Pub Date : 2024-11-21DOI: 10.1016/j.tca.2024.179912
Yang Liu , Weixin Li , Shudong Lin , Hui Liu , Zicheng Xie , Wanyan Li , Jiwen Hu , Xuefeng Gui
The styrene-acrylonitrile bulk copolymerization reaction has a high risk of thermal runaway, but the factors influencing the thermal hazards of the reaction have not been adequately investigated. In this paper, the effects of different factors on the thermal runaway behavior of the styrene-acrylonitrile copolymerization are investigated using a combination of simulation and calorimetric testing. The simulation results indicate that increasing the proportion of styrene in the monomer feed significantly delays the onset of thermal runaway. The calorimetric results show that for di-tert-butyl peroxide (DTBP), azodiisobutyronitrile (AIBN) and tert-butyl peroxy benzoate (TBPB) initiators as examples, the TBPB-initiated copolymerization is found to have the maximum temperature-rising rate and pressure-rising rate. Under adiabatic runaway, the temperature and pressure change significantly with increasing TBPB concentration, indicating a great potential risk of thermal runaway. Calculation of kinetic parameters based on calorimetric data reveals thermal runaway mechanism.
{"title":"Study on the factors influencing the thermal runaway hazards of styrene-acrylonitrile bulk copolymerization","authors":"Yang Liu , Weixin Li , Shudong Lin , Hui Liu , Zicheng Xie , Wanyan Li , Jiwen Hu , Xuefeng Gui","doi":"10.1016/j.tca.2024.179912","DOIUrl":"10.1016/j.tca.2024.179912","url":null,"abstract":"<div><div>The styrene-acrylonitrile bulk copolymerization reaction has a high risk of thermal runaway, but the factors influencing the thermal hazards of the reaction have not been adequately investigated. In this paper, the effects of different factors on the thermal runaway behavior of the styrene-acrylonitrile copolymerization are investigated using a combination of simulation and calorimetric testing. The simulation results indicate that increasing the proportion of styrene in the monomer feed significantly delays the onset of thermal runaway. The calorimetric results show that for di-tert-butyl peroxide (DTBP), azodiisobutyronitrile (AIBN) and tert-butyl peroxy benzoate (TBPB) initiators as examples, the TBPB-initiated copolymerization is found to have the maximum temperature-rising rate and pressure-rising rate. Under adiabatic runaway, the temperature and pressure change significantly with increasing TBPB concentration, indicating a great potential risk of thermal runaway. Calculation of kinetic parameters based on calorimetric data reveals thermal runaway mechanism.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"743 ","pages":"Article 179912"},"PeriodicalIF":3.1,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720264","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 : 2024-11-20DOI: 10.1016/j.tca.2024.179911
Sergey Vyazovkin
The activation energies (E) and temperatures (T) of a variety of chemical reactions are analyzed to reveal the following correlation: E(kJ/mol)=(35±12)+(0.46±0.04)T(°C). The correlation is statistically significant having the Pearson's coefficient of linear correlation 0.873. Consequently, 76 % of the observed variation in the activations energy is caused by the actual relationship between E and T, whereas only 24 % is attributed to chance. A statistically similar correlation is revealed for crystallization of glasses. In practice, such correlations can be used to estimate the initial E values in nonlinear optimization of kinetic models or to quickly check whether the experimental activation energies disagree excessively with the expected values. An attempt is made to identify the physical origins of the correlation.
通过分析各种化学反应的活化能 (E) 和温度 (T)，可以发现以下相关性：E(kJ/mol)=(35±12)+(0.46±0.04)T(°C).该相关性具有显著的统计学意义，皮尔逊线性相关系数为 0.873。因此，在观察到的活化能变化中，有 76% 是由 E 和 T 之间的实际关系引起的，只有 24% 是偶然因素。在统计上，玻璃的结晶也有类似的相关性。在实践中，这种相关性可用于估计动力学模型非线性优化中的初始 E 值，或用于快速检查实验活化能是否与预期值相差过大。本文试图找出相关性的物理根源。
{"title":"Correlation between activation energy and reaction temperature as observed in thermal analysis kinetics","authors":"Sergey Vyazovkin","doi":"10.1016/j.tca.2024.179911","DOIUrl":"10.1016/j.tca.2024.179911","url":null,"abstract":"<div><div>The activation energies (<em>E</em>) and temperatures (<em>T</em>) of a variety of chemical reactions are analyzed to reveal the following correlation: <em>E</em>(kJ/mol)=(35±12)+(0.46±0.04)<em>T</em>(°C). The correlation is statistically significant having the Pearson's coefficient of linear correlation 0.873. Consequently, 76 % of the observed variation in the activations energy is caused by the actual relationship between <em>E</em> and <em>T</em>, whereas only 24 % is attributed to chance. A statistically similar correlation is revealed for crystallization of glasses. In practice, such correlations can be used to estimate the initial <em>E</em> values in nonlinear optimization of kinetic models or to quickly check whether the experimental activation energies disagree excessively with the expected values. An attempt is made to identify the physical origins of the correlation.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"743 ","pages":"Article 179911"},"PeriodicalIF":3.1,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720267","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 : 2024-11-19DOI: 10.1016/j.tca.2024.179900
Zhaoyang Ren , Guojing Xu , Guangwei Geng , Junjie Wang , Zhenpeng Wang , Jian-Zheng Su , Xiang-Long Meng , Penglei Chen
Phosphotungstic acid/boehmite (PWA/B) is used to catalyze oil shale (OS) pyrolysis, where either the quality of thus-catalyzed pyrolyzates could be upgraded distinctly with regard to an evident removal of heteroatom-containing species and a remarkable enrichment in the content of hydrocarbons and short-chain aliphatic hydrocarbons, or the proportion of a number of valuable basic chemicals of extensive engineering/scientific interests, e.g., pyrroles, thiophenes, α-olefines and diolefines, could be enhanced substantially. We reveal that the density/acidity of Brønsted acids of PWA/B are larger/stronger than those of Lewis acids such that their collaborate-competition actions confer it with fascinating catalytic performances. Our work likely launches new opportunities for manufacturing value-added chemical/tecton or producing high-quality petroleum-like fuel using OS as feedstock, and it provides important guidance for the design and seeking of sophisticated catalyst for OS exploitation.
{"title":"Enhanced production of thiophenes, pyrroles, and olefines via a catalyst-assisted pyrolysis of oil shale","authors":"Zhaoyang Ren , Guojing Xu , Guangwei Geng , Junjie Wang , Zhenpeng Wang , Jian-Zheng Su , Xiang-Long Meng , Penglei Chen","doi":"10.1016/j.tca.2024.179900","DOIUrl":"10.1016/j.tca.2024.179900","url":null,"abstract":"<div><div>Phosphotungstic acid/boehmite (PWA/B) is used to catalyze oil shale (OS) pyrolysis, where either the quality of thus-catalyzed pyrolyzates could be upgraded distinctly with regard to an evident removal of heteroatom-containing species and a remarkable enrichment in the content of hydrocarbons and short-chain aliphatic hydrocarbons, or the proportion of a number of valuable basic chemicals of extensive engineering/scientific interests, <em>e.g.,</em> pyrroles, thiophenes, <em>α</em>-olefines and diolefines, could be enhanced substantially. We reveal that the density/acidity of Brønsted acids of PWA/B are larger/stronger than those of Lewis acids such that their collaborate-competition actions confer it with fascinating catalytic performances. Our work likely launches new opportunities for manufacturing value-added chemical/tecton or producing high-quality petroleum-like fuel using OS as feedstock, and it provides important guidance for the design and seeking of sophisticated catalyst for OS exploitation.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"743 ","pages":"Article 179900"},"PeriodicalIF":3.1,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720263","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 : 2024-11-16DOI: 10.1016/j.tca.2024.179901
Le Wang , Huiming Sun , Quanwei Li , Bin Fei , Renming Pan , Xia Zhou
The pyrolysis and combustion of gunpowder are inseparable. To explore the risk characteristics of single base propellant, the pyrolysis kinetics and spectral information of single base propellant during combustion were studied in this work. Notably, with an increased heating rate, the exothermic peak shifts to higher temperatures, and the exothermic rate intensifies during the pyrolysis process, resulting in an incomplete reaction and the formation of residues. The reaction of single base propellant encompasses decomposition stage and multiple level reactions, it is phase boundary reaction mechanism. NO is generated firstly at 441.108 K and is identified as the most influential substance in facilitating the transition from pyrolysis to combustion. It causes intensified molecular chain breakage, CO, NH3, H2O, HCN, CxHy, NO, CO2 are generated. The combustion process results in the destruction of the flocculent structure and amorphous regions within single base propellant, leading to a relatively smooth particle surface, reduced porosity, and structural collapse. Moreover, the combustion optical spectrum of single base propellant has a distinct characteristic absorptions at 589 nm, 767 nm, and 770 nm, corresponding to Na and K, respectively. The spectrals can be effectively discerned within 15 ms. During the from pyrolysis to combustion of the single base propellant, the reaction mechanism, spectral band and intensity provide valuable indicators for anticipating potential accidental combustion hazards.
火药的热解和燃烧密不可分。为了探究单基推进剂的危险特性，本研究对单基推进剂在燃烧过程中的热解动力学和光谱信息进行了研究。值得注意的是，随着加热速率的增加，放热峰向更高温度移动，热解过程中放热速率加剧，导致反应不完全并形成残留物。单基推进剂的反应包括分解阶段和多级反应，属于相界反应机理。NO 首先在 441.108 K 时生成，被认为是促进从热解向燃烧过渡的最有影响力的物质。它加剧了分子链的断裂，生成 CO、NH3、H2O、HCN、CxHy、NO 和 CO2。燃烧过程会破坏单基推进剂内部的絮状结构和无定形区域，导致颗粒表面相对光滑、孔隙率降低和结构坍塌。此外，单基推进剂的燃烧光学光谱在 589 纳米、767 纳米和 770 纳米处有明显的吸收特征，分别对应于 Na 和 K。这些光谱可在 15 毫秒内有效分辨。在单基推进剂从热解到燃烧的过程中，反应机制、光谱带和强度为预测潜在的意外燃烧危险提供了有价值的指标。
{"title":"Exploration of the combustion characteristic based on the pyrolysis and combustion spectral analysis of single base propellant","authors":"Le Wang , Huiming Sun , Quanwei Li , Bin Fei , Renming Pan , Xia Zhou","doi":"10.1016/j.tca.2024.179901","DOIUrl":"10.1016/j.tca.2024.179901","url":null,"abstract":"<div><div>The pyrolysis and combustion of gunpowder are inseparable. To explore the risk characteristics of single base propellant, the pyrolysis kinetics and spectral information of single base propellant during combustion were studied in this work. Notably, with an increased heating rate, the exothermic peak shifts to higher temperatures, and the exothermic rate intensifies during the pyrolysis process, resulting in an incomplete reaction and the formation of residues. The reaction of single base propellant encompasses decomposition stage and multiple level reactions, it is phase boundary reaction mechanism. NO is generated firstly at 441.108 K and is identified as the most influential substance in facilitating the transition from pyrolysis to combustion. It causes intensified molecular chain breakage, CO, NH<sub>3</sub>, H<sub>2</sub>O, HCN, C<sub>x</sub>H<sub>y</sub>, NO, CO<sub>2</sub> are generated. The combustion process results in the destruction of the flocculent structure and amorphous regions within single base propellant, leading to a relatively smooth particle surface, reduced porosity, and structural collapse. Moreover, the combustion optical spectrum of single base propellant has a distinct characteristic absorptions at 589 nm, 767 nm, and 770 nm, corresponding to Na and K, respectively. The spectrals can be effectively discerned within 15 ms. During the from pyrolysis to combustion of the single base propellant, the reaction mechanism, spectral band and intensity provide valuable indicators for anticipating potential accidental combustion hazards.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"743 ","pages":"Article 179901"},"PeriodicalIF":3.1,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720266","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 : 2024-11-10DOI: 10.1016/j.tca.2024.179898
Jun Zhang , Hanbang Wang , Qinglin Zheng , Jianhui Zhi , Lianghu Su
This study introduces a thermoanalytical approach utilizing sodium persulfate (PS) to expedite the humification of food waste (FW) through advanced oxidation processes (AOPs). The method harnesses heat-induced free radicals to break down complex organic compounds into simpler forms, leading to the formation of humic substances. We conducted an analysis of changes in soluble chemical oxygen demand (SCOD), dissolved organic carbon (DOC), ammonia nitrogen, soluble proteins, and sugars, employing advanced techniques such as three-dimensional fluorescence spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and scanning electron microscopy (SEM). The findings indicate that the activation of PS at 70 °C effectively increases SCOD and DOC levels, converts proteins into soluble forms, and enhances NH4+-N content. This study, which focuses on the utilization of thermal methods, affirms that the thermal activation of persulfate (PS) significantly boosts the humification of food waste (FW), presenting a sustainable approach for waste management and resource recovery.
{"title":"Sustainable humification of food waste slurry through thermally activated persulfate oxidation","authors":"Jun Zhang , Hanbang Wang , Qinglin Zheng , Jianhui Zhi , Lianghu Su","doi":"10.1016/j.tca.2024.179898","DOIUrl":"10.1016/j.tca.2024.179898","url":null,"abstract":"<div><div>This study introduces a thermoanalytical approach utilizing sodium persulfate (PS) to expedite the humification of food waste (FW) through advanced oxidation processes (AOPs). The method harnesses heat-induced free radicals to break down complex organic compounds into simpler forms, leading to the formation of humic substances. We conducted an analysis of changes in soluble chemical oxygen demand (SCOD), dissolved organic carbon (DOC), ammonia nitrogen, soluble proteins, and sugars, employing advanced techniques such as three-dimensional fluorescence spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and scanning electron microscopy (SEM). The findings indicate that the activation of PS at 70 °C effectively increases SCOD and DOC levels, converts proteins into soluble forms, and enhances NH<sub>4</sub><sup>+</sup>-N content. This study, which focuses on the utilization of thermal methods, affirms that the thermal activation of persulfate (PS) significantly boosts the humification of food waste (FW), presenting a sustainable approach for waste management and resource recovery.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"742 ","pages":"Article 179898"},"PeriodicalIF":3.1,"publicationDate":"2024-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658910","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 : 2024-11-10DOI: 10.1016/j.tca.2024.179891
Jinzhang Jia , Yumo Wu , Dan Zhao , Fengxiao Wang , Dongming Wang , Qiang Yang , Yinghuan Xing , Shan Lu
Oxygen-containing functional groups are the main heat source of coal spontaneous combustion, but their complex reaction pathways and microscopic mechanisms are still unclear. In this study, the molecular dynamics simulation of the composite combustion reaction model system with four oxygen-containing functional groups was conducted using the Machine Learning (ML) potential force field. The results showed that the stability order of these four oxygen-containing functional groups in the combustion reaction system is as follows: ‒OH < ‒COOH < ‒C‒O < ‒C = O. These simulation findings align with those obtained from in-situ FTIR experiments, thereby validating the accuracy of the ML potential force field. Notably, ‒C‒O exhibits the highest tendency for CO2 conversion (58.57 %); ‒COOH displays the highest tendency for H2O conversion (45.00 %); and ‒OH demonstrates the highest tendency for CO conversion (59.17 %). The essence of the oxidative combustion reaction pathway involving oxygen-containing functional groups lies in the heat accumulation resulting from the oxidative dehydrogenation effect.
含氧官能团是煤炭自燃的主要热源，但其复杂的反应途径和微观机理尚不清楚。本研究利用机器学习（ML）势力场对含有四个含氧官能团的复合燃烧反应模型体系进行了分子动力学模拟。结果表明，这四个含氧官能团在燃烧反应体系中的稳定顺序如下：-这些模拟结果与现场傅立叶变换红外实验的结果一致，从而验证了 ML 势场的准确性。值得注意的是，-C-O 对 CO2 的转化率最高（58.57%）；-COOH 对 H2O 的转化率最高（45.00%）；-OH 对 CO 的转化率最高（59.17%）。含氧官能团氧化燃烧反应途径的本质在于氧化脱氢效应产生的热量积累。
{"title":"Molecular dynamics simulation of combustion reaction process and products of oxygen-containing functional groups in coal based on Machine Learning Potential","authors":"Jinzhang Jia , Yumo Wu , Dan Zhao , Fengxiao Wang , Dongming Wang , Qiang Yang , Yinghuan Xing , Shan Lu","doi":"10.1016/j.tca.2024.179891","DOIUrl":"10.1016/j.tca.2024.179891","url":null,"abstract":"<div><div>Oxygen-containing functional groups are the main heat source of coal spontaneous combustion, but their complex reaction pathways and microscopic mechanisms are still unclear. In this study, the molecular dynamics simulation of the composite combustion reaction model system with four oxygen-containing functional groups was conducted using the Machine Learning (ML) potential force field. The results showed that the stability order of these four oxygen-containing functional groups in the combustion reaction system is as follows: ‒OH < ‒COOH < ‒C‒O < ‒C = O. These simulation findings align with those obtained from in-situ FTIR experiments, thereby validating the accuracy of the ML potential force field. Notably, ‒C‒O exhibits the highest tendency for CO<sub>2</sub> conversion (58.57 %); ‒COOH displays the highest tendency for H<sub>2</sub>O conversion (45.00 %); and ‒OH demonstrates the highest tendency for CO conversion (59.17 %). The essence of the oxidative combustion reaction pathway involving oxygen-containing functional groups lies in the heat accumulation resulting from the oxidative dehydrogenation effect.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"742 ","pages":"Article 179891"},"PeriodicalIF":3.1,"publicationDate":"2024-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658918","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 : 2024-11-09DOI: 10.1016/j.tca.2024.179899
Jure Voglar , Anže Prašnikar , Konstantin Moser , Elisa Carlon , Manuel Schwabl , Blaž Likozar
Phytoremediation is the use of vegetation for the in situ treatment of contaminated environments. After plants have been used for phytoremediation of soils, their biomass can be used for example as value-added products or converted by thermochemical processes. Large-scale application of pyrolysis technology for phytoremediation biomass requires accurate predictive kinetic models and a characterization of the toxicity of the materials produced. The pyrolysis of industrial hemp (Cannabis sativa L.) was investigated on a laboratory scale by varying the process conditions and accurately modelled by considering four pseudo-components with first reaction order. The average value of the coefficients of determination is 0.9980. Biomass and biochar were characterized and the main components of the gas phase were monitored. We found Cd, Pb, and Zn in the roots, although in lower amounts than in the soil. Especially the leaves and stems showed negligible traces of these elements, so that these parts can be used directly, even if the hemp was grown on the polluted soil. After pyrolysis, the concentration of pollutants in the solid fraction decreased, which could be attributed to the reduction of metal oxides (or salts) to elemental form and subsequent evaporation. This pyrolysis process has the potential to treat heavy metal-rich biomass, with gas phase purification via condensation, yielding agricultural-grade biochar, CO-rich gas and a highly concentrated heavy metal stream in absorbent material.
{"title":"Pyrolysis of industrial hemp biomass from contaminated soil phytoremediation: Kinetics, modelling transport phenomena and biochar-based metal reduction","authors":"Jure Voglar , Anže Prašnikar , Konstantin Moser , Elisa Carlon , Manuel Schwabl , Blaž Likozar","doi":"10.1016/j.tca.2024.179899","DOIUrl":"10.1016/j.tca.2024.179899","url":null,"abstract":"<div><div>Phytoremediation is the use of vegetation for the <em>in situ</em> treatment of contaminated environments. After plants have been used for phytoremediation of soils, their biomass can be used for example as value-added products or converted by thermochemical processes. Large-scale application of pyrolysis technology for phytoremediation biomass requires accurate predictive kinetic models and a characterization of the toxicity of the materials produced. The pyrolysis of industrial hemp (<em>Cannabis sativa</em> L.) was investigated on a laboratory scale by varying the process conditions and accurately modelled by considering four pseudo-components with first reaction order. The average value of the coefficients of determination is 0.9980. Biomass and biochar were characterized and the main components of the gas phase were monitored. We found Cd, Pb, and Zn in the roots, although in lower amounts than in the soil. Especially the leaves and stems showed negligible traces of these elements, so that these parts can be used directly, even if the hemp was grown on the polluted soil. After pyrolysis, the concentration of pollutants in the solid fraction decreased, which could be attributed to the reduction of metal oxides (or salts) to elemental form and subsequent evaporation. This pyrolysis process has the potential to treat heavy metal-rich biomass, with gas phase purification via condensation, yielding agricultural-grade biochar, CO-rich gas and a highly concentrated heavy metal stream in absorbent material.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"742 ","pages":"Article 179899"},"PeriodicalIF":3.1,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-08DOI: 10.1016/j.tca.2024.179896
Jiaming Liu , Xinwen Ma , Wenhao Wang , Weiduo Fei , Xiandie Zhang , Xiang Ke , Xiang Zhou
In this study, Cu(OH)F nanoparticles are prepared through a simple hydrothermal reaction and their effects on the thermal oxidation and ignition characteristics of micron-sized Al powder (μ-Al) are explored for the first time. Thermal analysis in air atmosphere (50∼1050 °C) shows that compared to raw μ-Al, the normalized weight gain of Al in Al-Cu(OH)F increases by about 36.9%, 64.8%, and 106.3% when the added Cu(OH)F is 1 wt%, 3 wt%, and 5 wt%, respectively. After mixed with NH4ClO4, electric ignition and open-air combustion tests show shortened ignition delay time (by 42.6%∼63.8%) and increased maximum light intensity (by 48.9%∼117.8%) for Al-Cu(OH)F. The effects of Cu(OH)F result from its decomposition products, namely, HF and CuO. HF reacts with alumina shell to form AlF3, which sublimes at high temperature and thus exposes Al core instantly, while CuO can react with Al core to release heat, further facilitating the thermal oxidation and ignition processes.
{"title":"Effects of Cu(OH)F nanoparticles on the thermal oxidation and ignition characteristics of micron-sized Al powder","authors":"Jiaming Liu , Xinwen Ma , Wenhao Wang , Weiduo Fei , Xiandie Zhang , Xiang Ke , Xiang Zhou","doi":"10.1016/j.tca.2024.179896","DOIUrl":"10.1016/j.tca.2024.179896","url":null,"abstract":"<div><div>In this study, Cu(OH)F nanoparticles are prepared through a simple hydrothermal reaction and their effects on the thermal oxidation and ignition characteristics of micron-sized Al powder (μ-Al) are explored for the first time. Thermal analysis in air atmosphere (50∼1050 °C) shows that compared to raw μ-Al, the normalized weight gain of Al in Al-Cu(OH)F increases by about 36.9%, 64.8%, and 106.3% when the added Cu(OH)F is 1 wt%, 3 wt%, and 5 wt%, respectively. After mixed with NH<sub>4</sub>ClO<sub>4</sub>, electric ignition and open-air combustion tests show shortened ignition delay time (by 42.6%∼63.8%) and increased maximum light intensity (by 48.9%∼117.8%) for Al-Cu(OH)F. The effects of Cu(OH)F result from its decomposition products, namely, HF and CuO. HF reacts with alumina shell to form AlF<sub>3</sub>, which sublimes at high temperature and thus exposes Al core instantly, while CuO can react with Al core to release heat, further facilitating the thermal oxidation and ignition processes.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"742 ","pages":"Article 179896"},"PeriodicalIF":3.1,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658908","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}
In this study, the non-isothermal kinetics and phase transformations within the Fe-Co-V-Mo alloy were investigated. Four distinct transformations were identified: disorder → order (T1), first-stage polymorphic (T2), order → disorder (T3), and second-stage polymorphic (T4). The activation energy (E) for each transformation was determined using isoconversional methods. Fitting model were employed to calculate the kinetic triplets, confirming that all transformations follow the Avrami model. The Johnson-Mehl-Avrami (JMA) and Šesták-Berggren (SB) models were used to determine other kinetic parameters (n, M, and N). The findings suggest that the growth mechanisms for transformations T3 and T4 are interface-controlled, whereas transformation T2 is diffusion-controlled. Consequently, the A3/2 and A3 mechanisms were identified as predominant mechanisms for transformations T2 and T4, respectively. Additionally, transformation T3 follows the A3 mechanism at heating rates of 10 and 20 K/min, and the A2 mechanism at 30 K/min. Kinetic analysis revealed that the addition of Mo in Fe-Co-V alloys, acting as a ferrite (α) stabilizer, decreases the onset temperatures of transformations T1 and T3. Conversely, it increases those of transformations T2 and T4. Furthermore, Mo influences the reduction of E associated with transformation T3.
本研究调查了铁-铜-钒-钼合金的非等温动力学和相变。确定了四种不同的转变：无序→有序（T1）、第一阶段多态（T2）、有序→无序（T3）和第二阶段多态（T4）。每种转化的活化能（E）都是用等转化法测定的。采用拟合模型计算动力学三元组，证实所有转化都遵循阿夫拉米模型。约翰逊-梅尔-阿夫拉米（JMA）和Šesták-Berggren（SB）模型用于确定其他动力学参数（n、M 和 N）。研究结果表明，转化 T3 和 T4 的生长机制由界面控制，而转化 T2 则由扩散控制。因此，A3/2 和 A3 机制分别被确定为转化 T2 和 T4 的主要机制。此外，在加热速率为 10 和 20 K/min 时，转化 T3 遵循 A3 机制，而在 30 K/min 时则遵循 A2 机制。动力学分析表明，在铁-铜-钒合金中添加钼作为铁素体（α）稳定剂，会降低转化 T1 和 T3 的起始温度。反之，则会提高 T2 和 T4 转变的起始温度。此外，钼还会影响与转变 T3 相关的 E 值的降低。
{"title":"Non-isothermal kinetic analysis of phase transformations in Fe-Co-V-Mo semi-hard magnetic alloy","authors":"Maryam Kamali-Ardakani , Alireza Mashreghi , Saeed Hasani , Saeed Sadeghpour","doi":"10.1016/j.tca.2024.179897","DOIUrl":"10.1016/j.tca.2024.179897","url":null,"abstract":"<div><div>In this study, the non-isothermal kinetics and phase transformations within the Fe-Co-V-Mo alloy were investigated. Four distinct transformations were identified: disorder → order (T<sub>1</sub>), first-stage polymorphic (T<sub>2</sub>), order → disorder (T<sub>3</sub>), and second-stage polymorphic (T<sub>4</sub>). The activation energy (<em>E</em>) for each transformation was determined using isoconversional methods. Fitting model were employed to calculate the kinetic triplets, confirming that all transformations follow the Avrami model. The Johnson-Mehl-Avrami (JMA) and Šesták-Berggren (SB) models were used to determine other kinetic parameters (<em>n, M</em>, and <em>N</em>). The findings suggest that the growth mechanisms for transformations T<sub>3</sub> and T<sub>4</sub> are interface-controlled, whereas transformation T<sub>2</sub> is diffusion-controlled. Consequently, the A3/2 and A3 mechanisms were identified as predominant mechanisms for transformations T<sub>2</sub> and T<sub>4</sub>, respectively. Additionally, transformation T<sub>3</sub> follows the A3 mechanism at heating rates of 10 and 20 K/min, and the A2 mechanism at 30 K/min. Kinetic analysis revealed that the addition of Mo in Fe-Co-V alloys, acting as a ferrite (<em>α</em>) stabilizer, decreases the onset temperatures of transformations T<sub>1</sub> and T<sub>3</sub>. Conversely, it increases those of transformations T<sub>2</sub> and T<sub>4</sub>. Furthermore, Mo influences the reduction of <em>E</em> associated with transformation T<sub>3</sub>.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"742 ","pages":"Article 179897"},"PeriodicalIF":3.1,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658909","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 : 2024-11-02DOI: 10.1016/j.tca.2024.179893
Josep Maria Morera , Esther Bartolí , Bernat Esteban
The main objective of this research is to validate the application of a recently developed isometric method for determining the resistance to denaturation of leather tanned with different vegetable extracts. The results obtained for shrinkage temperature and denaturation temperature are similar to those obtained by methods based on ISO 3380 (traditional) and Differential Scanning Calorimetry (DSC). The isometric method also allows evaluating the evolution of hydrothermal breakdown of the different types of collagen (leather) – tannin (vegetable tanning extract) bonds as a function of the thermal increase to which the leather is subjected. It is concluded that, with the isometric method, and for leathers tanned with vegetable extracts, much more comprehensive information is obtained about the denaturation process of vegetable-tanned leather than with the traditional method, without requiring significant investments as in the case of the DSC method.
这项研究的主要目的是验证最近开发的等距法在测定用不同植物提取物鞣制的皮革的抗变性能力方面的应用。所获得的收缩温度和变性温度结果与基于 ISO 3380（传统）和差示扫描量热法（DSC）的方法所获得的结果相似。等压法还可以评估不同类型的胶原蛋白（皮革）-单宁（植物鞣制提取物）键的水热分解演变情况，并将其作为皮革所受热量增加的函数。结论是，对于使用植物提取物鞣制的皮革，使用等压法可以获得比传统方法更全面的有关植物鞣革变性过程的信息，而无需像使用 DSC 方法那样进行大量投资。
{"title":"Study of the hydrothermal stability of leather tanned with vegetable extracts using an isometric method","authors":"Josep Maria Morera , Esther Bartolí , Bernat Esteban","doi":"10.1016/j.tca.2024.179893","DOIUrl":"10.1016/j.tca.2024.179893","url":null,"abstract":"<div><div>The main objective of this research is to validate the application of a recently developed isometric method for determining the resistance to denaturation of leather tanned with different vegetable extracts. The results obtained for shrinkage temperature and denaturation temperature are similar to those obtained by methods based on ISO 3380 (traditional) and Differential Scanning Calorimetry (DSC). The isometric method also allows evaluating the evolution of hydrothermal breakdown of the different types of collagen (leather) – tannin (vegetable tanning extract) bonds as a function of the thermal increase to which the leather is subjected. It is concluded that, with the isometric method, and for leathers tanned with vegetable extracts, much more comprehensive information is obtained about the denaturation process of vegetable-tanned leather than with the traditional method, without requiring significant investments as in the case of the DSC method.</div></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":"742 ","pages":"Article 179893"},"PeriodicalIF":3.1,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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