent overall properties, such as a high thermal decomposition temperature of 366°C, a high water contact angle of 108°, a high transmittance of 90% and good mechanical properties. Additionally, H-HEC combines impressive transparency with effective UV-shielding properties. We envision that this work provides a novel method to prepare thermoformable cellulose-based bioplastics with good water resistance, thermostability, transparency and mechanical properties. The combined thermoformability and superior overall performances will promote the practical application of cellulose-based bioplastics and contribute to the replacement of petroleum-based polymer by cellulose-based bioplastics.

SnS-induced element diffusion Simultaneous optimization of interface and bulk defects in High-Efficiency CZTSSe solar cells

High-quality interfacial contact and absorber are significant for high-efficiency Cu2ZnSn(S,Se)4 (CZTSSe) thin film solar cells. With this in mind, the paper puts forward the idea of using a sputtering SnS interlayer at the CZTSSe/Mo interface. The high-temperature decomposition of SnS allowed for the compensation of S and Sn elements in the absorber, as well as induced the redistribution of Na and Cu elements. The diffusion of Na element to the absorber optimizes the crystal quality and improves the interface contact, and the Cu-poor absorber reduces the concentration of CuZn defects. Introducing the SnS-10 interlayer significantly reduces the charge loss, bulk and interface recombination of the device, leading to further improvements in the open-circuit voltage (VOC), short-circuit current density (JSC), and filling factor (FF). Finally, the power conversion efficiency (PCE) of CZTSSe thin film solar cells increased from 8.92 % to 10.49 %, in which the contribution rates of VOC, JSC, and FF to PCE were 27.12 %, 32.33 %, and 40.55 %, respectively. The most significant contribution of the electrical parameters to the PCE was the reverse saturation current density (J0). This finding provides an effective solution to obtain a high-quality interface and absorber, effectively restraining carrier recombination.

Synthesis and Properties of Thermostable Energetic Benzotriazines.

In an effort to balance energy and molecular stability effectively, several energetic compounds (3-6) based on benzotriazine were designed and synthesized. These structures were comprehensively characterized using NMR, IR, and elemental analysis, with compounds 3, 5, and 6 further confirmed by single-crystal X-ray diffraction. Notably, 3-amino-5,7-dinitrobenzo[e][1,2,4]triazine 1-oxide (5), which features a face-to-face crystal stacking arrangement, exhibits good detonation velocity (Dv = 8050 m/s), a high thermal decomposition temperature (Td = 290 °C), and low sensitivities (impact sensitivity >40 J, friction sensitivity >360 N). The preparation of compound 5 was further optimized by using a commercially available flow microreactor system, achieving an improved yield of 62%. Overall, the comprehensive properties of compound 5 make it a promising candidate for heat-resistant explosive applications.

Advances in surface coating and performance enhancement of ammonium perchlorate

Abstract Ammonium perchlorate (AP), which has the advantages of high oxygen content, good thermal and chemical stability, and no solid residue after thermal decomposition, is considered to be the most widely used oxidiser for solid propellant applications. However, the high mechanical sensitivity, moisture absorption, and thermal decomposition temperature of AP seriously affect the performance of the solid propellant. In this paper, we systematically review the research progress of the improvement of desensitization, anti-hygroscopicity, and thermal decomposition performance by surface coating of AP. At the same time, the surface coating methods are focusing on electrospray technology, reduced pressure distillation, ultrasonic synthesis, liquid phase deposition, supercritical fluid, intermittent spray coating, and electrostatic self-assembly coating method. Among above, intermittent spray coating and liquid phase deposition method are the preferred surface coating method due to their uniformity of coating, ease of adhesion and good performance enhancement. It is expected that the research on surface coating and performance enhancement of AP can greatly promote the innovation and development of AP in the field of high burning rate solid propellant.

Impact of adding bismuth oxide nanoparticles functionalized with graphene oxide nanosheet on the polyvinyl chloride shielding properties

This study investigates the enhancement of polyvinyl chloride (PVC) by incorporating Bi2O3-GO nanocomposites. We produced nanocomposites with varying concentrations (1, 2.5, 5, and 10 wt%). The prepared samples were characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were also used. As well as the shielding effectiveness against ultraviolet rays and gamma radiation from 137Cs and ⁶⁰Co sources at energies of 662, 1173, and 1275 keV. Results indicate that the addition of Bi2O3-GO significantly improves the thermal stability of PVC, as evidenced by higher decomposition temperatures from TGA. The absorption coefficient increases, while energy gap values decrease with increased nanofiller weight concentrations. The linear attenuation coefficient (LAC) also rises with increasing nanofiller content and decreases with higher gamma-ray energies. Results were consistent with Phy-X software simulations. The sample with 10% wt of Bi2O3-GO composite demonstrated a highly fast neutron removal cross section (FNRC) and reduced mean free path (MFP). This indicates strong potential for use as a safe, environmentally friendly alternative to lead-based shielding materials. These PVC/Bi2O3-GO nanocomposites could be effectively utilized in radiation barriers and protective screens in settings involving neutron and low-energy gamma radiation, such as in radiography and radioactive material management.

Synthesis, characterization and irritant effects of nonivamide irritant riot control agent based on ionic liquids.

Active Pharmaceutical Ingredients-Ionic liquids (API-ILs) can increase drug solubility and bioavailability of solid drugs without changing the structure of drug molecules. In the present work, nonivamide (pelargonic acid vanillylamide, PAVA) was used as the active drug and choline (Ch) and citric acid (CA) were selected as the ions to prepare PAVA-based ionic liquid ([Ch][PAVA] and [PAVA]3 [CA]), respectively. The characterization and physical properties of [Ch][PAVA] and [PAVA]3 [CA], such as FT-IR spectra, 1H NMR spectra, thermal stability and hydrophilicity, were investigated. And the irritant effects of the PAVA-based ionic liquids were measured by the animal irritation experiment. [Ch][PAVA] has higher decomposition temperatures, better hydrophilicity and comparable irritant effects. The results show that the PAVA-based ILs synthesized in this study may potentially serve as a promising novel riot control agent.

Facile Preparation of Ultrafine Porous Copper Powders for Accelerating the Thermal Decomposition of Ammonium Perchlorate.

In this study, we innovatively proposed a facile method to synthesize ultrafine porous copper (Cu) powders under mild conditions by utilizing the reduction properties of reduced iron (Fe) powders. The results showed that Cu2+ was easily reduced to Cu at 1.05-1.1 times the theoretical iron powder content for a reaction time of 10~20 min at 20~25 °C. The obtained Cu powders with an average diameter of 10.2 μm did not show significant differences in crystal structure and purity compared to the commercial Cu powders with an average diameter of 6.6 μm, but the prepared Cu powders showed a loose and porous structure, which demonstrates their higher potential in catalyzing energetic materials. The ultrafine porous Cu powder resulted in a significant decrease in the high decomposition temperature of ammonium perchlorate (AP) from 441.3 °C to 364.2 °C at only 1% of the dosage, and also slightly advanced its low decomposition temperature, which confirmed its remarkable catalytic activity in the field of energetic materials. These meaningful results will provide a new method for the preparation of Cu powders and promote the development of the chemical reduction method for the preparation of ultrafine porous Cu powders, which is expected to promote the application of ultrafine porous Cu powders in the field of energetic materials catalysis.

Dependence of Carboxylate Anions on Physicochemical Properties of Tributyloctylphosphonium-Based Ionic Liquids

Ionic liquids, i.e. organic molten salts composed of cations and anions with melting points below 100°C, have unique properties such as high ionic conductivity, high thermal stability, low vapor pressure, low flammability, and so on. Among the numerous ionic liquids, considerable ionic liquids based on carboxylate anions have been reported1). On the other hand, several published papers reported ionic liquids based on quaternary phosphonium cations, demonstrating relatively high transport properties and thermal stability2,3). Our research group has preliminarily attempted to design and synthesize several carboxylate-based ionic liquids based on quaternary phosphonium cations. This paper discusses the dependence of carboxylate anions on physicochemical properties of room-temperature ionic liquids based on tributyloctylphophonium (P4448) cation in combination with various carboxylate anions (Fig. 1).The precursor hydroxides were synthesized from the corresponding phosphonium bromides by using an anion exchange resin (Amberlite IRN78 OH). Carboxylate-based phosphonium salts were obtained by adding equimolar amounts of carboxylic acids (formic, acetic, propionic, butyric, octanoic and lactic acids) into the hydroxide solution. The products were isolated by evaporation and then were dried under high vacuum at 50°C. The physicochemical properties of carboxylate-based ionic liquids, e.g. melting point, density, viscosity, conductivity and thermal decomposition temperature, were measured under argon atmosphere.Table 1 shows the melting points, glass transition temperature, thermal decomposition temperature and physicochemical properties of the carboxylate-based phosphonium ionic liquids at 25°C. All P4448-based ionic liquids became viscous liquids at room temperature, showing considerably low-melting behavior. It is noted that the density of P4448-Lac was higher than P4448-EtCO2. This result seems likely to be attributed to hydrogen bonding of the hydroxyl group in the lactate anion. The viscosity was decreased with increasing the carbon numbers in the alkyl chains of lower carboxylate anions. Although the details of this relationship between measured viscosity and the carbon numbers of the alkyl chains in carboxylate anions still remain unclear at present, the charge distribution of the anions is thought to be one of the factors. The acetate-, propionate-, butyrate-, and octanoate-based ionic liquids showed thermal decomposition temperatures around 280°C; however, lactate-based ionic liquids exhibited relatively high thermal decomposition temperature above 310°C. This may be due to the delocalization of the charge distribution in the lactate anion, resulting in the high thermal stability.References1) M. T. Clough, et al, Phys. Chem. Chem. Phys., 15, 20480 (2013).2) K. Tsunashima, et al, Electrochem. Commun., 9, 2353 (2007).3) K. Tsunashima, et al, Electrochemistry, 75, 734 (2007). Figure 1

Designing an Ammonia Compatible SOFC System

Ammonia (NH3) as a fuel in Solid Oxide Fuel Cell (SOFC) systems for marine applications is a promising approach towards carbon-neutral power generation. Ammonia offers distinct advantages over liquefied hydrogen in terms of handling, storage, and existing distribution infrastructure.In single cell testing, ammonia has been recognized as a potential fuel for SOFC stacks, demonstrating comparable performance to other fuels such as pure hydrogen and natural gas-based reformates. The nickel containing fuel electrodes of fuel cells, facilitate the decomposition of ammonia feed into nitrogen and hydrogen. Hydrogen is then utilized as a fuel for the power generating electrochemical reaction.However, challenges arise at the stack level when using ammonia, particularly concerning the use of state-of-the-art steel grades as interconnect plate materials. The high-temperature decomposition of ammonia generates highly reactive N3- ions, leading to nitridation reactions that degrade steel structures, impacting electrode contacts, and potentially resulting in significant performance losses and mechanical cracking of cells.This study introduces three approaches aimed at advancing the design and development of an ammonia compatible SOFC system. Ex-situ material testing was conducted to assess the material tolerances of common metals used in SOFC systems. The results provide insights for material selection and component development. Secondly, to gather comprehensive data on stack durability and degradation in an ammonia-containing environment, stack-level performance testing was performed using simulated pre-cracked ammonia feeds as the fuel for a 350 W SOFC short stack.Lastly, ensuring sufficient pre-cracking of ammonia is crucial for maintaining the durability of ammonia fueled SOFCs, as high concentrations of raw ammonia can lead to shortened lifespans. Thus, performance mapping of multi-fuel processing capable nickel catalyst was done at various temperatures. This led to the determination of optimal operating conditions for the highly endothermic ammonia cracking reaction, which could be sustained by the excess heat from the SOFC system.This study combines laboratory-scale experimental results from ex-situ material testing, stack-level durability experiments, and catalyst performance mapping for the cracker unit. These findings establish design parameters for the development of an upscaled ammonia compatible SOFC system. Acknowledgment This research was financially supported by the European Union’s Horizon Europe research and innovation programme under the grant agreement No 101069828 (project FuelSOME).

Comprehensive revelation of the influence mechanism for the thermal decomposition of ammonium perchlorate by ammonium oxalate

Rate inhibitors for combustion are crucial to decrease the burning rate and prolong the working time of solid propellants. Ammonium oxalate (AO), the most frequently utilized and effective rate inhibitor in propellants, faces the challenge of an unclear influence mechanism regarding ammonium perchlorate (AP). Therefore, it is necessary to elucidate the influence mechanism of AO on the thermal decomposition of AP. This study fabricated AP/AO composites with varying AO content via wet milling, the structural, thermal decomposition processes and products of these composites were investigated. Additionally, the adsorption between AP and NH3 was simulated. The findings indicate that the inclusion of AO inhibits the low-temperature decomposition (LTD) of AP while enhancing its high-temperature decomposition (HTD). Furthermore, it was observed that the heat release of AP/AO composites was lower than that of AP. The Gibbs free energy (ΔG≠) of the AP/AO composites exceeded that of the AP at the LTD stage and was lower than that of AP at the HTD stage. Further study using molecular dynamics simulations revealed that as the increase of NH3 concentration, its adsorption on the AP surface intensifies during LTD, inhibiting the forward progress of the AP decomposition reaction. However, NH3 molecules desorbed from the AP surface and actively participated in gas-phase reactions with increasing temperature, thereby promoting the HTD of AP. This work is helpful to fully understanding the mechanism of AO in the process of the LTD and the HTD of AP but also contributes to the exploration of novel inhibitors and advances the development of low-burning rate solid propellants.

A comprehensively experimental and kinetic modeling investigation of tetrahydropyran pyrolysis and oxidation in a jet-stirred reactor

Tetrahydropyran (THP), a kind of promising green cyclic-ether fuel derived from biomass, exhibits excellent resistance to autoignition characteristics and can be used as an alternative fuel or fuel additive to improve combustion efficiency as well as reduce harmful emissions. To further reveal insights into its high-temperature decomposition and low-and intermediate temperature oxidation behaviors closely related the deflagration to detonation in spark ignition engines, the comprehensive investigation of experiments and detailed kinetic modeling of THP were performed in the present work. The experiments at two equivalence ratios, i.e. ϕ = ∞ (pyrolysis) and ϕ = 1.0, were carried out in a jet-stirred quartz reactor at 1.0 atm and 733–1148 K. More than ten substances were identified and quantified by GC and GC/MS, including small hydrocarbons, oxygenated and stable products. A detailed kinetic model of THP pyrolysis and oxidation was developed by incorporating the O2 additions of fuel radicals and updating the rate constants of key reactions, and validated and showed the slight an improvement for the speciation profiles newly reported in this work and those available in the previous literature over a wide experimental range of 450–1260 K and 1.0–10.0 atm. Rate of production analysis indicated that the H-abstractions by H attacking are the important pathways governing THP reactivity with a minor contribution from C-C and C-O dissociations of ring-opening reactions in high-temperature pyrolysis, whereas the H-abstractions triggered by OH and HO2 largely control fuel consumption in low- and intermediate temperature oxidation. The formed three tetrahydropyranyls, especially α-tetrahydropyranyl, will proceed to decompose into acyclic C5H9O radicals via C-O and C-C β-scissions or C5H9OO2-2 intermediates via O2 addition in THP pyrolysis and oxidation, as the main source of small species. For the unique aromatics detected during the pyrolysis, the combination reactions of C2 + C4 unsaturated hydrocarbons predominantly determinate their generation. This work provides new experimental data and further analyses for understanding the pyrolysis and oxidation chemistry of THP and sheds light on directions for future practical application.

A Bio-Based Polybenzoxazine Derived from Diphenolic Acid with Intrinsic Flame Retardancy, High Glass Transition Temperature and Dielectric Properties.

A bio-based benzoxazine monomer, diphenolic methyl ester hexafluoro diamino benzoxazine (DPME-HFBz), was successfully synthesized from diphenolic acid (DPA), and the chemical structure was successfully verified. The curing kinetics were studied via non-isothermal differential scanning calorimetry (DSC). The activation energies of DPME-HFBz were calculated by Kissinger and Ozawa methods to be 136.15 and 139.92 kJ/mol, respectively, and the reaction order was calculated to be first order. Owing to the large number of hydrogen bonds after polymerization, poly(DPME-HFBz) presented an ultra-high glass transition temperature of 312 °C and a high initial decomposition temperature (350 °C under air and 345 °C under nitrogen). Because of the excellent charring ability (50.2% residue under nitrogen), the LOI value of poly(DPME-HFBz) was as high as 38%. Poly(DPME-HFBz) also exhibited a very low heat release capacity (HRC) of 90 J/(g·K). In addition, poly(DPME-HFBz) had a dielectric constant (Dk) of 1.88 at 1.5 MHz, which was much lower than the Dk of the reported low-dielectric polymers. This work provides an efficient and sustainable strategy for the synthesis of benzoxazine thermosetting materials with excellent comprehensive properties.

Nano-aluminum double coated with copper and HTPB by one pot method and its catalysis on AP

ABSTRACT Organic-inorganic double-coated aluminum nanopowders (HTPB/Cu/nAl) were synthesized using a one-pot method. The morphology and structure were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). The analysis revealed that Cu particles were uniformly dispersed around the nAl core, while HTPB formed a coating on the Cu/nAl surface. The thermal oxidation kinetics and catalytic effects on ammonium perchlorate (AP) were investigated through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results indicated a 9% increase in the active aluminum content of the double-coated nanopowders compared to uncoated nAl, and a reduction in the average activation energy for thermal oxidation from 297.75 kJ·mol-1 to 218.85 kJ·mol-1. The HTPB coating enhanced the friction and impact sensitivity of the Cu/nAl particles. Adding 5% HTPB/Cu/nAl to AP advanced the low- and high-temperature decomposition peaks by 5°C and 40°C, respectively, while reducing the activation energy of AP from 85.61 kJ·mol-1 to 79.79 kJ·mol-1. This addition significantly influenced the thermal decomposition of AP, improving combustion efficiency and enhancing compatibility within composite propellant formulations.

MoS2 stabilize Ti3C2 MXene for excellent catalytic effect of thermal decomposition of ammonium perchlorate

Ammonium perchlorate (AP), the most widely used oxidizer in energetic materials, is crucial for studying catalytic thermal decomposition. Newly discovered Ti3C2 MXene and MoS2 demonstrating promising prospects in the field of the pyrolysis catalyst in AP. In this study, we employed a hydrothermal method to anchor nano-sized MoS2 in situ on the surface of Ti3C2 MXene, leading to the fabrication of MoS2-Ti3C2 nanocomposites. Various characterizations indicated that MoS2 was attached to the surface and edges of Ti3C2, thereby enhancing the stability and conductivity. Results revealed that upon the addition of 4 wt% MoS2-Ti3C2, the low-temperature decomposition peak of AP reduced from 331.2 °C to 296.6 °C, while the high-temperature decomposition peak advanced from 427.5 °C to 387.1 °C, showing a superior catalytic effect compared to the individual MoS2 or Ti3C2. Additionally, the catalytic mechanism of MoS2-Ti3C2 on the thermal decomposition of AP may involve enhanced electrical conductivity, facilitating rapid proton transfer (H+), accelerated redox reactions, prompt release of gas products, and thereby expediting the progression of the decomposition reaction. Consequently, it can be anticipated that anchoring MoS2 on the surface of Ti3C2 represents an effective strategy for enhancing the catalytic activity of Ti3C2 MXene towards the thermal decomposition of AP.

Zinc phytate@chitosan bio-powder renders explosion suppression of titanium powder involved in industrial processes

Titanium powder easily accumulates during industrial processes, and its high reactivity poses unavoidable hazards to both industrial operations and human safety. To suppress the explosion of titanium powder, zinc phytate (Zn-PA) and chitosan (CS) are mixed and prepared into a new bio-inhibitor using hydrothermal-solvothermal synthesis. The suppression effects of Zn-PA@CS bio-powder on the explosion pressure and temperature of titanium powder under different inerting ratios (α) are investigated using a 20 L spherical explosion testing system. The results show that when the α of Zn-PA@CS bio-powder is 0.8, the maximum explosion pressure (Pmax) and the maximum rate of pressure rise ((dP/dt)max) of titanium powder decrease by 82.8% and 91.2%, respectively. Moreover, the maximum flame temperature (Tp) drops from the initial 647 °C–38 °C. Combined with TG-DSC analysis, Zn-PA@CS bio-powder produces phosphorus-containing substances during high-temperature thermal decomposition, which consume a large number of free radicals essential for the explosion. Furthermore, Zn-PA@CS bio-powder generates solid and gaseous substances, leading to the formation of a dense carbonaceous residue that covers the titanium powder, acts as an effective barrier, and dilutes oxygen concentration, thereby further inhibiting the explosion reaction. The Zn-PA@CS bio-powder exhibits a synergistic effect in both physical and chemical suppression. This study provides technical support for developing biomass explosion suppression powder and for preventing and controlling explosion accidents in industrial production.

A concise strategy for enhancing the performance of bio-based polyurethane aerogels using melamine-modified sodium alginate via Aza-Michael addition reaction

Bio-based waterborne polyurethane (PU) has garnered significant attention as a sustainable alternative petroleum-derived counterpart, offering environmentally friendly alternatives. In this work, a new approach is proposed to fabricate two kinds of composite aerogels of lowly/highly melamine-modified sodium alginate (SAML/SAMH) with methacrylate-terminated PU (SAML-PU and SAMH-PU) through dynamic covalent cross-linking via Aza-Michael addition reactions. We aim to improve the poor compatibility of polysaccharide and PU associated with traditional blending methods and impart the resulting aerogels with good biodegradability, compressive strength, thermal insulation, flame-retardant, and self-healing. Comprehensive characterizations, including Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy collectively demonstrate the successful derivatization of alginate and the effective synthesis of the Aza-Michael addition copolymer involving derivate alginate and PU. Substantial improvements in compressive strength and thermal properties are realized at comparable densities. Higher compressive strength, higher decomposition temperature and lower thermal conductivity are significantly achieved for SAML-PU (0.35 MPa, 410 °C and 0.024 W/m/K at 0.13 g/cm3) and SAMH-PU (0.58 MPa, 427 °C and 0.022 W/m/K at 0.12 g/cm3) compared to pristine PU foams (0.15 MPa, 330 °C and 0.031 W/m/K at 0.15 g/cm3). Additionally, molecular simulations of the Aza-Michael addition reaction and finite element simulations of aerogel thermal-insulation properties are conducted to corroborate experimental results. Notably, the dynamic polymers of SAML-PU and SAMH-PU exhibited excellent self-healing, recycling, biodegradability, and flame-retardant attributes. The elucidated preparation methodology and the exceptional performance and versatile applications of sodium alginate-based PU aerogels suggest a promising trajectory for future research endeavors and industrial implementation.

Increase of bridge length by ingenious grafting of ester chains, imparting epoxy resins superb thermal, smoke suppression, gas-phase flame retardancy, and mechanical properties

While bifunctional synergistic flame retardants have demonstrated efficacy in enhancing the fire safety of epoxy resins (EPs), the grafting of specific functional monomers into flame retardant molecules, elucidating their mechanisms of action through comparative analysis, and concurrently achieving a delicate balance among flame retardancy, heat resistance, and mechanical toughness remains a significant challenge. Herein, this research present an innovative strategy to derive a novel sulfur-based bifunctional flame retardant, DSTA, based on the structure of the original flame retardant, DST, by grafting the ester chains to increase the bridge length of the molecular structure. As expected, the addition of flexible ester chains enabled DSTA to have a very high initial decomposition temperature and the heat-resistance index. DSTA can be used in low dosage compared to DST, enabling EP to achieve UL-94 V-0 rating. Combustion behavior showed that DSTA had the best ability to heat and smoke suppression for EP, and had faster response speed and higher fire growth index. Notably, pyrolysis volatiles tested on DSTA revealed that the ester chains can pyrolysis to release large amounts of CO2, which occurs in the early stages of pyrolysis and works together with other N-containing inert gases and P-containing radicals in the gas-phase to efficiently extinguish flames. Meanwhile, DSTA improves all mechanical properties of EP, which was attributed to the presence of ester chains. In summary, this work presents a new strategy for examining the impact of specific functional groups on the flame retardant mechanisms of EP.

Enhancing the dehydrogenation properties of LiAlH4 through the addition of ZrF4 for solid-state hydrogen storage

Hydrogen energy is emerging as an essential alternative to fossil fuels due to its clean energy profile, generating energy without greenhouse gas emissions. Solid-state hydrogen storage, particularly using complex hydrides like LiAlH4, holds promise due to high hydrogen capacities. However, practical applications of LiAlH4 face obstacles due to slow dehydrogenation kinetics and high decomposition temperatures. This study investigates the catalytic effect of ZrF4 on LiAlH4 to improve hydrogen storage properties. Incorporating 10 wt% ZrF4 has significantly lowered the onset desorption temperature from 160 °C to 80 °C. Desoption kinetic result showed that the addition of 10 wt% ZrF4 can enables the release of 5.6 wt% hydrogen in 120 min at 100 °C, which is 50 times faster than in undoped samples. X-ray diffraction analysis indicated that ZrF4 facilitated the in-situ formation of Al3Zr and LiF phases during dehydrogenation, thereby enhancing catalytic efficiency. The desorption activation energies for first two reactions decreased significantly by ∼ 16 kJ/mol and ∼24 kJ/mol with ZrF4 doping. These findings suggest that ZrF4 effectively improves the hydrogen storage properties of LiAlH4, positioning it as a potential catalyst for solid-state hydrogen storage systems.

Synthesis and evaluation of bio-based Poly(oxime-urethane) with intrinsic antimicrobial properties

Intrinsic antimicrobial properties can give polyurethanes a wider range of applications. In this work, the bio-based chain extender, 2,5-diformylfuran dioxime (DFFD) possessing antimicrobial characteristic, is used to synthesize the intrinsical antimicrobial poly(oxime-urethane) (Dx-PU) with isophorone diisocyanate (IPDI) and poly(tetramethylene glycol) (PTMG-1000), and its properties are investigated. The results show that the tensile strength is 19.12 ± 0.49 MPa, the Young’s modulus of the poly(oxime-urethane) is 118.70 ± 11.40 MPa. The elongation at break and Shore A hardness were 292 ± 11 % and 93 ± 2, respectively. Additionally, the Dx-PU demonstrated a high thermal decomposition temperature of over 250 °C and a low glass transition temperature of the soft segments at approximately −60 °C. Meanwhile, research on Dx-PU coating has demonstrated that Dx-PU coating is 100 % antimicrobial against E. coli and S. aureus, and is suitable for use on a wide range of substrates, including glass, engineering plastics, metal and leather with excellent adhesion (ISO 0), pencil hardness (2H), impact resistance (0.5 m·kg) and flexibility (2 mm). The Dx-PU coating also has significant antibacterial performance in everyday environments. The outstanding flexibility, moderate Young’s modulus, high elongation at break, good thermal resistance, and excellent antimicrobial performance of Dx-PU make it highly suitable for applications on high-contact surfaces such as hospital walls, public sanitation facilities, countertops, and door handles. As a bio-based chain extender from renewable sources, DFFD offers new solutions for the synthesis of bio-based antimicrobial polyurethane and its coatings.

Synthesis, structure, and AP catalytic performance of two new 1D coordination polymers

Two 1D chain coordination polymers (CPs), [Co(DNDPA)(DMF)2] 1 and [Mn(DNDPA)(DMF)2] 2, were successfully synthesized (4,4′-dinitrodiphenic acid, DNDPA). Their structures were confirmed by single-crystal X-ray diffraction. Differential scanning calorimetry coupled with thermogravimetric analysis revealed that both CPs exhibit commendable thermal stability, with CP 1 and 2 decomposing at 368.9 °C and 375.5 °C, respectively. Non-isothermal kinetic studies confirmed that both CPs displayed significant catalytic activity for the decomposition of ammonium perchlorate (AP). In particular, CP 1 and 2 reduced the activation energy of AP from its intrinsic value to 100.5 kJ/mol and 127.45 kJ/mol, respectively, and its high-temperature decomposition peak to 354.3 °C and 327.7 °C, respectively. These findings underscore the potential of these CPs as effective catalysts for enhancing the combustion properties of AP.