Thermal Degradation Kinetics Research Articles

Investigation of the thermal degradation kinetics of ceramifiable silicone rubber-based composite

Investigation of the thermal degradation kinetics of ceramifiable silicone rubber-based composite

Synthesis, characterization, thermokinetic analysis and biological application of novel allyl glucosamine based glycopolymers

ABSTRACTThe synthesis of glycopolymers by copolymerising an allyl glucosamine (AG) monomer with co-monomers methyl methacrylate (MMA), acrylonitrile (AN) and 2-hydroxyethyl methacrylate (HEMA) was investigated via free-radical polymerisation of 2,2-azobisisobutyronitrile (AIBN) in dimethylformamide (DMF). Three new copolymers, poly(AG-co-MMA), poly(AG-co-AN) and poly(AG-co-HEMA), were obtained. The chemical structures of the glycopolymers were analysed using 1H-NMR, 13C-NMR and FTIR. The thermal properties and degradation kinetics of the three glycopolymers were examined by thermogravimetric (TG) analysis at different heating rates. The effects of different co-monomers on the copolymerisation yield, thermal properties and biological activities of the resulting glycopolymers were investigated. The activation energies of the decomposition stages were calculated using the Flynn–Wall–Ozawa (FWO) and Kissinger methods. Furthermore, the biological activity of AG monomers and glycopolymers was studied and compared to chitosan. Poly(AG-co-HEMA) had the most significant effect on MCF-7 cell viability, and all glycopolymers have a low toxic effect profile on MCF-7 cell lines.

Kinetic and thermodynamic study of micron waste polypropylene thermal degradation

AbstractHow to properly dispose of waste polymers is a recognized challenge all over the world. Thermal degradation is currently recognized as a promising method for recycling polymer waste into fuels or products with high energy density without polluting the environment. In the present study, the thermal degradation characteristics, kinetics, thermodynamic parameters, and volatiles of a representative and extremely widely‐used polymer (micron waste polypropylene [PP]) pyrolysis in nitrogen were investigated. The results indicate that the thermal degradation of micron waste polypropylene can be considered as a one‐step reaction with merely one distinct peak on the reaction rate curves. The peak and average reaction rates decrease with the heating rate. The most appropriate reaction model to characterize the thermal degradation is g(α) = 1−(1−α)1/4. The average values of activation energy and pre‐exponential factor are 128.76 kJ/mol and 6.79 × 109 min−1, respectively. The kinetic parameters obtained in this study are all larger than those of PP with the particle size of millimeters or larger. The predicted thermogravimetric curves of thermal degradation are in good agreement with the experimental results. The changes of enthalpy, Gibbs free energy, and entropy show that the thermal degradation of micron waste polypropylene is a non‐spontaneous and endothermic reaction. In addition, the concentrations of all volatiles in descending order are: H2O > Esters (COO) > CO2 > Alkanes (CH3) > R2CCH2 > Olefins (CC) > Alcohols (ROH) > Methylene group > CO.

Thermal Degradation Behavior of a Poly(n‐Butylmethacrylate‐Co‐Acrylic Acid)/Organobentonite Nanocomposite: Non‐Isothermal Decomposition Kinetic Study

AbstractThe aim of this study is to investigate the effects of a small amount of organomodified bentonite (OBT) on the thermal stability and degradation kinetics of the intercalated poly(n‐butylmethacrylate‐co‐acrylic acid) P(n‐BMA‐AA) nanocomposite. P(n‐BMA‐AA)‐18 copolymer containing 17.9 mol% of acrylic acid (AA) and P(n‐BMA‐AA)‐17/OBT3 nanocomposite containing 16.7 mol% of AA at 3 mass% of OBT are synthesized via in situ free radical polymerization and characterized. Thermogravimetric analysis (TGA) shows an improvement of the thermal stability of P(n‐BMA‐AA)‐17/OBT3 nanocomposite compared to the pure copolymer. The apparent activation energies Ea of thermal decomposition of the elaborated nanocomposite are higher than those of the virgin copolymer, reflecting the OBT stabilizing effect upon the matrix's decomposition. Besides, the TGA kinetic study reveals that the degradation kinetic of copolymer is well fitted by model F2 (g(α) = (1 – α)−1 – 1). Whereas, the A1F1 (g(α) = –ln(1 – α)) and R2 (g(α) = 1 − (1 – α)1/2) models are found to well represent the experiment for the first and second stages degradation in the nanocomposite.

Research the Thermal Decomposition Processes of Copolymers Based on Polypropyleneglycolfumaratephthalate with Acrylic Acid.

Kinetics of thermal degradation of polymeric materials is usually studied by weight loss at a constant temperature or during heating. Hence, the activation energy and other kinetic parameters of the thermal destruction process are determined. One of the fastest and most accessible methods for studying the kinetics of these processes is TGA. Weight methods of TGA do not provide an opportunity to judge the proportion of gaseous degradation products. This is especially true for processes associated with the release of hydrogen and other substances with low molecular weights, the accuracy of determining the amount of which by the weight method is low. Meanwhile, the study of the gas evolution process can provide additional information about the kinetics and mechanism of thermal destruction processes. Of great interest is also the joint study of the total weight loss and gas evolution during the polymer heating. Using mass spectrometry, IR spectroscopy combined with thermal analysis (TGA/DSC-IR and TGA/DSC-MS) we have defined product composition and thermal destruction kinetics. As a result of the TGA/DSC-MS study of gaseous products of thermolysis in nitrogen atmosphere, there were found products with 44, 45, 59, 60, 68, and 88 phr. Quite a similar pattern for p-PGFPh:AA copolymers is also observed in TGA/DSC-IR studies: the same products and the same temperature range. However, in contrast to the TGA/DSC-MS study, CO release was also recorded by this method (weak signal). Kinetic characteristics of the processes were determined based on Friedman, Ozawa-Flynn-Wall and modified NPC methods. Obtained values of the activation energy and thermodynamic characteristics make it possible to predict the composition of polymers, which make a significant contribution to the development of theoretical ideas about the features of the physicochemical properties of polymers.

Effect of LNR-g-MMA on the Mechanical Properties and Lifetime Estimation of PLA/PP Blends.

Polylactide (PLA) polymer, polypropylene (PP) polymer, and a PLA/PP (70:30 wt%) blend, with liquid natural rubber-graft-methy methacrylate (LNR-g-MMA) of 0.0, 2.5, 5.0, and 10.0 phr as compatibilizers, were prepared by internal mixing and compression molding. The effect of LNR-g-MMA content on the morphology, mechanical properties, water absorption, thermal degradation, and a lifetime of blends based on PLA and PP was investigated. Scanning electron microscopy (SEM) revealed that the PLA/PP blend underwent phase separation, and the presence of LNR-g-MMA in the PLA/PP blend showed a more homogenized and refined blend morphology. Hence, the addition of LNR-g-MMA was used as a compatibilizer to induce miscibility in the PLA/PP blend. The values of tensile strength, elongation at break, and impact strength of the polymer blends increased, whereas water absorption values decreased with increased LNR-g-MMA content. Thermal degradation kinetics was studied over a temperature range of 50-800 °C with multiple heating rates. The results demonstrated that the thermal stability of blends without LNR-g-MMA was greater than that of blends with LNR-g-MMA and that the thermal stability decreased with increasing LNR-g-MMA content. The activation energy (Ea) was calculated by using the Kissinger-Akahira-Sunose method. The Ea value of PLA was much lower than that of PP, and incorporating PP in the PLA matrix increased the Ea. The addition of LNR-g-MMA to the PLA/PP blend decreased the Ea. The lifetime of PLA/PP blends was reduced with the addition of LNR-g-MMA.

Thermal degradation behaviour, kinetics, and thermodynamics of Bombax Malabarica seeds through TG-FTIR and Py-GC/MS analysis

The pyrolysis process kinetics, thermodynamics, and product analysis of Simal cotton (Bombax Malabarica) seeds, a non-edible biomass feedstock were performed to evaluate its suitability as an alternative renewable energy source. The active pyrolysis region of 220 to 600 °C was perceived with peak temperatures between 338.1 and 362.4 °C using TG analysis. The degradation of hemicellulose was observed at temperatures <300 °C and cellulose in the range of 300–400 °C. The effect of heating rate on the composition of evolved mixed gases and functional groups was evaluated using the TG-FTIR. The evolved typical gaseous products include H2O, CO, CO2, CH4, C = O, CO, HCN, and NH3. The order of the volatile pyrolysis products: acids > phenols > amines > aliphatics > alcohols > furans > aldehydes > nitriles > ketones > esters was determined using Py-GC/MS for higher selectivity of value-added products. The mean values of Ea, ΔH, ΔG, and ln(A) of feedstock were in the range of 181.1–193.8, 176.1–188.7, 180.6–190.1 kJ mol−1, and 27.1–34.1 min−1, respectively. The above experimental data could be used to design a process for bio-oil and bioenergy production from the seed.

Superabsorbent Polymer Sponge for Saliva Absorption Pad

Aim: Saliva is a significant hindrance to most dental procedures (e.g., root canal treatment) as the flow of saliva increases in patients undergoing dental treatment due to anxiety. Saliva absorption pads based on superabsorbent polymers can provide a dry oral environment to ease the dental treatment procedure and reduce the swallowing reflexes common during cotton use. This study focused on developing an indigenous saliva absorption pad using biodegradable superabsorbent polymer (BSAP) sponges. Materials and Methods: BSAP sponges were synthesized using carboxymethyl cellulose (CMC) as the base matrix. Different crosslinking mechanisms were implemented to prepare BSAP sponges, such as ionic crosslinking using aluminum ammonium sulfate (AlAS) and chemical crosslinking using methylene bisacrylamide. Three different BSAP sponges (Sap-2, SAP-PAA-1, and SAP-PAA-2) were characterized for their free swell capacity and thermal degradation kinetics along with other characterization techniques to optimize the composition for saliva absorption pad. One-way ANOVA was used for statistical evaluation. Results: SAP-2, synthesized using 10 wt.% AlAS showed the highest free swell capacity in water and saline (83.21 ± 3.8 g/g and 40.7 ± 3.4 g/g, respectively). However, the moisture content of the particular BSAP sponge was higher (~13%) compared to the standard limit (ISO 17190-4:2001(E)). It was observed that as the crosslinking density increases free swell capacity increases to a threshold point and decreases thereafter. As reported earlier, percentage swelling was controlled by multiple factors including crosslinking that opposes swelling and polymer/water interaction and Donnan pressure that promotes swelling. Conclusion: BSAP sponge based on crosslinked CMC matrix is highly advantageous in developing saliva absorption pad. Hydrophobic surface modification is recommended to reduce the moisture content to improve the storage stability of BSAP sponges.

A novel pseudo-multicomponent isoconversional approach for the estimation of kinetic and thermodynamic parameters of potato stalk thermal degradation

This study examined the thermal degradation kinetics of potato stalk (PS) using a unique isoconversional technique. The kinetic analysis was assessed based on mathematical deconvolution approach with model-free method. The thermogravimetric analyzer (TGA) was used for the non-isothermal pyrolysis of PS at different heating rates. The Gaussian function was then used to extract three pseudo-components (PC) from the TGA findings. The average activation energy value for PS (125.99, 122.79, and 122.85 kJ/mol), PC1 (106.78, 103.83, and 103.92 kJ/mol), PC2 (120.26, 116.31, and 116.55 kJ/mol), and PC3 (373.12, 379.40, and 378.93 kJ/mol) based on OFW, KAS, and VZN model respectively. Furthermore, an artificial neural network (ANN) was used to forecast the thermal degradation data. The findings demonstrated a significant correlation between real and anticipated values. The kinetic and thermodynamic results, along with ANN are critical for constructing pyrolysis reactors that might use waste biomass as a potential feedstock for bioenergy production.

Effect of different thermoplastics on the thermal degradation behavior, kinetics, and thermodynamics of discarded bakelite.

In this work, the kinetics, thermodynamics, and mechanism for co-pyrolysis of thermoplastic (PP, HDPE, PS, PMMA)blended bakelite (BL) (1:1 by weight) are explored utilizing different kinetics models like model-fitting and KAS model-free method. The thermal degradation experiments of each sample are conducted from ambient to 1000°C temperature at 5, 10, 20, 30, and 50°C/min heating rates in an inert environment. Thermoplastic blended bakelite is degraded in four steps, including two significant weight loss steps. A significant synergetic effect was observed by the addition of thermoplastics, which is reflected in the change in the thermal degradation temperature zone and the weight loss pattern. Among the four thermoplastics blended bakelites, the promotional synergetic effect is more pronounced for PP addition, causing an increase in the degradation of discarded bakelite by 20%, whereas the addition of PS, HDPE, and PMMA enhances the degradation of bakelite by 10%, 8%, and 3% respectively. Again, the activation energy of the thermal degradation of PP blended bakelite is found lowest followed by HDPE blended bakelite, PMMA blended bakelite, and PS blended bakelite. The mechanism of thermal degradation of bakelite changed from F5 to F3, F3, F1, and F2.5 by the addition of PP, HDPE, PS, and PMMA respectively. A significant change in the thermodynamics of the reaction is also found in the addition of thermoplastics. The kinetics, degradation mechanism, and thermodynamics for thermal degradation of the thermoplastic blended bakelite contribute to the optimization of pyrolysis reactor design to increase valuable pyrolytic products.

Enhanced photocatalytic degradation of PE film by anatase/γ-MnO2

The photocatalytic degradation of low-density polyethylene (PE) films containing nanoparticles (NP) of titanium and manganese dioxides has been investigated. Composite PE films were prepared by the casting of p-xylene with the photocatalyst (TiO2, MnO2 or hybrid 1: 1 TiO2&MnO2) content of 1 wt%. The polyethylene degradation test has been carried out in a photoreactor with UV-irradiation (Hg lamp). Then, FTIR spectroscopy and gravimetric measurements have been conducted after the UV exposure at variable time to evaluate the NPs photocatalytic effects within the PE matrix. According to these tests, we detected the coupling effects of TiO2 and MnO2 nanoparticles on the PE photo-degradation. Moreover, the influence of TiO2 and TiO2&MnO2 on the tensile properties, thermal behavior under inert atmosphere and wettability characteristics of PE based films have been explored by DMA, TGA and water contact angle measurements, respectively. Based on TGA data, we studied the effects of TiO2 and TiO2&MnO2 nanoparticles on the kinetics of the PE thermal degradation.

Phosphorylated poly(vinyl alcohol) surface coatings as intumescent flame inhibitor for polymer matrix composites

Flammability is one of the main drawbacks affecting polymer matrix composites (PMCs), limiting metal replacement in several applications. Phosphorus compounds demonstrated a great ability in contrasting fire spreading. Here, phosphorylated poly(vinyl alcohol) (PPVA) has been synthesized and used as an intumescent flame inhibitor coating for carbon fiber reinforced polymer (CFRP) laminates. The synthesized PPVAs, with a phosphorylation degree up to 7.5 %wt, were investigated by spectroscopic (NMR and IR) and thermal (TGA and DSC) analyses. Moreover, thermal degradation kinetics was also rationalized by applying differential and integrals methods: the phosphorus catalytic effect combined with radicals-coupling behaviour deriving from the phosphorus species developed during the combustion has been highlighted, confirming the inhibitor role of PPVAs. Cone-calorimeter tests, simulating a small-scale fire scenario, were carried out on poly(vinyl alcohol)-coated and PPVA-coated materials prepared by solvent casting. Results highlight the anti-flame properties of PPVAs, especially as effective flame inhibitors: up to −58 % in the time of flame (TOF). Instead, poly(vinyl alcohol) coatings lead to an overall worsening of the material fire behaviour, highlighting the crucial role of phosphorous to reduce flammability. Such promising results pave the way for the use of PPVA coatings to reduce the fire risk of flammable composites making them safer.

Response of extreme environmental aging on the novel Moringa stenopetala husk fiber/epoxy composites: Understanding the characteristics and thermokinetic behavior

AbstractThe increasing use of composite components in various engineering disciplines necessitates detailed comprehension of their operation. When subjected to adverse environmental circumstances, such as variable humid surroundings and UV radiations, the structural and mechanical characteristics of the composites can deteriorate. Additionally, using these composite materials for structural applications such as rooftop buildings or household properties may reduce lifespan. In this study, the static and dynamic mechanical properties and the stability of novel lignocellulosic Moringa stenopetala (MS) husk fiber‐based epoxy composites exposed to various environmental factors were assessed. These harsh conditions were picked to imitate those encountered outside and influence the longevity of these composites. The obtained fiber from the husk was examined for its physiological, structural, and thermal characteristics. Using the Broido, Kissinger, Flynn‐Wall‐Ozawa (FWO), Coats‐Redfern and Kissinger‐Akahira‐Sunose (KAS) isoconventional models, the thermal degradation kinetics of the fibers were investigated. KAS method results in the best‐fitted curve and shows maximum activation energy of 175.13 KJ/mol. After husk fiber assessment, composite materials were fabricated using a Hand layup method, and their static and dynamic mechanical properties, water uptake rate, and contact angle analysis with surface energy behavior under various environmental aging circumstances were studied. In comparison to the composites “as developed,” the findings indicate that the mechanical characteristics of husk fiber‐based epoxy composites are significantly reduced by humidity and UV aging. Overall, the development of thermoset composites for structural applications can utilize husk fiber. Furthermore, after curing the water and UV‐aged composites, qualities can be recovered.

Kinetics of thermal degradation of raw lacquer enhanced by formaldehyde urea prepolymer

In this study, formaldehyde-urea prepolymer (FUP) were synthesized, which were used to modify the raw lacquer (RL) and this composition named LF, while the basic properties of the RL were tested. Thermal gravimetric (TG) analysis and scanning electron microscopy (SEM) were used to analyze the degradative characteristics and the surface morphology of RL before and after modification. The result indicated that FUP can significantly improve the performance of RL. The drying time of the LF is significantly shortened, the gloss, the pencil hardness, and the impact performance are significantly enhanced at the same time. TG analysis and thermal decomposition kinetics analysis illustrated that the thermal stability and the activation energy of LF2 were stronger than that of RL. In addition, SEM analysis illustrated that the surface smoothness of RL were also improved.

Evaluation thermal degradation kinetics of ionic liquid assisted polyetheretherketone‐multiwalled carbon nanotubes composites

AbstractThe incorporation of multiwalled carbon nanotubes (MWCNT) into polyetheretherketone (PEEK) composites has emerged as a promising strategy for enhancing the thermomechanical characteristics of PEEK composite materials. This study investigates the thermal behavior and kinetics prediction of PEEK/MWCNT composites comprising different ionic liquids (ILs), namely 1‐butyl‐3‐methylimidazolium hydrogen sulfate ([BMIM]HSO4), 1‐butyl‐3‐methylimidazolium acetate ([BMIM]Ac), 1‐ethyl‐3‐methylimidazolium acetate ([EMIM]Ac) and 1‐ethyl‐3‐methylimidazolium hydrogen sulfate ([EMIM]HSO4). Three non‐isothermal methods Coats‐Redfern, Broido, and Horowitz‐Metzger, were employed to model the thermal decomposition profiles of fabricated composites to calculate the activation energy. The highest decomposition temperature (580°C) was obtained for [BMIM]HSO4‐based PEEK/MWCNT composites. Moreover, a 3%–8% increase in the activation energy was obtained compared to PEEK/MWCNT manufactured without ILs. The Coats‐Redfern model was superior to Broido and Horowitz‐Metzger models in modeling the thermal degradation of developed composites, as evidenced from the higher value of the coefficient of determination (R2 ≥ 0.9899). By determining the Root Mean Square Error (RMSE) and R2 for the thermal degradation kinetics data, the artificial neural network (ANN) model was employed. The ANN model accurately predicted the mass loss curves, exhibiting R2 ≥ 0.9815 for the designed model. These findings can assist in establishing an IL‐assisted benign approach for PEEK/MWCNT/IL composites with superior thermal characteristics.

Effect of alkaline treatment on the thermal stability, degradation kinetics, and thermodynamic parameters of pineapple crown fibres

Pineapple crown is generally discarded as waste but constitutes an important source of lignocellulosic fibres. In this work, the effect of alkaline treatment on the chemical composition, pyrolysis kinetics, and thermodynamic characteristics of pineapple crown fibres (PCF) were investigated by chemical composition, Fourier transform infrared spectroscopy (FTIR), scanning electronic microscopy (SEM), X-rays diffraction (XRD), and thermogravimetry. Chemical composition analysis indicated cellulose content increased from 18.93 to 57.00% after NaOH treatment. PCF fibre diameter was reduced from 6.1 to 4.3 μm after mercerization. The FTIR results confirmed the removal of non-cellulosic compounds. XRD analysis indicated fibre's crystallinity index rose from 53 to 62% in reason of NaOH treatment. Thermogravimetric results confirm that alkaline-treated PCF (ATPCF) presented higher thermal stability than non-treated PCF (NTPCF). The solid-state thermal degradation mechanism for NTPCF and ATPCF occurred by the diffusion process and random nucleation, respectively. The thermodynamic parameters of NTPCF indicated that a small amount of energy is required to obtain the reaction products and thus bioenergy production from NTPCF pyrolysis will be easier, while ATPCF required more energy to initiate a degradation reaction and could be used as filler in polymeric composites.

Miscibility, thermal degradation and rheological analysis of epoxy/MABS blends.

The effect of the addition of the methyl methacrylate acrylonitrile butadiene styrene (MABS) copolymer on the miscibility, thermal degradation and rheological properties of epoxy systems is described. Epoxy resin/MABS blends containing 5, 10, 15 and 20 phr MABS were prepared using the solution mixing technique. Homogenous blends obtained using this technique have undergone a polymerization reaction induced phase separation process by the introduction of the curing agent 4,4'-diaminodiphenyl sulfone (DDS). The isothermal rheology at four different temperatures, 150, 160, 170 and 180 °C, was used to examine the effect of MABS on the gelation and vitrification time. The evolution of storage modulus, loss modulus and tan delta was found to be closely related to the evolution of complex phase separation. The increase in the complex viscosity during curing was determined by in situ rheometry and theoretically analysed by fitting with the Williams-Landell-Ferry equation. An exponential increase in complex viscosity was observed, which was induced by cross-linking. The variation of Tg before and after curing was studied using DSC analysis and dynamic kinetic modeling of the curing process was carried out by utilizing dynamic DSC scans. Thermal stability studies of completely cured epoxy/MABS blends using thermogravimetric analysis revealed that all the blends and neat epoxy exhibited single step degradation. Thermal degradation kinetics was calculated using the Coats Redfern equation.

Effect of pasteurization on color, ascorbic acid and lycopene of crushed tomato: A computational study with experimental validation

Pasteurization of crushed tomato in glass bottles was evaluated using a multiphysics model, aiming to understand the temperature profiles and quality losses during the heating and cooling stages of the process. In order to rigorously simulate the pasteurization process, a finite element model was built using experimentally measured product and heat transfer parameters (thermal conductivity, density, specific heat, and convective heat transfer coefficient) and the kinetics of thermal degradation of the quality parameters (color, lycopene and ascorbic acid). The developed model was successfully validated by considering both the temperature profile (R 2 = 0.99) and quality losses (relative differences <10%). After validation, equivalent thermal processes were simulated at three temperatures (80, 90 and 100 °C). Numerical results revealed that the process at 100 °C provided the best retention of quality compared to the 80 and 90 °C processes. For the three quality parameters evaluated, color ( a* value), lycopene and ascorbic acid, for 100 °C, retention values of 92.25, 74.76 and 83.68% were obtained, while for the 80 °C treatment, the retentions were 65.60, 18.35 and 36.13%, respectively. • A multiphysics model was built to study crushed tomato in glass bottle pasteurization. • The microbial inactivation during cooling was greater than 50% of the total P-value . • Coldest point was located on axial axis at 38.5% of the total height for all cases. • The best retention of quality was provided by the treatment at 100 °C. • The developed model can be used to design and optimize protocols for pasteurization.

Thermal and bisphenol-A adsorption properties of a zinc ferrite/β-cyclodextrin polymer nanocomposite.

The present study investigated the use of a nanocomposite, produced by reinforcing nanosize zinc ferrite (ZnFe2O4) in a porous β-CD based polymeric matrix (β-CD-E-T/ZnFe2O4), for the removal of Bisphenol A (BPA) from aqueous solutions via adsorption. The thermal stability of the β-CD-based polymer and β-CD-E-T/ZnFe2O4 nanocomposite were investigated using simultaneous thermal analysis at four heating rates. Non-isothermal isoconversion methods were employed to study the thermal degradation kinetics of the β-CD based polymer before and after ZnFe2O4 nano-filling. The results showed that ZnFe2O4 nano-reinforcement increased the activation energy barrier for the thermal degradation of the β-CD-based polymeric matrix. Adsorption experiments showed that the β-CD-E-T/ZnFe2O4 nanocomposite exhibited very high BPA adsorption within 5 minutes. Isotherm, kinetics, and thermodynamic investigations revealed that the adsorption of BPA was via multilayer adsorption on a heterogeneous β-CD-E-T/ZnFe2O4 surface. The thermodynamic studies indicated that BPA adsorption on β-CD-E-T/ZnFe2O4 was spontaneous and exothermic. Overall, the β-CD-E-T/ZnFe2O4 nanocomposite showed less thermal degradation and high efficiency for removing BPA from contaminated water, indicating its potential as a promising material for wastewater treatment applications.

A Study of Thermal Stability and Degradation Kinetics of Microcrystalline Cellulose (MCC)/Sol-Gel Silica (SiO&lt;sub&gt;2&lt;/sub&gt;) Hybrid Materials

Microcrystalline cellulose (MCC) has been widely used in the production of composite materials because it is inexpensive, easy to process, good mechanical properties and environmentally friendly. Despite its advantages, MCC has disadvantages such as poor thermal stability, hygroscopic and poor compatibility with hydrophobic materials. Understanding the thermal behavior of MCC is important because thermal degradation occurs at different rates and directly affects the final product. In this study, the MCC/ SiO2 hybrid materials were prepared using in-situ sol-gel synthesis, followed by the investigation of their thermal stability and degradation kinetics using thermogravimetric analysis (TGA). Degradation kinetics were analysed using two model-free analysis (i.e. Flynn-Wall-Ozawa, FWO and modified Coats-Redfern, CRm) to evaluate the degradation behaviour (conversion degree (α) of 0.1 to 0.8) and activation energies (Ea) of MCC, MCC/ sol-gel silica (MCC/SiO2) and modified MCC (mMCC/SiO2) at heating rates (β) of 10, 20, 30 and 40 °C/min. Thermal stability results showed that the presence of silica on MCC had no influence on the degradation temperature of the hybrid material however, it slightly shifted the Tonset to higher values. The presence of silica also increased the final residue of the hybrid, especially in mMCC/SiO2 samples. DTG curves clearly show that all samples exhibited one step degradation process. The kinetics study assumed that all samples has single reaction mechanism as the fitted line was parallel in almost all conversion degrees (α) in both FWO and CRm methods. Ea calculated for MCC, MCC/SiO2 and mMCC/SiO2 are in good fit with both FWO and CRm model where the R2 observed more than 0.97. Ea was increased in both methods, MCC/SiO2 and mMCC/SiO2 as compared to MCC, which implied that the addition of sol-gel silica to MCC could promote a stepwise degradation.