Kinetics of thermal degradation of polymeric materials is usually studied by weight loss at a constant temperature or during heating. Hence, the activation energy and other kinetic parameters of the thermal destruction process are determined. One of the fastest and most accessible methods for studying the kinetics of these processes is TGA. Weight methods of TGA do not provide an opportunity to judge the proportion of gaseous degradation products. This is especially true for processes associated with the release of hydrogen and other substances with low molecular weights, the accuracy of determining the amount of which by the weight method is low. Meanwhile, the study of the gas evolution process can provide additional information about the kinetics and mechanism of thermal destruction processes. Of great interest is also the joint study of the total weight loss and gas evolution during the polymer heating. Using mass spectrometry, IR spectroscopy combined with thermal analysis (TGA/DSC-IR and TGA/DSC-MS) we have defined product composition and thermal destruction kinetics. As a result of the TGA/DSC-MS study of gaseous products of thermolysis in nitrogen atmosphere, there were found products with 44, 45, 59, 60, 68, and 88 phr. Quite a similar pattern for p-PGFPh:AA copolymers is also observed in TGA/DSC-IR studies: the same products and the same temperature range. However, in contrast to the TGA/DSC-MS study, CO release was also recorded by this method (weak signal). Kinetic characteristics of the processes were determined based on Friedman, Ozawa-Flynn-Wall and modified NPC methods. Obtained values of the activation energy and thermodynamic characteristics make it possible to predict the composition of polymers, which make a significant contribution to the development of theoretical ideas about the features of the physicochemical properties of polymers.
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http://dx.doi.org/10.3390/polym15071725 | DOI Listing |
Nat Commun
December 2024
State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
Polychlorinated naphthalenes (PCNs) are persistent organic compounds that are regulated by the Stockholm Convention. Here, we estimate historical emissions from PCN production and use (1912-1987) and unintentional emissions from 20 categories (2000-2020). A random forest regression model projects emissions for 2020-2050.
View Article and Find Full Text PDFWaste Manag
December 2024
Jiangsu Key Laboratory of E-waste Recycling, School of Resources and Environmental Engineering, Jiangsu University of Technology, Changzhou 213001, PR China. Electronic address:
There are hazardous substances such as chloride salts and heavy metals in the municipal solid waste incineration fly ash (WIFA). During thermal treatment, the concentrated chlorides promote the volatilization of heavy metals, increasing the ecological risk. The water washing method is also employed as a pre-treatment for WIFA, but a substantial volume of wastewater with high chloride content is produced that poses challenges for effective treatment.
View Article and Find Full Text PDFWaste Manag
December 2024
School of Environmental Science and Engineering, Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Zhejiang Engineering Research Center of Non-ferrous Metal Waste Recycling, Zhejiang Gongshang University, Hangzhou, Zhejiang 310012, China. Electronic address:
This study demonstrates the potential of secondary aluminum dross (SAD) to enhance the vitrifying hazardous waste incineration fly ash (FA) and bottom slag (BS). Based on the CaO-SiO-AlO ternary phase diagram, a liquid phase can be achieved at relatively low temperatures by carefully adjusting the AlO content, particularly when the CaO to SiO ratio is around 0.66.
View Article and Find Full Text PDFPlast Reconstr Surg Glob Open
December 2024
From the Division of Surgery and Interventional Science, University College London, London, United Kingdom.
Background: The deep inferior epigastric perforator (DIEP) flap provides an effective and popular means for autologous breast reconstruction. However, with the complexity of the pathway, the environmental impact of the pathway has yet to be evaluated.
Methods: A retrospective analysis of 42 unilateral DIEPs at a single reconstructive center was performed.
Biotechnol J
December 2024
Department of Ultrasound Medicine, Tangdu Hospital, Fourth Military Medical University, Xi'an, Shaanxi, China.
Ultrasound (US) can easily penetrate media with excellent spatial precision corresponding to its wavelength. Naturally, US plays a pivotal role in the echolocation abilities of certain mammals such as bats and dolphins. In addition, medical US generated by transducers interact with tissues via delivering ultrasonic energy in the modes of heat generation, exertion of acoustic radiation force (ARF), and acoustic cavitation.
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