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Environmental Performance of Bio-Based Polymer Additives: Thermal Stabilizers and Antioxidants
Published in Moayad N. Khalaf, Michael Olegovich Smirnov, Porteen Kannan, A. K. Haghi, Environmental Technology and Engineering Techniques, 2020
Hussein A. Shnawa, Moayad N. Khalaf
By balance between the presence and amounts of antioxidants or thermal stabilizers in polymeric systems, it can be protecting these materials from the thermal degradation or thermal oxidation degradation. Bio-based materials in the field of polymer additives are considered as important and promising additives due to their unique structural features, chemical modification ability, abundant availability, and low cost. A large number of efficient chemicals and products have been used and developed dependent on the highly phenolic hydroxyl groups, aromatic rings, and other chemical groups of these natural raw material especially flavonoids-based structures. All these properties proved potential activity for thermal stabilization of polymeric materials. Accordingly, the interest is focused more and more on the potential use of natural antioxidants as example, for the stabilization of polymers during processing, as well as during applications.
Tribology of Polymer and their Composites
Published in Ahmed Abdelbary, Extreme Tribology, 2020
According to the American Society for Testing and Materials’ (ASTM) definitions, thermal degradation is “a process whereby the action of heat or elevated temperature on a material, product, or assembly causes a loss of physical, mechanical, or electrical properties”. In polymer tribosystems, polymers are often exposed to high friction heating during sliding. They undergo both physical and chemical changes resulting in unwanted changes to their properties. Thus, thermal and chemical stability are among the most important limiting factors in the tribological application of plastics at high temperatures. Degradation can present an upper limit to a polymer’s service temperature as much as the possibility of a mechanical property loss, softening and melting, because it can occur at temperatures much lower than those at which a mechanical failure is likely to occur. As polymers degrade by wear, their performance is generally observed with the surface temperatures approaching and exceeding the glass transition temperature. On the other hand, an elevated temperature can increase reaction rates, influence phase changes, increase diffusion, and enhance flow characteristics of materials (Villetti et al., 2002).
Ill Degradable Packaging
Published in Susan E. M. Selke, Packaging and the Environment, 1994
We will define degradation in this book to mean the chemical breakdown of a material into smaller molecules, or the incorporation of materials into living organisms. Biodegradation is, then, degradation resulting from the action of living organisms, of which microorganisms are generally the most significant. Photodegradation is degradation resulting from the action of light, the most significant component being ultraviolet light. Photodegradation, most commonly, is actually an oxidative process. Oxidation can also occur in the absence of light, but is typically much slower under those conditions. For some materials, hydrolytic degradation, degradation resulting from the action of water, is also important. All materials are subject to thermal degradation, the breaking down of chemical structures on exposure to heat.
Combined experimental and molecular dynamics removal processes of contaminant phenol from simulated wastewater by polyethylene terephthalate microplastics
Published in Environmental Technology, 2022
Christian Ebere Enyoh, Qingyue Wang
According to the TGA thermograms, the prepared pr-PET MPs is stable up to 397°C, as the temperature increases, its decomposition starts, being completed at approximately 570 and 588°C for size 1000 and 500 µm respectively, at which a weight loss of 43% (residual fraction of 57%) and 33% (residual fraction of 77%) is reached respectively. Similarly, the modified and aged PET MPs initiate a decomposition process from 397°C and exhibit a weight loss with an increase in temperature. However, Ag-PET MPs had a final weight loss of 40% (residual fraction of 60%) for sizes 1000 and 500 µm at 570°C. Meanwhile, the Mod-PET MPs had the highest residual fraction and lowest weight loss compared to other prepared materials except for the Pr-PET MPs (500 µm). For the size of 1000 µm, the final weight loss of 31% (residual fraction of 69%) was obtained at 585°C while the final weight loss of 37% (residual fraction of 63%) was obtained at 570°C for the size 500 µm. This test was conducted to determine the material's thermal resistance at elevated temperatures. Thermal degradation studies of polymeric materials are important for both practical and scientific reasons. On the practical side, TGA studies not only provide insight into the behaviour of polymers subjected to high temperatures, but also aid in the establishment of criteria for material selection for particular applications [40]. TGA research suggests that the modified and aged PET MPs has a good heat resilience and may be employed in a variety of environmental and engineering applications [41].
Thermal degradation of calcium lactate pentahydrate using TGA/FTIR/MS: thermal kinetic and thermodynamics studies
Published in Indian Chemical Engineer, 2022
Thermogravimetric analysis is an important analytical technique that can be utilised to detect the thermal degradation behaviour of the samples. The thermogravimetric (TG) and differential thermogravimetric (DTG) curves describe the degradation process as well as showing the thermal stability at different temperatures. The thermal degradation behaviour of the CLP was investigated using the SDT Q600 thermogravimetric analyzer (TA Instruments) from 25°C to 1000°C at different heating rates of 10°C/min, 20°C/min, 30°C/min, and 40°C/min under a 30 mL/min nitrogen gas flow. To ensure maximum accuracy and minimise errors, all experiments were studied at least triplicate. The simultaneous evolution of the gases during thermal degradation was determined using the Tensor27 FTIR (Bruker) and the mass spectrometer (AELOS 403 C QMS) coupled with thermogravimetric analysis with a heating rate of 20°C/min. The transfer lines from TGA to FTIR and TGA to MS was kept at 200°C to avoid gas condensation.
Expandable Graphite in Polyethylene: The Effect of Modification, Particle Size and the Synergistic Effect with Ammonium Polyphosphate on Flame Retardancy, Thermal Stability and Mechanical Properties
Published in Combustion Science and Technology, 2020
Jianing Liu, Xiuyan Pang, Xiuzhu Shi, Jianzhong Xu
Thermal degradation is the process of reducing the molecular weight of a polymer under the action of heat. Based on TG/DTG experiments under N2 atmosphere, the thermal stability of each 70LLDPEEGP/30EGP and 70LLDPEEGP/20EGP/10APP were detected, and the results were shown in Figure 7 and Table 3, respectively.