Thermochimica Acta最新文献

{"title":"Multistep kinetics of the thermal dehydration/decomposition of metakaolin-based geopolymer paste","authors":"Manami Shindo ,&nbsp;Aya Ueoku ,&nbsp;Wakana Okamura ,&nbsp;Shin Kikuchi ,&nbsp;Atsushi Yamazaki ,&nbsp;Nobuyoshi Koga","doi":"10.1016/j.tca.2024.179801","DOIUrl":"https://doi.org/10.1016/j.tca.2024.179801","url":null,"abstract":"<div><p>This study investigated the kinetics of the multistep thermal dehydration/decomposition of the metakaolin-based geopolymer paste. The component two reaction steps were characterized by the evolution of water vapor and the simultaneous evolution of water vapor and CO₂, respectively. In a stream of dry N₂, the kinetics of the first and second reaction steps were characterized by the apparent activation energy (<em>E</em>_a) values of 92 and 166 kJ mol⁻¹, respectively. Both reaction steps exhibited a diffusion-controlled rate behavior. In a stream of wet N₂, the mass loss curves systematically shifted to higher temperatures with an increase in the water vapor pressure (<em>p</em>(H₂O)). The first reaction step was significantly influenced by <em>p</em>(H₂O), and the apparent <em>E</em>_a increased to 175 kJ mol⁻¹ at <em>p</em>(H₂O) = 11.4 kPa. The second reaction step was less sensitive to the atmospheric water vapor, as characterized by its <em>E</em>_a of ∼165 kJ mol⁻¹, irrespective of the <em>p</em>(H₂O).</p></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141323463","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}

{"title":"Thermogravimetric Analysis of a New Series of Trimellitimide-Based Epoxy-Imide Resins","authors":"Ehsan Abbasi,&nbsp;Ali Jannesari","doi":"10.1016/j.tca.2024.179793","DOIUrl":"10.1016/j.tca.2024.179793","url":null,"abstract":"<div><p>The dynamic thermogravimetric analysis of a new series of aliphatic, cycloaliphatic, and aromatic trimellitimide-based epoxy-imide (EI) resins, compared to diglycidyl ether of bisphenol-A (DGEBA) and triglycidyl isocyanurate (TGIC) resins, in uncured and cured states, revealed that the EI resins/ systems, unlike DGEBA ones, have a multistep thermal degradation process with two chief steps corresponding to the degradation of the DGEBA and the imide moieties. Evaluating the influences of isothermal curing temperature (<em>T_Cure</em>) on their degradation behavior ascertained that, generally, the 1^st stage of the thermal degradation processes is more affected by <em>T_Cure</em>. Furthermore, the competition between epoxide-amine reactions with etherification/ homopolymerization plays the most crucial role in the impact of <em>T_Cure</em> on the systems' stability and decomposition behavior. Therefore, the most considerable changes can be observed in the thermograms of the cycloaliphatic system due to the highest difference between the melting temperature of its resin and <em>T_Cure</em>.</p></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141389679","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}

{"title":"Evaluation of model-based pre-exponential factor from differential isoconversional methods","authors":"Alireza Aghili ,&nbsp;Amir Hossein Shabani","doi":"10.1016/j.tca.2024.179784","DOIUrl":"https://doi.org/10.1016/j.tca.2024.179784","url":null,"abstract":"<div><p>This study introduces a model-based technique to evaluate the effective pre-exponential factor, conversion function and rate constant of reactions using differential isoconversional methods. In complex reactions, the effective pre-exponential factor depends on conversion and temperature and can be calculated using the modified Friedman method and compensation effect relationship. The innovative approach facilitates the computation of how pre-exponential factor varies with temperature across diverse heating rates, providing a valuable improvement in isoconversional analysis. The calculations revealed that the effective rate constant might be solely influenced by temperature, irrespective of the degree of conversion. The approach suggested in this research can also be applied in conjunction with the results of the traditional Friedman method. The technique was validated by applying it to kinetic data from various simulated reactions and experimental data on the thermal degradation of polyethylene.</p></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141323464","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}

{"title":"Thermal analysis of crystallization reveals subtle interactions in pristine graphene-polycaprolactone nanocomposites","authors":"R. Demoor,&nbsp;L.I. Silva,&nbsp;M. Sosa Morales,&nbsp;C.J. Perez,&nbsp;J.P. Tomba","doi":"10.1016/j.tca.2024.179792","DOIUrl":"10.1016/j.tca.2024.179792","url":null,"abstract":"<div><p>In this study, we investigate the melting behavior and crystallization of nanocomposites of poly(ε-caprolactone) (PCL), a biodegradable polymer, with pristine graphene, an economically feasible filler widely available from natural sources. Nanocomposites with pristine graphene loads between 0.01 and 5 wt% were prepared via solvent casting and primarily probed by Differential Scanning Calorimetry (DSC). Conventional DSC shows that the presence of graphene increases PCL crystallinity. Non-isothermal crystallization was studied using Mo's model, whereas other parameters as Activation Energy and Nucleation Activity were obtained. It is shown that graphene increases crystallization rates acting as nucleant, with no signatures of retardant effects. Compared with other classic nano-loads, like ad-hoc modified bentonite also analyzed for comparison, pristine graphene is more effective as nucleant, which indicates that it is better dispersed in PCL. Analysis by Self Successive Annealing (SSA), also carried out by DSC, reveals that graphene hinders the formation of crystals with lamellar thickness above 7.3 nm, as found in regular PCL. It may indicate that molecular interactions between PCL and pristine graphene disrupts the movement of polymeric chains, consequently limiting lamellar growth. Evidence of such interaction is found by Infrared and Raman spectroscopies that reveal broadening of the carbonyl peak of PCL and alteration of G and D' bands of graphene.</p></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141276134","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}

{"title":"The dissolution behavior of 3,4-O-isopropylidene clindamycin in twelve mono-solvents: Solubility, intermolecular interactions, and apparent thermodynamics","authors":"Huanxin Li ,&nbsp;Bo Zhu ,&nbsp;Kenan Sun ,&nbsp;Xin Ding","doi":"10.1016/j.tca.2024.179791","DOIUrl":"https://doi.org/10.1016/j.tca.2024.179791","url":null,"abstract":"<div><p>The solubility of 3, 4-<em>O</em>-isopropylidene clindamycin (OIC) was determined in twelve solvents at <em>p</em> = 101.3 kPa with the temperature from 273.15 K to 313.15 K. The solubility of OIC increases with the raise temperature. Among the selected solvents, 2-butanol showed the best dissolving ability for OIC, while acetonitrile showed the worst dissolving ability. The obtained data are neatly correlated with five models, including van't Hoff, Yaws, <em>λh</em>, Wilson, and nonrandom two-liquid interaction model (NRTL), with Yaws equation yielding the most accurate predicted results. Moreover, the Conductor-like Screening Model for Real solvents (COSMO-RS) provides better calculated results for the protic solvents than the aprotic ones except for acetonitrile. The dissolving mechanism of OIC was investigated with intermolecular interaction between OIC and solvents, and the analyses indicate that the dissolving process is affected by intermolecular interaction, molecular shape, and size of both solvents and the solute. The apparent thermodynamics analysis shows that the dissolving process of OIC before reaching equilibrium in the twelve solvents is spontaneous, endothermic, and enthalpy driven.</p></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141250255","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}

{"title":"Thermally induced phase separation of UHMWPE mixture with dioctyl adipate: Competition of liquid–liquid phase separation and polymer crystallization","authors":"Andrey V. Basko ,&nbsp;Tatyana N. Lebedeva ,&nbsp;Mikhail Y. Yurov ,&nbsp;Alexander S. Zabolotnov ,&nbsp;Sergey S. Gostev ,&nbsp;Sergey S. Gusarov ,&nbsp;Konstantin V. Pochivalov","doi":"10.1016/j.tca.2024.179787","DOIUrl":"https://doi.org/10.1016/j.tca.2024.179787","url":null,"abstract":"<div><p>The thermal behavior of ultra-high molecular weight polyethylene (UHMWPE) with dioctyl adipate (DOA) was investigated by the differential scanning calorimetry (DSC) method. Capillary-porous bodies were obtained via thermally induced phase separation of DOA mixtures with polyethylenes of different molecular weight at different cooling rates. Analysis of the morphology of the prepared porous bodies together with DSC data and results of cloud point estimation revealed an unexpected effect of a cooling rate on the type of phase separation occurring in the mixture during its cooling from homogeneous state. Particularly it was shown that increase in the cooling rate reduces the probability of realization of liquid – liquid phase separation in the mixture. It was argued that such behavior, different from the standard semicrystalline polymers, is a result of kinetic hindrance of liquid – liquid phase separation in mixtures containing a polymer with such a high molecular weight.</p></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141250254","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}

{"title":"Development of cationic oligodiaminogalactoses specifically binding to duplex RNA, but not to duplex DNA","authors":"Hidetaka Torigoe ,&nbsp;Sumire Nakayama ,&nbsp;Tomomi Shiraishi ,&nbsp;Kazuki Sato ,&nbsp;Rintaro Iwata Hara ,&nbsp;Takeshi Wada","doi":"10.1016/j.tca.2024.179789","DOIUrl":"https://doi.org/10.1016/j.tca.2024.179789","url":null,"abstract":"<div><p>Duplex RNA stabilization is important for the application in the artificial silencing of gene expression. Excess usage of cationic molecules with low binding affinity to duplex RNA may cause cytotoxicity due to nonspecific binding. Cationic molecules specifically binding to duplex RNA with high binding affinity are necessary for duplex RNA stabilization. Here, UV melting and isothermal titration calorimetric analyses revealed that our previously designed cationic oligodiaminogalactose 4 mer (ODAGal4) specifically stabilized duplex RNA by binding to it with approximately 10⁵ <em>M</em>⁻¹ binding constant, without binding to duplex DNA. Temperature dependence of thermodynamic parameters, including negative enthalpy and entropy changes, revealed that the magnitude of negative heat capacity change was quite large for small molecules binding to duplex RNA, suggesting the influence of the hydrophobic effect on the binding process. Our results suggest the therapeutic application of ODAGal4 as a key molecule for duplex RNA-binding specificity to prevent any nonspecific binding.</p></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141312992","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}

{"title":"Applying machine learning to reveal the microscopic heat transfer mechanism of nanofluids as coolants","authors":"Gaoyang Li ,&nbsp;Haiyi Sun ,&nbsp;Dan Han ,&nbsp;Shukai Cheng ,&nbsp;Guoqi Zhao ,&nbsp;Yuting Guo","doi":"10.1016/j.tca.2024.179788","DOIUrl":"10.1016/j.tca.2024.179788","url":null,"abstract":"<div><p>Nanofluids are considered as excellent coolants to optimize thermal management of electronic devices, where the nanoparticle morphology and the addition of surfactants can affect the thermal transport performance of nanofluids. Due to the limitations of high economic and computational cost in previous experimental and numerical simulation methods, the design of nanofluids urges for more efficient approaches. In this work, a novel machine learning framework coupled with molecular dynamics methods was proposed to model the multi-component mixing nanofluidic systems and explore the deep heat transfer mechanisms. Multi-input attribute point cloud dataset, dual channel sampling network and multi-nanoscale optimization scheme were used to improve the prediction performance of machine learning. The computational cost of the machine learning method is shortened by 36000 times compared with simulation methods. Moreover, our work can achieve up to 90 % prediction accuracy for surfactant adsorption properties. Furthermore, algorithm optimization strategy can improve the prediction accuracy of nanofluidic heat transfer performance by 40 %. The proposed framework has the potential to shorten the development cycle of nanofluidic design.</p></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141187820","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}

{"title":"Thermal decomposition and combustion of interior design materials","authors":"V.V. Dorokhov,&nbsp;G.V. Kuznetsov,&nbsp;S.S. Kropotova,&nbsp;A.S. Sviridenko,&nbsp;P.A. Strizhak","doi":"10.1016/j.tca.2024.179786","DOIUrl":"10.1016/j.tca.2024.179786","url":null,"abstract":"<div><p>Research findings on the patterns of thermal decomposition and combustion are reported for widely used interior design materials. The experiments were conducted using a hardware and software system including a thermogravimetric analyzer (to record the characteristics of thermal decomposition), a gas analyzer (with H₂, CH₄, H₂S, SO₂, CO and CO₂ sensors) and a high-speed camera (to record the characteristics of ignition and combustion). The temperature of the oxidizing medium ranged from 500 to 900°C to investigate the conditions of thermal decomposition initiation and sustained combustion. It was established that the highest concentrations of toxic emissions were typical of the combustion of polypropylene at a maximum temperature of the oxidizing medium (900°C). Wood showed the shortest ignition delay time and the longest duration of combustion. The experimental data were used for a physical problem statement and mathematical model of heat and mass transfer to explore the thermal decomposition and combustion of interior design materials in different rooms. A comparison of the experimental findings with the mathematical modeling results validates the developed model. The growth rates of carbon monoxide and carbon dioxide concentrations were determined for construction (wooden) and interior design (polymer) materials. The maximum concentrations of CO and CO₂, and the minimum times taken to reach their threshold values corresponded to wood and polyvinyl chloride panels. This research provides a deeper insight into the thermal decomposition of a wide range of fuels and the formation of gaseous pyrolysis products of these fuels. The results obtained can be used to evaluate the toxicity of construction and interior design materials during compartment fires as well as to estimate the safe egress time and risks involved in the process. They can also serve as a database for the development and testing of mathematical models describing fire outbreaks and propagation in confined spaces.</p></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141132118","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}

{"title":"Design, calibration and testing of a novel isothermal calorespirometer prototype","authors":"Christian Fricke ,&nbsp;Eliana Di Lodovico ,&nbsp;Maximilian Meyer ,&nbsp;Thomas Maskow ,&nbsp;Gabriele E. Schaumann","doi":"10.1016/j.tca.2024.179785","DOIUrl":"10.1016/j.tca.2024.179785","url":null,"abstract":"<div><p>A prototype of an innovative isothermal calorespirometer was developed to measure simultaneously heat production rate (calorimetry) and CO₂ evolution rate (respirometry) in real-time in a static batch vessel system. The relationship between these two variables forms the calorespirometric ratio, which serves as a crucial indicator for metabolic processes and allows for the differentiation of various metabolic pathways in simple (pure culture) and complex (e.g. soil) biological systems. The heat production rate is gauged by a thermoelectric generator situated at the bottom of the measuring channel (calorimetric unit), while the CO₂ evolution rate is monitored through a conductometric cell fixed on the lid of the channel (respirometric unit). The prototype is designed with a twin configuration, featuring both sample and reference channels. The spatial separation of the calorimetric and respirometric measuring units ensures the simultaneous measurement of the two rates from a single sample without the occurrence of crosstalk effects between the signals.</p><p>The electrical calibration of the calorimetric unit reveals heat losses (approx. 30 %) and response times (approx. 6 min) that are comparable to those of established isothermal calorimeters. In parallel, growth experiments conducted with baker`s yeast demonstrate the applicability of the calorespirometer prototype to biological systems.</p></div>","PeriodicalId":23058,"journal":{"name":"Thermochimica Acta","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0040603124001242/pdfft?md5=896f64ac07a9a71d3825cf798fc0f6c5&pid=1-s2.0-S0040603124001242-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141138403","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}