One of the solutions for overheating the interior in the summer without increasing energy consumption is the integration of phase change material (PCM) into interior plasters. However, adding PCM to plasters deteriorates their properties and thus their usability. The aim of this paper is to determine how the microencapsulated PCM affects the mechanical, thermal, and fire properties of plasters and how much PCM can be added to the plaster. Two sets of samples were prepared: in set S, part of the aggregate was replaced by PCM; and in set R, only PCM was added. The bulk density, flexural strength, compressive strength, tensile strength perpendicular to the surface, thermal conductivity coefficient, specific heat capacity, melting, and solidification temperatures and enthalpy were measured. A single-flame source fire test and a gross heat of combustion fire test were performed to determine the reaction to the fire class. The results show that with an increasing proportion of PCM, the strength of the samples of set R decreased more significantly than it did with the samples of set S. It was found that only up to about 10% PCM could be added to set R, while up to 30% PCM could be added to set S.
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http://dx.doi.org/10.3390/ma15031253 | DOI Listing |
Int J Mol Sci
November 2024
Institute of Natural Products and Cosmetics, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Stefanowskiego 2/22, 90-537 Lodz, Poland.
In this study, the DFT/M062X/PCM method was applied to investigate thermodynamic and kinetic aspects of reactions involved in possible mechanisms of antioxidant activity of caffeic acid against HOO radicals in aqueous medium at different pH values. Kinetic parameters of the reactions involved in HAT (Hydrogen Atom Transfer), RAF (Radical Adduct Formation), and SET (Single Electron Transfer) mechanisms, including reaction energy barriers and bimolecular rate constants, were determined, and identification and characterization of stationary points along the reaction pathways within HAT and RAF mechanisms were performed. Inspection of geometrical parameters and spin densities of the radical products formed within HAT and RAF mechanisms revealed that they are stabilized by hydrogen bonding interactions and the odd electron originated through the reaction with the HOO radical is spread over the entire molecule, resulting in significant radical stabilization.
View Article and Find Full Text PDFJ Mol Model
December 2024
Department of Chemistry, Faculty of Science, Ege University, TR-35100, Bornova, Izmir, Türkiye.
Context: Isatin-Schiff bases have wide applications in chemistry. The π conjugated electronic system and heterocylic structure of these materials make them valuable for use as photosensitized materials. The delocalization of π-electrons throughout the structure causes the UV-vis absorption spectra to shift to longer wavelengths.
View Article and Find Full Text PDFJ Mol Model
December 2024
Department of Chemistry, Bangalore University, Bangalore, 560 056, Karnataka, India.
Context: 1,2,4-Oxadiazole serves as a fundamental building block driving advancements across diverse scientific and technological arenas, contributing to the creation of innovative materials for various applications including devices, sensors, medications, agrochemicals, and biomedical instruments. Employing density functional theory (DFT) methods, we investigate the impact of different conformers of an oxadiazole substituted derivative, specifically 3,5-bis[4-(4-methylphenylcarbonyloxy)phenyl]-1,2,4-oxadiazole, in both monomeric and stacked configurations (dimeric and tetrameric). We analyze the electronic structures of various conformers, including assessment of HOMO-LUMO energy gaps, to detect the influence of diverse substituents and stacking arrangements.
View Article and Find Full Text PDFBMC Oral Health
November 2024
Department of Endodontics, Faculty of Dentistry, Cairo University, Cairo, 12613, Egypt.
J Mol Model
November 2024
Department of Chemistry, Faculty of Science Sivas Cumhuriyet University, 58140, Sivas, Turkey.
Context: This study investigates the antioxidant potential of alkyl gallates (C1-C10), focusing on the impact of alkyl chain length and solvent polarity on their antioxidant properties. Known for their biomedical relevance in mitigating oxidative stress, alkyl gallates' structure-activity relationships, particularly regarding chain length and environmental factors, still need to be explored. Key thermochemical parameters, including bond dissociation enthalpy (BDE), ionization potential (IP), proton affinity (PA), and electron transfer enthalpy (ETE), reveal that shorter alkyl chains (C1-C4) exhibit superior antioxidant activity.
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