NH4H2PO4 (ADP) and Ca(H2PO4)2 (CPM) were used to reduce potassium emissions in rice straw ash (RSA), but the interactions between additives and RSA and the resulting transformations were unclear. In this work, thermogravimetric analysis identified temperature windows for interactions between the additives and RSA. 31PNMR and XRD distinguished the resulting phosphate species. Potassium emissions were reduced by 9.26 kg/t with ADP and 4.77 kg/t with CPM. Additives increased both NH₄Ac-soluble and insoluble potassium fractions. The conversion of KCl to water-soluble K-phosphate occurred between 200-450 °C, a range previously overlooked due to only minor changes in water-soluble fraction up to 700 °C. NH₄Ac-soluble potassium species included K₄Ca(PO₄)₂ and K₂CaP₂O₇, while insoluble species included K-aluminosilicate, K-silicate and Ca₉MgK(PO₄)₇. These solubility distinctions provide new insights for understanding the transformation of P-containing complexes, though further investigation into the thermodynamic and kinetic factors governing these formations is needed.
{"title":"The properties and transformation of related products for potassium fixing in the interactions between the rice straw ash and NH4H2PO4 and Ca(H2PO4)2","authors":"Weixue Xiang, Tinggui Yan, Yunqi Wu, Peixu Zhu, Nanxi Luo, Banglian Tang, Miao Luo","doi":"10.1016/j.tca.2025.180150","DOIUrl":"10.1016/j.tca.2025.180150","url":null,"abstract":"<div><div>NH<sub>4</sub>H<sub>2</sub>PO<sub>4</sub> (ADP) and Ca(H<sub>2</sub>PO<sub>4</sub>)<sub>2</sub> (CPM) were used to reduce potassium emissions in rice straw ash (RSA), but the interactions between additives and RSA and the resulting transformations were unclear. In this work, thermogravimetric analysis identified temperature windows for interactions between the additives and RSA. <sup>31</sup>PNMR and XRD distinguished the resulting phosphate species. Potassium emissions were reduced by 9.26 kg/t with ADP and 4.77 kg/t with CPM. Additives increased both NH₄Ac-soluble and insoluble potassium fractions. The conversion of KCl to water-soluble K-phosphate occurred between 200-450 °C, a range previously overlooked due to only minor changes in water-soluble fraction up to 700 °C. NH₄Ac-soluble potassium species included K₄Ca(PO₄)₂ and K₂CaP₂O₇, while insoluble species included K-aluminosilicate, K-silicate and Ca₉MgK(PO₄)₇. These solubility distinctions provide new insights for understanding the transformation of P-containing complexes, though further investigation into the thermodynamic and kinetic factors governing these formations is needed.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"753 ","pages":"Article 180150"},"PeriodicalIF":3.5,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145265638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This work aims to valorize locally available plant fibers extracted from date palm, alfa, reed, and olive tree branches and to promote them as fillers for epoxy matrix composites specifically designed for thermal insulation in building envelopes. The motivation of this study lies in the urgent global demand for sustainable and eco-friendly insulation materials that can significantly reduce energy consumption in buildings and decrease greenhouse gas emissions, thereby contributing to climate change mitigation and improved energy efficiency. An exhaustive characterization of the fibers was carried out using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and energy-dispersive X-ray spectroscopy (EDS). The fibers exhibited significant porosity, enabling air entrapment and improving thermal performance. Variations in crystallinity index were observed, with alfa fibers showing the highest value at 51.76%. Chemical characterization revealed differences in oxygen-to-carbon ratios, reflecting the unique features of each fiber type. Composites were developed with a 50:50 mass ratio of fiber to epoxy resin. Thermal conductivity, measured using the guarded hot plate method, ranged between 0.059 and 0.097 W·m⁻¹·K⁻¹, confirming the crucial role of fiber internal structure, particularly the lumen, in limiting heat transfer. The specific heat capacity (Cp), evaluated using µDSC, varied from 1.343 to 1.460 J·g⁻¹·K⁻¹, indicating good thermal inertia suitable for maintaining indoor comfort. These findings highlight the strong potential of these bio-based composites as green, efficient, and locally sourced insulation materials for sustainable buildings. This study also opens perspectives for further research on fiber treatment optimization, durability assessment, and industrial-scale production to meet future demands for eco-friendly construction materials.
{"title":"Sustainable insulation materials from local plant fibers: Characterization and thermal properties of epoxy-based composites","authors":"Abderrahim Benallel , Amine Tilioua , Najma Laaroussi","doi":"10.1016/j.tca.2025.180146","DOIUrl":"10.1016/j.tca.2025.180146","url":null,"abstract":"<div><div>This work aims to valorize locally available plant fibers extracted from date palm, alfa, reed, and olive tree branches and to promote them as fillers for epoxy matrix composites specifically designed for thermal insulation in building envelopes. The motivation of this study lies in the urgent global demand for sustainable and eco-friendly insulation materials that can significantly reduce energy consumption in buildings and decrease greenhouse gas emissions, thereby contributing to climate change mitigation and improved energy efficiency. An exhaustive characterization of the fibers was carried out using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and energy-dispersive X-ray spectroscopy (EDS). The fibers exhibited significant porosity, enabling air entrapment and improving thermal performance. Variations in crystallinity index were observed, with alfa fibers showing the highest value at 51.76%. Chemical characterization revealed differences in oxygen-to-carbon ratios, reflecting the unique features of each fiber type. Composites were developed with a 50:50 mass ratio of fiber to epoxy resin. Thermal conductivity, measured using the guarded hot plate method, ranged between 0.059 and 0.097 W·m⁻¹·K⁻¹, confirming the crucial role of fiber internal structure, particularly the lumen, in limiting heat transfer. The specific heat capacity (Cp), evaluated using µDSC, varied from 1.343 to 1.460 J·g⁻¹·K⁻¹, indicating good thermal inertia suitable for maintaining indoor comfort. These findings highlight the strong potential of these bio-based composites as green, efficient, and locally sourced insulation materials for sustainable buildings. This study also opens perspectives for further research on fiber treatment optimization, durability assessment, and industrial-scale production to meet future demands for eco-friendly construction materials.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"753 ","pages":"Article 180146"},"PeriodicalIF":3.5,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145265636","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-02DOI: 10.1016/j.tca.2025.180152
Jingjing Wang , Weiyu Hao , Qian Xing , Rongbo Li , Xia Dong , Xiang Zhang
To improve the crystallization capability and mechanical properties of polyamide elastomer (PAE), 5-sulfonyl isophthalic acid dimethyl ester potassium salt (TMC301) was introduced into PAE via melt blending with varying compositions. The crystallization behavior, rheological property, and mechanical performance of PAE and its blends were systematically investigated. It showed that TMC301 significantly enhanced the nonisothermal and isothermal crystallization ability of PAE. Crystallization kinetics analysis demonstrated a reduction in activation energy with TMC301 addition, highlighting its strong nucleating effect. Isothermal crystallization studies further indicated that the half-crystallization time of PAE decreased, and the crystallization rate increased with higher TMC301 content. The Avrami index declined from 2.9 to approximately 1, confirming TMC301′s role in promoting heterogeneous nucleation. Mechanical testing showed improved tensile strength and elongation at break with TMC301 incorporation. However, excessive TMC301 (1.0 wt%) led to particle agglomeration, causing a decline in mechanical properties. Annealing treatment enhanced tensile strength and modulus but reduced elongation at break due to structural densification. Optimal performance was achieved at 0.7 wt% TMC301, where both tensile strength and elongation increased synergistically, likely attributed to a more uniform crystalline morphology. This work provides insights into tailoring PAE-based materials through nucleating agent addition and processing optimization.
{"title":"Tailoring crystallization and mechanical property of polyamide elastomer via low-molecular-weight nucleating agent incorporation","authors":"Jingjing Wang , Weiyu Hao , Qian Xing , Rongbo Li , Xia Dong , Xiang Zhang","doi":"10.1016/j.tca.2025.180152","DOIUrl":"10.1016/j.tca.2025.180152","url":null,"abstract":"<div><div>To improve the crystallization capability and mechanical properties of polyamide elastomer (PAE), 5-sulfonyl isophthalic acid dimethyl ester potassium salt (TMC301) was introduced into PAE via melt blending with varying compositions. The crystallization behavior, rheological property, and mechanical performance of PAE and its blends were systematically investigated. It showed that TMC301 significantly enhanced the nonisothermal and isothermal crystallization ability of PAE. Crystallization kinetics analysis demonstrated a reduction in activation energy with TMC301 addition, highlighting its strong nucleating effect. Isothermal crystallization studies further indicated that the half-crystallization time of PAE decreased, and the crystallization rate increased with higher TMC301 content. The Avrami index declined from 2.9 to approximately 1, confirming TMC301′s role in promoting heterogeneous nucleation. Mechanical testing showed improved tensile strength and elongation at break with TMC301 incorporation. However, excessive TMC301 (1.0 wt%) led to particle agglomeration, causing a decline in mechanical properties. Annealing treatment enhanced tensile strength and modulus but reduced elongation at break due to structural densification. Optimal performance was achieved at 0.7 wt% TMC301, where both tensile strength and elongation increased synergistically, likely attributed to a more uniform crystalline morphology. This work provides insights into tailoring PAE-based materials through nucleating agent addition and processing optimization.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"753 ","pages":"Article 180152"},"PeriodicalIF":3.5,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145265637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-02DOI: 10.1016/j.tca.2025.180151
Run Li, Minglong Zhang, Hongwei Li, Bo Ni, Baozhong Zhu, Shuangyan Wu, Yunlan Sun
Boron (B) powder is a promising fuel for propellants due to its high gravimetric and volumetric energy densities. However, its surface oxide layer (B2O3), with a low melting point and high boiling point, tends to form a protective coating during combustion, leading to particle agglomeration and reduced combustion efficiency. To address this, the tetrafluoroethylene hexafluoropropylene vinylidene@glycidyl azide polymer@B (THV@GAP@B) composite was prepared via a recrystallization method. Various characterization methods were employed to study the effects of THV and GAP on the ignition and combustion to reduce B agglomeration and improve its combustion efficiency. The two additives exhibit distinct effects in lowering the initial oxidation temperature, enhancing reaction heat, and suppressing agglomeration. When THV and GAP contents are comparable, the modified B exhibits the highest heat release and combustion intensity, outperforming unmodified and singly modified samples. This study offers a foundation for applying fluoropolymers and energetic binders in B-based propellants.
{"title":"Double-layer coated nano-sized boron powder by THV and GAP to promote its ignition and combustion","authors":"Run Li, Minglong Zhang, Hongwei Li, Bo Ni, Baozhong Zhu, Shuangyan Wu, Yunlan Sun","doi":"10.1016/j.tca.2025.180151","DOIUrl":"10.1016/j.tca.2025.180151","url":null,"abstract":"<div><div>Boron (B) powder is a promising fuel for propellants due to its high gravimetric and volumetric energy densities. However, its surface oxide layer (B<sub>2</sub>O<sub>3</sub>), with a low melting point and high boiling point, tends to form a protective coating during combustion, leading to particle agglomeration and reduced combustion efficiency. To address this, the tetrafluoroethylene hexafluoropropylene vinylidene@glycidyl azide polymer@B (THV@GAP@B) composite was prepared via a recrystallization method. Various characterization methods were employed to study the effects of THV and GAP on the ignition and combustion to reduce B agglomeration and improve its combustion efficiency. The two additives exhibit distinct effects in lowering the initial oxidation temperature, enhancing reaction heat, and suppressing agglomeration. When THV and GAP contents are comparable, the modified B exhibits the highest heat release and combustion intensity, outperforming unmodified and singly modified samples. This study offers a foundation for applying fluoropolymers and energetic binders in B-based propellants.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"753 ","pages":"Article 180151"},"PeriodicalIF":3.5,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145265641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Oil shale is one of the most important unconventional energies, and its pyrolyzed semi-cokes also have significant comprehensive utilization value. The characteristic of combustion mechanism and products generation during Jimsar (China) oil shale and spent semi-coke combustion is investigated. The combustion nature of semi-coke is mainly the oxidation of aromatic hydrocarbons in 400-650 °C and the decomposition of CaMg(CO3)2 in 650-850 °C. The lack of oxidation region of aliphatic hydrocarbons in 300-450 °C of semi-coke combustion results the 100 °C increase of ignition temperature and 66.8 % decrease of calorific value, but much decrease of CO2 and SO2 releasing than that of raw oil shale. The other reaction characteristic of aromatic hydrocarbons and carbonates, including the kinetic model, activation energy variation and gases releasing, are almost the same for oil shale and its semi-coke. Meanwhile, kinetics of gas components deriving from oil shale and semi-coke combustion are firstly studied in this work. The generation mechanisms of gas compounds from oil shale and spent semi-coke combustion are all Chemical Reaction models.
{"title":"Compositional, structural and kinetic analysis of Jimsar (China) oil shale and semi-coke combustion","authors":"Yuran Zhang, Yuanwei Li, Wenjie Wu, Dengcheng Wu, Jingwen Ma, Lixin Zhao, Luwei Pan","doi":"10.1016/j.tca.2025.180147","DOIUrl":"10.1016/j.tca.2025.180147","url":null,"abstract":"<div><div>Oil shale is one of the most important unconventional energies, and its pyrolyzed semi-cokes also have significant comprehensive utilization value. The characteristic of combustion mechanism and products generation during Jimsar (China) oil shale and spent semi-coke combustion is investigated. The combustion nature of semi-coke is mainly the oxidation of aromatic hydrocarbons in 400-650 °C and the decomposition of CaMg(CO<sub>3</sub>)<sub>2</sub> in 650-850 °C. The lack of oxidation region of aliphatic hydrocarbons in 300-450 °C of semi-coke combustion results the 100 °C increase of ignition temperature and 66.8 % decrease of calorific value, but much decrease of CO<sub>2</sub> and SO<sub>2</sub> releasing than that of raw oil shale. The other reaction characteristic of aromatic hydrocarbons and carbonates, including the kinetic model, activation energy variation and gases releasing, are almost the same for oil shale and its semi-coke. Meanwhile, kinetics of gas components deriving from oil shale and semi-coke combustion are firstly studied in this work. The generation mechanisms of gas compounds from oil shale and spent semi-coke combustion are all Chemical Reaction models.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"753 ","pages":"Article 180147"},"PeriodicalIF":3.5,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145332600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Understanding the curing kinetics of thermosetting resins is crucial for optimizing processing, predicting performance, and guiding design. This study developed a non-isothermal kinetic analysis method using in situ FTIR to investigate the commercial benzoxazine resin (CB7100), comparing the results with those obtained from conventional DSC. Both techniques demonstrated close agreement in peak curing temperatures, confirming the reliability of FTIR. The apparent activation energies calculated using the Kissinger and Ozawa methods were comparable, with values ranging from 80 to 86 kJ·mol⁻¹ for Kissinger and approximately 90 kJ·mol⁻¹ for Ozawa. Furthermore, the Flynn–Wall–Ozawa method, along with the Friedman approach and the Málek method, was employed to further investigate the curing kinetics. Notably, FTIR offers additional insights through 2D spectral analysis, making it a valuable complement to DSC in the kinetic evaluation of benzoxazine resins.
{"title":"Establishment and validation of a non-isothermal curing kinetic calculation method for benzoxazine based on in situ FTIR spectroscopy","authors":"Chenpei Li, Weihao Qin, Shenhao Song, Sentao Lin, Hongyang Zhang, Haitao Wan, Xin Meng, Changlu Zhou","doi":"10.1016/j.tca.2025.180148","DOIUrl":"10.1016/j.tca.2025.180148","url":null,"abstract":"<div><div>Understanding the curing kinetics of thermosetting resins is crucial for optimizing processing, predicting performance, and guiding design. This study developed a non-isothermal kinetic analysis method using in situ FTIR to investigate the commercial benzoxazine resin (CB7100), comparing the results with those obtained from conventional DSC. Both techniques demonstrated close agreement in peak curing temperatures, confirming the reliability of FTIR. The apparent activation energies calculated using the Kissinger and Ozawa methods were comparable, with values ranging from 80 to 86 kJ·mol⁻¹ for Kissinger and approximately 90 kJ·mol⁻¹ for Ozawa. Furthermore, the Flynn–Wall–Ozawa method, along with the Friedman approach and the Málek method, was employed to further investigate the curing kinetics. Notably, FTIR offers additional insights through 2D spectral analysis, making it a valuable complement to DSC in the kinetic evaluation of benzoxazine resins.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"753 ","pages":"Article 180148"},"PeriodicalIF":3.5,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145220580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-30DOI: 10.1016/j.tca.2025.180149
Shunsuke Fukunaga, Mito Hotta, Nobuyoshi Koga
The thermal dehydration of sodium acetate trihydrate (SA-TH) and the hydration of its anhydride form a potential thermochemical energy storage system. A comprehensive understanding of the thermal dehydration kinetics of SA-TH is imperative for evaluating its thermal stability and optimizing the thermal dehydration conditions. However, the kinetic characterization of the solid-state thermal dehydration of SA-TH is complicated due to the efflorescence of SA-TH at ambient temperature and its melting slightly above room temperature. The purpose of this study was to provide a comprehensive description of the kinetics across a range of varying temperatures and partial pressures of water vapor (p(H2O)), exploring the physico-chemical and physico-geometrical perspectives. As the initial report, this article presents the physico-geometrical kinetic behavior of the thermal dehydration of the SA-TH samples with varying particle sizes in flowing dry N2. A low-temperature thermogravimetry (TG) system was utilized to monitor the complete process of the thermal dehydration. The TG curves, systematically recorded under various heating conditions, were subjected to the formal kinetic analysis via the isoconversional plot and master plot methods. The kinetic results of the formal kinetic analysis, as well as in situ microscopic observation, revealed the physico-geometrical feature of the consecutive surface reaction (SR) and phase boundary-controlled reaction (PBR). The overall reaction process under isothermal conditions was successfully described by the SR–PBR model. However, the substantial impact of the self-generated p(H2O) on the kinetics was predicted in the results of both the formal kinetic analysis and physico-geometrical modeling using the SR–PBR model.
{"title":"Physico-geometrical kinetics of the solid-state thermal dehydration of sodium acetate trihydrate in flowing dry N2","authors":"Shunsuke Fukunaga, Mito Hotta, Nobuyoshi Koga","doi":"10.1016/j.tca.2025.180149","DOIUrl":"10.1016/j.tca.2025.180149","url":null,"abstract":"<div><div>The thermal dehydration of sodium acetate trihydrate (SA-TH) and the hydration of its anhydride form a potential thermochemical energy storage system. A comprehensive understanding of the thermal dehydration kinetics of SA-TH is imperative for evaluating its thermal stability and optimizing the thermal dehydration conditions. However, the kinetic characterization of the solid-state thermal dehydration of SA-TH is complicated due to the efflorescence of SA-TH at ambient temperature and its melting slightly above room temperature. The purpose of this study was to provide a comprehensive description of the kinetics across a range of varying temperatures and partial pressures of water vapor (<em>p</em>(H<sub>2</sub>O)), exploring the physico-chemical and physico-geometrical perspectives. As the initial report, this article presents the physico-geometrical kinetic behavior of the thermal dehydration of the SA-TH samples with varying particle sizes in flowing dry N<sub>2</sub>. A low-temperature thermogravimetry (TG) system was utilized to monitor the complete process of the thermal dehydration. The TG curves, systematically recorded under various heating conditions, were subjected to the formal kinetic analysis via the isoconversional plot and master plot methods. The kinetic results of the formal kinetic analysis, as well as in situ microscopic observation, revealed the physico-geometrical feature of the consecutive surface reaction (SR) and phase boundary-controlled reaction (PBR). The overall reaction process under isothermal conditions was successfully described by the SR–PBR model. However, the substantial impact of the self-generated <em>p</em>(H<sub>2</sub>O) on the kinetics was predicted in the results of both the formal kinetic analysis and physico-geometrical modeling using the SR–PBR model.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"753 ","pages":"Article 180149"},"PeriodicalIF":3.5,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145265640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-29DOI: 10.1016/j.tca.2025.180145
Mirko Schoenitz, Edward L Dreizin
Viton A, when used as a binder in energetic formulations, typically decomposes on millisecond time scales. Characterization of this reaction, however, has been traditionally carried out using conventional thermal analysis (TA), on time scales of minutes to hours. Here, the decomposition of thin films of Viton A in an inert environment is studied using fast scanning calorimetry with heating rates up to 20,000 K/s. Thus, the decomposition occurs within tens of milliseconds. The measurements are complemented by visual observation of the sensor, making it possible to correlate details of the heat flow signal with processes occurring at different parts of the sensor. Conventional TA measurements are also performed. In both fast and conventional TA experiments, the heat flow signal does not return to an identifiable baseline, making interpretation of the results challenging. Nevertheless, it is observed that the volatilization is accompanied by an exothermic heat effect of 150.3 ± 16.7 J/g that slightly precedes the removal of the material, or mass loss in conventional thermal analysis. Kinetic processing shows an activation energy of 218 ± 2 kJ/mol, broadly consistent with literature data.
{"title":"Rapid thermal decomposition of Viton A","authors":"Mirko Schoenitz, Edward L Dreizin","doi":"10.1016/j.tca.2025.180145","DOIUrl":"10.1016/j.tca.2025.180145","url":null,"abstract":"<div><div>Viton A, when used as a binder in energetic formulations, typically decomposes on millisecond time scales. Characterization of this reaction, however, has been traditionally carried out using conventional thermal analysis (TA), on time scales of minutes to hours. Here, the decomposition of thin films of Viton A in an inert environment is studied using fast scanning calorimetry with heating rates up to 20,000 K/s. Thus, the decomposition occurs within tens of milliseconds. The measurements are complemented by visual observation of the sensor, making it possible to correlate details of the heat flow signal with processes occurring at different parts of the sensor. Conventional TA measurements are also performed. In both fast and conventional TA experiments, the heat flow signal does not return to an identifiable baseline, making interpretation of the results challenging. Nevertheless, it is observed that the volatilization is accompanied by an exothermic heat effect of 150.3 ± 16.7 J/g that slightly precedes the removal of the material, or mass loss in conventional thermal analysis. Kinetic processing shows an activation energy of 218 ± 2 kJ/mol, broadly consistent with literature data.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"753 ","pages":"Article 180145"},"PeriodicalIF":3.5,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145220578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-29DOI: 10.1016/j.tca.2025.180144
A.V. Lazarev , T.A. Semenov
The influence of instrumental conditions (heating rate and sample size) on the accuracy of determining the Arrhenius parameters (activation energy E and pre-exponential factor k0) using the model of non-isothermal decomposition in a first-order reaction was investigated. A criterion was obtained that provides a kinetic control regime in the experiment (equality of sample and program heating temperatures), allowing the processing of experimental data by traditional methods. Based on this criterion, a real experiment on the decomposition of hydrogen trioxide H2O3 is selected. The obtained kinetic parameters for this reaction were then utilized in a model experiment to assess the impact of the chemical and thermodynamic properties of the sample, heat transfer, and experimental instrumental conditions (sample size and programmed heating rate) on the precision of determining the kinetic parameters.
{"title":"Model of experiment in non-isothermal kinetics of thermal decomposition reaction","authors":"A.V. Lazarev , T.A. Semenov","doi":"10.1016/j.tca.2025.180144","DOIUrl":"10.1016/j.tca.2025.180144","url":null,"abstract":"<div><div>The influence of instrumental conditions (heating rate and sample size) on the accuracy of determining the Arrhenius parameters (activation energy E and pre-exponential factor k<sub>0</sub>) using the model of non-isothermal decomposition in a first-order reaction was investigated. A criterion was obtained that provides a kinetic control regime in the experiment (equality of sample and program heating temperatures), allowing the processing of experimental data by traditional methods. Based on this criterion, a real experiment on the decomposition of hydrogen trioxide H<sub>2</sub>O<sub>3</sub> is selected. The obtained kinetic parameters for this reaction were then utilized in a model experiment to assess the impact of the chemical and thermodynamic properties of the sample, heat transfer, and experimental instrumental conditions (sample size and programmed heating rate) on the precision of determining the kinetic parameters.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"753 ","pages":"Article 180144"},"PeriodicalIF":3.5,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145220579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-29DOI: 10.1016/j.tca.2025.180089
Tobias Lange , Daniel Axthammer , Daniel Jansen , Torben Gädt
The chemical reactivity of inorganic binders such as Portland cement is frequently studied using isothermal heat flow calorimetry. Most often, water and binder are mixed outside of the calorimeter, and the paste is inserted into the calorimeter after 5 to 10 min at the earliest. Consequently, the heat of early hydration reactions is usually not included in the experimental data. The only way to record the heat of hydration from the first contact of water with the binder is to use custom-built internal mixing devices. For this purpose, different mixers have been reported. However, their reliability has yet to be studied and compared systematically. This study compares three internal mixer designs regarding the early heat flow, experimental repeatability, and mixing quality at different water-to-cement ratios. Finally, we study the phase composition of the cement before and during hydration using quantitative X-ray diffraction. Combining the experimental Rietveld data with thermodynamic modeling demonstrates that the observed experimental heat after 60 min of hydration corresponds to the formation of ettringite from C3A and sulfates, while the contribution of the other cement phases is small.
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