Activation Energy Of Thermal Degradation Research Articles

Controlled functionalisation of PE in molten state using ozone at the gas-fluid interface

High-value recycling petroleum-based polyethylene (PE) can effectively reduce carbon emissions and promote a circular economy. This study proposed a new method for functionalisation of low density polyethylene (LDPE) matrix at gas-liquid interface. The controlled functionalisation of LDPE at molten state was successfully achieved using ozone by altering reaction parameters. After ozone treatment, functionalised groups such as ketone (CO), ether (COC) and carboxyl groups (-COOH) were generated in ozonized PE (OPE) confirmed by FTIR and XPS. The contact angle with water dropped from 99 ° of pristine PE to 85.4 ° of OPE, which demonstrated that the hydrophilicity of OPE was improved significantly. The degree of ozonation was sensitive to temperature. A slight degradation of PE predominantly occurred under the mild condition (below 220 ℃ within 2 h) while the cross-linking structure was primarily generated after further oxidation (beyond 240 ℃ over 4 h), which revealed that functionalisation of OPE could be controllably achieved. Due to the formation of cross-linking structure, the crystallinity of OPE decreased from 33.8 % to 11.0 %. Meanwhile, the residue weight of OPE had a slight increase while its activation energy of thermal degradation reduced. Therefore, the functionalisation of PE using ozone is a promising technical and environmental-friendly approach to upcycle PE in the future.

Synthesis and pyrolysis mechanism of phenolphthalein poly(aryl ether sulfone) containing isopropyl groups

A novel phenolphthalein poly(aryl ether sulfone) polymer containing isopropyl groups (iPrPESC) has been successfully synthesized by SN2 aromatic nucleophilic polycondensation reaction. The pyrolysis mechanism and behavior of iPrPESC were investigated by thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR) and pyrolysis combined with gas chromatography/mass spectrometry (Py-GC/MS). TG-FTIR and Py-GC/MS were used to identify the thermal decomposition products and to determine the possible thermal degradation mechanism. The main mechanism for iPrPESC was one-stage pyrolysis involving main-chain random scission, and the major products of SO2 and phenol were released from the sulfone and ether groups in iPrPESC. The thermal degradation activation energy of iPrPESC was calculated to be 151 ± 4 and 139 ± 4 kJ mol−1 by the Flynn–Wall–Ozawa and Kissinger methods, respectively, which were much lower than that of phenolphthalein poly(aryl ether sulfone). Furthermore, introduction of isopropyl groups on the main chain can significantly reduce the char yield.

Polyoxymethylene/Reduced Graphene Oxide-g-Melamine Nano-composites With Low Formaldehyde Emission: Intercalation Structure and Synergistic Thermal Oxidative Stabilization Effect

Formaldehyde emission produced by polymer degradation would cause serious environment pollution. Melamine (MA) as highly efficient formaldehyde scavenger has been widely applied in polyoxymethylene (POM) industry. However, the volatilization, migration and physical loss of MA during processing and application have become a serious problem for POM production. In this work, MA was first grafted onto graphene oxide (GO) surface through amidation reaction, and reduced graphene oxide-g-melamine (rGO-MA) hybrid was prepared by subsequent reduction. The POM/rGO-MA nano-composite was then manufactured via conventional melt processing. By incorporation of MA, hydrogen bonding was enhanced for composite, and POM molecules were intercalated into reduced graphene oxide (rGO) layers effectively with high intercalation ratio, while rGO was exfoliated and uniformly distributed in POM matrix. Compared with neat POM, the formaldehyde emission amount (FEA) of POM/rGO-MA decreased notably by 50.8%, and the thermal degradation temperature and degradation activation energy (Ea) were improved significantly. Meanwhile, the retention of mechanical property of POM/rGO-MA remained stable, while melt index increased much slowly during thermo-oxygen aging process. By grafting MA onto rGO surface, both the thermal migration resistance of MA and radical scavenging ability of GO were enhanced, while rGO-MA exhibited excellent synergistic removal effect of formaldehyde generated by POM degradation. Besides, the composite showed extraordinary oxygen barrier property, and thermal oxidation degradation of POM was delayed effectively.

Effect of low aspect ratio one-dimensional nanoparticles on properties of photocrosslinked alginate nanocomposite hydrogels

One-dimensional nanoparticles such as fibers, wires, represent an exciting type of filler for obtaining nanocomposite hydrogels due to their high aspect ratio. Unlike continuous fibers, in composites with short fibers, stress transfer occurs not only at the cylindrical surface of the fiber but also at the fiber ends. This work aimed to study the influence of the length of low aspect ratio one-dimensional nanoparticles on the rheological, swelling and thermal properties of nanocomposite hydrogels. We synthesized nanocomposite hydrogels via photopolymerization of methacrylated alginate macromonomers and aluminum oxide nanoparticles, nanowires and nanofibers as fillers. The main difference between the nanoparticles lies in their length. Longer nanoparticles (nanofibers) provided a glassier structure and a more significant reinforcement to the hydrogel, for example, at the concentration of 0.5 wt% the complex modulus increased approximately 2-fold and 8-fold for nanowires and nanofibers, respectively. Similarly, the incorporation of nanofibers produced hydrogels with a lower swelling capacity (2.5-fold decrease), which was attributed to a more connected network structure due to the higher aspect ratio of the nanofibers. Finally, both nanoparticle types produced an increase in the activation energy of thermal degradation.

Effect of non-rubber components on the crosslinking structure and thermo-oxidative degradation of natural rubber

Non-rubber components (NRCs) in natural rubber (NR), including proteins, phospholipids, fatty acids, etc., determine to a large extent the structure and properties of NR. In this study, the effects of NRCs on the network structure and thermo-oxidative aging behavior of unvulcanized and vulcanized NR were investigated. NRCs were found to form physically crosslinked networks in the unvulcanized NR and acted as a natural antioxidant to scavenge free radicals, which contributed to improved thermo-oxidative stability of the unvulcanized NR. Swell analysis, chemical probe analysis (DPPH), and XPS results showed that the NRCs accelerated the vulcanization reaction and increased the crosslink density, and promoted the formation of more mono- and disulfide bonds during vulcanization. When aged at high temperatures, more monosulfide bonds were formed in the vulcanized rubber with high contents of NRCs by cleaving and rearranging the poly- and disulfide bonds. NRCs were also found to increase the activation energy of thermal degradation and led to the better mechanical stability of vulcanized NR against thermal oxidation.

Thermal Degradation Kinetics Analysis of Polymer Composite Electrolyte Membranes of PEVOH and PBT Nano Fiber.

The thermal degradation kinetics of high-performance polymer composite electrolyte membranes were investigated by thermal gravimetric analysis in this study. The novel porous polymer composite membranes were fabricated by crosslinking poly (ethylene-co-vinyl alcohol) (EVOH) with polybutylene terephthalate (PBT) nano fiber. The PBT nano-scale fiber non-woven cloth was first prepared by the electrospinning method to form a labyrinth-like structure, and the crosslinking was carried out by filtering it through a solution of EVOH and crosslinking agent triallylamine using the Porcelain Buchner funnel vacuum filtration method. The PBT–EVOH composite membranes with various crosslinking agent ratios and ethylene carbonate/dimethyl carbonate (EC/DMC) immersion times were investigated for their thermal stability and ionic conductivity. The results showed that the higher crosslinking agent content would lower the crystallinity and enhance thermal stability. The thermal degradation activation energy was dramatically increased from 125 kJ/mol to 340 kJ/mol for the 1.5% crosslinking agent content sample at 80% conversion. The triallylamine crosslinking agent was indeed effective in improving thermal degradation resistivity. The best ionic conductivity of the polymer composite membranes was exhibited at 5.04 × 10−3 S cm−1 using the optimal weight ratio of EVOH/PBT composite controlled at 1/2. On the other hand, the EC/DMC immersion time was more effective in controlling the Rb value, thus the ionic conductivity of the membranes. A higher immersion time, such as 48 h, not only gave higher conductivity data but also provided more stable results. The triallylamine crosslinking agent improved the membrane ionic conductivity by about 22%.

Synthesis and characterization of novel sulfonamide functionalized maleimide polymers: Conventional kinetic analysis, antimicrobial activity and dielectric properties

In this study, novel maleimide monomers, N-sulfamethoxazole maleimide(SMM), and N-sulfanilamide maleimide(SAM) were synthesized. Homopolymers of SMM and SAM were obtained by free radical polymerization method in 1,4-dioxane solvent at 65 °C. The structural characterizations of monomers and their homopolymers were carried out via FTIR, 1H- and 13C-NMR techniques. The glass transition temperature (Tg) of the polymers was determined using differential scanning calorimetry (DSC). Using the thermogravimetric analysis (TGA) method determined the thermal stability of the polymers. The thermal degradation activation energies (Ea) of the polymers were calculated by Kissinger, Flynn Wall Ozawa (FWO), and Kissinger-Akahira-Sunose (KAS) methods. The biological activities of compounds have been also studied on various bacteria and fungi. The weight average (Mw) and number average (Mn) molecular weights of the polymers were determined by gel permeation chromatography (GPC). Photochemical properties of polymers were investigated with ultraviolet (UV) and fourier transform infrared (FTIR) spectra. In addition, some physical constants of polymers such as density, solubility parameter, and viscosity were determined. Finally, the dielectric constant, dielectric loss factor and ac conductivity values ​​of the polymers were estimated in the frequency range of 100 Hz–20 kHz.

Thermal decomposition behaviors of a self‐intumescent flame retardant epoxy resin

AbstractThis paper focuses on revealing the thermal decomposition behaviors of a self‐intumescent flame retardant (IFR) epoxy (EP) resin (EP/15%APP‐Cu2O) employing 12 wt% ammonium polyphosphate (APP) as a halogen‐free flame retardant and 3 wt% copper (I) oxide (Cu2O) as char forming rate regulator. Initially, the thermal stability of EP/15%APP‐Cu2O was analyzed and compared to virgin EP resin and flame retardant EP (EP/15%APP) containing 15 wt% APP as flame retardant by thermogravimetric analysis test at different heating rates under nitrogen atmosphere. It was shown that the incorporation of APP altered the decomposition pathway of EP and decreased the onset decomposition temperature. Luckily, compared to EP/15%APP, the onset decomposition temperature of EP/15%APP‐Cu2O was just slightly reduced from 300.4 to 292.8°C. Then, the thermal degradation kinetics of EP, EP/15%APP and EP/15%APP‐Cu2O were further evaluated by Kissinger and Flynn‐Wall‐Ozawa methods. It was worth noted that the addition of APP or APP‐Cu2O enhanced the thermal degradation activation energies of EP, which contributed to the protective effect of the char formation. Particularly, the incorporation of 3 wt% Cu2O significantly decreased the thermal degradation activation energies at the early decomposition stage of EP. This may be the main contribution for intumescent char formation, which resulted in higher fire safety of EP/15%APP‐Cu2O compared to EP/15%APP. These information can potentially help to develop alternative IFR systems.

Thermal degradation of calcium lactate pentahydrate using TGA/FTIR/MS: thermal kinetic and thermodynamics studies

ABSTRACT The objective of this study is to investigate the thermal degradation kinetics and thermodynamics of the calcium lactate pentahydrate (CLP) crystals by means of a thermogravimetric analyzer (TGA) at four different heating rates from 25°C to 1000°C in N2 atmosphere. First, the CLP crystals were precipitated at pH 6 and 25°C in a batch-type crystallizer and the obtained crystals were characterised by X-ray powder diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). The XRD result showed that the calcium l-lactate pentahydrate (L-CLP) was the only crystalline phase produced. Then, the activation energy and pre-exponential factor of thermal degradation were determined based on the Coats–Redfern, Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), and Starink models. The degradation reaction order was determined as 1.5 by Coats-Redfern model. The average activation energy of the CLP was 34.7, 33.0, and 33.3 kJ/mol for the FWO, KAS, and Starink models, respectively. Thermodynamic parameters as changes in enthalpy, entropy and Gibbs free energy were calculated depending on the conversion degree. Finally, TGA in combination with FTIR and mass spectrometer (MS) was utilised to detect the evolved gases during the degradation of CLP. H2O and CO2 were identified as the main evolved products.

Synthesis, stereocomplex crystallization, homo-crystallization, and thermal properties and degradation of enantiomeric aromatic poly(lactic acid)s, poly(mandelic acid)s

Enantiomeric aromatic poly(lactic acid)s, i.e., poly(l-mandelic acid) (PLMA) and poly(d-mandelic acid) (PDMA), with different number-average molecular weight (Mn) values were synthesized by polycondensation and their stereocomplex (SC) crystallization and homo-crystallization by solvent-evaporation, as well as thermal properties and degradation were investigated in detail. The SC crystallization was confirmed by wide-angle X-ray diffraction and differential scanning calorimetry. However, Fourier-transfer infrared spectroscopy could not identify SC crystallization, excluding the lowered peak width of the carbonyl group. Predominant SC crystallization was observed for high molecular weight PLMA/PDMA (Mn = 1.7 × 104 and 1.5 × 104 g mol–1, respectively) blends and low molecular weight PLMA/PDMA (Mn = 5.8 × 103 and 7.2 × 103 g mol–1) blends, except for low molecular weight PLMA/PDMA blend with a PLMA fraction of 75%, where both SC crystallization and homo-crystallization occurred. This can be explained by the lower crystallizability of homo-crystallites at high Mn values compared to that of SC crystallites. The glass transition temperatures of poly(mandelic acid)s (87 °C − 112 °C) were higher than those previously reported for poly(lactic acid)s (PLAs) (approximately 60 °C), poly(2-hydroxybutanoic acid)s [P(2HB)s] (24 °C − 44 °C), and poly(phenyllactic acid) (32 °C − 47 °C). In marked contrast with the results previously reported for enantiomeric PLAs and P(2HB)s, melting temperatures of SC crystallites of PMAs (105 °C – 127 °C) were lower than those of homo-crystallites (162 °C − 180 °C). The thermal degradation temperatures at 10% weight loss for unblended PLMA, PDMA, and their (50/50) blend (290 °C − 313 °C) were much higher than those reported for unblended enantiomeric PLAs, and their (50/50) blend (218 °C − 243 °C) and similar to those reported for enantiomeric P(2HB)s, and their (50/50) blend (300 °C − 330 °C). The thermal degradation profiles and temperatures of unblended PLMA, PDMA, and their blend were similar with each other, whereas the activation energy for thermal degradation (ΔEtd) of PLMA/PDMA blend (136.7− 163.0 kJ mol–1) was between those of unblended PLMA (117.7 − 154.4 kJ mol–1) and unblended PDMA (196.3 − 226.6 kJ mol–1). These results contrast with those previously reported for enantiomeric PLAs and P(2HB)s, wherein ΔEtd values were increased by enantiomeric polymer blending. Furthermore, the crystallizability of aromatic poly(mandelic acid) and poly(phenyllactic acid) was compared.

Highly efficient Oil/Water and brine Separations: Superhydrophobic hybrid isobornyl methacrylate coatings

A rapid and facile method to obtain a fluorine-free, superhydrophobic/superoleophilic coating with superior thermal stability based on a cyclic methacrylate chemistry is reported. The chemical structure of the coating is based on the crosslinking reaction of isobornyl methacrylate, ethylene glycol dimethacrylate (crosslinker) and a 3-(trimethoxysilyl)propyl methacrylate (adhesive), using AIBN as initiator, toluene as solvent, and silica nanoparticles. Chemorheology results showed that the coating can be fully cured in 10 min at 100 °C, exhibiting a water contact angle (CA) of 165 ± 3°, and an oil CA of 0° for eight oils of wide commercial interest (gasoline, diesel, petroleum ether, kerosene, hexane, toluene, chloroform and dichloromethane). The superhydrophobic/superoleophilic exhibited nanostructures and multiscale roughness throughout the surface, and excellent adhesion properties on the mesh screen. Also, the coating exhibited outstanding oil/water separation efficiency (>99 %) for all eight types of oil/water mixtures studied, as well as for hexane/saturated brines of NaCl, KCl or MgSO4, besides having high recyclability. Isothermal and non-isothermal TGA revealed its high thermal stability, and the activation energy of thermal degradation according to the Kissinger and modified Ozawa models were 115.6 and 119.2 kJ/mol, respectively.

Degradation of Tryptophan by UV Irradiation: Influencing Parameters and Mechanisms

The chlorination of dissolved amino acids can generate disinfection by-products (DBPs). To prevent the formation of DBPs, we examined the UV-induced degradation of tryptophan (Trp). In order to further understand the impact of UV disinfection on Trp, the effects of initial concentrations of Trp, pH, temperature, concentrations of NO3−, HCO3− and Cl− on Trp removal were investigated, and a degradation mechanism was also proposed. The results demonstrated that degradation fitted a pseudo first-order reaction kinetic model. The degradation of Trp was mainly caused by direct UV degradation. The apparent rate constant kobs decreased with the increase in initial Trp concentration and increased with increases in pH and temperature. The thermal degradation activation energy was 19.65 kJ/mol. Anions in water also had a significant influence on the degradation of Trp. HCO3− and NO3− contributed to the kobs of Trp, but Cl− inhibited the degradation rate. By electron paramagnetic resonance (EPR) spectroscopy, ·OH was proven to be formed during the degradation of Trp by UV. Based on the intermediate products of C11H15NO3, C10H15N and C9H13N detected by LC-MS-MS, the degradation pathway of Trp was speculated.

Effect of monomer type on polydopamine modification of bamboo flour and the resulting interfacial properties of bamboo plastic composites

Bamboo flour (BF) was modified with mussel-inspired polydopamine to enhance compatibility with high-density polyethylene (HDPE) in BF/HDPE composites. Polydopamine was synthesized using dopamine, catechol, and dopa as monomers. The modified BF exhibited better physicochemical properties. Dopamine-modified BF surface showed the greatest elevation in free energy and roughness. The largest increase in wettability, specific surface area, and thermal degradation temperature was displayed by dopa-modified BF. The improved processability of modified BF boosted interaction between BF and HDPE, thus physicomechanical performance of compression-molded composites was promoted. Composites with dopamine-modified BF won the strongest interfaical bonding, the lowest water sorption, the best mechanical performance, and the highest heat distortion temperature. The highest glass transition temperature and melting temperature were found in composites with catechol-modified BF. Composites with dopa-modified BF triggered the biggest thermal degradation activation energy. Overall, dopamine modification gave composites more merits, but catechol and dopa were useful when tailoring some thermal properties.

Mechanical and Thermal Properties of Epoxy/Poly(Styrene‐co‐Acrylonitrile) (SAN)/Organoclay Nanocomposites

AbstractThis article focuses on the investigations on mechanical and thermal properties of the epoxy/poly(styrene‐co‐acrylonitrile) (SAN)/cloisite 20A nanocomposites. The analysis is performed in two particular compositions of epoxy/SAN blends to study the effect of nanoclay addition. The compositions of blends, epoxy/5 phr SAN and epoxy/15 phr SAN, are selected based on the difference in phase separation mechanism and microstructure. An increment in tensile strength is observed for epoxy/5 phr SAN/1 wt% cloisite 20A nanocomposite. Young's modulus is increased in epoxy/15 phr SAN/cloisite 20A nanocomposites. A surge in the toughness and impact properties is observed for the nanocomposites. Beneficial increment in activation energy for thermal degradation is observed for epoxy/SAN blends and epoxy/SAN/cloisite 20A nanocomposites. The nanocomposites are suitable for high temperature applications without much compromise in the mechanical properties.

Thermal degradation behavior of ionic liquid/ fluorinated polymer composites: Effect of polymer type and ionic liquid anion and cation

This work reports on the evaluation of the thermal degradation of poly(vinylidene fluoride) (PVDF) and PVDF co-polymer (PVDF-TrFE, PVDF-HFP and PVDF-CTFE) composite films with different imidazolium ionic liquids (ILs). The influence of the IL type, including cation and anion type, cation chain length and content up to 40 wt% were evaluated. Independently of the fluorinated polymer type, all neat samples present a single degradation step. Upon the incorporation of the IL [C2mim][TFSI] into the different polymers, a decrease in the thermal stability occurs, indicating the IL imidazolium interaction with the CH2-CF2 groups of the fluorinated matrix. Further, it was stablished that the thermal stability of the composite material decreases with increasing cation chain length. The Ozawa-Flynn-Wall and Kissinger models were applied to evaluate the activation energies of the samples during isothermal experiments, showing that the thermal degradation activation energy ranges from 161 ± 6 kJ mol−1 ([C2mim][TFSI]/PVDF) to 131 ± 14 kJ mol−1 ([C2mim][TFSI]/PVDF-CTFE). No large differences were observed on the effect of IL inclusion in PVDF, PVDF-TrFE, PVDF-HFP and PVDF-CTFE polymer matrices.

Synthesis and application of new macromolecular hindered phenol antioxidants of polyamide 6

AbstractThe two macromolecular antioxidants, P(3,5‐di‐tert‐butyl‐4‐hydroxy cinnamic acid‐alt‐N‐phenylmaleimide) (PCN) and P(3‐butene‐1‐yl‐3,5‐di‐tert‐butyl −4‐hydroxyphenyl propionate‐alt‐N‐phenylmaleimide) (PPN) were designed and synthesized via free radical copolymerization. The structures of the resulting PCN and PPN antioxidants were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy (1H NMR), and gel permeation chromatography. In addition, the effect of the two macromolecular antioxidants on the thermal oxidation aging resistance of polyamide 6 (PA6) was studied. According to the analysis of differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis, dynamic viscosity, and the mechanical property of PA6 and its blends, these two types of macromolecular antioxidants protected the molecular chain of PA6 from breaking, protected the crystallization of PA6 and maintained the stability of PA6 crystal form, improved the activation energy of thermal degradation and thermal stability of PA6, enhanced the strength and elasticity of PA6 and maintained the mechanical properties of PA6 during aging to a certain extent.

Thermal Degradation Kinetics and Modeling Study of Ultra High Molecular Weight Polyethylene (UHMWP)/Graphene Nanocomposite.

The incorporation of nanofillers such as graphene into polymers has shown significant improvements in mechanical characteristics, thermal stability, and conductivity of resulting polymeric nanocomposites. To this aim, the influence of incorporation of graphene nanosheets into ultra-high molecular weight polyethylene (UHMWPE) on the thermal behavior and degradation kinetics of UHMWPE/graphene nanocomposites was investigated. Scanning electron microscopy (SEM) analysis revealed that graphene nanosheets were uniformly spread throughout the UHMWPE’s molecular chains. X-Ray Diffraction (XRD) data posited that the morphology of dispersed graphene sheets in UHMWPE was exfoliated. Non-isothermal differential scanning calorimetry (DSC) studies identified a more pronounced increase in melting temperatures and latent heat of fusions in nanocomposites compared to UHMWPE at lower concentrations of graphene. Thermogravimetric analysis (TGA) and derivative thermogravimetric (DTG) revealed that UHMWPE’s thermal stability has been improved via incorporating graphene nanosheets. Further, degradation kinetics of neat polymer and nanocomposites have been modeled using equations such as Friedman, Ozawa–Flynn–Wall (OFW), Kissinger, and Augis and Bennett’s. The "Model-Fitting Method” showed that the auto-catalytic nth-order mechanism provided a highly consistent and appropriate fit to describe the degradation mechanism of UHMWPE and its graphene nanocomposites. In addition, the calculated activation energy (Ea) of thermal degradation was enhanced by an increase in graphene concentration up to 2.1 wt.%, followed by a decrease in higher graphene content.

Kinetic modeling and analysis of pyrolysis of polymethyl methacrylate using isoconversional methods

Pyrolysis the waste plastic into fuel is a promising way to protect the environment. In this study, we study the thermal decomposition processes of polymer Poly (methyl methacrylate) PMMA. This work used the microscale combustion calorimeter (MCC) as a tool to study the degradation. MCC is an applicable method to calculate the material combustion parameters by using milligram samples. The experiments were carried out at four heating rates 0.25, 0.5, 0.75, and 1 K/s. The temperature range in which the pyrolysis reaction occurs is « 300-470 oC. We applied several isoconversional methods such as Friedman, Ozawa, Flynn-Wall-Ozawa (FWO), and Kissinger-Akahira-Sunose (KAS) to estimate the apparent activation energy of thermal degradation of Poly(methyl methacrylate). Determine the activation energy from each method evaluated against the experimental data. With investigation, the FWO method shown much higher values for activation energy for PMMA polymer more than the other two methods, and the average value much higher than the Friedman and KAS methods. On the other hand, as a differential method, Friedman showed more accurate results Ea=216.65kJ/mol, and KAS method 228.61 kJ/mol. Our investigation may give a few experiences to how to more readily portray trial results with hypothetical expectations and essential data for calculating the activation energy of potential pyrolysis reactors.

Remarkable enhancement of thermal stability of epoxy resin through the incorporation of mesoporous silica micro-filler

For the first time, we incorporated mesoporous micro-silica (5 μm, pore size = 50 nm) as a filler in epoxy resin aiming to enter polymer into the pore of the silica. As expected, the thermal stability of the composite increased remarkably, followed by noteworthy thermal degradation kinetics when compared to the controlled cured epoxy resin. Composites were prepared by the direct dispersion of modified nano-silica, modified mesoporous micro-silica, unmodified mesoporous micro-silica, non-porous micro-silica, and irregular micro-silica of various pore sizes as fillers in diglycidyl ether of bisphenol-A epoxy resin via ultra-sonication and shear mixing, followed by oven-curing with 4,4-diaminodiphenyl sulfone. DSC and TGA analyses demonstrated a higher glass transition temperature (increased by 3.65–5.75 °C) and very high activation energy for thermal degradation (average increase = 46.2%) was obtained for the same unmodified silica composite compared to pure epoxy, respectively.

Graphite-LDH hybrid supported zirconocene for ethylene polymerization: Influence of the support on the crystallization kinetics and thermal stability of polyethylene

A hybrid nanomaterial, low crystallinity graphite-layered double hydroxide, was used as a support for zirconocene catalyst. The hybrid nanomaterial graphite-NiAl layered double hydroxides (G/LDH) were synthesized by the co-precipitation method. The synthesized nanomaterial was used as a support for zirconocene catalyst. The polymerization reactions were carried out for ethylene polymerization. The synthesized polyethylene (PE) was analyzed by using differential scanning calorimetry (DSC), Crystallization analysis & fractionation (CRYSTAF), and thermogravimetric analysis for its thermal and microstructural characteristics. The crystallization kinetics were studied by the Ozawa and combined Ozawa and Avrami models. It was found that the presence of G/LDH from the catalyst support nucleated the PE crystallization and shifted the crystallization onset temperature to a higher value. However, the overall crystallization rate was slowed by the presence of the nanomaterial due to growth impingement. Moreover, the PE synthesized by G/LDH supported catalyst possessed higher thermal stability than PE synthesized by unsupported zirconocene catalyst. The integral isoconversional method was used to evaluate the activation energy of thermal degradation and crystallization kinetics. The degradation mechanism was validated by the application of the integral master plot technique. The degradation mechanism of neat PE resembled phase boundary controlled mechanism second and third-order, i.e. (R2, R3), while PE synthesized by G/LDH supported catalyst had a shift in degradation mechanism from (R2, R3) to a diffusion-limited mechanism at the later stages of degradation.