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The study presents the chemiluminescence based (CL) evaluation of the recyclability of linear styrene block copolymers. This analysis can provide insight into the material's degradation state and predict its suitability for further recycling cycles, helping to avoid unnecessary energy consumption during processing.The thermal stability of four similar copolymer structures − styrene-isoprene-styrene (SIS), styrene-butadiene-styrene (SBS) copolymers with different styrene/butadiene ratios, and styrene-ethylene-butadiene-styrene (SEBS) − was studied using isothermal and non-isothermal chemiluminescence (CL). The activation energies for oxidative degradation were calculated based on oxidation induction times indicated by the CL intensities evolution. The results, which highlight the influence of molecular structure on stability under aging conditions, as presented by the calculated for the activation energy (kJ mol−1), show the following sequence: SBS (styrene 30%) (117 kJ mol−1) ≈ SIS 120 (kJ mol−1) < SBS (styrene 40%) (176 kJ mol−1) < SEBS (180 kJ mol−1). The CL data were correlated with infrared (IR) spectroscopy and differential scanning calorimetry (DSC) data, providing a comprehensive understanding of the thermal stability and degradation mechanisms during recycling proces. The sequence of the composing units determines the degradation process, with weaker points predominantly attacked in the linear moieties of isoprene, butadiene, and vinyl segments. The experimental data indicate that SIS and SBS (30% styrene) copolymers degrade the fastest likely due to the rapid accumulation of hydroperoxide radicals. The SEBS copolymer also experiences significant degradation, but this occurs at higher temperatures (above 220 ⁰C) and progresses more gradually once it begins. In contrast, the SBS copolymer with 40% styrene content degrades more slowly and exhibits minimal mass loss, primarily due to the formation of less reactive keto degradation products. [ABSTRACT FROM AUTHOR]

This work aims to investigate the combustion characteristics, kinetics triplets, and thermodynamic parameters of microporous triazine-based organic polymers. The polymers were prepared by the incorporation of aliphatic and aromatic diamines (e.g., 1,4-hexane diamine (Hex) and 1,4-phenylenediamine (Bz)) with triazine core (Tr) via polycondensation polymerization. Both polymers Tr–Hex-diamine and Tr–Bz-diamine are microporous with a surface area of 212 and 524 m2/g, respectively. The successful synthesis was confirmed from FTIR and solid-state 13C CP-MAS. The combustion index (SN), kinetic triplets, apparent activation energy (Ea), pre-exponential factor (A), and thermodynamic parameters were estimated from the thermal degradation profiles of the polymers (TGA) at different heating rates. At the maximum heating rate (20 °C/min) the SN of Tr–Bz-diamine is 2.08, while it reached 4.2 for Tr–Hex-diamine, which indicates the high rate of combustion of the aliphatic hexyl chains. The other kinetic and thermodynamic parameters were determined by applying model-free isoconversional methods including Kissinger–Akahira–Sunose (KAS), Flynn–Wall–Ozawa (OFW), and Kissinger. From KAS, the average Ea for Tr–Bz-diamine and Tr–Hex-diamine are 163.4 and 147.8 kJ/mol, while 169.2 and 151.7 kJ/mol from OFW calculations. These values are higher in the case of the Kissinger method. The degradation mechanism and the rate of decomposition were determined from the Coats–Redfern method and by applying the master plot methods. Comparing the Ea values of the CR method with the integral method shows the possibility of the chemical reaction F3 mechanism beside multiple parallel reactions as shown by the master plot. The pre-exponential factor (A) along with the thermodynamic parameters (e.g., heat of enthalpy, entropy, and Gibbs free energy) were also determined and found to be within the same range of all methods. [ABSTRACT FROM AUTHOR]

A series of blends of polyamide 6 (PA-6) (nylon-6) and a copoly(ether-ester) (HYTREL) were prepared by the melt-mixing method using a twin-screw extruder. The HYTREL content was varied from 0% to 25% by weight of the blends. Thermal and rheological studies on the blends using differential scanning calorimetry, dynamic mechanical analysis (DMA) and capillary rheometer showed that the blends are semi-compatible in nature. A two-phase globular morphology of the blends was established by scanning electron microscope (SEM) analysis. The matrix ligament thickness (interparticle distance) in each blend composition was measured from SEM images and compared with those calculated using Wu's equation. The impact strength of the blends as measured by the Izod impact test was found to be substantially improved as a result of the incorporation of HYTREL. The toughness determined by loss area calculation from the DMA spectrum showed similar trends. The toughness was found to be optimal in a blend having 15 wt.% HYTREL with an average dispersed particle size of around 450 nm. The yield stress of the blend decreased in comparison to PA-6 on addition of HYTREL, while the thermal stability of PA-6 remained unaffected. [ABSTRACT FROM AUTHOR]

To determine the thermal kinetic triplets and elucidate the reaction mechanism of thin intumescent fire-retardant coatings (IFR) of steel structures, one efficient combined kinetic approach was implemented in this study. Thermogravimetric experiments were conducted in air atmosphere at four heating rates, and the whole IFR thermal degradation process was divided into two stages. The average activation energy values derived by model-free methods were 78.9 kJ/mol and 175.16 kJ/mol for Stage I (0<α < 0.2) and Stage II (0.2<α < 0.9), respectively. Furthermore, the linear Coats-Redfern (CR) and non-linear Masterplots models were applied to identify the possible reaction mechanism. It was found that the F3/2 mechanistic model was better suited to the main thermal degradation process. Then model reconstruction based on the F3/2 mechanism model was performed. The results showed that the reconstructed model had a strict linear relationship in the independence analysis and KCE analysis, along with a good agreement between the theoretical and experimental results. The current study provided new insights into the systematic thermal degradation mechanism of IFR, and the proposed kinetic model would be helpful for the thermal protection prediction for steel structure during fire. [ABSTRACT FROM AUTHOR]

This paper describes the investigation of the influence of the substitution position of ethynyl groups in benzoxazines on their ring-opening polymerization (ROP) and the thermal stability of the resulting polybenzoxazines. A series of benzoxazines derived from bisphenol A with ethynyl groups at various positions are synthesized and structurally characterized using Fourier transform infrared (FT-IR) spectroscopy and 1H nuclear magnetic resonance (1H-NMR) spectroscopy. Monitoring of the curing behavior via in situ FT-IR and differential scanning calorimetry analyses reveals the occurrence of position-dependent effects during curing. Kinetic studies of the curing process, conducted via the Kissinger and Ozawa methods, indicate that the presence of ethynyl groups not only promotes the ROP but also reduces the activation energy required for the process. Compared to conventional ethynyl-free polybenzoxazine, ethynyl-functionalized polybenzoxazines exhibit superior thermal stability, including increased glass transition temperature. In particular, the introduction of the ethynyl groups at the meta position provides the greatest enhancement of the thermal properties, reaching an increase in the char yield of approximately 21%. This position also allows reducing the curing temperature, underscoring its critical role in the development of high-performance polybenzoxazines. [ABSTRACT FROM AUTHOR]

Continuous heat generation in perovskite solar cells (PSCs), caused by solar radiation, poses a significant challenge to their lifespan. Existing active cooling methods require extra energy input and might not be effective at high temperatures. Most reported passive radiative cooling materials either lack solar transparency or require complex fabrication processes. Here, mesoporous silica nanoparticles are designed, synthesized, and assembled into multilayered stacks with a graded refractive index (GRI) by spray coating them on top of PSCs made from methylammonium lead iodide (MAPbI3) over a large scale (15.6 × 15.6 cm2). This coating offers both high transparency in the visible wavelength and high emissivity in the mid‐infrared region, leading to an average temperature reduction of 6.65 ±  1.48 °C in GRI‐coated MAPbI3 PSCs under outdoor conditions compared to non‐coated references. After 50 d, the GRI‐coated PSCs maintain 80.9 ± 8.7% of their initial photoconversion efficiency, in contrast to 6.1 ± 5.9% for the noncoated ones. The calculated cooling power of the GRI‐coated PSCs is 28.9% higher than that of the reference cells. [ABSTRACT FROM AUTHOR]

This paper presents research aimed at laboratory experiments on static and cyclic fatigue testing of low-density polyethylene (LDPE) recovered from post-consumer waste in order to develop a recycled product exhibiting satisfactory mechanical and thermo-mechanical properties. The results of the cyclic fatigue tests set up to 80% of the maximum load in static tensile testing demonstrated satisfactory functionality of the recycled material developed by using the injection molding process. There was no significant change in the tensile strength under static and cyclic fatigue tests. Under cyclic loading, there was a quasi-static effect manifested by plastic deformation, and the displacement increased significantly. The static and cyclic tensile tests indicated improvement in the mechanical performance of the recycled LDPE as compared to the virgin material, owing to the high quality of the regranulates. Fourier Transform Infrared Spectroscopy (FTIR) was conducted to analyze the functional groups in virgin and recycled LDPE samples. The analysis showed no significant change in the transmittance spectra. The thermal degradation performance was also analyzed by Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA). The results were quite similar for both virgin and recycled LDPE. [ABSTRACT FROM AUTHOR]

Although it is seen in the literature that composite pipes are produced by filament winding, there are limited number of studies on the use of fabric wrapping and autoclave. In this study, in order to fill this gap and contribute to the literature and industry, composite pipes were produced using fabric wrapping and autoclave methods together and their mechanical and thermal properties were investigated. The effect of carbon nanotube (CNT) reinforcement on these properties was also investigated. According to low velocity impact (LVI) test, 10%–25% impact strength increase was observed with CNT reinforcement. Thermogravimetric analysis (TGA) shows that mass loss decreased by ⁓10% and the degree of thermal degradation increased by ⁓10%. In dynamic mechanical analysis (DMA), it is observed that epoxy glass transition temperature (Tg) increased by 11% with CNT reinforcement. At the end of the study, the mechanical and thermal properties of the pipes produced by autoclave and fabric wrapping methods were improved compared to the literature and contributed to science and therefore to the increased use of prepreg carbon pipes in the industry. Highlights: Composite carbon pipes were produced by applying prepreg fabric wrapping and autoclave curing methods together.The mechanical and thermal properties of multi‐walled carbon nanotube (MWCNT) reinforced and unreinforced carbon composite pipes were investigated.According to TGA, it was observed that the mass loss decreased.Thermal decomposition temperature increased for MWCNT reinforced and unreinforced samples.According to DMA, Tg of epoxy decreased for MWCNT unreinforced sample and increased for MWCNT reinforced sample. [ABSTRACT FROM AUTHOR]

Fibers collected from the husk of areca nut trees were chopped to a length of 30 mm and were either used as such or subjected to alkaline treatment by immersion in a 5% sodium hydroxide (NaOH) solution. The untreated and treated fibers were investigated using thermogravimetric analysis (TGA) before the fabrication of composites using an epoxy matrix. Different amounts of fibers were introduced in the matrix, fabricating the composite by compression molding. The composites were subjected to tensile, flexural, and Charpy impact and Shore D hardness testing, which all demonstrated the considerable advantage obtained with the growing quantity of fibers, especially when employing treated fibers, except in the case of hardness, where limited advantages were encountered. Wear tests were carried out on treated fiber composites and the surface morphology of the worn-out samples was studied, which also demonstrated the improvement in fiber-matrix bonding obtained with the growing amount of fibers. The main limitation of the fibers was their low elongation even after treatment. The fibers hardly reached 4%, which might represent a quite normal value for this kind of fibers, possibly due to with tendency to fibrillation. This would somehow compare these composites with others with similar amounts and lengths of natural fibers. [ABSTRACT FROM AUTHOR]

The effect of added microalgae biomass to styrene–butadiene–styrene triblock composites (SBS) loaded with Chlorella vulgaris and Arthrospira platensis biomass was evaluated by nonisothermal chemiluminescence (CL), infrared spectroscopy, and differential scanning calorimetry (DSC) analysis. The high biomass content of up to 20% for Chlorella vulgaris and 30% for Arthrospira platensis create appropriate conditions for the propagation of oxidation, which is a convenient manner applicable to the degrading digestion of polymer matrix. The chemiluminescence spectra on these ecological formulations indicate the contribution of additives to the optimization of polymer waste disintegration. The degrading activities of the studied microalgal biomass added to the polymer matrix are influenced not only by concentration and source but also by the temperature evolution, which determines the proper thermal regime of material decay. The thermal aging of SBS/microalgal composites progresses peculiarly under the action of various pro-oxidant components. The amplitudes of oxidative conversion of SBS support are discussed with values of main kinetic parameters, onset, and intermediate oxidation temperatures. Although the addition of biomass to the polymer matrix introduces various transformations that affect its thermal behavior, the combined CL and DSC studies indicate that these changes ultimately enhance the polymer's stabilization. The control SBS composite was the most stable, likely due to its homogeneous structure compared to the heterogeneous mixture in the microalgae SBS composites. Prolonged heating at elevated temperatures (80 °C and 120 °C) can lead to thermal aging and degradation of the polymer matrix, causing changes such as chain scission or cross-linking, which alter the material's thermal properties. [ABSTRACT FROM AUTHOR]

Non-isocyanate polyurethanes (NIPUs) are considered as a class of environmentally-safe polymers that show promising properties, such as chemical and mechanical resistance. An important feature that may limit some important applications is the thermal degradation behavior of NIPUs and their composites and hybrids. Hence, this article comprehensively reviews recent developments in these materials groups, focusing on the thermal stability and degradation routes. Influence of urethane linkage vicinity, molar mass and ratio of carbonate and amine components, and chemical structure on NIPU thermal degradation behavior was discussed. The onset temperature of degradation was found to be mainly influenced by urethane bonds concentration and crosslinking density of NIPU material. Chain length of amine component has also a significant impact on the thermal degradation profile. The incorporation of bio-sourced and nano-scaled additives (carbon- and silica-based nanoparticles) and their impact on thermal stability of NIPU matrix was analyzed, too, and future outlooks were given. [ABSTRACT FROM AUTHOR]

Mineral–rubber composites based on phosphorylated butadiene rubber (PhBR), including pure expanded perlite (EP) and modified phosphorylated expanded perlite (PhEP) as fillers, are developed. The process involves forming PhBR and its composites—EP/PhBR and PhEP/PhBR—through the oxidative chlorophosphorylation (OxCh) reaction. An in‐depth comparative analysis is conducted on the thermal destruction of the PhBR matrix and the EP/PhBR, and PhEP/PhBR composites. The thermogravimetric (TG)/differential thermogravimetry (DTG) analyses reveal three stages of thermal degradation for the PhBR matrix and both composites, highlighting the notable effects of EP and PhEP in the second and third stages of the degradation process. In comparison, the PhEP/PhBR composite exhibits reduced weight loss, the highest integral procedural decomposition temperature (IPDT) value, and a lower Tmax on the DTG curve, compared with the EP/PhBR composite and the PhBR matrix. The mechanism of the thermal destruction reaction and the kinetic parameters Ea and A are calculated using the model‐fitting Coats–Redfern method. [ABSTRACT FROM AUTHOR]

The present study investigates the reactions of polystyrene and epoxy/polystyrene powder composites, exploring different weight percentages (8%, 12%, and 16%) of polystyrene during decomposition under highly elevated temperatures within a nitrogen atmosphere. The findings reveal that polystyrene content significantly influences the thermal behavior of pure epoxy, with a higher polystyrene content correlating with the increased thermal stability of the composites. This study observed a three-stage mass loss process by examining the reaction kinetics of thermal decomposition using the Coats-Redfern approach. Initially, weight reduction occurs due to moisture and volatile elimination, followed by a smooth mass loss phase attributed to weaker polymer chain linkages and, ultimately, char formation. Chemical kinetic parameters, such as activation energy and frequency factor, were successfully determined using the Coats-Redfern approach, with a first-order reaction observed across all data points, demonstrating a high R-square mean value of 99.8%. Differential scanning calorimetry (DSC) and thermal gravitational analysis (TGA) analyses revealed an increase in glass temperature from 86.95 to 92.85 °C and an elevation in activation energy from 75.38 to 92.85 kJ/mol with increasing polystyrene content (0–16 wt%). Furthermore, the study investigated the influence of thermodynamic parameters. In terms of mechanical properties, increasing polystyrene content reduced impact strength (from 8.5 to 4.23 Kj/m²). In contrast, hardness increased from 77.5 for pure epoxy to 80.4 at 12 wt% polystyrene content in the composite. These findings underscore the importance of thermal stability results in developing a comprehensive understanding of thermal decomposition processes, informing future research endeavors and industrial applications. [ABSTRACT FROM AUTHOR]

Organic binders are always necessary for the fabrication of advanced ceramics by 3D-printing, which are mainly discharged from the ceramic green bodies through a thermal debinding process. Thermal debinding process of organic binders thus has a significant impact on the quality of 3D-printed green bodies and is crucial for fabricating high-quality advanced ceramics to implement applications. Theory and practice in the thermal debinding process of the representative 3D-printed green bodies were reviewed. Based on the composition and function of organic binders, the heat removal methods of different molecular weight organic binders were compared. The interaction between organic binders and ceramic particle surface and the effect of degreasing atmosphere on thermal degradation of organic binders were discussed. Then the thermal debinding process was divided into three stages and the development of the green body structure was described. Three mass transfer channels were analyzed: liquid was transferred by the capillary force, vapor diffused in the liquid phase, and vapor diffused or permeated through the pore nets. Origin causes of the defects such as cracks and distortion lying in the thermal debinding process and the previous steps were analyzed and some control measures were put forward. [ABSTRACT FROM AUTHOR]

In recent scenario, biocomposites are considered counterpart to synthetic fiber reinforced polymer composites due to their comparable specific mechanical characteristics, sustainability, low energy consumption during manufacturing, low cost and biodegradable nature. In this investigation, the influence of fiber loading and sodium hydroxide (NaOH) treatment on thermo-mechanical, morphological and water absorption properties of Areca Catechu tree peduncle fibers (ACTPFs) reinforced in Unsaturated Polyester Resin (UPR) matrix biocomposite has been explored. The biocomposites with 40 wt.% of ACTPF exhibited maximum mechanical characteristics with tensile, flexural, hardness and impact properties of 63 MPa, 56 MPa, 68 HRRW and 5.33 J/cm2 respectively. Also, the NaOH treatment of ACTPF reinforcement improved the tensile, flexural, hardness and impact properties of biocomposite specimens by 3.9%, 4%, 4.12% and 4.4% respectively. The scanning electron microscopic (SEM) images, X-ray diffraction (XRD) spectrum and Fourier Transform Infrared (FTIR) spectrum of the biocomposites were witnessed to ensure its suitability in industrial applications. The acceptable hydrophilic nature, less density and thermal stability up to 237 °C of biocomposite specimens achieved through NaOH-treated ACTPF reinforcements suit well for interiors of automobile and aerospace sectors. [ABSTRACT FROM AUTHOR]

This study investigates the thermal stability of omega fatty acid-enriched vegetable oils, focusing on their behavior under high-temperature conditions commonly encountered during frying. This research aims to evaluate changes in fatty acid composition, particularly the degradation of essential omega-3, -6, and -9 fatty acids, and the formation of harmful compounds such as trans fatty acids (TFAs). Various commercially available vegetable oils labeled as containing omega-3, omega-6, and omega-9, including refined sunflower, high-oleic sunflower, rapeseed, and blends, were analyzed under temperatures from 180 °C to 230 °C for varying durations. The fatty acid profiles were determined using gas chromatography–mass spectrometry (GC-MS). The results indicated a significant degradation of polyunsaturated fatty acids (PUFAs) and an increase in saturated fatty acids (SFAs) and TFAs with prolonged heating. The findings highlight the varying degrees of thermal stability among different oils, with high-oleic sunflower and blended oils exhibiting greater resistance to thermal degradation compared to conventional sunflower oils. This study underscores the importance of selecting oils with favorable fatty acid compositions for high-temperature cooking to minimize adverse health effects associated with degraded oil consumption. Furthermore, it provides insights into optimizing oil blends to enhance thermal stability and maintain nutritional quality, crucial for consumer health and food industry practices. [ABSTRACT FROM AUTHOR]

The thermal decomposition modeling of starch granules (rice, maize, and potato) is investigated in this work. Thermogravimetric analysis (TGA) under nitrogen conditions and different heating rates is carried out. First, a model‐free analysis is carried out to determine the variability of the activation energy with the relative conversion. The results reveal that the sequence of activation energy is rice > maize > potato. In turn, the activation energy is positively correlated (ρ = 0.98) with the relative crystallinity determined by X‐ray diffraction (XRD) analysis. Then, a fractional‐order version of the Sestak–Berggren equation is used to model the starch thermal decomposition. A least‐squares approach is used to estimate the underlying parameters by fitting non‐isothermal TGA curves. The results show that the parameters depend on the heating rate, but more strongly on the XRD relative crystallinity. Overall, the results reported in this study indicate that fractional‐order kinetics models provide an accurate description of the starch thermal degradation, without the use of the traditional TGA heuristic methods used for parameter estimation. [ABSTRACT FROM AUTHOR]

Biomass-to-biofuel conversion represents a critical component of the global transition to renewable energy. One of the most accessible types of biomass is sewage sludge (SS). This by-product from wastewater treatment plants (WWTPs) contains microplastics (MPs) originating from household, industrial and urban runoff sources. Due to their small size (<5 mm) and persistence, MPs present a challenge when they are removed from sewage systems, where they mainly accumulate (~90%). The presence of MPs in SS poses environmental risks when biosolids are applied as fertilizer in agriculture or incinerated for the purpose of energy production. The key problem is the efficient and reliable identification and reduction of MPs in sewage systems, due to the lack of standardized procedures. The reduction methods for MPs might involve physical, chemical, biological, and hydrothermal approaches, including hydrothermal carbonization (HTC). The HTC of SS produces hydrochar (HC), a solid biofuel, and presents a cutting-edge approach that simultaneously addresses secondary microplastic pollution and renewable biomass-derived energy production. In this article, we review briefly the MPs content in biosolids from different countries, and present HTC as a promising method for their removal from SS. In conclusion, HTC (i) effectively reduces the abundance of MPs in biosolids, (ii) produces an improved solid source of energy, and (iii) contributes to circular SS management. [ABSTRACT FROM AUTHOR]

In order to improve the properties of melamine foam (MF), a new polyimide–melamine composite foam (PI–MF) was prepared by microwave irradiation foaming with polyimide microspheres (PI) as a modifier and melamine resin as matrix. The micromorphology, temperature resistance, flame retardant and smoke suppression properties and mechanical properties of the foam were characterized and tested. It was observed by SEM that PI microspheres were closely connected to the skeleton of the MF, FT-IR characterization proved the existence of polyimide in the PI–MF. When the amount of PI microspheres is 30%, the overall performance of PI–MF is better. The temperature of 5% weight loss (T5%) is 326.02°C, the limit oxygen index is 35.48%, the maximum smoke density is 9.21%, the smoke density rank is 5.43, the formaldehyde content is 46.65 mg kg−1, and the elongation at break of the foam is 35.89%. The introduction of PI microspheres has a good effect on the modification of the thermal stability, flame retardant and smoke suppression properties, and mechanical properties of the MF, and has broadened the application range of polyimide. It also provides a new method for the modification of MF. [ABSTRACT FROM AUTHOR]

Mesquite tree gum (Prosopis gum), an agro waste, has been investigated as an innovative flame-resistant material. The extracted mesquite gum is adjusted at three different pH (5, 9 & 12) and applied on selected bleached cotton fabrics. The vertical flammability test and the limiting oxygen index (LOI) have been used to analyse the flame-retardant qualities of cotton (control and finished) fabrics. The mesquite gum finished fabric at alkaline pH (12) shows LOI value of 27%, which is 1.5 times greater than that of the control fabric. Besides, a char length of 85mm indicates self-extinguishment. The char surface morphology indicates that mesquite tree gum preserves fibre integrity. Durability of the flame-retardant property of the treated fabric to washing and rubbing has also been studied. The results of thermal degradation show 35 % weight loss with control cotton fabric against 29% weight loss of the mesquite tree gum finished fabric sample at 900 °C. Hence, mesquite tree gum has a good potential to be a sustainable flame retardant. [ABSTRACT FROM AUTHOR]

Abstract The study presents the chemiluminescence based (CL) evaluation of the recyclability of linear styrene block copolymers. This analysis can provide insight into the material’s degradation state and predict its suitability for further recycling cycles, helping to avoid unnecessary energy consumption during processing.The thermal stability of four similar copolymer structures − styrene-isoprene-styrene (SIS), styrene-butadiene-styrene (SBS) copolymers with different styrene/butadiene ratios, and styrene-ethylene-butadiene-styrene (SEBS) − was studied using isothermal and non-isothermal chemiluminescence (CL). The activation energies for oxidative degradation were calculated based on oxidation induction times indicated by the CL intensities evolution. The results, which highlight the influence of molecular structure on stability under aging conditions, as presented by the calculated for the activation energy (kJ mol−1), show the following sequence: SBS (styrene 30%) (117 kJ mol−1) ≈ SIS 120 (kJ mol−1)

Epoxidized natural rubber with 50 mol% epoxide (ENR-50) was compounded with zinc chloride (ZnCl2) and subjected to torque response analysis using a moving die rheometer. It was found that different ZnCl2 concentrations (3, 5, 7, 9, and 12 millimoles (mmol)) mixed in ENR-50 exhibited positive torque responses, prompting further molecular characterization using Fourier transform infrared spectroscopy. The results indicated distinct absorption peaks at wavenumbers of 442 and 809 cm–1, which signify the presence of –O–Zn–O– coordination linkages. The curing characteristics of ENR and ZnCl2 compounds showed that increasing ZnCl2 content resulted in higher minimum and maximum torque values, but also led to a decrease in scorch time and cure rate index (CRI). Moreover, higher ZnCl2 concentrations enhanced the strength properties (tensile strength, moduli, stiffness, toughness, and hardness), crosslink densities, dynamic shear moduli, initial modulus during relaxation experiments, and thermal resistance, as evidenced by temperature scanning stress relaxation (TSSR), thermogravimetric analysis, and dynamic mechanical analysis. However, an increase in ZnCl2 content led to a reduction in elongation at break due to the higher crosslink density within the coordination networks in the ENR matrix, which resulted in the movement constraint of the rubber vulcanizate.

Abstract The consumption of palm oil has particularly increased in Nigeria due to increased population, lifestyle changes, and its health benefits. The conversion and recycling of the ever-growing food waste from household and commercial is one of the known cost-effective and sustainable management strategies. This study investigates the effect of processing on the physicochemical properties of palm oil. Neat palm oil (NPO) and waste palm oil (WPO) samples, derived from frying four different Nigerian food items, were analyzed to determine changes in their physicochemical properties. The outcome of the investigation reveals that higher temperature during frying and contamination from different food items weakens the molecular structure of the palm oil thereby reducing the quality and stability of the samples which is expressed by the differences in their physicochemical properties. The density, peroxide value, and carbon, hydrogen, and oxygen (CHO) values of NPO were 886 kg/m3, 9.473 meqO2/kg, and 39.233% while that of the WPO samples vary between 3.989–4.692 kg/m3, 10.858–15.362 meqO2/kg, and 52.346–58.468%, for density, peroxide value, and CHO, respectively. The result of the descriptive statistics shows that in the 1 series, the mean ± standard deviation (SD) [coefficient of variation (CV%)] is 119.76 ± 263.87 (220.33%). Both the SD and CV% are greater than the mean; this is due to the heterogeneous nature of the parameter values in the samples. When subjected to inferential statistical analysis, the results show that the error of prediction of relationship in NPO sample versus WPO samples is just 5.290% whereas the reduction in the error is 94.71%. More collaborative investigations are needed to determine the ease of conversion to biodiesel and the properties of biodiesel produced from WPO used to fry different Nigerian food items.

Fibers collected from the husk of areca nut trees were chopped to a length of 30 mm and were either used as such or subjected to alkaline treatment by immersion in a 5% sodium hydroxide (NaOH) solution. The untreated and treated fibers were investigated using thermogravimetric analysis (TGA) before the fabrication of composites using an epoxy matrix. Different amounts of fibers were introduced in the matrix, fabricating the composite by compression molding. The composites were subjected to tensile, flexural, and Charpy impact and Shore D hardness testing, which all demonstrated the considerable advantage obtained with the growing quantity of fibers, especially when employing treated fibers, except in the case of hardness, where limited advantages were encountered. Wear tests were carried out on treated fiber composites and the surface morphology of the worn-out samples was studied, which also demonstrated the improvement in fiber-matrix bonding obtained with the growing amount of fibers. The main limitation of the fibers was their low elongation even after treatment. The fibers hardly reached 4%, which might represent a quite normal value for this kind of fibers, possibly due to with tendency to fibrillation. This would somehow compare these composites with others with similar amounts and lengths of natural fibers.

Abstract Lateritic soils are important to various engineering applications, especially in tropical regions, where they serve as key components in road construction, embankments, and other geotechnical structures. This study investigated the combined effects of elevated temperature and heating duration on the index and engineering properties of lateritic soils derived from two distinct parent rocks (charnockite and quartzite) in Ado-Ekiti, Nigeria. Disturbed lateritic soil samples were heated in a furnace at various temperatures (100, 200, 300, and 400 °C) for two designated durations (2 and 3 h). Standard geotechnical tests were conducted to evaluate Atterberg limits, compaction parameters, and unconfined compressive strength. The results showed that elevated temperature led to a decrease in the plastic limit, liquid limit, plasticity index, optimum moisture content (OMC), and UCS for both soils, though the extent varied between the two parent rocks. For instance, at 400 °C for 3 h, the plasticity index decreased by 47.82% for charnockite-derived soil and 55.22% for quartzite-derived soil. At the same temperature for 2 h, it decreased by 38.79% for charnockite-derived soil and 48.92% for quartzite-derived soil. Similarly, UCS decreased by 29.83% for charnockite-derived soil and 25.97% for quartzite-derived soil at 400 °C for 3 h, while at 400 °C for 2 h, UCS decreased by 21.20% for charnockite-derived soil and 23.48% for quartzite-derived soil. Conversely, maximum dry density (MDD) increased with temperature, rising by up to 20.64% for charnockite-derived soil and 14.66% for quartzite-derived soil at 400 °C for 3 h, and by 18.29% for charnockite-derived soil and 12.62% for quartzite-derived soil at 400 °C for 2 h. Longer heating durations (3 h) generally caused more pronounced changes in soil properties compared to shorter durations (2 h). For instance, OMC decreased by 13.41% for charnockite and 14.18% for quartzite at 400 °C for 3 h compared to a 2-h duration. Statistical analyses indicated that temperature had a significant influence on most properties, while the effect of heating duration was less consistent. These findings highlight the need to consider both temperature and heating duration when evaluating the engineering behavior of lateritic soils exposed to elevated temperatures. Practical implications include potential adjustments in construction practices and design parameters for road construction and embankments in regions prone to high temperatures, such as those experiencing frequent forest fires.

Renewable resources based polymers have been the focus of materials science scientists since they help to protect the environment in addition to reducing the petroleum resources use. Among renewable polymers poly (lactic acid) (PLA) has emerged due to its biodegradable character and proper performance similar to engineering resins, which afford wide field of applications. In this work the thermal degradation of esterified PLA with itaconic acid (PLA ITA) and the biocomposite PLA ITA FLAX was investigated using thermogavimetry (TG) which data were corroborated through Fourier transform infrared spectroscopy (FTIR). Isothermal TGs scans and FTIRs spectra were acquired from 150 to 600°C, collected data evidenced that FLAX improved PLA ITA thermal stability, delaying the decomposition of PLA ITA by up to 100 min at 250°C, ensuring safer processability at higher temperatures. From the deconvolution of the DTG peaks, the peak at lower temperature is suggested to be linked to itaconic anhydride decomposition which undergoes macromolecule dissociation, converting into itaconic anhydride and releasing water and afterwards being converted into citraconic anhydride, while the peak at higher temperature is associated to the thermal degradation of telechelic PLA. Degradation mechanism is proposed, evidenced by changes in the wavelength of CO group under the effect of temperature, as evidenced in TG‐IR spectra. [ABSTRACT FROM AUTHOR]

This study examines the intricate thermal decomposition of sweet sorghum bagasse, an agricultural residue with significant potential as a renewable energy and biofuel feedstock. Both slow and flash pyrolysis has been conducted over a temperature range of 300–450°C and flash pyrolysis experiments were performed through analytical pyrolysis via Py-GC/MS to comprehensively assess the pyrolysis behaviour and elucidate the biomass degradation pathways. In the slow pyrolysis experiments, sweet sorghum bagasse underwent controlled thermal decomposition at different temperatures (300–450°C), allowing for the investigation of the influence of temperature on product yields and compositions. The evolved volatile compounds and biochar products were analyzed to determine the impact of temperature on biomass degradation. The results revealed that 400°C is the optimum pyrolysis temperature for maximizing valuable bio-oil production with approximately 42 wt.% yields with an overall conversion of 73%. Various characterization techniques were employed to analyze the slow pyrolysis products, including GC-MS, TGA, FTIR, SEM, and XRD. Flash pyrolysis was employed to provide a detailed understanding of the rapid biomass breakdown under extreme heating conditions with a heating rate of 20°C/ms to complement the slow pyrolysis findings. This technique elucidated the primary mechanisms responsible for the degradation of sweet sorghum bagasse, shedding light on the fragmentation patterns and the formation of vital intermediate compounds during flash pyrolysis. These insights into the transient phenomena occurring during pyrolysis provide valuable information for developing efficient and sustainable biomass conversion processes. The pyrolysis behaviour of sweet sorghum bagasse (SSB) is comprehensively assessed using TGA, slow pyrolysis via lab scale glass tubular reactor and flash pyrolysis via analytical tool Py-GC/MS from 300–450°C. The study reveals the potential use of SSB as a renewable energy and biofuel feedstock. [ABSTRACT FROM AUTHOR]

Scrimber is processed by laminating wood fiber mats impregnated with phenolic resin under hot pressing. One of its essential components is phenolic resin. In this study, the effect of phenolic resin content on the structural, water-resistant, mechanical, and thermal properties of pinewood scrimbers was investigated. Results showed that phenolic resin facilitated the collapse of cell walls at low pressure during lamination, and higher resin content markedly reduced cell wall cracking. The cellulose I structure of pinewood remained intact, whereas its crystallinity decreased as resin content increased. Moreover, the resin significantly improved water resistance and dimensional stability; an increase in resin content led to a more pronounced improvement. The water absorption in 35 h at a resin content of 15 wt.% was approximately 1/10 of that at 9 wt.%. Scrimbers with a resin content of 9 wt.% exhibited a 50% increase in modulus of rupture (MOR) and a more than 1.4-fold increase in modulus of elasticity (MOE) relative to that of solid pine wood. As the resin content increased, MOR remained stable, MOE slightly decreased, and shearing strength increased. In addition, phenolic resin promoted the thermal degradation of scrimbers, and the higher resin content in the scrimber led to better thermal degradation. [ABSTRACT FROM AUTHOR]

Dibutyl phosphate-bound natural rubber (DBNR) was prepared by reacting epoxidized natural rubber with 20 mol% (ENR-20) with dibutyl phosphate in a latex medium. Fourier transform infrared spectroscopy (FTIR) was used to confirm the molecular structures of ENR-20 and DBNR and to quantify the epoxide contents. The shear flows and thermal properties of DBNR were then characterized and compared with ENR-20 and natural rubber (NR). The DBNR exhibited the lowest viscosity curves, but it depicted the highest glass transition temperature (Tg) and residue from thermogravimetric evaluation, indicating higher thermal resistance. Subsequently, different NR/DBNR blend ratios were compounded, with and without flame resistance additives, compared with unmodified NR and chloroprene rubber (CR) compounds. We found that all natural rubber compounds exhibited reversion behavior due to the breakage of newly formed sulfidic bonds. However, chloroprene rubber showed marching cured curves, as evidenced by the increasing torque with prolonged testing time. Additionally, antimony trioxide retarded the curing reaction of NR, while tris(2-ethylhexyl) phosphate accelerated it. Therefore, the combination of these additives synergists with the intrinsic flame retardant properties of DBNR. The study revealed that the burning rate of NR/DBNR blends, exhibited very high flame resistance capability compared to gum NR and NR compounded with flame resistance additives.

This paper presents a study of the flammability and thermal decomposition products of glass fiber-reinforced epoxy resin (GFRER) with the addition of cardanol-based phosphorus-containing benzoxazine monomer (CBz) and graphene and their combinations in different proportions (up to 20 wt.%). The addition of CBz alone or in combination with graphene resulted in an increase in the limiting oxygen index (LOI) and self-extinguishing in the UL-94 HB test. The flame-retardant samples had better tensile mechanical properties than the sample without additives. The differential mass-spectrometric thermal analysis (DMSTA) of the thermal decomposition products of GFRER without additives and with the addition of CBz and graphene was carried out. CBz addition promoted the thermal decomposition of high-molecular-weight products of epoxy resin decomposition in the condensed phase and at the same time decreased the time of release of low-molecular-weight thermal decomposition products into the gas phase. Graphene addition resulted in an increase in the relative intensities of high-molecular-mass peaks compared to GFRER without additives. [ABSTRACT FROM AUTHOR]

Thermochemical recycling of plastics in the presence of catalysts is often employed to facilitate the degradation of polymers. The choice of the catalyst is polymer-oriented, while its selection becomes more difficult in the case of polymeric blends. The present investigation studies the catalytic pyrolysis of polymers abundant in waste electric and electronic equipment (WEEE), including poly(acrylonitrile-butadiene-styrene) (ABS), high-impact polystyrene (HIPS) and poly(bisphenol-A carbonate) (PC), along with their blends with polypropylene (PP) and poly(vinyl chloride) (PVC). The aim is to study the kinetic mechanism and estimate the catalysts' effect on the activation energy of the degradation. The chosen catalysts were Fe2O3 for ABS, Al-MCM-41 for HIPS, Al2O3 for PC, CaO for Blend A (comprising ABS, HIPS, PC and PP) and silicalite for Blend B (comprising ABS, HIPS, PC, PP and PVC). Thermogravimetric experiments were performed in a N2 atmosphere at several heating rates. Information on the degradation mechanism (degradation steps, initial and final degradation temperature, etc.) was attained. It was found that for pure (co)polymers, the catalytic degradation occurred in one-step, whereas in the case of the blends, two steps were required. For the estimation of the activation energy of those degradations, isoconversional kinetic models (integral and differential) were employed. In all cases, the catalysts used were efficient in reducing the estimated Eα, compared to the values of Eα obtained from conventional pyrolysis. [ABSTRACT FROM AUTHOR]

The management of end‐of‐life tyres faces challenges due to insufficient recycling infrastructure and technologies, as well as limited markets for the materials recovered from them. To mitigate this, waste rubber can be upcycled and used as filler material for polymer matrix composites. Before rubber‐reinforced composites can be certified for fire‐prone applications, their thermal and flammability properties must be understood. This research investigates the effect of rubber fillers on the thermal stability, flammability and flame spread characteristics of epoxy matrix syntactic foam. Thermogravimetric analysis, Fourier Transform Infrared spectrometry (FTIR), scanning electron microscopy and attenuated total reflection FTIR spectrometry were employed to elucidate changes in thermal degradation behaviours. The influence of rubber fillers on the flammability of syntactic foam was assessed using the cone calorimeter. The fire reaction properties of rubber‐reinforced foam were affected by the intensity of the incident heat flux. Regardless of the incident heat flux, an increase in rubber content led to higher total heat release. At the lower heat flux of 35 kW/m2, the fire growth rate increased with rubber content, but at the higher heat flux of 50 kW/m2, the fire growth rate decreased as the rubber content increased. Importantly, all rubber‐reinforced syntactic foams achieved a UL94 HB ranking and exhibited reduced flame spread rates compared to the unmodified foam. This study demonstrated the potential for upcycling waste rubber into sustainable engineering products and expanded the knowledge base on fire reaction properties and flame spread characteristics of such hybrid composite materials. [ABSTRACT FROM AUTHOR]

Hydrogel features can be designed and optimized using different crosslinking agents to meet specific requirements. In this regard, the present work investigates the physico-chemical features of cellulose-based hydrogels, designed by using different epoxy crosslinkers from the same glycidyl family, namely epichlorohydrin (ECH), 1,4-butanediol diglycidyl ether (BDDE), and trimethylolpropane triglycidyl ether (TMPTGE). The effect of the crosslinker's structure (from simple to branched) and functionality (mono-, bi- and tri-epoxy groups) on the hydrogels' features was studied. The performances of the hydrogels were investigated through the gel fraction, as well as by ATR-FTIR, DVS, SEM, DSC, and TG analyses. Also, the swelling and rheological behaviors of the hydrogels were examined. The advantages and limitations of each approach were discussed and a strong correlation between the crosslinker structure and the hydrogel properties was established. The formation of new ether bonds was evidenced by ATR-FTIR spectroscopy. It was emphasized that the pore size is directly influenced by the crosslinker type, namely, it decreases with the increasing number of epoxy groups from the crosslinker molecule, i.e., from 46 ± 11.1 µm (hydrogel CE, with ECH) to 12.3 ± 2.5 µm (hydrogel CB, with BDDE) and 6.7 ± 1.5 µm (hydrogel CT, with TMPTGE). The rheological behavior is consistent with the swelling data and hydrogel morphology, such as CE with the highest Qmax and the largest pore size being relatively more elastic than CB and CT. Instead, the denser matrices obtained by using crosslinkers with more complex structures have better thermal stability. The experimental results highlight the possibility of using a specific crosslinking agent, with a defined structure and functionality, in order to establish the main characteristics of hydrogels and, implicitly, to design them for a certain field of application. [ABSTRACT FROM AUTHOR]

Nanocellulose (CNC) seems to be a promising surfactant, which, together with expandable graphite (EG), forms the essence of an effective natural-based fire-retardant wood coating. In our research, the most suitable composition of the mixture was tested concerning good solubility, dispersion, and consistency. Favorable results were achieved with the formulation composed of a 4% CNC alkaline solution with 80 wt.% of the selected EG. Subsequently, six different types of EG were used to prepare these wood fire-retardant coatings. The effectiveness of treatments was verified using a test with a radiant heat source, where the test samples' relative weight loss, relative burning rate, and surface temperature during 600 s were evaluated. All prepared formulations can be characterized as more or less equally effective. However, the best results were obtained with the EG of GG 200–100 N, where the mass loss of the sample was 8.10 ± 1.24%. Very good results were also achieved by graphite 25 E + 180 HPH (8.70 ± 0.89%), which is similar to the previous one, even according to the microscopic assessment of the coating as well as the expanded layer. The graphite type 25 K + 180 (8.86 ± 0.65%) shows the expanded layer's best adhesion, coating uniformity, and ease of application. The results of this work confirmed that the CNC coating itself has significant retardation effects. [ABSTRACT FROM AUTHOR]

The object of this study is a hybrid energy system that integrates the processes of recycling used tires with the use of alternative energy sources to design a sustainable and environmentally safe power generation system. The problem addressed in this study is to find effective methods for recycling waste tires for electricity generation, as traditional recycling methods are energy-intensive and lead to the loss of valuable resources. Three methods of tire processing have been considered: pyrolysis, thermal degradation, and mechanical grinding. The method of electricity generation using pyrolysis has demonstrated high environ mental performance due to a significant reduction in greenhouse gas emissions and a high rate of renewable energy (80 %). According to the results of the study, the use of 5 MW pyrolysis furnaces in combination with 500 kW solar panels provides a reduction in dependence on fossil sources, reducing CO2 emissions to 50.0 kg/year. The method has high capital costs (NPC USD 4.2 million), but the cost of energy production (COE USD 0.18/kWh) makes this method competitive in the long run. Thermal degradation provides a balanced approach in terms of energy efficiency (75 %) and environmental performance. Although its CO2 emissions are higher than in pyrolysis, the method makes it possible to obtain additional products that could be used in other industries, thereby increasing economic efficiency. Mechanical shredding has the lowest average energy costs (USD 0.12/kWh) and the lowest CO2 emissions (30.0 kg/year), making it ideal for cost-conscious businesses. The study confirms the possibility of effective integration of renewable sources with tire recycling methods. The practical use of the research results is possible during the implementation of grant projects for the recycling of used tires, and in the work of relevant government structures for devising a policy for the disposal of used tires. [ABSTRACT FROM AUTHOR]

Virgin and environmentally aged polypropylene (PP) micropowders (V-PP and E-PP, respectively) were used as reference microplastics (MPs) in comparative photo- and thermo-oxidative ageing experiments performed on their mixtures with a natural ferrous sand (NS) and with a metal-free silica sand (QS). The ferrous NS was found to catalyze the photo-oxidative degradation of V-PP after both UV and simulated solar light irradiation. The catalytic activity in the V-PP/NS mixture was highlighted by the comparatively higher fraction of photo-oxidized PP extracted in dichloromethane, and the higher carbonyl index of the bulk polymer extracted with boiling xylene, when compared with the V-PP/QS mixture. Similarly, NS showed a catalytic effect on the thermal degradation (at T = 60 °C) of E-PP. The results obtained indicate that, under suitable environmental conditions (in this case, an iron-containing sediment or soil matrix, combined with simulated solar irradiation), the degradation of some types of MPs could be much faster than anticipated. Given the widespread presence of iron minerals (including the magnetite and iron-rich serpentine found in NS) in both coastal and mainland soils and sediments, a higher than expected resilience of the environment to the contamination by this class of pollutants is anticipated, and possible routes to remediation of polluted natural environments by eco-compatible iron-based minerals are envisaged. [ABSTRACT FROM AUTHOR]

Employing a thermogravimetric analyzer, the degradation behaviour and kinetics of blends of Nigerian bituminous coal and palm kernel shell (PKS) were studied at temperatures ranging from 30 to 900 0C and with a blend ratio of 10, 20, 30, 40, and 50% weight of PKS. All fuel blends showed a peak devolatilization temperature that was higher than the bituminous coal's, causing a shift in coal devolatilization in the direction of a higher temperature. The maximal rate of mass loss falls as the blend's PKS content rises. Blends of bituminous coal and PKS with ratios of 10% and 20% yielded the lowest maximum rate of mass losses and the lowest peak devolatilization temperature. Furthermore, a blend containing 10% PKS produced the lowest activation energy. The outcomes demonstrated that PKS had a considerable impact on the coal/PKS blends' response rate. The significant impact of PKS structure on coal/PKS blends during co-pyrolysis further demonstrated the synergy between bituminous coal and palm kernel shell. [ABSTRACT FROM AUTHOR]

Polymer gel has been accepted as a useful tool for solving many sealing operations such as fluid loss control, enhanced oil recovery, water and gas shutoff, wellbore integrity, and well stimulation in the upstream of petroleum industry. In a previous study, we used acrylamide (AM), N,N'-Methylenebisacrylamide (MBA), xanthan (XC) and chromium acetate (Cr3+) to obtain ultra-high strength gel (USGel). Some interesting phenomena, such as the more than 10 times increase in gel strength by 0.05% Cr3+ and the counter-conventional decrease in gel strength by inorganic particles such as layered silicate materials (LSM), silicon dioxide nanoparticles (SiO2) and laponite (RDS), have not been well explained. In this paper, the gelation kinetics and mechanism of USGel were investigated mainly by bottle, DSC, infrared spectroscopy, and environmental scanning electron microscopy (ESEM) experiments, which explained that Cr3+ significantly increased the gel strength of USGel, while inorganic particles had a negative effect on the gel strength. The experimental results showed that Cr3+ preferentially cross-linked AM and XC than MBA, and the gelation rates of Cr3+-XC and Cr3+-AM were 107% and 92.9% faster than AM-MBA, respectively. It is speculated that the triple network structure and physical entanglement formed by AM-MBA, XC-Cr3+, and AM-Cr3+ are the main reasons for significant improvement of gel strength by Cr3+, and the cross-linking competition between LSM and Cr3+ and reduction of entanglement number are the main reasons for the significant reduction of gel strength by LSM. This paper provides new insights into the preparation of ultra-high strength gels and the usage of inorganic particles. [ABSTRACT FROM AUTHOR]

Gums and hydrocolloids are two typical biomass wastes commonly found in the most tropical countries. However, despite their enormous potential as energy sources, they are understudied, and their thermal characteristics are still not well known. The main objective of this study was to evaluate the thermal degradation of angico gum. Gum degradation was studied using non-isothermal thermogravimetric analysis and performed under three heating rates (β) constant (5, 15, and 25 °C min−1) in a nitrogen atmosphere. The thermogravimetric curves were used in the kinetic analysis through the methods of Flynn–Wall–Ozawa (FWO), Kissinger, and Coats–Redfern adjustment for the solid-phase reaction mechanism. The FWO method showed stability in the activation energy in the range of a greater mass loss of the gum. The linear regression coefficients were above 0.9 for the FWO and Coats–Redfern methods. In addition, four reaction mechanisms were tested in the Coats–Redfern method and the first-order chemical reaction mechanism showed the best linear regression coefficient. Comparing the literature, angico gum activation energies seems to be close to of cashew tree gum, xanthan, and guar gum. The results obtained in this study can be useful for the development of new composites based on angico gum. [ABSTRACT FROM AUTHOR]

Purpose: NPB-22 (quinolin-8-yl 1-pentyl-1H-indazole-3-carboxylate), Adamantyl-THPINACA (N-(1-adamantantyl)-1-[(tetrahydro-2H-pyran-4-yl)methyl]-1H-indazole-3-carboxamide), and CUMYL-4CN-B7AICA (1-(4-cyanobutyl)-N-(2-phenylpropan-2-yl)-1H- pyrrolo[2,3-b]pyridine-3-carboxamide), synthetic cannabinoids were evaluated in terms of CB1 (cannabinoid receptor type 1) and CB2 (cannabinoid receptor type 2) activities, and their biological effects when inhaled similar to cigarettes were examined. Methods: The half maximal effective concentration values of the aforementioned synthetic cannabinoids at the CB1 and CB2 were investigated using [35S]guanosine-5'-O-(3-thio)-triphosphate binding assays. In addition, their biological effects were evaluated using the inhalation exposure test with mice. The smoke generated was recovered by organic solvents in the midget impingers, and the thermal degradation compounds of the smoke components were identified and quantified using a liquid chromatography–photo diode array detector. Results: NPB-22 and Adamantyl-THPINACA had equivalent CB1 activity in in vitro assays. Meanwhile, NPB-22 had a weaker biological effect on some items on the inhalation exposure test than Adamantyl-THPINACA. When analyzing organic solvents in the midget impingers, it was revealed that NPB-22 was degraded to 8-quinolinol and pentyl indazole 3-carboxylic acid by combustion. In addition, these degradation compounds did not have CB1 activity. Conclusion: It was estimated that the biological effects of NPB-22 on the inhalation exposure test weakened because it underwent thermal degradation by combustion, and the resultant degradation compounds did not have any CB1 activity in vitro. [ABSTRACT FROM AUTHOR]

Impregnation of potassium can enhance thermal decomposition and thermal reactions of biomass. In this study, the addition of potassium to biomass using potassium carbonate (K2CO3) was investigated to better understand the effects of solution concentration and impregnation time on the pretreatment process of as-received (macro-scale) sugarcane bagasse (SCB). The morphology and thermal degradation of SCB were characterized by FTIR, XRD, and TGA. Following that, the optimal condition was determined by using response surface methodology (RSM). As a result, K2CO3 significantly disorders the cellulose structure and the thermal decomposition temperature of impregnated SCB which is lower than the untreated bagasse in the difference of 25–57 °C. In addition, K2CO3 has a significant impact on char formation, which results in increased char yield. In summary, the RSM results suggest that the appropriate condition for K2CO3 pretreatment is at the solution concentration of 0.25 M and impregnation time of 60 min, resulting in the lowest crystallinity index (59.88%) with an acceptable value of activation energy (77.98 kJ/mol). Furthermore, it is recommended that K2CO3 pretreatment condition is required to apply for SCB before undergoing the torrefaction process, which could practically improve the torrefaction of SCB for a biomass power plant application. [ABSTRACT FROM AUTHOR]

Chickpeas are more sustainable than other food systems and have high a nutritional value, especially regarding their vitamin composition. One of the main vitamins in chickpeas is vitamin B6, which is very important for several human metabolic functions. Since chickpeas are consumed after cooking, our goal was to better understand the role of leaching (diffusion) and thermal degradation of vitamin B6 in chickpeas during hydrothermal processing. Kinetics were conducted at four temperatures, ranging from 25 to 85 °C, carried out for 4 h in an excess of water for the diffusion kinetics, or in hermetic bags for the thermal degradation kinetics. Thermal degradation was modeled according to a first-order reaction, and diffusion was modeled according to a modified version of Fick's second law. Diffusivity constants varied from 4.76 × 10−14 m2/s at 25 °C to 2.07 × 10−10 m2/s at 85 °C; the temperature had an impact on both the diffusivity constant and the residual vitamin B6. The kinetic constant ranged from 9.35 × 10−6 at 25 °C to 54.9 × 10−6 s−1 at 85 °C, with a lower impact of the temperature. In conclusion, vitamin B6 is relatively stable to heat degradation; loss is mainly due to diffusion, especially during shorter treatment times. [ABSTRACT FROM AUTHOR]

In this study, Schiff bases (SCH-1 and SCH-2) were synthesized from the condensation reaction of 2-aminobenzothiazole with 3-hydroxy-4-methoxybenzaldehyde and 3-hydroxy-4-ethoxybenzaldehyde. Poly(phenoxy-imine)s were synthesized from Schiff bases via oxidative polycondensation by NaOCl (6–14% aqueous solution) as oxidant in alkaline medium and H2O2 (35% aqueous solution) as oxidant in THF medium. The structures characterizations of Schiff bases and poly(phenoxy-imine)s were confirmed by FT-IR, 1H and 13C NMR, CV, UV–Vis and TGA analyses. Limit oxygen index (LOI) and the heat resistance index (THRI) temperature were determined from thermogravimetric measurements of compounds. P-SCH-2-A showed the highest LOI as 45.50 with self-extinguishing according to other polymers (18–30). The optical band gap of P-SCH-2-A was determined to be 1.99 eV. Additionally, the optical band gap energy of compounds were calculated by using the Tauc method. According to the Tauc method, the optical band gap (Eg) value of P-SCH-2-A was calculated to be 2.20 eV. The glass transition temperatures (Tg) and surface properties of poly(phenoxy-imine)s were determined from DSC and SEM analyses, respectively. The weight average molecular weight (Mw) values of P-SCH-1-O, P-SCH-2-O, P-SCH-1-A and P-SCH-2-A were calculated to be 7400, 8400, 3100 and 19,100 g mol−1 from gel permeation chromatography (GPC) measurements. [ABSTRACT FROM AUTHOR]

CO2 capture by absorption and stripping with aqueous amine is a well‐understood and widely used technology. However, drawbacks still exist in the practical applications, such as high energy consumption and easy degradation of the absorbents during the desorption process. In this paper, a novel NE‐1 absorbent was developed, and its suitable operating conditions were determined: concentration (45 wt.%), absorption temperature (40 °C), and desorption temperature (100 °C). The NE‐1 absorbent exhibits a high CO2 absorption capacity of 3.73 mol/kg, 1.33 times that of 30% monoethanolamine (MEA). After optimizing with carbamide as a corrosion inhibitor, 45% NE‐1a1 may attain an effective CO2 capacity of 2.5 mol/kg and over 70% desorption rate in five cycles, demonstrating excellent cycling stability performance. The research results have significant implications for developing an efficient and stable commercial carbon capture solvent and promoting the development of carbon reduction technologies. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In the interaction of high-molecular ammonium polyphosphate with polyethylene polyamine, thermoplastic polymers with Tg = 46.3–50.7°C, Tsoft = 43–92°C, and Tflow = 85–152°C are obtained. Thermal heat resistance, moisture resistance, and the degree of crystallinity depending on the concentration of polyethylene polyamine are measured. The bending strength of polymers and reinforced composites is measured. A chemical scheme for the formation of a polycomplex is proposed and its structure is considered. [ABSTRACT FROM AUTHOR]

In this study, a novel fluorine-containing carbon nanosphere was synthesized by high-temperature carbonization of waste fluororubber trimmings, and its mixing method with fluororubber was investigated. It was found that the solution mixing method resulted in the highest tensile strength (7.6 %) and modulus at 100 % strain (13.3 %) of fluororubber compared to the mechanical mixing method. Furthermore, the addition of fluorine-containing carbon nanosphere can significantly enhance fluororubber's heat resistance, inhibit its thermal degradation, and increase its ultimate service temperature (266.3 °C, 2 years). This work provides new insights into the preparation of high-performance fluororubber composites.