Criado Method Research Articles

Utilization of Waste Bamboo Fibers in Thermoplastic Composites: Influence of the Chemical Composition and Thermal Decomposition Behavior.

In this study, four types of waste bamboo fibers (BFs), Makino bamboo (Phyllostachys makinoi), Moso bamboo (Phyllostachys pubescens), Ma bamboo (Dendrocalamus latiflorus), and Thorny bamboo (Bambusa stenostachya), were used as reinforcements and incorporated into polypropylene (PP) to manufacture bamboo–PP composites (BPCs). To investigate the effects of the fibers from these bamboo species on the properties of the BPCs, their chemical compositions were evaluated, and their thermal decomposition kinetics were analyzed by the Flynn–Wall–Ozawa (FWO) method and the Criado method. Thermogravimetric results indicated that the Makino BF was the most thermally stable since it showed the highest activation energy at various conversion rates that were calculated by the FWO method. Furthermore, using the Criado method, the thermal decomposition mechanisms of the BFs were revealed by diffusion when the conversion rates (α) were below 0.5. When the α values were above 0.5, their decomposition mechanisms trended to the random nucleation mechanism. Additionally, the results showed that the BPC with Thorny BFs exhibited the highest moisture content and water absorption rate due to this BF having high hemicellulose content, while the BPC with Makino BFs had high crystallinity and high lignin content, which gave the resulting BPC better tensile properties.

Study of the kinetic behaviour of biomass and coal during oxyfuel co-combustion

In this study, the thermogravimetric analysis (TGA) method has been used to evaluate the kinetic behavior of biomass, coal and its blends during oxyfuel co-combustion. The thermogravimetric results have been evaluated by the Coats–Redfern method and validated by Criado's method. TG and DTG curves indicate that as the oxygen concentration increases the ignition and burn out temperatures approach a lower temperature region. The combustion characteristic index shows that biomass to coal blends of 28% and 40% respectively can achieve enhanced combustion up to 60% oxygen enrichment. In the devolatilization region, the activation energies for coal and blends reduce while in the char oxidation region, they increase with rise in oxygen concentration. Biomass, however, indicates slightly different combustion characteristic of being degraded in a single step and its activation energies increase with rise in oxygen concentration. It is demonstrated in this work that oxygen enrichment has more positive combustion effect on coal than biomass. At 20% oxygen enrichment, 28% and 40% blends indicate activation energy of 132.8 and 125.5 kJ·mol−1 respectively which are lower than coal at 148.1 kJ·mol−1 but higher than biomass at 81.5 kJ·mol−1 demonstrating synergistic effect of fuel blending. Also, at char combustion step, an increase in activation energy for 28% blend is found to be 0.36 kJ·mol−1 per rise in oxygen concentration which is higher than in 40% blend at 0.28 kJ·mol−1.

Thermal degradation of rice husk: Effect of pre-treatment on kinetic and thermodynamic parameters

Pyrolysis of untreated, acid treated and alkali treated rice husk (URH, ARH and ALRH, respectively) was investigated. Pre-treatment resulted in change in values of proximate and ultimate analyses parameters, gross calorific values and cellulose, hemi-cellulose and lignin contents. Thermal degradation experiments were carried out from ambient to 800 °C at heating rates of 5, 10 and 15 °C/min in presence of nitrogen (flow rate 50 mL/min). Analysis of the pyrolysis data was carried out using, Flynn – Wall – Ozawa (FWO), Kissinger – Akahira – Sunose (KAS) and Starink iso-conversional models. The activation energy was estimated to be 219.67, 220.09 and 218.83 kJ/mol using FWO model; 222.18, 222.69 and 227.98 kJ/mol using KAS model and 222.19, 223.57 and 228.38 kJ/mol using Starink model for URH, ARH and ALRH, respectively. Thermodynamic parameters (ΔH, ΔG, ΔS) were also evaluated in each case. Effect of pre-treatment on the pyrolysis reaction mechanism was predicted using Criado method. The results indicated that pre-treatment of RH improved its thermal degradation process.

Non-isothermal kinetic study of fodder radish seed cake pyrolysis: performance of model-free and model-fitting methods

The scientific community has shown concern about the suitable application of different methods (model-free/model-fitting) for the determination of kinetic parameters. The application of an unsuitable method may lead to unreliable kinetic parameters. In this study, the performance of five methods for the determination of the kinetic parameters of fodder radish seed cake (FRSC) pyrolysis was evaluated. This is the first detailed study of the pyrolysis kinetics of FRSC. The characterization was performed through thermogravimetric analysis at different heating rates (5, 10, and 25 K/min) and temperatures ranged from 298 to 1073 K. Four model-free isoconversional methods (Friedman, Kissinger, Kissinger–Akahira–Sunose and Flynn–Wall–Ozawa) were used to determine the activation energy. A model-fitting (five pseudo-components model—FPCM) method was used to obtain the kinetic parameters of fodder radish seed cake pyrolysis. A detailed evaluation of the performance of these methods to estimate the kinetic parameters of fodder radish seed cake pyrolysis was performed. The Criado method was applied to verify reaction mechanisms that governed the pyrolysis process. The activation energies (Ea) ranged from 127.70 to 991.53 kJ/mol from the four model-free methods, which presented themselves as unreliable. The FPCM presented a better performance, with higher R2 values. At low conversions, pyrolysis was controlled by diffusion mechanisms, while at higher conversions, a third-order reaction became the governing pyrolysis mechanism.

Kinetic study on the slow pyrolysis of nonmetal fraction of waste printed circuit boards (NMF-WPCBs).

In this study, the pyrolysis behaviour of nonmetal fraction of waste printed circuit boards (NMF-WPCBs) was studied based on five model-free methods and distributed activation energy model (DAEM). The possible decomposition mechanism was further probed using the Criado method. Thermogravimetric analysis indicated that the NMF-WPCBs pyrolysis process could be divided into three stages with temperatures of 37-330°C, 330-380°C and 380-1000°C. The mass loss at different heating rate was determined as 26.85-29.98%, 13.47-24.21% and 20.43-23.36% for these stages, respectively. The activation energy (Eα) from various model-free methods first increased with degree of conversion (α) increasing from 0.05 to 0.275, and then decreased beyond this range. The coefficient (R) from the Flynn-Wall-Ozawa (FWO) method was higher, and the resulting Eα fell into the range of 214.947-565.660 kJ mol-1. For the DAEM method, the average Eα value was determined as 337.044 kJ mol-1, comparable with 329.664 kJ mol-1 from the FWO method. The thermal decomposition kinetics of NMF-WPCBs could be better described by the second-order reaction.

Mechanistic Investigation and Thermal Degradation of Eichhornia Crassipes Using Thermogravimetric Analysis

The study deals with the thermal degradation of water hyacinth (WH) using thermogravimetric analysis. Pyrolytic kinetic study of the feedstock was done using four isoconversional methods i.e. Friedman, Starink, Flynn-Wall- Ozawa (FWO), and Kissinger- Akahira-Sunose (KAS). Average values of activation energy of pyrolysis of WH were found to be 298.48, 252.26, 260.58 and 251.33 kJ/mol using Friedman, Starink, FWO, and KAS method, respectively in the conversion range of 0.15 – 0.75. Pyrolysis of biomass exhibit strong dependence on the degree of conversion ( α ). Solid-state reaction mechanism of pyrolysis was studied by the Criado method. The obtained result shows that the decomposition of biomass followed a two-dimensional diffusion mechanism for α ≤ 0.5. In contrast, for α ≥ 0.5 the reaction is well described by nucleation and growth mechanism. The large value of Δ S indicates higher reactivity and lesser time is consumed for the formation of the activated complex. Results of these analyses show that water hyacinth has substantial potential and can be used as a useful feedstock for bioenergy production.

Evaluation on the non-isothermal combustion kinetics of lignite and sewage sludge through microwave pretreatment

Lignite and sewage sludge powder were pretreated through microwave heating at a power level of 119 W. The non-isothermal combustion characteristics of lignite and sewage sludge powder through the microwave pretreatment were examined based on a thermo-gravimetric technique at three heating rates (10, 20 and 30 °C min−1). The effect of the microwave pretreatment on the combustion performance index and kinetic parameters was addressed. The ignition temperature region of the lignite samples was in between 357 and 376 °C, which was higher than that of the sewage sludge samples ranged from 219 to 235 °C. The comprehensive performance index of the treated lignite and sewage sludge increased by 22.5% and 2.3%, respectively. The combustion kinetic parameters of the samples were evaluated based on KAS method coupled with Criado method. The average activation energies of the untreated lignite and sewage sludge were 213.83 and 176.92 kJ mol−1, while that for the treated samples were 232.64 and 203.01 kJ mol−1.

Non-isothermal Thermogravimetric Degradation Kinetics, Reaction Models and Thermodynamic Parameters of Vinylidene Fluoride Based Fluorinated Polymers

Commercial fluororubber SKF 32, fluoroplastic F-32L, fluoroelastomer Kel-F, fluoroplastic FK 800 (labeled as SKF 32, F-32L, Kel-F and FK 800) and an in-house prepared poly(vinylidene fluoride-chlorotrifluoroethylene) (FKM) copolymer were investigated in terms of their thermal degradation kinetics, reaction models and corresponding thermodynamic parameters. All samples underwent a single step thermal degradation using thermogravimetric analysis (TGA) at different heating rates under nitrogen atmosphere. The kinetic parameters were determined through the Kissinger method and three isoconversional methods; viz. the Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Starink. The activation energies of the SKF 32, F-32L, Kel-F, FK 800 and FKM obtained using the Kissinger method were 206, 200, 185, 221 and 243 kJ mol‒1, respectively. The activation energy values for the degradation obtained using the KAS method were: 180–225 kJ mol−1 for SKF 32, 192–209 kJ mol−1 for F-32L, 163–185 kJ mol−1 for Kel-F, 213–227 kJ mol−1 for FK 800 and 187–269 kJ mol−1 for FKM with the extents of conversion (α) = 0.1–0.9. These values of the activation energies obtained from the KAS method were in good agreement with those obtained using the FWO and Starink methods. In addition, the appropriate degradation reaction models were determined by means of the Coats-Redfern and Criado methods. The thermodynamic parameters, such as activation Gibb free energy, ΔG*, activation enthalpy, ΔH*, and activation entropy, ΔS*, for formation of the activated complexes during the thermal degradation were also determined and discussed. The positive values of the Ea, ΔG*, ΔH*, and ΔS* for SKF 32, F-32L, FK 800 and FKM indicated a non-spontaneous process, while the positive values of the Ea, ΔG* and ΔH*, and negative value of ΔS* for Kel-F meant that the formation of the activated complex was accompanied by a smaller decrease of entropy than for the other polymers.

Kinetic modeling study on the combustion treatment of cathode from spent lithium-ion batteries.

Thermal treatment offers an alternative method for the separation of aluminum foil and cathode materials during spent lithium-ion batteries recycling. In this work, the combustion kinetic of cathode was studied based on six model-free (isoconversional) methods, namely Flynn-Wall-Ozawa (FWO), Friedman, Kissinger-Akahira-Sunose, Starink, Tang, and Boswell methods. The possible decomposition mechanism was also probed using a master-plots method (Criado method). Thermogravimetric analysis showed that the whole thermal process could be divided into three stages with temperatures of 37-578°C, 578-849°C, and 849-1000°C. The activation energy (Eα) derived from these model-free methods displayed the same trend, gradually increasing with a conversion range of 0.002-0.013, and significantly elevating beyond this range. The coefficients from the FWO method were larger, and the resulted Eα fell into the range of 10.992-40.298 kJ/mol with an average value of 20.228 kJ/mol. Comparing the theoretical master plots with an experimental curve, the thermal decomposition of cathode could be better described by the geometric contraction models.

Kinetic modeling of thermal decomposition of sugarcane bagasse in the inert gas environment

AbstractSugarcane bagasse was characterized by thermogravimetric analysis (TGA) with the different heating rates, and nitrogen carrier from 30 to 800 oC. Through decreasing the sample's mass by temperature, the stage of thermal decomposition could be determined. Specifically, there were three stages of decomposition including moisture escape stage, decomposition of cellulose stage, hemicellulose and lignin decomposition stage. On the other hand, based on the results of TGA the activation energy of decomposition process was determined by the inverse of the Flynn‐Wall‐Ozawa (FWO) method and Kissinger‐Akahira‐Sunose (KAS) method. The calculated results were compared with the activation energy by the Coats‐Redfern method and Criado method in order to find the kinetics of bagasse pyrolysis process. Accordingly, when the conversion of reaction was lower than 75 %, corresponding to the decomposing process of hemicellulose and cellulose, the thermal decomposing process of bagasse obeyed diffusion kinetics of model D2, D3 and D4.

Intrinsic kinetics, thermodynamic parameters and reaction mechanism of non-isothermal degradation of torrefied Acacia nilotica using isoconversional methods

The objective of this work is to examine the suitability of torrefied biomass for bio-energy generation by investigating its physicochemical characteristics, kinetic and thermodynamic parameters as well as reaction mechanism during pyrolysis. Thus, torrefaction of Acacia nilotica was performed in a fixed bed reactor at 220, 250 and 280 °C, with constant residence time (40 min) and heating rate (15 °C/min). Pyrolysis of torrefied biomass obtained at 220 °C (T-220), 250 °C (T-250) and 280 °C (T-280) was performed using thermogravimetric analyzer at three different heating rate viz. 5, 10 and 15 K/min. Further, isoconversional models namely, Kissinger-Akahira-Sunose (KAS), Ozawa-Wall-Flynn (OWF), Friedman and Starink were employed to calculate the kinetic parameters (activation energy and pre-exponential factor) of raw and torrefied biomass. Using kinetic parameters obtained from KAS method, thermodynamic parameters (enthalpy, Gibbs free energy, and entropy) were calculated at a heating rate of 10 K/min. The activation energy for raw and T-220, T-250, and T-280 using KAS method were found to be 221.49, 241.58, 185.06, and 121.83 kJ/mol, respectively. The increase in activation energy of T-220 might be due to a higher percentage of cellulose content in it than raw biomass. Reaction mechanism during pyrolysis of raw and torrefied biomass was predicted using Criado method (Z-master plot). For raw biomass and T-220, diffusion models were followed; however, for T-250 and T-280, random nucleation models were dominant. Overall, results provide a deep understanding of kinetics and improved characteristics of torrefied biomass as good quality solid fuel.

An experimental and theoretical mechanistic analysis of thermal degradation of polypropylene/polylactic acid/clay nanocomposites

Polypropylene/polylactic acid (PP/PLA) blends containing 5 wt% of nanoclay in presence and absence of an ethylene‐butylacrylate‐glycidyl methacrylate terpolymer as compatibilizer were prepared by melt‐mixing process. A matrix‐droplet–type morphology confirmed by transmission electron microscope (TEM) and scanning electron microscopy (SEM) studies is formed in presence and absence of the compatibilizer in which the clay platelets were mainly localized in the polylactic acid (PLA) dispersed phase. Degradation studies by means of thermogravimetry analysis (TGA) and analysis of degradation activation energy (Ea), Tmax (maximum degradation temperature), and ΔT (difference between initial and final degradation temperatures) parameters for each polymer component of the system revealed that incorporation of less stable PLA phase to polypropylene (PP) decreases Ea and Tmax parameters, and hence, reduces the thermal stability of PP phase, while incorporation of clay nanoplatelets to the neat blend further reduces its thermal stability attributed to their lack of localization in PP phase. Compatibilization of the filled system results in migration of clay nanoplatelets toward PP and improves Ea and Tmax of PP phase. On the other hand, the Ea and Tmax of PLA phase of the blend were increased with incorporation of clay and its localization within that phase, while compatibilization of the filled system slightly reduces thermal stability of PLA phase due to migration of clay toward PP. A correlation was found between Ea and intensity of the thermogravimetry analysis Fourier‐transform infrared spectroscopy (TGA‐FTIR) peaks of the evolved products. Using the Criado method, a detailed analysis on degradation mechanism of each component was performed, and the changes in the degradation mechanism of the developed systems were determined.

Impact of environment on the kinetics involved in the solid-state synthesis of bismuth ferrite

Synthesis of bismuth ferrite by a solid-state reaction between Bi2O3 and Fe2O3 was investigated through thermogravimetry/derivative thermogravimetry/differential thermal analysis (TG/DTG/DTA) technique. The reaction was performed at various heating rates (2, 5, 10 and 15 °C/min) from ambient temperature to 800 °C, in nitrogen and oxygen environments. The main aim was to investigate kinetic parameters and the impact of environment on the reaction. The results obtained from TG/DTG revealed that the reaction occurred in four distinct stages in both environments and substantial conversion was only observed in stage II-III. The activation energy was evaluated for the main stages (stage II-III) in both environments by the Fynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods. The trend of activation energy remains identical in both environments. The mechanism involved in the reaction was identified by using the Criado method. It was observed that the reaction mechanism in stage II-III significantly vary with the environment. The magnetization of the BFO sample prepared in nitrogen and oxygen environment was estimated through the Vibrating-sample magnetometer (VSM) at room temperature. The results indicated that nitrogen atmosphere was more suitable for the synthesis of bismuth ferrite with improved magnetization.

Thermal degradation kinetics of sugarcane leaves (Saccharum officinarum L) using thermo-gravimetric and differential scanning calorimetric studies

Pyrolysis of sugarcane (Saccharum officinarum L) leaves (SCL) has been investigated using DTA/TGA and DSC techniques. Proximate and ultimate analyses and calorific value measurement have been carried out using standard protocols. The sugar cane leaves contain 44% cellulose, 22% hemicellulose and 17% lignin. The pyrolysis have been carried out at six heating rates varying from 5 to 40 °C/min. Analysis of the pyrolysis results has been carried using iso-conversional model free methods as well as multiple linear regression method. For the fractional conversion range of 0.05–0.95, the average apparent activation energy values evaluated from iso-conversional methods have ranged from 214.9 to 239.6 kJ/mol where as in the case of multiple linear regression analysis it has ranged from 25.06 to 57.23 kJ/mol. The multi-step reaction mechanism has been investigated using the Criado method. The results of this study are useful for the design of large scale biomass thermal conversion process.

Synthesis and Characterization of Polystyrene (PS)/Modified Ni‐Al LDH Nanocomposite: Role of Composition, Modifier and Synthesis Route of Layered Double Hydroxides (LDH)

Layered double hydroxides (LDH) are two‐dimensional nanostructured materials, which impart flame retardancy property and improvement in various properties on incorporation into the polymer matrix. In this study, Ni‐Al LDH with a molar ratio of 2:1 and 3:1 (2NiAl and 3NiAl) was prepared by co‐precipitation method and Ni‐Al LDH with a molar ratio of 2:1 (NiAl urea) was also synthesized by the urea hydrolysis method. As the d‐spacing of these as‐synthesized LDHs is very small (≈0.8 nm) as well as hydrophilic in nature, hence, the unmodified LDHs are unsuitable for polymer nanocomposite preparation. In order to enhance the d‐spacing of LDHs, a simple regeneration method was employed to organically modify LDHs using two anionic surfactants such as sodium dodecyl benzene sulfate (SDBS) and sodium dodecyl sulfate (SDS). The hydrophobic tail of these anionic surfactants replaced the nitrate ions present in the unmodified LDHs leading to higher d‐spacing value, which was evident from XRD analysis. The above prepared LDHs (3 wt%) were incorporated into PS matrix by the solvent blending method to make PS nanocomposites. The 003 peak of modified LDHs did not appear in the XRD pattern of PS nanocomposites due to the disorientation of LDH layers in the PS matrix that was confirmed by TEM analysis. The TGA results clearly demonstrated that the thermal stability of the PS nanocomposite samples was increased by 26, 22 and 22 °C (PS/2NiAl SDS, PS/3NiAl SDS, and PS/NiAl urea SDS) for SDS modified LDH fillers, while in the case of SDBS modified LDH fillers, the improvement was around 32 °C in comparison with PS, when 15% weight loss was taken as a reference. The degradation mechanism, thermal degradation kinetics, and integral procedural decomposition temperature (IPDT) for all the nanocomposite systems were also evaluated using Criado method, Coats‐Redfern method, and Doyle's method, respectively. The effect of dispersion of the modified LDH fillers into PS matrix was examined using melt rheological analysis.

Mechanism and kinetics of thermal degradation of insulating materials developed from cellulose fiber and fire retardants

The mechanism and kinetics of thermal degradation of materials developed from cellulose fiber and synergetic fire retardant or expandable graphite have been investigated using thermogravimetric analysis. The model-free methods such as Kissinger–Akahira–Sunose (KAS), Friedman, and Flynn–Wall–Ozawa (FWO) were applied to measure apparent activation energy (Eα). The increased Eα indicated a greater thermal stability because of the formation of a thermally stable char, and the decreased Eα after the increasing region related to the catalytic reaction of the fire retardants, which revealed that the pyrolysis of fire retardant-containing cellulosic materials through more complex and multi-step kinetics. The Friedman method can be considered as the best method to evaluate the Eα of fire-retarded cellulose thermal insulation compared with the KAS and FWO methods. A master-plots method such as the Criado method was used to determine the possible degradation mechanisms. The degradation of cellulose thermal insulation without a fire retardant is governed by a D3 diffusion process when the conversion value is below 0.6, but the materials containing synergetic fire retardant and expandable graphite fire retardant may have a complicated reaction mechanism that fits several proposed theoretical models in different conversion ranges. Gases released during the thermal degradation were identified by pyrolysis–gas chromatography/mass spectrometry. Fire retardants could catalyze the dehydration of cellulosic thermal insulating materials at a lower temperature and facilitate the generation of furfural and levoglucosenone, thus promoting the formation of char. These results provide useful information to understand the pyrolysis and fire retardancy mechanism of fire-retarded cellulose thermal insulation.

Thermal degradation of typical plastics under high heating rate conditions by TG-FTIR: Pyrolysis behaviors and kinetic analysis

Pyrolysis of plastics has gained more attention recently due to the advantages of environmental protection and energy conversion. In this study, low-density polyethylene (LDPE), polypropylene (PP) and polyvinyl chloride (PVC) were studied under high heating rate conditions to investigate pyrolysis behaviors and find the most suitable kinetic reaction mechanisms. The TG and DTG curves for LDPE were similar to those for PP, but different from those for PVC. It was found that high heating rate led to the shifting of initial, end and peak temperatures to higher values. The FTIR results showed the main products of LDPE and PP were alkanes and alkenes, and the major products of PVC were HCl, alkenes and a small number of aromatic compounds. A comparative study of model-free methods like Ozawa-Flynn-Wall (OFW), Kissinger-Akahira-Sunose (KAS) and Friedman method were discussed to calculate activation energy. Kinetic reaction mechanisms were predicted by using model-fitting methods including Coats-Redfern and Criado method. The pyrolysis reaction mechanism of LDPE was summarized as contracting sphere model, PP was summarized as contracting cylinder model, whereas that of PVC was concluded that two-dimension nucleation for the first stage and three-dimension diffusion (Jander) for the second stage.

Rheological characterization and modeling of vulcanization kinetics of natural rubber/starch blends

ABSTRACTVulcanization kinetics of natural rubber/starch (NR/ST) blends was investigated by oscillating disc rheometer. The scorch and cure times are significantly reduced with the loading of starch in all blends from 1.15 and 2.22 to 0.91 and 1.88 min, respectively, to improve curing rate. Meanwhile, the maximum torque values and the maximum vulcanization rate of NR/ST blend increase with the starch loading from 1.51 N m and 0.387 min−1 to 2.224 N m and 0.492 min−1 respectively. The results of vulcanization kinetics of NR and its blends revealed that it is controlled by two‐stages, chemical and diffusion. The experimental data of the vulcanization rate of NR/ST blends did not fit with autocatalytic kinetic model except the pure natural rubber. Therefore, the Criado method was used and it was observed that the reaction kinetic model of pure NR and its blends with starch is best described by the D diffusion model (D2). © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46347.

Thermal degradation kinetics of polylactic acid/acid fabricated cellulose nanocrystal based bionanocomposites

Cellulose nanocrystals (CNC) are fabricated from filter paper (as cellulosic source) by acid hydrolysis using different acids such as sulphuric (H2SO4), phosphoric (H3PO4), hydrochloric (HCl) and nitric (HNO3) acid. The resulting acid derived CNC are melt mixed with Polylactic acid (PLA) using extruder at 180°C. Thermogravimetric (TGA) result shows that increase in 10% and 50% weight loss (T10, T50) temperature for PLA-CNC film fabricated with HNO3, H3PO4 and HCl derived CNC have improved thermal stability in comparison to H2SO4-CNC. Nonisothermal kinetic studies are carried out with modified-Coats-Redfern (C-R), Ozawa-Flynn-Wall (OFW) and Kissinger method to predict the kinetic and thermodynamic parameters. Subsequently prediction of these parameter leads to the proposal of thermal induced degradation mechanism of nanocomposites using Criado method. The distribution of Ea calculated from OFW model are (PLA-H3PO4-CNC: 125–139 kJmol−1), (PLA-HNO3-CNC: 126–145 kJmol−1), (PLA-H2SO4-CNC: 102–123 kJmol−1) and (PLA-HCl-CNC: 140–182 kJmol−1). This difference among Ea for the decomposition of PLA-CNC bionanocomposite is probably due to various acids used in this study. The Ea calculated by these two methods are found in consonance with that observed from Kissinger method. Further, hyphenated TG-Fourier transform infrared spectroscopy (FTIR) result shows that gaseous products such as CO2, CO, lactide, aldehydes and other compounds are given off during the thermal degradation of PLA-CNC nanocomposite.

Study of thermal decomposition process and the reaction mechanism of the eucalyptus wood

The mass loss of eucalyptus wood was measured against time and temperature at four different heating rates (5, 10, 15, 20 °C/min), in nitrogen environment, through thermogravimetry analysis technique. These measurements revealed that the decomposition of wood samples occurred in three stages (dehydration stage, active stage and passive stage), and the maximum decomposition peak in DTG curve shifted towards higher temperature range with increase in heating rate. In addition, the decomposition kinetic parameters were determined by adopting two thermal kinetic methods viz. Flynn–Wall–Ozawa and modified Coats and Redfern. Further, from the master curves (generated through different values of g(α) and f(α)) and experimental curve obtained using the Criado method, the kinetic mechanism involved in the pyrolysis of the eucalyptus wood was commented.