Activation Energy Of Thermal Decomposition Research Articles

Synthesis, characterization, and thermal degradation kinetics of poly(decamethylene 2‐oxoglutarate)

AbstractPoly(decamethylene 2‐oxoglutarate) [poly (DMOG)] was synthesized by a melt polycondensation reaction. The structure of poly(DMOG) was confirmed by means of Fourier transform infrared, 1H‐NMR, and 13C NMR spectroscopies. The molecular weight distribution values of poly(DMOG) were determined with size exclusion chromatography. The number‐average molecular weight, weight‐average molecular weight, and polydispersity index values of poly(DMOG) were found to be 13,200, 19,000, and 1.439, respectively. Also, characterization was made by thermogravimetry (TG)–dynamic thermal analysis. The kinetics of the thermal degradation of poly (DMOG) was investigated by thermogravimetric analysis at different heating rates. TG curves showed that the thermal decomposition of poly(DMOG) occurred in one stage. The apparent activation energies of thermal decomposition for poly(DMOG), as determined by the Tang method, the Flynn–Wall–Ozawa method, the Kissinger–Akahira–Sunose method, and the Coats–Redfern method were 122.5, 126.8, 121.4, and 122.9 kJ/mol, respectively. The mechanism function and pre‐exponential factor were also determined by the master plots method. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

SYNTHESIS, CHARACTERIZATION AND THERMAL DEGRADATION KINETICS OF POLY(IMINO ISOPHTHALOYL IMINO (2,4,8,10-TETRAOKSOASPIRO [5,5] UNDEKAN-3,9-DIPROPYLENE))

A new polymer, poly(imino isophthaloyl imino (2,4,8,10-tetraoksoaspiro [5,5] undekan-3,9-dipropylene)) [poly(IPIT)] was synthesized by an interfacial polycondensation reaction. The characterization of poly(IPIT) was conducted by using FT-IR, 13C-NMR, TG and DTA techniques. The kinetics of the thermal degradation of poly(IPIT) was investigated by thermogravimetric analysis at different heating rates. TG curves showed that the thermal decomposition of poly(IPIT) occurred in three stages. The apparent activation energies of thermal decomposition for poly(IPIT), as determined by the Tang method (TM), the Flynn-Wall-Ozawa method (FWO) and the Kissinger-Akahira-Sunose method (KAS) are 58.09, 57.7 and 61.0 kJ/mol for the first stage decomposition, 106.1, 105.6 and 109.8 kJ/mol for the second stage decomposition, and 138.1, 137.5 and 141.4 kJ/mol for the third stage decomposition, respectively.

Thermal Decomposition Kinetics of Hexanitrohexaazaisowurtzitane by Mass Spectrometry

Thermal decomposition of hexanitrohexaazaisowurtzitane (HNIW) was studied by mass spectroscopy (MS) with low impacting electron energy. Non-isothermal kinetics treating method for ion curves in mass spectroscopy was established. The mechanism of HNIW thermal decomposition was analyzed according to the Arrhenius curves of ion products. The results showed that the apparent activation energy of the HNIW thermal decomposition was 145.1 kJ·mol-1. Between 130 and 150 ℃, ion products are mainly produced by electron impact, and activation energy is between 28 and 41 kJ·mol-1. Between 213 and 228 ℃, ion products are mainly produced by thermal decomposition, and activation energy is between 143 and 179 kJ·mol-1. The kinetic compensation effect occurs in thermal decomposition of HNIW between 213 and 228 ℃, and the compensation effect equation is lnA=0.252Ea-0.645. The main reactions of HNIW thermal decomposition are as HNIW.438→6NO2+2HCN+HNIW.108, HNIW.438→6NO2+3HCN+HNIW.81, HNIW.438→6NO2+4HCN+HNIW.54.

NEW POLY(METHACRYLATE)S CONTAINING OXIME ESTERS MOIETIES BASED ON CYCLOHEXANON AND CYCLOPENTANON

The synthesis of two new methacrylates such as 2-((cyclohexylideneamino)oxy)-2-oxoethyl methylacrylate (CHOEMA) and 2-((cyclopentylideneamino)oxy)-2-oxoethyl methylacrylate (CPOEMA) are described. The monomers produced from the reaction of corresponding cyclohexanone O-(2-chloroacetyl) oxime and cyclopentanone O-(2- chloroacetyl) oxime with sodium methacrylate was polymerized in 1,4-dioxane solution at 65°C using AIBN as an initiator. The monomers and their polymers were characterized by IR, 1 H- and 13 C-NMR spectroscopy. The glass transition temperature of the polymers was investigated by DSC and the apparent thermal decomposition activation energies (Ed) were calculated by Ozawa and multiple heating rate kinetics (MHRK) method using the Shimadzu TGA thermobalance. By using gel permeation chromatography, weight-average (Mw) and number-average (Mn) molecular weights and polydispersity indices of the polymers were determined. The antibacterial and antifungal effects of the monomers and polymers were also investigated on various bacteria and fungi. The photochemical properties of the polymers were investigated by UV and FTIR spectra.

Copolymers of 4‐(1‐methyl‐1‐mesityl‐3‐cyclobutyl)‐2‐N‐1, 3‐thiazole‐2‐yl methacrylamide with 2‐[(5‐methylisoxazol‐3‐yl) amino]‐2‐oxo‐ethyl methacrylate: Synthesis, characterization, monomer reactivity ratios and biological activity

AbstractThe free radical copolymerization of 4‐(1‐methyl‐1‐mesityl‐3‐cyclobutyl)‐2‐N‐1, 3‐thiazole‐2‐yl methacrylamide (MCTMA) with 2‐[(5‐methylisoxazol‐3‐yl)amino]‐2‐oxo‐ethyl methacrylate (IAOEMA) has been carried out in 1, 4‐dioxane at 65 °C ± 1 and were analyzed by Fourier transform infrared, 1H NMR, 13C NMR, and gel permeation chromatography. 1H‐NMR analysis was used to determine the molar fractions of MCTMA and IAOEMA in the copolymers. The monomer‐reactivity ratios were calculated according to the general copolymerization equation using Kelen–Tüdõs and Finemann–Ross linearization methods. The reactivity ratios indicated a tendency toward random copolymerization. The polydispersity indices of the polymers, determined with gel permeation chromatography, suggested a strong tendency for chain termination by disproportionation. The thermal behaviors of copolymers with various compositions were investigated by differential scanning calorimetry and thermogravimetric analysis. The glass‐transition temperature of the copolymers increased with increasing MCTMA content in the copolymers. Also, the apparent thermal decomposition activation energies were calculated by the Ozawa method with a Shimadzu TGA 60 thermogravimetric analysis thermobalance. All the products showed moderate activity against different strains of bacteria and fungi. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 530–542, 2008

Preparation and Analytical Properties of Amphoteric Chelating Resin

The chelating ion exchange resin AFM was synthesized by condensation of anthranilic acid with formaldehyde and m‐cresol in DMF media at 100 oC ± 6°C. The identification of resin structure was performed by elemental and FTIR analysis. The thermodynamic parameters such as activation energy (Ea), entropy (S*), enthalpy (H*) and free energy (G*) for thermal decomposition were calculated from thermal data. The morphology of AFM resin shows transition material between crystalline and amorphous phase. The rate of exchange was rapid. i.e. t1/2 < 22 min for Pb(II) and pH dependence of exchange of metal ions on the resin has been determined for several metal ions [Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II)]. Successive separations and recovery of some pair of metal ions [Pb(II)‐Cd(II), Pb(II)‐Zn(II) and Zn(II)‐ Cu(II)] have been performed by using distribution coefficient (Kd).

Thermal, mechanical, and structural investigation of the effect of electron beam‐irradiation in Bayfol nuclear track detector

AbstractSamples from sheets of the polymeric material Bayfol have been exposed to electron beam in the dose range 10–100 kGy. The resultant effect of electron beam irradiation on the thermal properties of Bayfol has been investigated using thermogravimetric analysis. The onset temperature of decomposition T0 and activation energy of thermal decomposition Ea were calculated, results indicating that the Bayfol polymer decomposes in one main weight loss stage. Also, the electron irradiation in the dose range 40–100 kGy led to a more compact structure of Bayfol polymer, which resulted in an improvement in its thermal stability with an increase in activation energy of thermal decomposition. The variation of transition temperatures with electron dose has been determined using differential thermal analysis. The results indicate that the electron irradiation in the dose range 40–100 kGy causes crosslinking that destroys the crystalline structure depressing the melting temperature and this is most suitable for applications requiring the molding of this polymer at lower temperatures. In addition, the mechanical and structural properties of Bayfol samples were measured and the results revealed that the tensile strength, elongation at break, yield strength, and intrinsic viscosity were affected by the electron doses. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

Kinetics and mechanism of thermal decomposition of pre-oxidized polycarbosilane fibers

The thermal decomposition of pre-oxidized polycarbosilane(PCS)fibers was carried out in a thermogravimetric analyzer under non-isothermal condition.The Coats-Redfern equation was used to estimate the apparent activation energy in thermal decomposition and the mechanism of thermal decomposition was studied by IR,XRD and SEM.It was found that the thermal decomposition of pre-oxidized PCS fibers was a first order reaction and the apparent activation energy was estimated to be 19.826kJ/mol.The thermal decomposition process was a dehydrogenation and dehydrocarbonation condensation with the evaporation of low molecular components at low temperature.With increasing temperature the fibers were converted into an inorganic structure by decomposition of the side chains of the polymer.When the temperature was further increased,the crystallite size of SiC increased and the fibers became completely inorganic;above 1250℃.The mechanical properties of the SiC fibers became lower with the rapidly increasing crystallite size of the β-SiC.

Investigation of the effect of intensive ball milling in a planetary ball mill on the thermal decomposition of cadmium carbonate and basic zinc carbonate

The kinetics of thermal decomposition of cadmium carbonate CdCO3 and basic zinc carbonate ZnCO3·nZn(OH)2 and the effect of intensive milling in a planetary ball mill on its parameters, have been investigated. The values of the reaction heat and of the activation energies of thermal decomposition have been determined for both the compounds. Investigations of the thermal decomposition of the products of ball milling of investigated compounds revealed a slight effect of milling conditions on the reaction temperature and heat consumed during the thermal decomposition of ZnCO3·nZn(OH)2. No effect of ball milling on the thermal decomposition of CdCO3 has been found.

Fast neutron irradiation effects in PM-355 nuclear track detector

Samples from sheets of the polymeric material PM-355 have been exposed to neutrons of incident energy in the range 0.8–19.2 MeV. The resultant effect of neutron irradiation on the thermal properties of PM-355 has been investigated using thermo-gravimetric analysis (TGA). The onset temperature of decomposition T o and thermal activation energy of decomposition E a were calculated, results indicating that the PM-355 detector decomposes in two weight loss stages. The variation of transition temperatures with neutron energy has been determined using differential thermal analysis (DTA). The results indicate the PM-355 thermograms to be characterized by the appearance of an endothermic peak due to melting. Melting temperature was found to be dependent on the neutron energy. In addition, structural property studies using X-ray diffraction and infrared spectroscopy were performed on both non-irradiated PM-355 samples and all of the samples that were irradiated. The results indicate that both the degree of ordering and the absorbance of the PM-355 polymer are dependent on neutron energy.

Thermal Decomposition and Oxidation Ageing Behaviour of Polypropylene/Halloysite Nanotube Nanocomposites

The thermal decomposition and oxidation ageing behaviour of polypropylene (PP) and PP/halloysite nanotube (HNT) nanocomposites were studied. The kinetics of thermal decomposition were calculated by integral models. The thermal oxidation ageing was investigated by Fourier transform infrared spectroscopy (FTIR). The PP nanocomposites showed a higher activation energy of thermal decomposition than neat PP. Their surface treatment and lower HNT loading led to a higher activation energy of decomposition. Their improved thermal stability in nitrogen was attributed to entrapment of decomposition products at initial decomposition stage and to barrier effects. Nanocomposites made by using silane-modified HNT (m-HNT) and also those with lower quantities of (unsilanated) HNT showed improved resistance to thermo-oxidative ageing. The rate of thermo-oxidative ageing was correlated with the number of acidic sites and the volume of entrapped oxygen in the lumen of the HNT and in cavities.

Cu 2Te synthesis and in-vacuum thermal decomposition: Chemical-kinetics analysis and comparison to equilibrium vapor-pressure measurements

In this study, polycrystalline Cu-foil substrates are exposed to elemental Te vapor at substrate temperatures below 373 K. Auger electron spectroscopy measurements indicate that copper-telluride films are formed at the substrate surface that have a 2:1 Cu-to-Te ratio, as predicted by the Cu–Te phase diagram. When these films are annealed above about 700 K in vacuum, Te desorbs from the substrate with zero-order kinetics. An analysis of Te-desorption traces that assumes the reaction Cu 2Te( s) → 2Cu( s) + αTe( ν) + 1/2(1 − α)Te 2( ν) finds a thermal-decomposition activation energy of 217 ± 3 kJ mol − 1 . These Te-desorption data are compared to the Te impingement rate calculated from Cu 2Te equilibrium vapor-pressure data from the literature and found to be in excellent agreement.

Modification induced by proton irradiation in Makrofol-DE polycarbonate

Makrofol-De Polycarbonate is a class of polymeric solid state nuclear track detector which has many applications in various radiation detection fields. In the present work, Makrofol samples were irradiated using different fluences ( 10 11 – 10 15 / cm 2 ) of 1 MeV protons at the University of Surrey Ion Beam Center, UK. The structural modifications in the proton irradiated Makrofol samples have been studied as a function of fluence using different characterization techniques such as X-ray diffraction, thermogravimetric analysis, differential thermal analysis and color difference studies. The proton irradiation in the fluence range 10 14 – 10 15 / cm 2 led to a more compact structure of Makrofol polymer, which resulted in an improvement in its thermal stability with an increase in the activation energy of thermal decomposition. The melting temperature of the polymer, T m , was investigated to probe the crystalline domains of the polymer. At a fluence range of 10 14 – 10 15 / cm 2 , the defect generated destroys the crystalline structure, thereby reducing the melting temperature. Further, the transmission of these samples in the wavelength range of 200 – 2500 nm , as well as any color changes, was studied. The color intensity Δ E * was greatly increased with increasing the proton fluence, and was accompanied by a significant increase in the red and yellow color components.

Kinetic of thermal degradation of poly(isobornyl methacrylate)

The kinetic of the thermal degradation of poly(isobornyl methacrylate) (PIBORNMA) was investigated by thermo gravimetric (TG) analysis at different heating rates. TG curves showed that the thermal decomposition of PIBORNMA occurred in one stage. The apparent activation energies of thermal decomposition of PIBORNMA was determined by Tang, Flynn-Wall-Ozawa (FWO), Kissenger–Akahira–Sunose (KAS) and Coats-Redfern methods and the values were 80.30, 84.69, 79.81 and 84.413 kJ/mol, respectively. The mechanism function and pre-exponential factor was determined by master plots method.

Thermodegradation of poly(4-vinylpyridine- co-crotonic acid- co-divinylbenzene) and N-oxide derivatives

Copolymer networks based on 4-vinylpyridine (4VPy)/crotonic acid (CrA)/divinylbenzene (DVB) and their N-oxide derivatives have been investigated by thermogravimetric analysis (TG) to evaluate their thermal stability in nitrogen atmosphere at fixed heating rate. Thermal stability was determined from TG curves to investigate the influence of 4VPy content and introduction of N-oxide groups. The TG and DTG curves of unmodified copolymers clearly show two thermodegradation stage and the same kinetic pathway. The decomposition temperatures do not depend on the 4VPy content. The copolymers modified by oxidation present lower thermostability than unmodified showing that the introduction of N-oxide groups modifies their kinetic pathways. A kinetic model Ozawa was used to determine the kinetic parameters. The apparent thermal decomposition activation energies (Δ E d) of the unmodified copolymer under nitrogen was higher than that in modified copolymer. Also, the characterizations of copolymer networks were done by Fourier transform infrared spectroscopy (FTIR).

Thermodegradation of Poly(4-Vinylpyridine-co-Maleic Acid-co-Divinylbenzene) and N-oxide Derivatives: Modeling of TG and DTG Curves

Copolymer networks based on 4-vinylpyridine (4VPy)/maleic acid (MA)/divinylbenzene (DVB) and their N-oxide derivatives have been investigated by thermogravimetric analysis (TG) to evaluate their thermal stability in nitrogen atmosphere at fixed heating rate. Thermal stability was determined from TG curves to investigate the influence of 4VPy content and introduction of N-oxide groups. The TG and DTG curves of unmodified copolymers clearly show one thermodegradation stage and the same kinetic pathway. The decomposition temperatures do not depend on the 4VPy content. The copolymers modified by oxidation present lower thermostability than unmodified showing that the introduction of N-oxide groups modifies their kinetic pathways. A kinetic model Ozawa was used to determine the kinetic parameters. The apparent thermal decomposition activation energies (Δ E d) of the unmodified copolymer under nitrogen was higher than that in modified copolymer.

Effect of gamma and laser radiations on the thermal properties of Makrofol nuclear track detector

A study of the modification possibility of the thermal properties of Makrofol polycarbonate solid-state nuclear track detector using gamma and laser radiations has been carried out. Samples from 300 μm thickness Makrofol sheets were classified into two main groups. The first group was irradiated with gamma doses at levels between 50 and 400 kGy, whereas the second group was exposed to infrared laser radiation with energy fluences at levels between 0.5 and 15 J/cm2. Non-isothermal studies were carried out using thermo-gravimetric analysis (TGA) to obtain the thermal activation energy of decomposition for the Makrofol detector. The results of TGA indicate that the Makrofol samples decompose in one main weight loss stage. Also, the irradiation of Makrofol polymer with gamma doses in the range 135–300 kGy or the exposure to laser energy fluences at levels between 8.3 and 15 J/cm2 leads to further enhancement of the thermal stability of the polymer samples due to the cross-linking phenomenon. This suggests that gamma radiation could be a suitable technique for producing a plastic material with enhanced properties that can be a useful candidate for high-temperature applications. In addition, the variation of transition temperatures with the gamma or laser doses has been determined using differential thermal analysis DTA. The results indicate that the irradiation with gamma in the dose range 50–135 kGy or the exposure to laser energy fluences at levels between 8.3 and 15 J/cm2 decreases the melting temperature of the Makrofol samples, and this is most suitable for applications requiring the molding of this polymer at lower temperatures.

Optothermal Property and Decomposition Characteristics of PtOx Ultrathin Film Sandwiched Between ZnS–SiO2 for Super-Resolution Near-Field Recording

We have investigated the optothermal property and decomposition characteristics of PtO(x) ultrathin film protected by ZnS-SiO2 layers and effects of the constituent phases of PtO(x) on super-resolution capability and read stability of the super-RENS disk. All the ZnS-SiO2/PtO(x)/ZnS-SiO2 multilayers exhibited a steep reflectivity drop at the temperature range between 265 and 350 degrees C, corresponding to the decomposition of PtO(x). The decomposition temperature of the 4-nm-thick PtO(x) ultrathin film protected by ZnS-SiO2 layers was much lower than those obtained in thick PtO(x) films without protection. The activation energy for thermal decomposition was approximately 1.3 eV. Both the decomposition temperature and activation energy for thermal decomposition were unaffected by the constituent phases of PtO(x). Carrier to noise ratios (CNR) of over 40 dB for mark size of 150 nm were achieved in all super-resolution near-field structure (super-RENS) disks, while the super-resolution readout was limited to 2.5 x 10(3) approximately 4.5 x 10(4) cycles. The effect of constituent phases of PtO(x) on the super-resolution capability of super-RENS disk with a PtO(x) mask layer was minimal. However, as the constituent phases of PtO(x) mask layer transformed from a mixture of Pt and PtO, to pure PtO, and then to a mixture of PtO and PtO2, the readout stability of super-RENS disk increased dramatically since less heat was absorbed by the PtO(x) mask layer composed of PtO and PtO2 during the readout process, prohibiting the diffusion of materials inside the bubble to the GeSbTe phase change layer.

Studies on thermal degradation of oligo-2-[(4-morpholin-4-yl-phenyl)imino methyl] phenol and oligomer–metal complex compounds

Thermogravimetric studies of 2-[(4-morpholin-4-yl-phenyl) imino methyl]phenol (2-MPIMP), oligo-2-[(4-morpholin-4-yl-phenyl) imino methyl] phenol (O-2-MPIMP) and its oligomer–metal complex compounds were investigated by thermal analysis. Four kinetic methods were used to investigate the thermal decomposition of these materials. These investigated methods are those of Coats and Redfern (CR), MacCallum and Tanner (MC), van Krevelen (vK) and Madhusudanan, Krishnan and Ninan (MKN). The values of the apparent activation energies of thermal decomposition E a, the reaction order n, pre-exponential factor A, the entropy change ΔS *, enthalpy change ΔH *, free energy change ΔG *, obtained by the above-mentioned methods were all in good in agreement with each other. It was found that the thermal stabilities of the complexes follow the order Cu(II) > Co(II) > Zn(II) > Zr(IV) > Pb(II) > Cd(II).

Effect of Polyethers for Photo and Thermal Decomposition of Photosensitive Diazo Compounds

Inclusion compound formation of polyethylene glycol (PEG) with p-substituted benzene diazo compounds (SBD) in aqueous solutions was decided from activation energy (Ea) of thermal decomposition, dissociation constant Kd by Lineweaver-Burk plot modified with Michaelis-Menten formula and degradation temperature Dt, and compared with constitution of complex by WinMOPAC calculation. Thermal decomposition rate of p-chlorobenzene diazo compound (ClBD) with PEG was accelerated as with βcyclodextrine (CD) which include the benzene ring of the diazo compound. Kd of ClBD with PEG was larger than that with CD. PEG is not a ring, but a linear molecule. Dt of SBD with PEG in solid was higher than that without PEG300. Effect of molecular weight of PEG for Dt was, in a decreasing order, no additives - PEG300