Non-isothermal Degradation Kinetics Research Articles

Multistep kinetic analysis of additive-enhanced plastic degradation

In the realm of non-isothermal degradation kinetics, the utilization of multi-heating rate data has unveiled a fascinating distributed apparent activation energy (Eα) profile when employing isoconversional methods. The advanced isoconversional method (AIC) emerges as a reliable tool, offering Eα values that evolve as chemical reactions progresses. This phenomenon finds its roots in the complex solid-state degradation of plastics, where long-chain hydrocarbons undergo intricate transformations into smaller components through a web of parallel and sequential reactions under the influence of heat. To comprehensively characterize this multifaceted kinetic process, variable pre-exponential factor (A) values were calculated, considering all available heating rate data, in conjunction with the isoconversional principle. These factors complement the changing Eα values, providing crucial insights into the evolving material transformations throughout the reaction. Remarkably, our investigation revealed that in the initial degradation stage, centered around the breakdown of Brominated Flame Retardant (BFR), the reaction follows a contracting spherical model (R3). Transitioning to the subsequent stage, the polymer material undergoes degradation following the diffusion model D4. The incorporation of the isoconversional principle and Criados' masterplot technique effectively facilitates the precise determination of all three kinetic parameters. The process layout we present holds considerable promise for advancing the understanding and control of complex kinetic phenomena.

Mechanical Properties, Morphological Characterization and Melt Dripping Studies of Polypropylene (PP) + High Density Polyethylene (HDPE) + Polystyrene (PS) Ternary Polymer Blends: Non-Isothermal Degradation Kinetics of Compatibilized and Uncompatibilized Blends

Polymer composites have been widely used due to its light weight, performance with good mechanical properties, corrosion resistant, solvent resistance and it becomes an important part of the industries. Polypropylene (PP), polystyrene (PS) and high-density polyethylene (HDPE) are applied to various commercial as well as automobile spare parts. In this study PP, PS and HDPE were melt mixed together to form a ternary polymer blend and mechanical, morphological, thermogravimetric analysis were conducted to determine its potential applications. The compatibilization of the blend was achieved by the combination of ethylene-propylenediene- monomer (EPDM) and styrene-ethylene-butylene-styrene (SEBS). Model free methods like Flynn Wall Ozawa (FWO), Kissinger-Akahira- Sunose equation (KAS) and Friedman methods were applied to estimate the activation energy values at different heating rates of 5, 10 and 15 ºC/min. The compatibilized blend of 80PP/5PS/15HDPE with 5% SEBS/EPDM showed better tensile strength compared to uncompatibilized. Freidman method produced a higher value of average activation energy as 203.4 kJ/mol. The melt dripping characteristics was also analyzed were the time to ignition and time for first drip was found to be in the range of 6 to 9 s and 14-16 s. Pure and compatibilized blends showed a very low limiting oxygen index (LOI) values as in the range of 18.7 to 18.9. Elastomeric/rubber blend compatibilization was achieved and the material can be applied to light weight automobile applications. From morphological characterization, it was understood that compatibilized blends are more durable and easily transfer the stress uniformly through the interface. This compatibilized blend can also be used in low temperature regions.

Porous‐structured vermiculite/polybutylene adipate terephthalate composite films: The morphology, mechanical properties, and nonisothermal degradation kinetics

AbstractTo examine the impact of vermiculite (VMT) on the environmental and physical aspects of polybutylene terephthalate (PBAT), the thermal degradation behavior of VMT/polybutylene terephthalate polyadipate (VMT/PBAT) composite films was investigated by using the thermogravimetric analysis (TGA). To ensure precise calculation of the specific activation energy values of VMT/PBAT composite films in thermal degradation performance experiments, the Kissinger method (K‐method) and Flynn–Wall–Ozawa method (FWO method) were utilized. Additionally, the reaction mechanism was analyzed using the Coats–Redfern equation (CR equation). The introduction of VMT into the PBAT co‐polyester structure leads to an increase in the thermal degradation activation energy Ek of composite films.; the apparent activation energies were calculated by the Coats–Redfern method for different reaction mechanisms, and the interfacial diffusion reaction mechanism of the composite film was determined, with a thermal degradation reaction principle properties of g(α) = [1 − (1 − α)]2 and the number of reaction steps of 2.Highlights VMT/PBAT composite films prepared using a simple method. Analyzing nonisothermal degradation kinetics using K‐method and FWO method. Analyzing the degradation mechanisms using the Coats–Redfern equation. Addition of VMT enhances the thermal degradation properties of composite films. Addition of VMT reduces the mechanical properties of the composite film.

Synthesis, characterization and non-isothermal degradation kinetics of rose Bengal end capped poly(aniline)/Cr2O3 nanocomposite

Synthesis, characterization and non-isothermal degradation kinetics of rose Bengal end capped poly(aniline)/Cr2O3 nanocomposite

The Effect of Polyepoxyphenylsilsesquioxane and Diethyl Bis(2-hydroxyethyl)aminomethylphosphonate on the Thermal Stability of Epoxy Resin.

Polyepoxyphenylsilsesquioxane (PEPSQ) and diethyl bis(2-hydroxyethyl) aminomethylphosphonate (DBAMP) can improve the flame retardancy of epoxy resin (EP). In this paper, the results of the limiting oxygen index (LOI) and UL94 tests exhibited that PEPSQ and DBAMP had good synergistic flame retardancy. The non-isothermal degradation kinetics of EP containing PEPSQ and DBAMP was investigated by the Kissinger and Flynn-Wall-Ozawa methods. The results of the Kissinger method displayed that the addition of two flame retardants, PEPSQ and DBAMP, can slightly enhance the activation energy of EP, indicating that the additives delayed the thermal degradation of EP. The Flynn-Wall-Ozawa method further confirmed that the activation energy of EP during the whole thermal degradation process can be significantly increased by addition of the two flame retardants PEPSQ and DBAMP. When the degree of conversion exceeded 80%, the increase was more significant. This illustrated that the flame retardants finally achieved the purpose of improving the flame retardancy of EP by stabilizing the char layer.

Thermogravimetric properties and degradation kinetics of biomass during its thermochemical conversion process

Developing a low-cost disruptive technology for producing high-quality eco-friendly biofuel has become the prime focus of achieving environmental harmony. As a research effort to achieve this, the non-isothermal degradation kinetics, and the thermogravimetric properties of pine sawdust (PSD) during its thermochemical conversion were studied. The Kissinger-Akahira-Sunose (KAS) and Friedman model-free methods were employed to estimate the parametric degradation kinetics of PSD. In contrast, the integral master plot models were used to evaluate the process's most effective reaction model. The kinetic model was studied over a 10–75% conversion range and heating rates of 10, 15, and 20 K/min. The estimated activation energies for the KAS and Friedman methods were 93.33–309.18 kJ/mol and 98.31–313.60 kJ/mol, respectively. The degradation process's average activation energy was 168.21 kJ/mol using the model-free techniques. It was found to lie between 156.34 and 183.36 kJ/mol using the F6 and F7 integral master-model. Hence, the differential form f∝=1-∝6-7 described the thermal degradation of pine sawdust. Experimental observations obtained from this study will pave the way for further exploration of biomass as an energy source and provide vital information on designing an optimized thermochemical conversion reactor by modeling biomass's devolatilization process.

Silane‐functionalized Al2O3‐modified polyurethane powder coatings: Nonisothermal degradation kinetics and mechanistic insights

AbstractThis work reports on nonisothermal degradation kinetics of polyurethane (PU)‐based powder coatings containing 1, 3, and 5%wt% vinyltrimethoxysilane functionalized Al2O3 (V‐Al2O3) nanoparticles. Thermogravimetric analysis of PU/V‐Al2O3 powder coatings with different V‐Al2O3 contents has been performed at different heating rates. Variation of activation energy (Ea) of PU/V‐Al2O3 powder coatings was modeled as a function of partial mass loss by using Kissinger–Akahira–Sunose, Ozawa–Wall–Flynn and modified Coats–Redfern isoconversional approaches. The results revealed hindered decomposition process of PU/V‐Al2O3 nanocomposite powder coatings, featured by an increase in activation energy of degradation from ∼158 for blank PU to 225, 183, and 229 kJ/mol for nanocomposites filled with 1, 3, and 5 wt% of V‐Al2O3, respectively. Likewise, pre‐exponential factor values increased for samples containing V‐Al2O3 nanoparticles compared to that of blank sample. Sestak–Berggren kinetic model appropriately captured thermal degradation behavior of PU/V‐Al2O3 nanocomposites than that of nth order decomposition kinetic reaction models.

Determination of activation energy during the thermal degradation of Polyamide 66/glass fiber composites

The objective of this study was to clarify the mechanical properties and the non-isothermal degradation kinetics of Polyamide 66 (PA 66)/glass fiber (GF) composites. The non-isothermal degradation behavior of the samples was studied by thermal gravimetric analysis under nitrogen purge. The perfect compatibility of GFs with polymer matrix in composites was studied by scanning electron microscopy. It was found that with increasing content of GFs in samples due to good distribution of fibers in PA 66, the degradation temperature and calculated activation energy in composites increased in all heating rates. The activation energy was calculated by the Flynn–Wall–Ozawa method (isoconversional method). It was concluded that the model-free methods can be a reliable way to determine the kinetic parameters. Furthermore, the isokinetic relationship was used to estimate a model-independent pre-exponential factor (ln A) corresponding to a given degree of conversion.

Synthesis, characterization and non-isothermal degradation kinetics of poly(ε-caprolactone)/Fe3O4-dye nanocomposites

Congo red (CR) dye functionalized magnetic nanoparticle was synthesized and characterized by Fourier Transform Infra Red, UV–visible, fluorescence emission spectra, field emission scanning electron microscopy and vibrating sample magnetometry like analytical techniques. The prepared nanohybrid was chemically tagged with poly(e-caprolactone) (PCL) via ring opening polymerization of e-caprolactone. The PCL/Fe3O4–CR nanocomposites were characterized by the same techniques and differential scanning calorimetry and thermogravimetric analysis methods. The magnetic moment values of the Fe3O4 after the formation of the nanohybrid and nanocomposite were found to be reduced due to the encapsulation and surface functionalization effects. The magnetic moment value of Fe3O4 was decreased for the nanohybrid and nanohyrbid tagged PCL. The non-isothermal degradation kinetics was characterized in order to find out the energy of activation (Ea) for the thermal degradation of the PCL. For the sake of comparison, the non-isothermal degradation kinetics of the methylorange functionalized Fe3O4 end capped PCL was carried out and the results were critically compared.

Non-isothermal degradation kinetics of novel poly(monoethyleneglycol dimethacrylate-co-anthranilic acid cinnamoyl ester) synthesized via aza-Michael addition polymerization reaction

A new type of co-polymer between anthranilic acid cinnamoyl ester and monoethyleneglycol dimethacrylate was synthesized via aza-Michael addition polymerization reaction by bulk polymerization method without adding any catalyst. The polymerization reaction was carried out at 100 °C for 2 h under N2 atmosphere with mild stirring. The co-polymer was synthesized at various monomer ratios. The above-synthesized co-polymer was characterized by Fourier transform infrared (FTIR) spectroscopy, UV–visible reflectance spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy, etc. The FTIR data confirmed the 0.032 order of reaction with respect to [M1/M2]. The amorphous nature of the above-synthesized polymer was confirmed by XRD. The non-isothermal degradation kinetics was followed at five different heating rates with five different models. The goal of the present work is to compare the results from TGA data and select the best approach for the synthesized polymer. The activation energy (Ea) values were also determined by model-free methods. The experimental results were carefully analysed and compared with the literature values.

Bis(isomaleimide) and diphenol blends: Non-isothermal degradation kinetics and TG-FTIR studies

Blends of 4,4′-bisisomaleimidodiphenyl methane (VS) with structurally different diphenols are made in 1:1 molar ratio and thermally polymerized. Thermogravimetric studies of the cured materials show that the thermal stability, the degradation pattern and the char yield are much dependent on the structure of the diphenol that is used for blending. The decreased thermal stability of materials from the blends is attributed to decreased cross links owing to the opening of the isomaleimide rings by diphenols during thermal polymerization. The materials with trimethylphenylindane and tetramethylspirobiindane units exhibit char residue of 21% at 800°C. This is due to the thermal stability of the indane and spirobiindane moieties present in the diphenol molecules. The apparent activation energy for thermal degradation ( Ea-D) and pre-exponential factor (ln A) are derived. The Friedman, corrected Flynn–Wall–Ozawa, corrected Kissinger–Akahira–Sunose and advanced Vyazovkin methods are used to calculate the Ea-D values for various reaction extents ( αs). The Ea-D values of poly(4,4′-bisisomaleimido-diphenyl methane) vary from 168 to 226 kJ mol−1. A slight decrease in Ea-D is noted for the initial α levels and increases constantly up to α = 0.3–0.75 and then the Ea-D values decrease with increasing α values. The highest values of Ea-D and ln A are observed for the polymer derived from the blend of VS with tetramethylspirobiindane diphenol. The volatile products obtained during the thermal degradation of these polymers are analysed using thermogravimetry–Fourier transform infrared (TG-FTIR) spectroscopy. The TG-FTIR studies showed the compounds carbon monoxide, carbon dioxide and aromatic amines are the major degradation products from the polymerized blends.

Characterization, thermal degradation kinetics, and morphological properties of a graphene oxide/poly (vinyl alcohol)/starch nanocomposite

In this study, we synthesized a biodegradable nanocomposite containing starch, polyvinyl alcohol (PVA), and graphene oxide (GO). The non-isothermal degradation kinetics of this nanocomposite was investigated by thermogravimetric analysis. Accordingly, the kinetic parameters, such as activation energy (Ea), exponential factor (A), rate constant (k), and degradation time, were calculated. The calculated kinetic parameters are used to predict the lifetime. The master plot analysis showed that the kinetic function of the thermal degradation changed from A2 to A3 upon addition of GO to the PVA/starch blend. The reaction heat (ΔH), glass transition temperature (Tg), and melting point (Tm) of the PVA/starch film and PVA/starch/GO nanocomposite were determined by the differential scanning calorimetry analysis. Also, the Tg values were determined by dynamic mechanical thermal analyzer. The changes in peak bandwidth, strength, and frequency in the samples are identified by FTIR spectra. The structure and morphology of the nanocomposite were studied by X-ray diffraction analysis and field emission scanning electronic microscope.

Thermal degradation behaviour and crystallization kinetics of poly (lactic acid) and cellulose nanocrystals (CNC) based microcellular composite foams

The current investigation addresses the thermal degradation and non-isothermal crystallization behaviour of the fabricated poly (lactic acid) foam (nPLA) and poly (lactic acid) (PLA)/cellulose nanocrystal (CNC) based foams at three different loadings of CNC (i.e. 1%, 2% and 3%) as PLA/CNC 1, PLA/CNC 2 and PLA/CNC 3 having highly porous, interconnected and microcellular morphology. The formation of various gaseous products at two different conversions (α = 0.3 and α = 0.7) are investigated by using thermogravimetric analyser hyphenated Fourier transmission infrared spectroscopy (TGA-FTIR) analysis in isothermal condition. Effect of porosity and CNC reinforcement towards thermal degradation and crystallization of the PLA is thoroughly investigated by using mercury intrusion porosimetry (MIP). “Model-free” and “modelistic” approaches like Friedman, Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sinouse (KAS), Kissinger and Augis & Bennet have been utilized for non-isothermal degradation kinetics of the fabricated foams. Non-isothermal melt crystallization kinetics of fabricated foams reveals that both primary and secondary crystallization process taking place. The apparent activation energy calculated from FWO are ~175.8 kJ/mol, ~198.6 kJ/mol, ~175.5 kJ/mol and ~174.7 kJ/mol for nPLA, PLA/CNC 1, PLA/CNC 2 and PLA/CNC 3 respectively. It is also observed that at higher conversions, complex three dimensional diffusion mechanism of degradation might be taking place in accordance with Criado plots.

Non-isothermal degradation kinetics of Ethylene-Vinyl Acetate Copolymer nanocomposite reinforced with modified Bacterial Cellulose Nanofibers using advanced isoconversional and master plot analyses

The non-isothermal degradation kinetics of Ethylene-Vinyl Acetate (EVA) Copolymer containing modified Bacterial Cellulose Nanofibers (MBC) was reported to determine its service temperature. The apparent activation energies are estimated using advanced isoconversional and various model-free methods, which indicate the two-stage degradation mechanism. The kinetic mechanisms are determined using the differential f(α) and combined Z(α) master plots by comparing the experimental plot with the theoretical master curves. The results on ‘FZ master plots’ reveal that the degradation proceed via D2 mechanism in the range of (α≤0.3) exhibiting that the simultaneous acetate groups and MBC degradations is controlled by two-dimensional diffusion of the volatiles. However, for (α≥0.3) there is a gradual change to F1 mechanism that means the scission of the residual main chains of EVA is performed by random nucleation with one nucleus on the individual particle. The calculated kinetic triplets are used to predict the lifetime.

Thermocatalytic Conversion of Automotive Shredder Waste and Formation of Nanocarbons as a Process Byproduct

Thermocatalytic conversion of plastic wastes using titanium dioxide (TiO2) is a novel and promising approach for waste management and sustainable production of materials. In this approach, the heat-treatment of a mixture of plastic waste and TiO2 at elevated temperatures helps to achieve fast and complete decomposition and offers several advanced byproducts. In this study, the different physicochemical interactions between TiO2 and an industrial plastic waste (i.e., automotive shredder residue, ASR) at elevated temperatures were investigated. The nonisothermal degradation kinetics of ASR, with and without TiO2, were calculated from the thermogravimetric analysis (TGA) and results confirmed that the TiO2 influences and catalyzes the degradation of ASR. The analysis of the resulting gas showed that the TiO2 limits the formation of CO2 gas, which is considered an unfavorable product of thermal processes, without changing the quality of the hydrocarbons (i.e., oils) generated during the heat treatment of ASR. While ASR decomposes, TiO2 transforms into value-added Ti-based ceramics; this transformation generates a high yield of CO that can be collected for commercial purposes. In addition, TiO2 led to the formation of considerable quantities of onion-like carbon nanoparticles (OLC-NPs) from the gas phase; this product was characterized and its formation mechanism was discussed.

Synthesis, characterisation and non-isothermal degradation kinetics of novel poly(mono ethylene glycol dimethacrylate-co-4-aminobenzoate)

Synthesis of a novel co-polymer made by the addition polymerisation between MEGDMA and 4-AB by aza-Michael addition (AMA) polymerisation method is a fascinating field of research. The present investigation yielded a hazardous metal catalyst-free and toxic solvent-free methodology. The AMA polymerisation was carried out at five different [ M 1/M 2] values under N2 atmosphere at 100∘C for 2 h. Thus, obtained co-polymer was characterized by Fourier transform infrared spectroscopy, UV–visible reflectance spectroscopy, X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis and scanning electron microscopy (SEM). The SEM image confirmed the formation of polymer nanoparticles. The non-isothermal degradation kinetics was followed with four different models, such as Flynn-Wall-Ozawa, Auggis-Bennet, Kissinger and Friedman method. Among the models used, the Kissinger method yielded the lowest degradation kinetics. The degradation kinetics of the co-polymer was followed with the help of model-free methods. Moreover, it was critically compared with the literature.

Thermal degradation behaviour of nanoamphiphilic chitosan dispersed poly (lactic acid) bionanocomposite films

In the present study, nano-amphiphilic chitosan termed as chitosan-grafted-oligo l-lactic acid (CH-g-OLLA), is synthesized by microwave initiated insitu condensation polymerization. The synthesized CH-g-OLLA becomes hydrophobic in nature due to chemical bond formation between chitosan backbone and OLLA chains. Further, CH-g-OLLA (30%) bionanocomposite is used as a nanofiller in poly (lactic acid)/chitosan-grafted-oligo l-lactic acid (PLA/CH-g-OLLA) bionanocomposite films. Surface morphology shows a homogeneous dispersion of CH-g-OLLA in the form of spherical aggregates, which vary in the range of ∼20 to 150nm. Non-isothermal degradation kinetics, proposed by Kissinger, Kissinger-Akahira-Sunose, Flynn-Wall-Ozawa and Augis & Bennett models, are utilized to estimate the activation energies (Ea) for PLA, which are 254.1, 260.2, 257.0 and 259.1kJmol−1 respectively. The reduction in Ea values of bionanocomposite films may be elucidated by intermolecular distance and enrichment in chain mobility. The evolved gaseous products like hydrocarbons, carbon dioxide, carbon monoxide and cyclic oligomers are successfully identified with TG-FTIR analysis.

Nonisothermal Degradation Kinetics and Life Prediction of the Pendent Phenyl-Containing Polyarylate

ABSTRACTThe nonisothermal degradation kinetics of a pendent phenyl-containing polyarylate (PAR-P)were studied using different kinetic models, including the Kissinger method, Flynn–Wall–Ozawa (FWO) method, and Coats–Redfern (CR) method. The “three kinetic factors” of degradation, namely, activation energy (E), pre-exponential factor (A), and the reaction mechanism function (f(α)) were determined by these methods. Moreover, the lifetime equations of PAR-P were deduced, and its lifetime was predicted. The Kissinger method could be used to describe the nonisothermal degradation of PAR-P, and the results indicated that PAR-P could be degraded more easily in air than in nitrogen. The FWO method was expected to give more reliable values of the activation energy (209.71 kJ·mol−1 in nitrogen and 176.22 kJ·mol−1 in air) due to not having to introduce the reaction mechanism function during the calculation. According to the results of the CR method, the thermal degradation reaction mechanism was probably the R1 model in nitrogen, while it was likely to be the F2 model in air. The long-term and short-term use temperatures of PAR-P in air were 260°C and 300°C, respectively. The lifetime of PAR-P in nitrogen was much longer than that in air at low temperature, but had little difference when the use temperature exceeded 260°C. Although the lifetime of PAR-P obtained from the present work was unrealistic due to probable contributions from other unconsidered factors and being determined by a single factor method, it still could play a guiding role for designing the structure and determining the use conditions of the material.

Non-Isothermal Degradation Kinetics of Asphalt in Relation to its Chemical Composition

Analysis of the complex and variable nature of the chemical composition of asphalt has been a challenge to engineers and scientists, especially as a means to understand its behavior and suggest ways to improve its properties. In this study, the thermal behavior and the non-isothermal degradation kinetics were analyzed using the isoconversional methods, through Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC). TGA and DSC data show gradual change in the mass of the material at increasing temperature, suggesting behavior typical of a homogenous mixture. Kinetic analysis from the TGA data using the Starink modification of the Kissinger-Akahira-Sunose Isoconversional method show an apparent increase in the magnitude of the activation energies at different conversion degree, which suggests a gradual change in the composition of the material at each successive conversion due to a single heat-promoted transformation of each of the components.

From automotive shredder residue to nano-ceramics and graphitic carbon—Thermal degradation kinetics

Automotive shredder residue (ASR) has become a challenging problem due to its large and increasing production volumes. ASR consists primarily of plastics of high calorific value, making its processing by thermochemical processes a viable solution. The aim of this study is to develop a new sustainable approach, in which syngas, tars and valuable nano-ceramics can be generated from the fast and high-temperature pyrolysis of ASR. This work consists of two parts; in the first part, the characteristics and kinetics of ASR non-isothermal degradation were studied by correlating the thermogravimetric data via four models namely, Coats–Redfern model, Freeman and Carroll model, distributed activation energy model (DAEM) and Flynn–Wall–Ozawa model (FWO). Coats–Redfern model was not applicable to obtain the kinetic parameters of ASR pyrolysis, while the other models gave nearly similar and reasonable results. In the second part, ASR was treated by fast pyrolysis at 1550°C and the carbonaceous residues were analysed. The carbonaceous residues were found to contain reasonable quantities of TiN and SiC nanoparticles that can be valuable precursors to produce hard ceramics for many applications. Other materials such as graphite and calcium magnesium aluminosilicate microspheres coated with TiN were also identified in the carbonaceous residues.