Thermochemical Transition in Non-Hydrogen-Bonded Polymers and Theory of Latent Decomposition

Tsioptsias, Costas

doi:10.3390/polym14235054

Cited by 4 publications

(5 citation statements)

References 42 publications

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“…Quercetin and gallic acid were also found to depress the thermochemical transition temperature of CA membranes [18]. Other polymers, such as poly(vinyl chloride) and polypropylene-graft-maleic anhydride were reported to exhibit thermochemical transition [19]. According to literature, similar peculiarities have also been reported for other substances, e.g., for lithium potassium tartrate monohydrate [20], flavonoids (quercetin dihydrate and rutin dihydrate) [21], and potassium perchlorate [22].…”

Section: Introductionmentioning

confidence: 52%

Thermal Behavior of Poly(vinyl alcohol) in the Form of Physically Crosslinked Film

et al. 2023

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Evaluation and understanding of the thermal behavior of polymers is crucial for many applications, e.g., polymer processing at relatively high temperatures, and for evaluating polymer-polymer miscibility. In this study, the differences in the thermal behavior of poly(vinyl alcohol) (PVA) raw powder and physically crosslinked films were investigated using various methods, such as thermogravimetric analysis (TGA) and derivative TGA (DTGA), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Various strategies were adopted, e.g., film casting from PVA solutions in H2O and D2O and heating of samples at carefully selected temperatures, in order to provide insights about the structure-properties relationship. It was found that the physically crosslinked PVA film presents an increased number of hydrogen bonds and increased thermal stability/slower decomposition rate compared to the PVA raw powder. This is also depicted in the estimated values of specific heat of thermochemical transition. The first thermochemical transition (glass transition) of PVA film, as for the raw powder, overlaps with mass loss from multiple origins. Evidence for minor decomposition that occurs along with impurities removal is presented. The overlapping of various effects (softening, decomposition, and evaporation of impurities) has led to confusion and apparent consistencies, e.g., from the XRD, it is derived that the film has decreased crystallinity, and apparently this is in agreement with the lower value of heat of fusion. However, the heat of fusion in this particular case has a questionable meaning.

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Section: Introductionmentioning

confidence: 52%

Thermal Behavior of Poly(vinyl alcohol) in the Form of Physically Crosslinked Film

et al. 2023

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“…Additionally, the mass loss at the first degradation step is significant and shifts the DSC signal in the exothermic direction. Hence, the first signal observed on the DSC curve is exothermic as a result of various reactions occurring simultaneously [ 38 ], but it should be noted that the decomposition is initially endothermic. To confirm the mechanism of copolymer decomposition, FTIR analysis of the emitted volatile degradation products was performed.…”

Section: Resultsmentioning

confidence: 99%

Thermal Characterization of Crosslinked Polymeric Microspheres Bearing Thiol Groups Studied by TG/FTIR/DSC under Non-Oxidative Conditions

Maciejewska,

Łastawiecka,

Grochowicz

2024

Materials

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This paper presents the thermal behavior of polymer microspheres based on glycidyl methacrylate (GMA) and crosslinking agents benzene-1,4-diylbis(2-methylprop-2-enoate) (1,4DMB) and trimethylolpropane trimethacrylate (TRIM) before and after functionalization with thioglycolic acid (TGA). The thermal stability of the polymers was determined using thermogravimetric analysis and differential scanning calorimetry under non-oxidizing conditions. The evolved gases were detected by FTIR and NMR spectroscopy, and the chemical structure of solid residues after preheating was assessed by FTIR/ATR spectroscopy. The post-functionalized microspheres showed higher thermal stability (within 270–290 °C) than the initial copolymers (within 240–250 °C). In this paper, examples of decomposition patterns of polymer microspheres before and after functionalization are presented. The decomposition of the initial microspheres starts with the emission of GMA monomers, acrolein, carbon dioxide, and the formation of unsaturated bonds in the solid residue. In the case of functionalized microspheres, degradation involves the transesterification of ester groups with the -SH groups, resulting in the emission of carbonyl sulfide, acrolein and carbon dioxide. Furthermore, lactone groups are created in the solid residue. The degradation of the functionalized copolymers is a complex process due to their crosslinked structure, rendering the identification of all the degradation products unattainable.

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“…Moreover, combined with TGA and DSC curves, it was found that when the temperature reached the softening temperature of PI and PI-SiCw, the nanocomposites had a certain amount of mass loss, which may be due to the fact that latent decomposition reached a maximum at the softening point [ 37 ]. This also explained the phenomenon of mass loss in PI-SiCw in the TGA curve before reaching a temperature of 100 °C.…”

Section: Resultsmentioning

confidence: 99%

“…Overall, the residual weight of PI-SiCw nanocomposites was larger than that of the matrix, which increased from 44% to 49%. Moreover, the mass loss rate of PI-SiCw nanocomposites was fast around 65 • C and 450 • C. In the process of heating, the mass loss detected by TGA ranging from 50 • C to 100 • C may be due to the evaporation of water and some latent decomposition of polymer composites by heating [37]. The reaction process was divided into two stages.…”

Section: Tga and Dtg Analysismentioning

confidence: 99%

High-Impact Performance and Thermal Properties of Polyimine Nanocomposites Reinforced by Silicon Carbide Nano-Whiskers

Zhang

Wang

et al. 2023

Materials

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Polymer nanocomposites, which combine the advantages of polymers and fillers, are widely used in the field of automobile and aviation. Polyimine (PI) is an emerging thermoset material with remarkable properties, such as malleability, recyclability, and self-healing. Silicon carbide nano-whiskers (SiCw), as a cheap and high-hardness filler material, are chosen to enhance the properties of polyimine matrix. Silicon carbide nano-whisker-reinforced polyimine (PI-SiCw) nanocomposites were successfully fabricated by heat pressing, which was confirmed by FTIR and XPS tests. According to the results of mechanical tests, the mechanical properties of PI-SiCw nanocomposites were obviously improved. For example, with the addition of 0.5% SiCw, bending strength and bending elongation at break can be simultaneously increased by 33% and 148%, respectively. Surprisingly, the impact strength of PI-SiCw nanocomposites with 2% SiCw was increased by 154% compared to the matrix. SEM and EDS tests showed that the evenly distributed SiCw in the polyimine matrix enhanced the mechanical properties of PI-SiCw nanocomposites according to the mechanism of whiskers pulling out and the bridging principle. According to the TGA test results, the PI composites with SiCw retain a higher weight percentage at 800 °C. The reason was the combined effect of the good thermal stability of SiCw and their strong interactions with the PI matrix. As a result, introducing SiCw into the PI matrix imparts a slight improvement in thermal stability. This article presents an avenue of cost-effective research to enhance the mechanical properties of polyimine composites.

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Thermochemical Transition in Non-Hydrogen-Bonded Polymers and Theory of Latent Decomposition

Cited by 4 publications

References 42 publications

Thermal Behavior of Poly(vinyl alcohol) in the Form of Physically Crosslinked Film

Thermal Behavior of Poly(vinyl alcohol) in the Form of Physically Crosslinked Film

Thermal Characterization of Crosslinked Polymeric Microspheres Bearing Thiol Groups Studied by TG/FTIR/DSC under Non-Oxidative Conditions

High-Impact Performance and Thermal Properties of Polyimine Nanocomposites Reinforced by Silicon Carbide Nano-Whiskers

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