Onset Decomposition Temperature Research Articles

Investigating Phase Changes in Cyanide-Containing Organic Compounds with High Melting Points Based on Quantitative Structure-Property Relationship Modelling

Cyanide-containing organic compounds exhibit heat-resistant properties due to their high melting points, which can exceed 250°C. These compounds find widespread applications in various industries. To predict their thermal decomposition temperatures, a straightforward model is introduced in this study. Unlike complex descriptors and computer codes, this model relies on structural parameters specific to cyanide-containing organic compounds. The investigation revealed that certain structural variables significantly influence the onset decomposition temperature. Among these, the number and type of rings play a crucial role. The model was developed and tested using a dataset of 77 experimental thermal decomposition onset temperatures for cyanide-containing organic compounds. For training and test sets comprising 62 and 15 compounds, respectively, the predicted values demonstrated good agreement with experimental data. Specifically, the coefficient of determination (R2) was 0.922 for the training set and 0.897 for the test set. The root mean square deviation (RMSD) and average absolute deviation (AAD) were 14.37 and 17.11K for the training set, and 11.10 and 13.80K for the test set. Furthermore, the proposed model outperformed a more complex existing model when applied to 13 cyanide-containing organic compounds. Additionally, this method can be utilized for designing cyanide-containing organic compounds with desired decomposition temperatures.

Non-Flammable Epoxy Composition Based on Epoxy Resin DER-331 and 4-(β-Carboxyethenyl)phenoxy-phenoxycyclotriphosphazenes with Increased Adhesion to Metals

Functional cyclophosphazenes have proven to be effective modifiers of polymer materials, significantly improving their performance properties, such as adhesive characteristics, mechanical strength, thermal stability, fire resistance, etc. In this study, 4-(β-carboxyethenyl)phenoxy-phenoxycyclotriphosphazenes (CPPP) were obtained by the condensation of 4-formylphenoxy-phenoxycyclotriphosphazene with malonic acid. Its structure was studied using 31P, 1H, and 13C NMR spectroscopy and MALDI-TOF mass spectrometry, and the thermal properties were determined by DSC and TGA methods. Molecular modeling using the MM2 method showed that CPPPs are nanosized with diameters of spheres described around the molecules in the range of 1.34–1.93 nm, which allows them to be classified as nanosized structures. The epoxy resin DER-331 was cured with CPPP, and the conversion of epoxy groups was assessed using IR spectroscopy. Using optical interferometry, it was shown that CPPPs are well compatible with epoxy resin in the temperature range from 80 to 130 °C. It was established that the cured epoxy composition was fire resistant, as it successfully passed the UL-94 vertical combustion test due to the formation of porous coke during the combustion process and also had high heat resistance and thermal stability (decomposition onset temperature about 300 °C, glass transition temperature 230 °C). The composition has low water absorption, high resistance to fresh and salt water, fire resistance, and adhesive strength to steel and aluminum (11 ± 0.2 MPa), which makes it promising for use as an adhesive composition for gluing parts in the shipbuilding and automotive industries, the aviation industry, and radio electronics.

Thermo‐mechanical properties of epoxy composites filled with inorganic particulate fillers for robust solder mask application

AbstractFiller components play a crucial role as thermo‐mechanical reinforcement to the epoxy‐based solder mask, ensuring effective insulation and passivation. This study investigates the impact of different inorganic filler types (talc, silica (SiO2), boron nitride (BN) and barium sulfate (BaSO4)) and loadings (5 and 15 wt%) on the tensile and thermal properties of the epoxy composites. The composites were blended, cast and thermally cured. Of these composites, only 15 wt% SiO2/epoxy composite exhibits notable increments in both tensile strength and modulus, surpassing unfilled epoxy by 11.65% and 31.9%, respectively. It also displays the highest elongation at break, supported by small particle size, high specific surface area and minimal void volume fraction. For thermal tests, the addition of all fillers increases the storage modulus in both glassy and rubbery regions, especially 15 wt% talc/epoxy composite with 30.09% increment at 25 °C. Additionally, all fillers raise the glass transition temperature (Tg), notably improving it by 9 °C in the 15 wt% BN/epoxy composite. Moreover, their inclusion generally enhances the onset decomposition temperature (Tonset) and reduces weight loss during decomposition. © 2024 Society of Chemical Industry.

Effect of chain extension on processability and mechanical properties of poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate)

AbstractPoly(3‐hydroxybutyrate‐4‐hydroxybutyrate) (P34HB) copolyester is a new type of biodegradable polymer material, but it cannot meet the market requirements because of its poor thermal stability. In this work, P34HB with a low degree of cross‐linking was successfully prepared by incorporating a small amount of a multiple epoxy chain extender, known as Joncryl ADR‐4380 (styrene‐methacrylic acid glycidyl ester copolymer), through reactive extrusion. The rheological properties, thermal stability, thermal behavior, and mechanical properties of the materials were investigated. Fourier transform infrared spectroscopy and gel content test showed that there was a significant chemical interaction between P34HB and ADR4380, and a cross‐linked structure was produced. Compared with pure P34HB, the samples after chain extension showed improved rheological properties, with increased viscosity and melt elasticity due to the formation of a gel network. Thermogravimetric analysis, dynamic time scanning experiment, and melt flow index (MFI) provided strong evidence for the enhanced of thermal stability of P34HB. The onset decomposition temperature of P34HB increased by 13.5°C, and its MFI decreased from 23.30 to around 5 at 170°C, and the complex viscosity remained relatively stable with time after modification. In terms of mechanical properties, the maximum elongation at break increased by 88.08% due to the improvement of toughness.

Taming cyclo-pentazolate anions with a hydrogen-bonded organic framework

Because of its high energy, aromaticity, and carbon- and hydrogen-free structure, the cyclo-pentazolate anion (c-N5-) has attracted increased attention as a potential polynitrogen structural unit for the research of next-generation high energy density materials. However, the poor thermal stability of c-N5--based compounds has become an important factor restricting their development. Here, we show that a hydrogen-bonded organic framework (HOF) self-assembles with and stabilizes c-N5-, with c-N5- situated in the pores of the resulting framework through the formation of symmetrical c-N5- hydrogen bonds as the main stabilizing factors. These factors result in an onset decomposition temperature of 153 °C for the c-N5-@HOF portion, which exceeds the thermal stabilities generally observed for c-N5--based derivatives of below 135 °C. We envisage that further c-N5--based materials with enhanced stabilities and better performance will be developed in the future.

Synthesis of Hydroxylammonium Nitrate and Its Decomposition over Metal Oxide/Honeycomb Catalysts

The objectives of this study were to prepare a high-purity hydroxylammonium nitrate (HAN) solution and evaluate the performance of various types of metal oxide/honeycomb catalysts during the catalytic decomposition of the HAN solution. Hydroxylammonium nitrate was prepared via a neutralization reaction of hydroxylamine and nitric acid. FT-IR was used to analyze the chemical composition, chemical structure, and functional groups of the HAN. The aqueous HAN solution obtained from pH 7.06 showed the highest concentration of HAN of 60% and a density of 1.39 g/mL. The concentration of HAN solution that could be obtained when the solvent was evaporated to the maximum level could not exceed 80%. In this study, catalysts were prepared using a honeycomb structure made of cordierite (5SiO2-2MgO-2Al2O3) as a support, with Mn, Co, Cu, Pt, or Ir impregnated as active metals. The pore structure of the metal oxide/honeycomb catalysts did not significantly depend on the type of metal loaded. The Cu/honeycomb catalyst showed the strongest effect of lowering the decomposition onset temperature in the decomposition of the HAN solution likely due to the intrinsic activity of the Cu metal being superior to that of the other metals. It was confirmed that the effect of the catalyst on the decomposition mechanism of the aqueous HAN solution was negligible. Through a repetitive cycle of HAN decomposition, it was confirmed that the Cu/honeycomb catalyst could be recovered and reused as a catalyst for the decomposition of an aqueous HAN solution.

Properties Optimization of Polypropylene/Montmorillonite Nanocomposite Drawn Fibers.

In this study, the mechanical properties and thermal stability of composite polypropylene (PP) drawn fibers with two different organically modified montmorillonites were experimentally investigated and optimized using a response surface methodology. Specifically, the Box-Behnken Design of Experiments method was used in order to investigate the effect of the filler content, the compatibilizer content, and the drawing temperature on the tensile strength and the onset decomposition temperature of the PP composite drawn fibers. The materials were characterized by tensile tests, thermogravimetry, and X-ray diffraction. Two types of composites were investigated with the only difference being the type of filler, namely, Cloisite® 10A or Cloisite® 15A. In both cases, statistically significant models were obtained regarding the effect of design variables on tensile strength, while poor significance was observed for the onset decomposition temperature. Nanocomposite fibers with tensile strength up to 540 MPa were obtained. Among the design variables, the drawing temperature exhibited the most notable effect on tensile strength, while the effect of both clays was not significant.

Kinetics and thermal properties of polydiethylsiloxane initiated by potassium trimethylsilanolate

AbstractThis work reports the kinetics of anionic ring‐opening polymerization of hexaethylcyclotrisiloxane (D3Et) with potassium trimethylsilanolate as initiator and diglyme and N,N‐dimethylformamide (DMF) as promoters. The polymerization rate of D3Et is influenced by the nature of promoters and the reaction temperatures. With the use of DMF as a promoter, the polymerization activation energy is 107.89 kJ/mol, and the polymerization rate constant at 110°C is 0.08466 min−1 with [P]/[I] = 3.0. Gel permeation chromatography and 29Si NMR spectra showed that the intermolecular redistribution occurred during the late stage of polymerization, which facilitated the synthesis of high‐molecular‐weight polydiethylsiloxane (PDES). Differential scanning calorimetry analysis showed that PDES exhibited a glass transition temperature of −142°C and complex crystallization phenomena. Thermogravimetric analysis illustrated that the PDES that was prepared using this method had good thermal stability with onset decomposition temperatures of 483 and 452°C under nitrogen and air conditions, respectively. This work presents innovative approaches for achieving a more energy‐efficient synthesis of PDES to meet the demands of industrial‐scale production.

Elevating the energetic capabilities of metal coordination compounds by incorporating nitrate anions.

In the realm of energetic materials research, there has been notable interest in energetic coordination compounds (ECCs) owing to their remarkable thermal stability and resistance to mechanical stimuli. This study successfully demonstrated the synthesis of an azole-based C-C bonded ECC1 under ambient conditions. A comprehensive characterization study, employing techniques such as IR, TGA-DSC, NMR and single-crystal X-ray diffraction analysis, was conducted. The bulk compound was investigated by PXRD analysis. In-depth exploration of its physicochemical and energetic performance revealed good detonation properties such as a detonation velocity (VOD) of 8553 m s-1 and a detonation pressure (DP) of 36.2 GPa, which surpass those of heat resistant explosives HNS and TATB. Due to its remarkable high melting and onset decomposition temperature (278/379 °C), it also outperforms the benchmark explosive HMX (279 °C) and the heat-resistant explosive HNS (318 °C) and shows a high impact sensitivity (IS) of 20 J and friction sensitivity (FS) of 360 N. The study also employed Hirshfeld surface and 2D fingerprint analysis to elucidate the close contact of atoms within the molecules. The combination of high detonation properties, thermal stability, and low sensitivity makes the synthesized ECC1 intriguing for further investigations and suggests its potential applications as a safe and high-energy-dense material.

Mechanical and thermal properties of a newly developed sepiolite filler-filled rPET/PA11 thermoplastic nanocomposites

The study examined the impact of sepiolite filler-filled nanocomposites in a novel recycled polyethylene terephthalate (rPET)/polyamide (PA11)/joncryl® blend. Sepiolite filler significantly improved the mechanical and thermal properties of nanocomposites. A twin-screw extruder and injection moulding machines were employed to manufacture five different formulations of nanocomposites. The tensile strength (37.6 MPa) and Young's modulus (944.25 MPa) of the blend NCS-0 improved with the addition of 2 phr of sepiolite. The tensile strength and Young's modulus of nanocomposites (NCS-2) were recorded at 41.3 MPa and 974.25 MPa, respectively. The lowest sepiolite filler content (2 phr) had the maximum tensile strength among all other ratios. The flexural strength of NCS-2 was recorded at 47.3 MPa. The tensile and flexural modulus of nanocomposites were significantly enhanced by incorporating 2 phr of sepiolite. The impact strength of NCS-2 (252.98 MPa) was much higher than NCS-8. The addition of sepiolite filler increased the glass transition temperature (Tg) by 38 %. The onset of decomposition temperature (Tonset) of the blend (NCS-0) improved by 20–22° Celsius (oC). Overall, nanocomposites with 2 phr sepiolite demonstrated the ultimate mechanical and thermal properties. These results explored new ways of using rPET/PA11 compatibilized blend in the automotive industry.

Synthesis, characterization, and thermal decomposition performance of 1,2,3-triazolyl-substituted 1,3,5-triazines with carbonyl, ester, and azide functional groups

Based on the organocatalytic reaction of enamine azide addition of 2,4,6-triazido-1,3,5-triazine to acetylacetone acetoacetic ester, we synthesized a series of previously unknown mono-, di-, and tri(1,2,3-triazolyl)-substituted-1,3,5-triazines that additionally carried carbonyl, ester, and azide groups. The structure of the obtained compounds was proved by NMR (1H, 13C) and IR spectroscopy, and the composition was confirmed by elemental analysis. With the aid of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) coupled to mass spectrometry (TG-MS), we obtained data on the thermal behavior and decomposition mechanism for these compounds. We demonstrated that di(1,2,3-triazolyl)-substituted 1,3,5-triazines have an increased thermal stability and have higher values of decomposition onset temperature (220–250 °C) in comparison with tri(1,2,3-triazolyl)-substituted 1,3,5-triazines (180 °C and 160 °C, respectively).

Insights into the thermal safety of ambient pressure dried hydrophobic montmorillonite/silica aerogel composites

To improve the thermal safety of hydrophobic silica aerogels (SAs), montmorillonite (MMT) was used as a dopant to prepare MMT/silica aerogel composites (MMT/SAs) and their basic physicochemical properties and thermal safety were investigated in detail. It finds that a physical combination is formed between MMT and SAs, and the introduction of MMT does not change the three-dimensional mesoporous structures of the MMT/SAs. With the MMT content increasing, the MMT/SAs maintain a low density (0.12–0.19 g/cm3), high porosity (91.1–93.5 %), low thermal conductivity (0.023–0.025 mW/(m∙K)) and high hydrophobicity (>140°). Compared with pure SAs, the thermal stability of the MMT/SAs was significantly improved, with the onset and peak temperatures of thermal decomposition increasing by 147° and 117°, respectively. The gross calorific value, peak heat release rate (PHRR) and total heat release (THR) decrease by 50.8 %, 29.6 % and 34.7 % respectively, while the time to ignition (TTI) increases, all of these verify the greatly reduced flammability and fire risk. This work confirms that introducing MMT into hydrophobic SAs is feasible to improve their thermal safety without impairing their excellent properties too much, thus contributing to the expansion of their thermal insulation applications.

Nucleation and property enhancement mechanism of robust and high-barrier PLA/CNFene composites with multi-level reinforcement structure

The demand for biopolymer-based green packaging has attracted growing attention because of its outstanding properties and consistency with clean environmental principle, unfortunately, its slow crystallization rate and narrow processing window are challenging. Inspired by combined functions in nanocellulose-based conductive hybrids, this work developed high-performance polylactic acid (PLA) composites using conductive cellulose nanofiber (CNFene). Interestingly, CNFene has multiple functions as highly graphitized carbon and abundant hydroxyl groups, delivering stimulating properties to PLA composites. As nucleating agents, 3 wt% CNFene has a carbon layer on the surface combined with a hydrogen bonding network synergistically enhancing the tensile and crystallization properties of PLA-C3, with a tensile strength of ∼ 53.7 MPa, crystallinity of ∼ 33.9 %, and 6.6 °C decrease in the cold crystallization temperature. Additionally, the compatibility between CNFene and PLA can form a multi-level “reinforcement” network structure, further improving thermal stability and barrier properties. The resultant PLA-C3 showed higher thermal decomposition onset temperature (T0), wider melt-processing window (197.6 °C) and extremely lower overall migration levels in ethanol (68.6 μg/kg) and isooctane (16.3 μg/kg), due to that improved interaction between CNFene and PLA positively affects crystallization ability and kinetic/mechanism of PLA to meet the requirements of industrial and green biopackaging applications.

Regulation of ester contents enabled tunable thermal and mechanical properties of poly(ester amide)

AbstractPoly(ε‐caprolactone‐co‐ε‐caprolactam) was synthesized through ring‐opening copolymerization of ε‐caprolactone (CLO) and ε‐caprolactam catalyzed by ethylmagnesium bromide (EtMgBr) or sodium ε‐caprolactam. Varied ester contents were achieved from 0 to 100 mol%. EtMgBr enabled the copolymerization with high yield of over 95%. Thermal properties vary with different ester contents. With increasing CLO content, the onset decomposition temperature (273.36 to 240.97 °C) and glass transition temperature (52.1 to −56.3 °C) gradually decreased. The results of melting behavior of resultant poly(ester amide)s through differential scanning calorimetry and theoretical calculation indicated a eutectic temperature of 46.6 °C. The mechanical properties of obtained copolymers were systematically investigated. The enhancement of CLO incorporation led to a decrease in tensile strength (70.99 to 9.88 MPa) and Young's modulus (690.03 to 19.18 MPa). Copolymer with CLO incorporation of 70 mol% exhibited a eutectic temperature of 46.6 °C, and enabled a high elongation at break (658%) and enhanced impact strength (138.5 kJ m−2). © 2023 Society of Chemical Industry.

Highly stable hybrid porous polymers containing polyhedral oligomeric silsesquioxane (POSS)/Dibenzo[g,p]chrysene and Dibenzo[b,d]thiophene units for efficient Rhodamine B dye removal

In this study, we employed the Heck reaction method to synthesize three types of hybrid porous organic/inorganic polymers (HPPs) incorporating octavinylsilsesquioxane (OVS) units. Specifically, we synthesized OVS-TBN-DBTH, OVS-TBN-THS, and OVS-TBN-THSO2 HPPs by reacting OVS with different brominated organic compounds, namely, 2,7,10,15-tetrabromodibenzo[g,p]chrysene (TBN-Br4)/2,8-dibromodibenzo[b,d]thiophene (DBTH-Br2), TBN-Br4/2,3,7,8-tetrabromothianthrene (THS-Br4), and TBN-Br4/2,3,7,8-tetrabromothianthrene-5,5,10,10-tetraoxide (THSO2-Br4). Based on thermal analysis (TGA), the onset decomposition temperatures (Td10) for these HPPs were as follows: OVS-TBN-DBTH at 575 °C, OVS-TBN-THS at 313 °C, and OVS-TBN-THSO2 at 490 °C. Additionally, these HPPs exhibited high char yields, with values of 83, 53, and 67 wt% for OVS-TBN-DBTH, OVS-TBN-THS, and OVS-TBN-THSO2 HPPs, respectively. Furthermore, when analyzed using nitrogen adsorption–desorption measurements, both OVS-TBN-DBTH and OVS-TBN-THSO2 HPPs demonstrated impressive specific surface areas (SBET) of up to 380 m2/g. In addition, the OVS-TBN-DBTH and OVS-TBN-THSO2 HPPs provide an adsorption capacity of 70.62 and 77.1 mg g−1 (qmax from Langmuir isothermal Mode) toward RhB dyestuff at room temperature. In this adsorption system, after calculation, the OVS-TBN-THS HPP could be inferred that the adsorption is a pseudo-first order adsorption model. The OVS-TBN-THS HPP and OVS-TBN-THSO2 HPP in the pseudo-secondary order model have a better representation of the adsorption system for rhodamine B. This study introduces an innovative method for developing HPPs as adsorbents for water treatment and purification.

The impact of oxygen-clustering on the transformation of electrochemically-derived graphite oxide framework

Oxygen-clustering in graphene oxide is the activated process of diffusion of oxygen functionalities: hydroxyls and epoxides, to form clusters and to trigger sp2 percolation, a key element for electrical conductivity. Impact of oxygen-clustering is thoroughly analyzed in electrochemically-derived graphite oxide (EGO), amine-functionalized frameworks (EGOF), and their pyrolyzed forms. Amine pillars within EGOF were suspected to amplify oxygen-clustering in EGOF as onset temperature of thermal decomposition was smaller in EGOF than in EGO. Thermochemical analysis proves that pillars within EGOF significantly augment oxygen-clustering aiding the reduction mechanism as inferred by the activation energy of thermal decomposition. Defective oxygen-clustering mechanism is evidenced using multiple techniques, including XRD, and is harnessed to enhance nitrogen doping. The pyrolytic morphological transformation from lamellae of EGOF into ravioli is revealed through SEM. A labyrinthic network of array prismatic dislocations provides stability to pyrolyzed EGOF ravioli whilst confining long chains of electron delocalization (localized π-orbitals), as unprecedently confirmed by HR-TEM/EELS and conductive AFM (C-AFM). Oxygen-clustering not only improves nitrogen doping in ravioli, but also improves density of array prismatic dislocations, which ultimately boosts Faradaic redox activity as observed in cyclic voltammetry (CV). Results show that Faradaic response originating from redox-active nitrogen groups predominantly relies on abundance of extended localized π-orbitals, which are geometrically and chemically confined within ravioli array prismatic dislocations. Our first-of-a-kind HR-TEM/EELS, C-AFM, and CV comparative and correlative analysis of pyrolyzed forms of EGO, EGOF, and their oxygen-clustered derivatives, confirms emergent role of confined electron delocalizations in amplifying Faradaic redox activity.

Microstructure and hydrogen storage properties of Mg1.8Y0.2Ni1−yCoy (y = 0, 0.05, 0.1, 0.15, 0.2) alloys

The Mg1.8Y0.2Ni1−yCoy (y = 0, 0.05, 0.1, 0.15, 0.2) hydrogen storage alloys were prepared following the principles of metallurgy, the phase composition and microstructure of the alloys were studied using XRD and SEM/EDS techniques, and the hydrogen absorption and desorption properties of the alloys were studied using PCT and DSC techniques. The results showed that the addition of Co did not affect the phase composition of Mg1.8Y0.2Ni1−yCoy alloys in the as-cast state and after hydrogen absorption. The Co addition could help refine the microstructure of the alloys to a certain extent. The de-/hydrogenation kinetics of Mg1.8Y0.2Ni1−yCoy (y = 0, 0.1, and 0.2) alloys were improved by adding Co, and the best results were obtained at y = 0.1. The onset decomposition temperature of Mg1.8Y0.2Ni1−yCoy (y = 0, 0.1, and 0.2) alloys were recorded to be 180 °C, 156 °C, and 210 °C, respectively, which were significantly lower than that of Mg2Ni (253 °C). The results revealed that the addition Co could improve the thermodynamic performance of the dehydrogenation process.

Exploring the High‐Temperature Window of Operation for Organic Photovoltaics: A Combined Experimental and Simulations Study

AbstractThe global climate change negatively affects the photovoltaic performance of traditional solar cell technologies. This article investigates the potential of organic photovoltaics (OPV) for high‐temperature environments, ranging from urban hot summers (30—40 °C) and desert regions (65 °C) up to (aero) space conditions (130 °C), the thermal window in which OPV can operate. The approach is based on a combination of experiments and simulations up to 180 °C, moving significantly beyond the conventional temperature ranges reported in the literature. New 2H‐benzo[d][1,2,3]triazole‐5,6‐dicarboxylic imide‐based copolymers with decomposition onset temperatures above 340 °C are used for this study, in combination with non‐fullerene acceptors. Contrary to their inorganic counterparts, OPV devices show a positive temperature coefficient up to ≈90 °C. At temperatures of 150 °C, they are still operational, retaining their room temperature efficiency. Complementary simulations are performed using an in‐house developed software package that numerically solves the drift‐diffusion equations to understand the general trends in the obtained current–voltage characteristics and the materials’ intrinsic behavior as a function of temperature. The presented methodology of combined high‐temperature experiments and simulations can be further applied to investigate the thermal window of operation for other OPV material systems, opening novel high‐temperature application routes.

Fabrication of Energetic Metal-Organic Frameworks: Potassium 5-Carboxylato-3,4-Dinitropyrazole and Potassium 5-(Hydrazinecarbonyl)-3,4-Dinitropyrazole.

Energetic materials have been widely applied in civil and military fields, whose thermostability is a key indicator to evaluate their safety levels under severe conditions. Herein, two novel energetic metal-organic frameworks (EMOFs), namely, 4 and 6, were experimentally obtained and comprehensively characterized. The two EMOFs both possess unique three-dimensional (3D) coordination structures. With a high crystal density of 2.184 g·cm-3, EMOF 4 exhibits outstandingly superior thermostability (onset: 290 °C; peak: 303 °C), while EMOF 6 features onset and peak decomposition temperatures of 220 and 230 °C. The calculated energetic parameters of 4 and 6 are as follows: detonation velocity: 8731 m·s-1 and 8294 m·s-1; detonation pressure: 26.5 and 26.4 GPa. Compared to EMOF 6, EMOF 4 features high energy, excellent thermostability, and low mechanical sensitivities, which should be partly attributed to more plentiful coordination interactions. More coordination bonds are conducive to strengthening the EMOF framework, which needs much more energy to collapse, thereby maintaining higher thermal stability. The above favorable characteristics not only indicate EMOF 4 has a promising future in applications as a thermostable explosive but also provide an effective and feasible strategy for developing novel heat-resistant energetic materials via reinforced frame structures of EMOFs.

Effects of Overload on Thermal Decomposition Kinetics of Cross-Linked Polyethylene Copper Wires.

During an overload fault in an energized wire, the hot metal core modifies the structure of the insulation material. Therefore, understanding the thermal decomposition kinetics of the insulation materials of the overloaded wire is essential for fire prevention and control. This study investigates the thermal decomposition process of new and overloaded cross-linked polyethylene (XLPE) copper wires using thermogravimetry-Fourier-transform infrared spectroscopy and cone calorimetry. The thermal decomposition onset temperature and activation energy of the overloaded XLPE insulation materials were reduced by approximately 15 K and 20 kJ mol-1, respectively, and its reaction mechanism function changed from D-ZLT3 to A2 (0 < α < 0.5). The FTIR shows that the major spectral components produced during the pyrolysis of the XLPE insulation material are C-H stretching, H2O, CO2, C-H scissor vibrations, and C=O and C=C stretching. Additionally, the four functional groups in the PE chains produced the spectral components in the following decreasing order of wavenumber: C-H stretching > CO2 > C-H scissor vibration > C=O and C=C stretching.