Thermal degradation of polyimides—I. Investigation of the role of isoimide structure on degradation process

Microplastics (MPs) are distributed in a wide range of aquatic and terrestrial ecosystems throughout the planet. They are known to adsorb hazardous substances and can transfer them across the trophic web. To eliminate MPs pollution in an environmentally friendly process, we propose using a photocatalytic process that can easily be implemented in wastewater treatment plants (WWTPs). As photocatalysis involves the formation of reactive species such as holes (h+), electrons (e−), hydroxyl (OH●), and superoxide ion (O2●−) radicals, it is imperative to determine the role of those species in the degradation process to design an effective photocatalytic system. However, for MPs, this information is limited in the literature. Therefore, we present such reactive species’ role in the degradation of high-density polyethylene (HDPE) MPs using C,N-TiO2. Tert-butanol, isopropyl alcohol (IPA), Tiron, and Cu(NO3)2 were confirmed as adequate OH●, h+, O2●− and e− scavengers. These results revealed for the first time that the formation of free OH● through the pathways involving the photogenerated e− plays an essential role in the MPs’ degradation. Furthermore, the degradation behaviors observed when h+ and O2●− were removed from the reaction system suggest that these species can also perform the initiating step of degradation.

Download Full-text

Current insights into the implications of m6A RNA methylation and autophagy interaction in human diseases

Cell & Bioscience ◽

10.1186/s13578-021-00661-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Xuechai Chen ◽

Jianan Wang ◽

Muhammad Tahir ◽

Fangfang Zhang ◽

Yuanyuan Ran ◽

...

Keyword(s):

Intervertebral Disc Degeneration ◽

Rna Binding ◽

Rna Binding Proteins ◽

Degradation Process ◽

Human Diseases ◽

Rna Modification ◽

Rna Methylation ◽

M6a Rna Methylation ◽

The Impact

AbstractAutophagy is a conserved degradation process crucial to maintaining the primary function of cellular and organismal metabolism. Impaired autophagy could develop numerous diseases, including cancer, cardiomyopathy, neurodegenerative disorders, and aging. N6-methyladenosine (m6A) is the most common RNA modification in eukaryotic cells, and the fate of m6A modified transcripts is controlled by m6A RNA binding proteins. m6A modification influences mRNA alternative splicing, stability, translation, and subcellular localization. Intriguingly, recent studies show that m6A RNA methylation could alter the expression of essential autophagy-related (ATG) genes and influence the autophagy function. Thus, both m6A modification and autophagy could play a crucial role in the onset and progression of various human diseases. In this review, we summarize the latest studies describing the impact of m6A modification in autophagy regulation and discuss the role of m6A modification-autophagy axis in different human diseases, including obesity, heart disease, azoospermatism or oligospermatism, intervertebral disc degeneration, and cancer. The comprehensive understanding of the m6A modification and autophagy interplay may help in interpreting their impact on human diseases and may aid in devising future therapeutic strategies.

Download Full-text

Role of Metal Vacancies in the Mechanism of Thermal Degradation of InGaN Quantum Wells

ACS Applied Materials & Interfaces ◽

10.1021/acsami.0c21293 ◽

2021 ◽

Vol 13 (6) ◽

pp. 7476-7484

Author(s):

Julita Smalc-Koziorowska ◽

Ewa Grzanka ◽

Artur Lachowski ◽

Roman Hrytsak ◽

Mikolaj Grabowski ◽

...

Keyword(s):

Thermal Degradation ◽

Quantum Wells ◽

Metal Vacancies ◽

Ingan Quantum Wells

Download Full-text

Distribution of Acidity and Alkalinity on Degraded Manuscripts Containing Iron Gall Ink

Restaurator International Journal for the Preservation of Library and Archival Material ◽

10.1515/res-2015-0002 ◽

2015 ◽

Vol 36 (3) ◽

Author(s):

Eva Marín ◽

Maria Carme Sistach ◽

Jessica Jiménez ◽

Miguel Clemente ◽

Guillem Garcia ◽

...

Keyword(s):

Good Condition ◽

Degradation Process ◽

Degradation Processes ◽

Alkaline Reserve ◽

Hydrolysis Of Cellulose ◽

Relevant Variables ◽

Long Time ◽

Iron Gall ◽

The Stability

AbstractLong-time preservation of manuscripts depends on the stability of their support. One of the most important degradation processes of paper manuscripts containing iron gall ink is the acid hydrolysis of cellulose. The heterogeneity of the distribution of their constituent materials, together with the defined position of ink as a source of degradation agents, makes it difficult to obtain reliable and detailed information about degradation processes. The aim of this study is to contribute to the knowledge of the acid degradation process by looking at the distribution of relevant variables (pH, acidity and alkaline reserve) on real untreated iron gall ink containing manuscripts at different degradation stages. The study discusses the well-known differences between surface and cold extraction pH determination. It corroborates the relationship between pH, acidity and alkalinity and degradation stages, pointing out that acidity values for some manuscripts in apparent good condition are not far from those obtained for degraded manuscripts. The results indicate that in some partially degraded manuscripts, the coexistence of acid areas and areas with an alkaline reserve which do not participate in the neutralization process is possible. The role of water as a solvent for this equilibrium has also been evaluated.

Download Full-text

INVESTIGATION OF THERMAL DEGRADATION OF POULTRY PROCESSING DEWATERED SLUDGE USING THERMOGRAVIMETRIC ANALYSIS METHOD

Jurnal Teknologi ◽

10.11113/jt.v76.5522 ◽

2015 ◽

Vol 76 (5) ◽

Author(s):

N. Aniza ◽

S. Hassan ◽

M. F. M. Nor ◽

K. E. Kee ◽

Aklilu T.

Keyword(s):

Particle Size ◽

Thermogravimetric Analysis ◽

Thermal Degradation ◽

Heating Rate ◽

Degradation Process ◽

Heating Rates ◽

Initial Stage ◽

Poultry Processing ◽

Effect Of Particle Size ◽

Dewatered Sludge

Thermal degradation of Poultry Processing Dewatered Sludge (PPDS) was studied using thermogravimetric analysis (TGA) method. The effect of particle size on PPDS samples and operational condition such as heating rates were investigated. The non-isothermal TGA was run under a constant flow of oxygen at a rate of 30 mL/min with temperature ranging from 30ºC to 800ºC. Four sample particle sizes ranging between 0.425 mm to 2 mm, and heating rate between 5 K/min to 20 K/min were used in this study. The TGA results showed that particle size does not have any significant effect on the thermogravimetry (TG) curves at the initial stage, but the TG curves started to separate explicitly at the second stage. Particle size may affect the reactivity of sample and combustion performance due to the heat transfer and temperature gradient. The TG and peak of derivative thermogravimetry (DTG) curves tend to alter at high temperature when heating rate is increased most likely due to the limitation of mass transfer and the delay of degradation process.

Download Full-text

Role of ionic chlorine in the thermal degradation of metal chloride-doped graphene sheets

Journal of Materials Chemistry C ◽

10.1039/c2tc00008c ◽

2013 ◽

Vol 1 (2) ◽

pp. 253-259 ◽

Cited By ~ 18

Author(s):

Ki Chang Kwon ◽

Buem Joon Kim ◽

Jong-Lam Lee ◽

Soo Young Kim

Keyword(s):

Thermal Degradation ◽

Metal Chloride ◽

Graphene Sheets ◽

Doped Graphene

Download Full-text

Thermal degradation of polystyrene-II the role of abnormalities

European Polymer Journal ◽

10.1016/0014-3057(70)90174-6 ◽

1970 ◽

Vol 6 (2) ◽

pp. 423-433 ◽

Cited By ~ 53

Author(s):

G.G. Cameron ◽

G.P. Kerr

Keyword(s):

Thermal Degradation

Download Full-text

Non-isothermal degradation kinetics for polycarbonate/ polymethylphenylsilsesquioxane composites

e-Polymers ◽

10.1515/epoly.2010.10.1.1 ◽

2010 ◽

Vol 10 (1) ◽

Cited By ~ 9

Author(s):

Jiangbo Wang ◽

Zhong Xin

Keyword(s):

Activation Energy ◽

Thermogravimetric Analysis ◽

Thermal Degradation ◽

Flame Retardancy ◽

Degradation Kinetics ◽

Degradation Process ◽

Nitrogen Atmosphere ◽

Ozawa Method ◽

Degradation Behaviors ◽

Thermal Degradation Process

AbstractThe thermal degradation behaviors of PC/PMPSQ (polymethylphenylsilsesquioxane) systems were investigated by thermogravimetric analysis (TGA) under non-isothermal conditions in nitrogen atmosphere. During non-isothermal degradation, Kissinger and Flynn-Wall-Ozawa methods were used to analyze the thermal degradation process. The results showed that a remarkable decrease in activation energy ( E ) was observed in the early and middle stages of thermal degradation in the presence of PMPSQ, which indicated that the addition of PMPSQ promoted the thermal degradation of PC. Flynn-Wall-Ozawa method further revealed that PMPSQ significantly increased the activation energy of PC thermal degradation in the final stage, which illustrated that the PMPSQ stabilized the char residues and improved the flame retardancy of PC in the final period of thermal degradation process

Download Full-text

Characterization and thermal degradation kinetics of thermoplastic polyimide based on BAPP

High Performance Polymers ◽

10.1177/0954008317729741 ◽

2017 ◽

Vol 30 (7) ◽

pp. 787-793 ◽

Cited By ~ 4

Author(s):

Xu Su ◽

Yong Xu ◽

Linshuang Li ◽

Chaoran Song

Keyword(s):

Thermogravimetric Analysis ◽

Thermal Degradation ◽

Degradation Kinetics ◽

Degradation Process ◽

Thermal Degradation Kinetics ◽

Heating Rates ◽

Step Method ◽

Nitrogen Derivative ◽

Degradation Reaction ◽

Kinetics Of

Two kinds of thermoplastic polyimides (PIs) were synthesized via a two-step method with 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), 4,4′-oxydianiline (ODA) diamine, and 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), and their thermal degradation kinetics was studied by thermogravimetric analysis at different heating rates under nitrogen. Derivative thermogravimetric analysis curves indicated a simple, single-stage degradation process in PI BTDA-BAPP and a two-stage degradation process in PI BTDA-ODA-BAPP. The activation energies ( Eas) of the thermal degradation reaction were determined by the Flynn–Wall–Ozawa and Kissinger–Akahira–Sunose methods without a knowledge of the kinetic reaction mechanism. By comparing the values of Ea and weight loss temperatures, it was demonstrated that the thermal stability of PI BTDA-ODA-BAPP was superior to that of PI BTDA-BAPP.

Download Full-text