Synchronous Thermal Analysis Research Articles

The synthesis, structures and characterizations of (C5H12NO)4Cd3Cl10·2H2O and (C5H12NO)2BiCl6·H5O2 crystals

Two new organic-inorganic hybrid crystals (C5H12NO)4Cd3Cl10·2H2O and (C5H12NO)2BiCl6·H5O2 were synthesized by solution method, and their basic physical properties, including structures, thermal stability analysis, UV–Vis diffuse reflectance absorption spectra and photoluminescent characteristic were characterized. The two crystals both crystallize in same monoclinic crystal system, but different P21/c and C2/c space group for (C5H12NO)4Cd3Cl10·2H2O and (C5H12NO)2BiCl6·H5O2, respectively. Their infrared, Raman and mass spectrometry were measured, with related characteristic peaks were identified. The Raman peaks at 249 and 88 cm−1 are ascribed to Cd-Cl stretching vibration and Cl-Cd-Cl deformation vibration, respectively. The mass spectra analysis confirm the existence of C5H12NO+ cation, [CdCl]+ and Na-(C5H12NO)2BiCl6·H4O2. A phase transition peak that respectively located at 378 and 403 K for (C5H12NO)4Cd3Cl10·2H2O and (C5H12NO)2BiCl6·H5O2 was detected by the synchronous thermal analysis, which is related with the loss of crystalline water in their structures. In addition, the maximum absorption peak at 230 and 240 nm, with corresponding band gap of 3.35 and 3.15 eV were fitted for (C5H12NO)4Cd3Cl10·2H2O and (C5H12NO)2BiCl6·H5O2, respectively. Furthermore, (C5H12NO)4Cd3Cl10·2H2O features a bluish white emission with the peak centering at 496 nm when it was excited at 380 nm by a Xenon lamp. This work extends the catalog of organic-inorganic hybrid metal halides and presents the potential application of (C5H12NO)4Cd3Cl10·2H2O in optical field.

Thermophysical Properties' Enhancement of LiNO3-NaNO3-KNO3-NaNO2-KNO2 Mixed with SiO2/MgO Nanoparticles.

The aim of this study is to further enhance the thermal storage and heat transfer performances of a low-melting-point quinary salt. The eutectic salt was prepared using LiNO3, NaNO3, KNO3, NaNO2, and KNO2 as raw materials, followed by the doping of nano-SiO2 and nano-MgO into the base salt using a microwave-assisted method. The thermal properties of the samples were analyzed using a Synchronous Thermal Analyzer and a Laser Flash Apparatus. The co-doping of two types of nanoparticles was found to significantly enhance the specific heat capacity of the base salt. The maximum specific heat reached 2.36 J/(g·K), showing a 50.4% increase compared to the base salt. The thermal conductivity of molten salts can be affected by nanoparticles. An observed sample demonstrated a thermal diffusivity of 0.286 mm2/s, indicating a 19.2% improvement over the base salt, which may be attributed to enhanced phonon thermal efficiency. In addition, this study revealed that while interfacial thermal resistance can enhance specific heat capacity, it can also lead to a decrease in the thermal conductivity efficiency of materials. This work can offer insights and references for the enhancement of molten salt properties.

Серпентиниты зоны меланжа на севере массива Рай-Из, вмещающие ювелирный гранат (андрадит-демантоид)

The chemical composition was studied; spectroscopic (FTIR, EPR) and X-ray diffraction analyses of serpentines from the host rocks of gem garnet andradite-demantoid occurrences of their melange zone in the northern part of the Ray-Iz massif were carried out. The quantitative species composition of the serpentinites was determined by the method of synchronous thermal analysis. We found that serpentines were represented by three varieties of lizardite-1T and chrysotile-2Mcl in sample PTM-1 and chrysotile-Orcl in sample PTM-2. The complex of conducted studies allowed specifying the mineral composition of the studied serpentinite samples and greenschist (chrysotile) facies of progressive contact metamorphism.

Study on organic carbon in medium-low mature shale oil reservoirs rich in type II kerogen: Oxidation behavior, thermal effect, and kinetics

In-situ combustion technology (ISC) was a potential technology for efficient development of medium–low maturity shale oil reservoirs. Clarifying the exothermic behavior of organic carbon oxidation will be beneficial for better control of ISC processes. In this work, the organic carbon composition, type II kerogen and residual oil, were separated and extracted from the shale samples of typical medium–low maturity shale oil reservoirs in the Ordos Basin, China. The synchronous thermal analyzer and mass spectrometry (STA-MS), Fourier transform infrared spectroscopy (FTIR), and ROCK-EVAL VI were used to study the products, heat release, and functional group changes of type II kerogen, residual oil, and shale during the oxidation process. The results indicated that the oxidation heat release of shale mainly came from the oxidation reaction between its residual oil and type II kerogen, but the oxidation heat release range of shale was relatively lagging compared to the single residual oil or type II kerogen affected by rock debris. Secondly, under atmospheric pressure, the type II kerogen experiences obviously higher heat release than residual oil and heavy oil, indicating its superior potential of in-situ heat release. In addition, the major productions that CO, H2O, SO2, and CO2 were quantitatively characterized, with CO2 having the highest production of 882.25 mg/g. Furthermore, combined with the molecular weight, an oxidation reaction equation of type II kerogen was constructed. Finally, the oxidation kinetics parameters of type II kerogen, residual oil, and shale were determined using Friedman and Ozawa-Flynn-Wall (OFW) models. It was found that the activation energy of shale was higher than II kerogen and residual in low temperature oxidation (LTO) and fuel deposition (FD) stages. This may be due to the joint reaction between kerogen and residual oil, thus exacerbating the challenge of shale in-situ ignition. However, due to the catalytic effect of rock debris, the activation energy of shale was lower than LTO in high temperature oxidation (HTO) stage, indicating that once fuel deposition was completed, organic carbon will undergo stable combustion. This study has theoretical guidance for the numerical simulation research of ISC development technology of maturity-low shale oil reservoirs.

Low temperature carbonization and synergistic flame retardancy of cotton fabric coated by phosphorus‑nitrogen flame retardants

To solve the problems of flammability and smoldering of cotton fabric, its flame-retardant finishing was executed with biomass wool keratin (WK) and cyclic phosphate ester (CPE) through the soaking and baking process. The synergistic mechanism of WK low-temperature melting and CPE catalytic dehydration prompted the formation of protective carbonization layer on cotton fabric surface, and this protective layer reduced its pyrolysis rate, inhibited the production of combustible materials and improved its flame retardancy. The results of synchronous thermal analysis indicate that the initial decomposition temperature of WK and CPE is lower than that of cotton fabric, and they precede the endothermic degradation before fabric main body. This effectively promotes the low-temperature carbonization of cotton fabric and inhibits its pyrolysis. The initial decomposition temperature of WK/CPE treated fabrics advances by 47.9 °C–97.8 °C, presenting significant low-temperature carbonization trend. Moreover, they form 3.0 %–20.0 % aromatic structural char before the pyrolysis of cotton cellulose due to the low-temperature dehydration and carbonization reactions. The damage length after vertical burning is only 4.0 cm for treated fabric with five layers, its after-flame and smoldering disappear, and its limiting oxygen index value increases to 28.7 %. This research provides an effective idea for the flammability and smoldering problems of cotton fabric.

Pore Morphology and Oxidation Behaviour of Deep-Loaded Granular Coal at High Initial Temperatures

ABSTRACT As coal mining proceeds deeper, fragmented coal is subjected to high geostress and elevated thermal environments, causing changes in its micro-physical properties and spontaneous combustion (SC) risks. Deep mining operations entail significant risks of coal fires. In order to investigate the effects of high stress and high thermal environments on the microstructural and physicochemical damage of fragmented coal, and to elucidate the mechanisms influencing oxidation behavior, we conducted experiments including low-temperature nitrogen adsorption, synchronous thermal analysis, and in-situ diffuse reflectance spectroscopy. These experiments aimed to explore the pore morphology and oxidation characteristics of high initial temperature unloading granular coal (HITU-GC) unloading conditions. The results indicate that with increasing initial temperature, characteristic point temperatures initially rise and then decrease, while both the mass loss and heat release during the low-temperature oxidation stage decrease. After pressure-unloading composite treatment, the oxidation process accelerates with more intense reactions, resulting in an overall increase in heat release. The pore shapes of HITU-GC show no significant difference compared to the original coal, mainly comprising non-rigid aggregates of micropores, platy or layered matrix particles, including numerous slit-shaped pores. The coal surface also exhibits ink bottle-shaped pores and cone-shaped pores. Higher pre-oxidation temperatures correlate with higher specific surface areas. Higher stress levels from pressurized unloading correlate with lower specific surface areas. The specific surface area of sample O60-P16 is reduced by 0.879 m2/g compared to sample O60-P0. Pressurized unloading treatment disrupts mesoporous pores. Following thermal environment and pressure-unloading, the coal’s aromatic hydrocarbon content decreases, while the contents of hydroxyl, aliphatic hydrocarbons, and oxygen-containing functional groups (FG) all increase. Sample O60-P4 shows the highest content of active FG. While thermal environments enhance coal oxidation activity, pressure-unloading treatment increases the extent of coal surface fragmentation. The synergistic effect of both significantly increases the SC risk of coal. This study provides a theoretical basis for controlling thermal hazards associated with high-initial-temperature unloading fragmented coal in deep goaf areas.

Influence of Nano-Activated CaCO3-Metakaolin on Early Strength and Microstructure of Cement

The early strength, microstructure, and structure of cement mortar under low-temperature curing conditions were investigated through compressive strength tests, scanning electron microscopy, x-ray diffraction, synchronous thermal analysis (thermogravimetric analysis coupled with differential scanning calorimetry), and nuclear magnetic resonance tests. The study focused on the impact of the single addition of nano-activated CaCO3 (NAC) and the simultaneous addition of metakaolin (MK) on cement mortar. The results indicate that the addition of NAC accelerated the early hydration of cement. At a 1% dosage, the compressive strength increased by 6.84%, 14.77%, and 18.58% at 1 day, 3 days, and 7 days, respectively. When 5% MK was co-added, the compressive strength increased by 15.16%, 27.85%, and 21.66% at 1 day, 3 days, and 7 days, respectively. The combination of NAC and MK accelerated the hydration of cement, refined the products, reduced the porosity, improved the microstructure, and enhanced the early compressive strength of cement-based materials.

Energy potential of plant and animal biomass using in relation to its thermal processing

Relevance. The need for effective utilization of biomass waste generated in significant quantities. Pyrolysis, accompanied by exothermic reactions, is a promising way of biomass processing. Aim. Assessment of the possibility of covering the thermal costs of plant and animal biomass pyrolysis due to heat release during decomposition. Methods. Proximate and ultimate analysis of biomass are determined according to certified methods. Thermal analysis of the studied raw materials was carried out on a Netzsch STA 449 F5 Jupiter synchronous thermal analyzer with an integrated gas analyzer QMS 403 Aeolos; quantitative yield of pyrolysis products was determined according to GOST 3168-93, gas composition was established using the gas analyzer TEST-1 (БОНЭР, Russia). Results and conclusions. According to the results of thermal analysis, it was found that pyrolysis of plant (pine nut shells) and animal (cattle manure) biomass is accompanied by exothermic reactions associated with the organic part decomposition in the temperature range 240–700°C. The value of heat release of exothermic reactions during pine nut shell destruction is 1.39 MJ/kg, a similar value during manure decomposition is 0.31 MJ/kg. This amount of heat allows you to fully cover the thermal costs of pine nut shell pyrolytic processing, the share of covering the thermal costs of manure pyrolysis is ∼30%. An additional source of heat is pyrolysis gaseous products with energy potential equal to 3.28 and 1.58 MJ of thermal energy per 1 kg of processed pine nut shells and manure, respectively.

Preparation and Properties of Composite Double-Network Gel for Inhibiting Coal Spontaneous Combustion.

In order to improve the inhibition effect of gel on coal spontaneous combustion, a chitosan (CS)/polyacrylamide (PAM)/metal ion (Al3+) composite double-network gel was developed in this study. The optimum formula of the composite double-network gel was determined using orthogonal experimentation. The microstructure, water retention, compressibility, and anti-destruction properties of the composite double-network gel were analyzed. The inhibition effect of the composite double-network gel on coal spontaneous combustion was studied via infrared spectroscopy and a synchronous thermal analyzer from the micro and macro perspectives. The results show that the composite double-network gel has a denser interpenetrating double-network structure and a larger void ratio than the ordinary gel. The water retention rate was 55% after standing at 150 °C for 12 h. The deformation memory ratio of the composite double-network gel was 78%, which was 26.8% higher than that of the ordinary gel, and the compressive strength also increased by 59.96%. In addition, the critical temperature point and the maximum thermal weight-loss rate temperature point decreased by 7.01 °C and 39.62 °C, respectively, and the composite double-network gel effectively reduced active functional groups in the treated coal sample, such as hydroxyl and aliphatic hydrocarbons. In this study, a CS/PAM/Al3+ composite double-network gel was produced, which exhibited good gel performance and inhibition effects, with physical effects such as the covering, wetting, and cementation of coal.

Low temperature carbonization, smoke suppression and durable flame retardancy of cotton fabric spray-assisted coated by phosphorus nitrogen silicon composite system

To solve the problems of flammability, smoldering, smoking and flame retardant durability of cotton fabric, flame retardant fininshing was executed using spray assisted self-assembly method, and P/N/Si synergistic flame retardant system was constructed by polyethylene imine (PEI), phytic acid (PA) and 3-aminopropyltriethoxysilane (APTES). Cotton cellulose carbonized at low temperature prompting by PA catalytic effect, and this cooperated with PEI thermal decomposition to endow cotton fabric with flame retardancy and smoking suppression by reducing its pyrolysis rate at high temperature and lessening combustible products. Meanwhile APTES as silane coupling agent further improved its flame retardant durability and smoke suppression effect. The synchronous thermal analysis results indicate that cotton fabrics treated by PA/PEI/APTES composite system present significant low-temperature carbonization trend, and their initial decomposition temperatures advance by 46.5℃-75.9℃. Moreover, they form 4.6 %-44.9 % aromatic structure char through dehydration and carbonization reactions during the low-temperature carbonization process, improving their thermal stability at high temperature, and their after-flame and smoldering phenomena disappear. The damaged length of treated fabric with five layers reduces to 5.0 cm, its limiting oxygen index reaches 33.7 %, and it presents excellent flame retardant durability and smoke suppression effect. This low-temperature carbonization mechanism possesses importantly innovative significance for the flame retardant finishing of cotton fabric, and it not only more actively guides the selection of flame retardants to make them match with the material required, but provides a new thinking method for flame retardant material research in the future.

Magnetic solid phase adsorption of ceftiofur sodium in water by deep eutectic solvent modified banana peel‐MnFe2O4 biochar

AbstractMagnetic solid phase adsorption separation (MSPA) technology is an efficient and convenient separation method, which can simplify the separation step and shorten the separation time. It has wide application value in the purification of antibiotic pollutants in water. In this study, a novel magnetic biochar adsorbent (DES1@MnFe2O4‐BBC) with strong selectivity and high adsorption capacity was synthesized. It was composed of banana peel as the biochar source, Mn/Fe bimetallic oxide as the magnetic source and deep eutectic solvent (DES) as the functional monomer. The physicochemical properties of DES1@MnFe2O4‐BBC were systematically characterized by nitrogen adsorption–desorption, synchronous thermal analyzer, vibrating sample magnetometer, X‐ray diffractometer, X‐ray photoelectron spectroscopy, and field emission electron microscopy. The adsorption conditions were optimized by the single‐factor optimization method. Also, under the optimal adsorption conditions, the maximum adsorption capacity of DES1@MnFe2O4‐BBC for ceftiofur sodium was 75.01 mg·g−1. The test of adsorption thermodynamics and kinetics illustrated that the Langmuir isotherm adsorption model and pseudo‐second‐order kinetic equation were suitable well with the adsorption system established in this article. Adsorbent regeneration cycle experiment revealed that the DES1@MnFe2O4‐BBC was an efficient and reusable adsorbent. In the end, all research proves the novel magnetic adsorbent synthesized in this study can provide a new idea for the removal of antibiotics in water.

Preparation of amorphous coal-based activated coke via a two-step process of carbonization and steam activation

The coal-based activated coke (AC) is suitable for desulfurization and denitrification in coal-fired power plants. However, the current studies on millimeter-sized amorphous AC are limited. To evaluate the preparation parameters of millimeter-sized amorphous AC, two typical middle-low rank coal samples, Fugu coal and Datong coal, are selected as the raw materials. The effects of carbonization/activation parameter, particle size and steam flow rate on the yield and pore structure of AC are studied. Samples are analyzed by the synchronous thermal analyzer and the fully automatic rapid specific surface and porosity analyzer. The results show that carbonization and the long-time steam activation at a low temperature can make the internal pores of samples fully developed, significantly increasing the specific surface area and pore volume. The coke yield, specific surface area and mesoporous proportion of Fugu AC obtained by activation at 700 °C for 3 h are 60.95 %, 429.54 m2/g and 29.60 %, respectively. The corresponding values of Datong AC obtained at 850 °C for 3 h are 53.19 %, 892.20 m2/g and 23.01 %, separately. Both of Fugu AC and Datong AC belong to the hierarchical porous AC. The influence of particle sizes on the performance of AC at the millimeter level is within the acceptable range. Therefore, the same carbonization and activation parameters can be chosen to prepare Fugu AC and Datong AC with different particle sizes, respectively. The water vapor flow rate has a significant effect on the pore structure of AC. There is a moderate flow rate (0.03 mL min−1 at this study’s experimental conditions) for preparing the hierarchical porous amorphous AC. The study shows that it is feasible to prepare the amorphous AC with the hierarchical pore structure by employing the millimeter-sized medium–low rank coal particles. The AC could be applied for the pollutants removal in the coal-fired power plants.

Enhance thermal response behavior of energetic composite by doping fluorinated graphene

Fluorinated graphene (FGO) is a two-dimensional layered compound with thermal conductivity and hydrophobicity. Different percentage of FGO (1.00 wt.%, 3.00 wt.%, 5.00 wt.%) was added to the composite energetic system boron/potassium nitrate (B/KNO3). Through elemental analysis (EA), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), the results show that with the increase of fluorination degree, the stretching vibration peak of C-F bond was more obvious, and the contents of fluorocarbon functional groups, especially C-F2 rise. The results of synchronous thermal analysis and mass spectrometry (DSC-TG-MS) showed that the initial decomposition temperature of fluorinated graphene was around 400 ℃, the enthalpy value was about 7279 J g−1, and a large number of fluorine-containing gas products arising therefrom. The effect of fluorinated graphene on the thermal decomposition performance of energetic system was analyzed by DSC-MS. The results show that fluorinated graphene delayed initial exothermic peak temperature of B/KNO3 system, and promoted subsequent exothermic reaction. The service performances of B/KNO3 composites were compared with or without FGO. While adding fluorinated graphene, the moisture resistance and thermal conductivity of the B/KNO3 composites was improved, flame sensitivity was reduced, thermal safety was improved, gaseous products and combustion heat were increased, flame duration was prolonged, and the ignition delay period was shortened. It is implied that the present of FGO made the composite energetic materials safer under lower heat and more reliable under high heat. FGO plays a role of intelligent regulation and smart responds to different thermal stimuli.

High temperature transformations and thermal expansion of halotrichite FeAl<sub>2</sub> (SO<sub>4</sub>)<sub>4</sub>⋅22H<sub>2</sub>O

Halotrichite is a widespread mineral in post-volcanic environments and oxidation zones of ore deposits. Halotrichite is stable at temperature up to 70 °C; further heating leads to the formation of an X-ray amorphous phase I. There are reflections of millosevichite (prevailing) and mikasaite appearing in the range of temperatures 340–660 °C. Millosevichite and mikasaite are decomposing at temperatures 660 °C with the formation of an X-ray amorphous phase II. According to data of the synchronous thermal analysis, the transition from halotrichite into anhydrous sulfates is accompanied by the loss of H2O molecules, which makes about 42.9 wt %, the transition to the X-ray amorphous phase II is caused by the loss of SO3, which is ca. 37.4 wt %, associated with two endothermal effects. The thermal expansion of halotrichite is sharply anisotropic, the maximum expansion is determined by the shear deformations of the lattice in its monoclinic plane along the bisectrix of the obtuse angle β, and the minimum one – in the direction of strong S–O–Fe bonds inside [Fe(SO4)(H2O)5]0 complexes. The significant volumetric expansion of halotrichite (9(3)∙10-5 ºC-1) occurs due to the determing role of hydrogen bonds in composition of the crystal structure.

PREPARATION AND CHARACTERIZATION OF PERFLUOROETHYLSUBSTITUTED ALKYLAMMONIUM OLIGOFLUOROPHOSPHATES

Mono-, di-, triperfluoroethyl substituted fluorophosphate anions are building blocks in the molecular design of salts with onium cations, and are used to increase hydrophobicity, modify surfactant properties and electrical conductivity. The work proposes methods for the synthesis of superacid H+[PF3(C2F5)3]- by the reaction of tri(pentafluoroethyl)difluorophosphorane with a solution of hydrofluoric acid, as well as superacids H+[PF4(C2F5)2]- and H+[PF5C2F5]- by step-by-step removal of the pentafluoroethyl substituent by hydrolysis with subsequent treatment with HF solution. Ionic compounds were synthesized by metathesis of anions at 0 °C from the corresponding quaternary ammonium chloride based on the obtained superacids. The article presents NR4FAP-class ionic compounds with the tributylmethylammonium (TBMA) cation of the general formula [(C4H9)3NCH3]+[PF6-n(C2F5)n]-, where n = 1, 2, 3. The square bipyramidal structure of the three studied anions was confirmed by nuclear magnetic resonance (NMR) spectroscopy and X-ray diffraction (XRD) data. The study shows, the synthesized compounds are characterized by extremely low vapor pressure up to 300 °C, a wide range of the liquid state with a width of up to 310 K by the methods of differential scanning calorimetry (DSC) and synchronous thermal analysis (STA). Melting temperatures and enthalpies were determined. The TBMA salts belong to ionic liquids (IL's), including one type liquid at room temperature (RT-IL). The general patterns of compounds decomposition were analyzed by the analysis of evolved gases (STA-EGA); it was shown that in all cases, the decomposition of the studied ionic liquids begins with the destruction of the anion. The electrical resistance of a pure ionic liquid at room temperature was studied. The described characteristics of perfluoroethylsubstituted alkyl ammonium oligofluorophosphates open up prospects for their use as electro conducting and antistatic additives for petrochemicals, fuels and polymers. For citation: Mokrushin I.G., Pinegina O.A., Krasnovskikh M.P., Dmitriev M.V., Markin I.V., Kozen A.L. Preparation and characterization of perfluoroethylsubstituted alkylammonium oligofluorophosphates. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 5. P. 54-61. DOI: 10.6060/ivkkt.20246705.6916.

Recovered carbon black from tires as carbon carrier in metal oxide catalytic systems

Pyrolysis is one of the most common methods of end-of-life tires (ELTs) recycling. This study considered the use of carbon black from pyrolysis of ELTs as a carbon carrier for metals (Co, Ni, Cu, Fe) and their oxides to produce catalytic systems. The synchronous thermal analysis showed the positive effect of metal oxides/recovered carbon black (MOs/rCB) on ammonium perchlorate thermolysis. It was selected as a model catalytic reaction. Metal oxides/recovered carbon black (MOs/rCB) catalysts facilitated a reduction in the thermal decomposition phases of ammonium perchlorate, resulting in a significant narrowing of the decomposition interval. The greatest narrowing (22.7 °C) was observed at 103.5 °C for non-catalytic process. All tri-metallic catalytic systems showed high catalytic efficiency, providing a narrowing of the decomposition interval on average 2.5 times more in comparison with mono-metallic catalysts. Trioxide catalyst CuO/CoO/FeO/rCB showed the most significant shift in the high-temperature decomposition stage by 13% (from 334.0 °C to 293.2 °C). The activity of di-, tri-, and tetra-metallic catalytic systems was further enhanced by the synergistic effect induced by the addition of a second (or more) metal to the system. Efficient use of rCB for impregnated catalyst systems production could improve the economic efficiency of ELTs pyrolysis.

Adhesive interaction in hybrid polymer composites. Energy characteristics of phases at the air interface

Introduction: The study of the adhesive strength formation mechanisms in polymer composites involves the deliberate selection of components to facilitate their joint action in transferring stresses from the fibers to the binder through the phase interface. The strength of the adhesive interaction between components can be expressed through their energy characteristics, provided technological and other factors are ensured. Purpose of the study: The study aims to investigate the energy characteristics of hybrid polymer composite phases at the air interface. Methods: The optical method was used to capture micrographs of wetting fibers of different nature by liquids, based on which contact angles were determined. Tensile tests of fibers were conducted, and thermal analysis of fibers was performed using a synchronous thermal analyzer. The surface tension of epoxy resin and the epoxy resin / hardener system was determined using a tensiometer. Results: The method for determining surface energies of solids was upgraded. The upgraded method makes it possible to determine the free surface energy of fibers of different nature and the surface tension of the binder. The effect of oiling compositions (finishing agents) was quantitatively evaluated.

Investigated on hot mix epoxy resin used in steel bridge deck pavement affected by collaborative toughen

The hot-mix epoxy resin commonly used in the market has insufficient toughness, resulting in cracking of steel bridge deck pavement. To obtain the excellent toughness of hot mix epoxy resin, the collaborative toughen is put forward to overcome the shortcoming. In order to character epoxy resins and epoxy asphalts affected by toughening agent, standard test method of tensile properties for plastics is used. The synergistic toughening mechanism and lyotropy of 1# rubber additive and 2# rubber additive are approved by analyzing scanning electron microscope. Synchronous thermal analyzer is applied to study reactivity of epoxy resin. The viscosity, reactivity and rheological performance of epoxy asphalt, which affected by toughen agent, are investigated by Brinell rotary viscometer and Dynamic shear rheometer respectively. According to the results, the excellent epoxy resin is obtained, when the dosage of toughen agent is 15 %. The activation energy of epoxy resin before and after toughen are 48.6 KJ/mol and 42.4 KJ/mol, respectively. Besides the toughen agent can reduce the viscosity of epoxy asphalt. Finally, R1 and R2 can enhance the elastic of epoxy asphalt and reduce the glass transition temperature of epoxy asphalt. In summary, with R1 and R2 added, the toughen of epoxy resin improved obviously. The application of toughened epoxy resin to the pavement of orthotropic steel bridge deck will has a very broad prospect.

Characterizing the hydration process of cement based on synchronous thermal analysis method

Research on the characterization method of cement hydration progress - synchronous thermal analysis cement hydration progress is closely related to the strength of cement concrete materials. How to intuitively and effectively characterize cement hydration progress has been puzzling by researchers in this field. In this project, the content of various hydration products in the thermal analysis process of cement slurry and its variation law with age were obtained by simultaneous thermal analysis of the benchmark cement and the benchmark cement doped with early strength agent ZQ-1. By comparing the three DTG spectra of cement slurry mixed with early strength agent and blank benchmark cement slurry with maximum thermal weight loss on thermal decomposition, calcium hydroxide of hydration products with peak temperature between 400°C ~ 450°C can better characterize the effect of different admixtures on the hydration process of cement slurry. Early strength admixtures can better promote the early hydration of benchmark cement.

Sustainable production and evaluation of bio-based flame-retardant PU foam via liquefaction of industrial biomass residues

The utilization of low-cost renewable feedstock, such as furfural residue and crude glycerol, presents great potential for advancing the bio-based polymer industry. Firstly, this study explored the feasibility of using furfural residue liquefaction in the presence of crude glycerol to synthesize biopolyols. The optimal conditions for liquefaction were determined to be 220 ℃, 3 h, with a 7% sodium hydroxide loading and 9% biomass loading. The hydroxyl and acid numbers of prepared biopolyols were found to be comparable to those of commercial polyols, which were 460 mg KOH/g and 2.25 mg KOH/g, respectively. Subsequently, newly bio-based flame-retardant polyurethane (PU) foam was produced using obtained biopolyols, isocyanate, and flame retardants. The foam demonstrated a compressive strength of 286 kPa and a density of 0.050 g·cm−3, with its thermal conductivity measured at 0.032 W·m−1·K−1. To enhance the flame retardant and insulation properties of the PU foam, 2% of modified hollow silica (Kh-SiO2) was incorporated. PU foams produced under optimal conditions exhibited a limiting oxygen index of 27.25%, demonstrating exceptional fire-retardant characteristics. Cone calorimetry tests revealed that the PU composites had a 45.7% lower peak heat release rate and a 35.7% lower smoke release rate than neat PU foam. Additionally, the synchronous thermal analyzer (STA) revealed that the PU foam exhibited potential thermal insulation performance. This study provides a technically feasible and sustainable approach to valorize furfural residue and crude glycerol for producing biopolyols and flame-retardant insulation PU foam.