Activation Energy Of Thermal Decomposition Research Articles

Mechanical and aging resistance performance of acrylic sheets containing EPDM-graft-poly(styrene-co-methyl methacrylate)

The addition of ethylene-propylene-diene rubber (EPDM) into acrylic sheets was expected to enhance their thermal and UV aging resistance for outdoor applications. According to the dissimilar polarity of EPDM and styrene (ST)/methyl methacrylate (MMA) monomer mixture (20/80% (w/w)) used for preparation of acrylic sheets, this research aimed to modify EPDM via graft copolymerization with ST and MMA to increase its compatibility. The graft copolymerization of ST and MMA at a ST/MMA ratio of 25/75% (w/w) onto EPDM was carried out in the solution polymerization initiated by benzoyl peroxide at 90 °C for 16 h, resulting in 88.1% grafting efficiency. The addition of 1.0–3.0% (w/w) of graft EPDM (GEPDM) into the acrylic sheets increased their impact strength (~ 17–22%), but decreased their flexural strength (~ 12–36%). However, their mechanical properties were improved after thermal and UV aging. Scanning electron microscopy (SEM) based analysis of the modified acrylic sheets revealed that the fracture surface shifted from brittle to ductile failure characteristics after modification. The thermogravimetric analysis results also exhibited that the addition of GEPDM improved the thermal and UV resistance of the modified acrylic sheets by increasing their initial decomposition temperature and activation energy of thermal decomposition.

Kinetics Study on Thermal Decomposition of Polyepoxyphenylsilsesquioxane/Epoxy Resin Systems

The thermal decomposition kinetics of epoxy resin (EP) containing polyepoxyphenylsilsesquioxane (PEPSQ) was studied by thermogravimetric analysis (TGA) in a nitrogen atmosphere. Kissinger and Flynn–Wall–Ozawa methods were both used to analyze the thermal decomposition process under nonisothermal conditions. The results showed that a slight increase of activation energy was observed in the presence of PEPSQ, which indicated that the addition of PEPSQ retarded the thermal decomposition of EP. The Flynn–Wall–Ozawa method further revealed that PEPSQ significantly increased the activation energy of the whole EP thermal decomposition, especially in the final stage of the thermal decomposition process, which is attributed to the PEPSQ stabilizing the char layer and improving the flame retardancy of EP.

Thermal-mechanical stability of ethylene tetrafluoroethylene alternating copolymer, and modification thereof

It is generally accepted that ethylene tetrafluoroethylene alternating copolymers (ETFEs) are exceptionally thermal stable materials. However, we found that ETFEs will decompose to some extent when exposed to heat, especially above 300 °C and during a dynamic shear process (thermal mechanical degradation, thermal-stress-oxidation synergistic destruction). In this article, the dynamic mechanical degradation of ETFE was first verified by dynamic rheometry with the aid of IR analysis, then a facile, environmental friendly solution—namely the addition of the antiaging agent N,N′-di-2-naphthyl-p-phenylenediamine (DNP)—was adopted to prevent the degradation. Rotational rheometry and thermogravimetry analysis results proved that this is an applicable strategy. The addition of DNP led to remarkable increases in the initial thermal decomposition temperature, dynamic shear stable duration time, and thermal decomposition activation energy of ETFE without sacrificing its mechanical properties.

Characterization and Thermal Decomposition Kinetics of Poly(ethylene 2,6-naphthalate) Nanocomposites Reinforced with TiO2 Nanoparticles

Poly(ethylene 2,6-naphthalate) (PEN) reinforced with TiO2 nanoparticles (nano-TiO2) were prepared by direct melt compounding. Thermogravimetric analysis was conducted on the PEN/nano-TiO2 nanocomposites to clarify the effect of nano-TiO2 on the thermal decomposition behavior of the resultant nanocomposites. There is a significant dependence of thermal decomposition behavior for PEN/nano-TiO2 nanocomposites on the content of nano-TiO2 and heating rate. The variation of the activation energy for thermal decomposition reflected the improvement of the thermal stability of the PEN/nano-TiO2 nanocomposites. The incorporation of nano-TiO2 into the PEN matrix increased the storage modulus of the PEN/nano-TiO2 nanocomposites.

Thermal, structural, and optical properties of γ‐irradiated poly(vinyl alcohol)/poly(ethylene glycol) thin film

AbstractPoly(vinyl alcohol)/poly(ethylene glycol) (PVA/PEG) copolymer was prepared using casting technique. The obtained PVA/PEG thin films have been irradiated with gamma rays with doses ranging from 1.5 to 20 Gy. The resultant effect of gamma irradiation on the thermal properties of PVA/PEG has been investigated using thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The onset temperature of decomposition To and activation energy of thermal decomposition Ea were calculated, results indicating that the PVA/PEG thin film decomposes in one main weight loss stage. Also, the gamma irradiation in dose range 4–12 Gy led to a more compact structure of PVA/PEG copolymer, which resulted in an improvement in its thermal stability with an increase in the activation energy of thermal decomposition. The variation of transition temperatures with gamma dose has been determined using DTA. The PVA/PEG thermograms were characterized by the appearance of an endothermic peak due to melting of crystalline phase. In addition, structural property studies using X‐ray diffraction and infrared spectroscopy were performed on both nonirradiated and irradiated samples. Furthermore, the transmission of the PVA/PEG samples and any color changes were studied. The color intensity (E was greatly increased with increasing the gamma dose and was accompanied by a significant increase in the blue and green color components. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Morphology and Properties of Polypropylene Blends Containing Phenolic Resin Produced from the Liquefaction of Empty Fruit Bunch Fibres

Phenol formaldehyde (PF) resin prepared from phenol-liquefied empty fruit bunch (EFB) fibres was blended with polypropylene (PP) using a co-rotating twin-screw extruder. The effects of the PF content (10, 20, 30 and 40 wt.%) blended with PP on the properties of the PP/PF board were investigated. SEM images depicted the formation of spherical protuberances and voids in the PP/PF board with the increasing PF content. The size of the protuberances was also increased with the PF content. The formation of void could be due to the release of water, ammonia and formaldehyde during the blending and hot-press processes. The density, moisture content and maximum water absorption of the PP/PF board increased with the increase of PF content. The TG curves of the PP/PF boards revealed that the PF and PP in the PP/PF board decomposed at different temperature ranges, i.e., 200–420 and 425–480 °C, respectively. The addition of PF to PP reduced the activation energy of the first stage thermal decomposition of the PP/PF boards. The addition of 10 wt.% PF was the optimum content to produce PP/PF board with optimum mechanical properties.

Thermal behavior and morphological properties of novel magnesium salt–polyacrylamide composite polymers

AbstractMagnesium salt–polyacrylamide composite polymers have been prepared by blending magnesium chloride and magnesium hydroxide, respectively, with polyacrylamide aqueous solution. The thermal behavior of the dried magnesium salt–polyacrylamide composite polymers has been studied. Differential scanning calorimetric (DSC) analysis and thermal gravimetric analysis (TGA) were carried out to investigate the changes of the composite polymers' behavior with temperature. The kinetics of the thermal decomposition of magnesium salt–polyacrylamide composite polymers was investigated over temperature range of 35–800°C with three heating rates of 10, 20, and 40°C/min under nitrogen atmosphere. Flynn and Wall's model was usedto determine the activation energies of thermal decomposition for magnesium salt–polyacrylamide composite polymers. The activation energies needed to decompose 50 wt% of magnesium hydroxide‐polyacrylamide (MHPAM) composite polymer ranged from of 28.993–174.307 kJ/mol which are higher than the values for magnesium chloride–polyacrylamide (MCPAM) composite polymer (21.069–39.412 kJ/mol). Therefore, MHPAM composite polymer has a better thermal stability compared with MCPAM composite polymer. The morphological properties of magnesium salt–polyacrylamide composite polymers were studied using scanning electron microscopy (SEM). Energy‐dispersive X‐ray (EDX) spectroscopy was used to determine the composition of the chemical elements. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

Non-isothermal kinetic studies on thermal decomposition of energetic materials

Thermal stability and decomposition kinetics for two energetic materials, potassium nitroform (KNF) and 5-Nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (NTO), were investigated to obtain information on their safety for handling, storage, and use. Differential scanning calorimetry (DSC) and simultaneous thermogravimetry-differential thermal analysis (TG-DTA) techniques have been used to study thermal behavior of these energetic compounds. The results of TG analysis revealed that the main thermal degradation for the KNF occurs during two temperature ranges of 270–330 and 360–430 °C. Meanwhile, NTO decomposes completely in temperature range of 250–300 °C. TG-DTA analysis of KNF indicates that this energetic compound dehydrated (at about 108 °C) before its decomposition. However, NTO is thermally stable until its decomposition. The decomposition kinetic of energetic materials was studied by non-isothermal DSC under various heating rates. Kinetic parameters such as activation energy and frequency factor for thermal decomposition of energetic compounds were obtained via the methods proposed by ASTM E696 and Starink. Also, thermodynamic parameters correspond to the activation of thermal decomposition and critical ignition temperatures of the compounds were obtained.

Studies on Thermal Stability and Rheological Property of PU/PVDF Blend

In this article, the thermal stability of PU/PVDF blend was investigated by thermogravimetry (TG), and their rheological property was studied through testing and analyzing the rheological curves. The results showed that, with the increase in PVDF content, the thermal decomposition temperature of PU/PVDF blend increased, and by fitting relevant data to thermal decomposition dynamic equations, it was found that thermal decomposition activation energy of the blend increased gradually, i.e. the thermal stability of the blend increased gradually. Meantime, based on the curves of shear stress vs. shear rate of the blend at 180°C and 200°C, it was shown that for PU/PVDF blend, with the decrease of temperature and the increase in PVDF content, the non-Newtonian index decreased, while the viscosity of the blend increased.

Thermal decomposition behavior of carbon nanotube reinforced thermotropic liquid crystalline polymers

AbstractThermotropic liquid crystalline polymers (TLCP), 4‐hydroxybenzoic acid (HBA)/6‐hydroxyl‐2‐naphthoic acid (HNA) copolyester, and HNA/hydroxylbenzoic acid (HAA)/terephthalic acid (TA) copolyester reinforced by carbon nanotube (CNT) were prepared by melt compounding using Hakke internal mixer. The thermal behavior and degradation of CNT reinforced HBA/HNA copolyester and HNA/HAA/TA copolyester have been investigated by dynamic thermogravimetric analysis under nitrogen atmosphere in the temperature range 30 to 800°C to study the effect of CNT on the thermal decomposition behavior of the TLCP/CNT nanocomposites. The thermal decomposition temperature at the maximum rate, residual yield, integral procedural decomposition temperature, and activation energy for thermal decomposition was studied to investigate thermal stability of TLCP/CNT nanocomposites. The thermal stability of CNT reinforced HBA/HNA copolyester was increased by addition of a very small quantity of CNT and the residual weight was 42.4% and increased until 50.8% as increasing CNT contents. However, the thermal stability of CNT reinforced HNA/HAA/TA copolyester was decreased initially when a very small quantity of CNT added. The residual weight was decreased from 50.4% to 45.1%. After addition of CNTs in the TLCP matrix, the thermal stability of CNT reinforced HNA/HAA/TA copolyester increased as increasing content of CNT and the residual weight was increased until 53% as increasing CNT contents. The activation energy was calculated by multiple heating rate equations such as Friedman, Flynn‐Wall‐Ozawa, Kissinger, and Kim‐Park methods to confirm the effect of CNT in two different TLCP matrices. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

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

The kinetics of thermal decomposition of basic nickel carbonate NiCO3Ni·(OH)2·nH2O 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 energy of thermal decomposition have been determined. Investigations of the thermal decomposition of the products of ball milling of investigated compound revealed a distinct effect of milling on the reaction temperature and heat consumed during the thermal decomposition of investigated compound.

Thermal, electrical and optical properties of proton-irradiated Makrofol DE 7-2 nuclear track detector

Samples from sheets of the polymeric material Makrofol DE 7-2 have been exposed to 1 MeV protons of fluences in the range 2.5×1013–5×1015 p/cm2. The resultant effect of proton irradiation on the thermal properties of Makrofol has been investigated using thermogravimetric analysis and differential thermal analysis (DTA). The onset temperature of decomposition T o and the activation energy of thermal decomposition E a were calculated, and the results indicated that the Makrofol detector decomposes in one weight loss stage. Also, the proton irradiation in the fluence range 7.5×1013–5×1015 p/cm2 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 variation of transition temperatures with proton fluence has been determined using DTA. The Makrofol thermograms were characterized by the appearance of an endothermic peak due to the melting of the crystalline phase. The melting temperature of the polymer, T m, was investigated to probe the crystalline domains of the polymer. At a fluence range of 7.5×1013–5×1015 p/cm2, the defect generated destroys the crystalline structure, thus reducing the melting temperature. In addition, the V–I characteristics of the polymer samples were investigated. The electrical conductivity was decreased with the increasing proton fluence up to 5×1015 p/cm2. Further, the refractive index, transmission of the samples and any color changes were studied. The color intensity Δ E was greatly increased with the increasing proton fluence and was accompanied by a significant increase in the red and yellow color components.

Phase transition induced improvement in H2 desorption kinetics: the case of the high-temperature form of Y(BH4)3

The high-temperature (HT) phase of Y(BH(4))(3) has been prepared by heating of the as mechanochemically synthesised low-temperature (LT) phase of Y(BH(4))(3) to 194-216 °C and subsequent rapid cooling to ambient temperature. Although the differences in the crystal structure and vibrational spectra for these closely-related polymorphs are rather small, yet the NMR MAS (1)H and CP MAS (89)Y spectra reveal clear differences in the chemical shifts for both nuclei. The thermal decomposition process of both forms differs noticeably below 260 °C, decomposition being faster and more facile for the HT phase. The activation energy for thermal decomposition, calculated according to the Kissinger equation, is nearly three times lower for the HT than for the LT polymorph for the first step of the thermal decomposition signalling giant improvement of kinetics of H(2) desorption.

Azomethine-based phenol polymer: Synthesis, characterization and thermal study

Azomethine-based phenol polymer, poly-2-{[(6-aminopyridin-2-yl)imino]methyl}-phenol (PAPIMP), was synthesized through the combination of condensation reaction and oxidative polymerization. Polymer isolated from aqueous solution was characterized by UV–vis, FT-IR, NMR and TG, SEC analysis. According to the SEC chromatograms, the number-average molecular weight (Mn), weight-average molecular weight (Mw) and polydispersity index (PDI) values of PAPIMP were determined to be 33,550, 78,900gmol−1 and 2.352, respectively. Also, optical band gaps (Eg) of APIMP and PAPIMP calculated from cyclic voltammetry (CV) measurements. Also, electrical conductivities of each component measured with four-point probe technique. TG analysis showed that PAPIMP was stable up to 300°C. The thermal decomposition kinetics of PAPIMP was investigated by means of thermogravimetric analysis in dynamic nitrogen atmosphere at four different heating rates: 5, 10, 15 and 20°Cmin−1. The apparent activation energies for thermal decomposition of PAPIMP were obtained by Tang, Flynn–Wall–Ozawa (FWO), Kissenger–Akahira–Sunose (KAS) and Coats–Redfern methods (CR) were 96.97, 105.33, 97.28 and 88.60kJmol−1, respectively; the mechanism function and pre-exponential factor were determined by master plots method. The most likely decomposition process was a Dn Deceleration type in terms of the Coats–Redfern and master plots results.

Synthesis and thermal analysis of linear triblock copolymers based on methacrylate ester

Two linear triblock copolymers poly(t-butyl methacrylate-b-2-hydroxyl ethyl methacrylate-b-N,N-dimethylaminoethyl methacrylate) (PtBMA97-b-PHEMA18-b-PDMAEMA98) and poly(t-butyl methacrylate-b-glycidyl methacrylate-b-styrene) (PtBMA137-b-PGMA23-b-PSt156) were controlled synthesized with living RAFT polymerization technique under the chain transfer of cumyl dithiobenzoate. The results of FT-IR spectra illustrate that the characteristic groups of copolymer fit well with the result of 1H-NMR, which successfully determines the corresponding molecular structure of triblock copolymers. The thermal stability of PtBMA-b-PGMA-b-PSt and PtBMA-b-PHEMA-b-PDMAEMA was also complementarily explained by the activation energy of thermal decomposition from Friedman differential method and Ozawa–Flynn–Wall integral method. The results show that the degradation energy of the former copolymer was much higher than that of the latter copolymer, because the aromatic groups were introduced into the polymer segments of the former copolymer during the RAFT polymerization process, and the other reason is the oxirane rings are typically reactive which they occurred intermolecular crosslinking reaction during the thermal decomposition.

Copolymers of a new methacrylate monomer bearing oxime ester and ether with methyl methacrylate: Synthesis, characterization, monomer reactivity ratios, and biological activity

AbstractThe free‐radical copolymerization of 2‐metil‐1‐{[(1‐{4‐[(4‐nitrobenzil)oksi]fenil}etilidene)amino]oksi}prop‐2‐en‐1‐on (NBOEMA) with methyl methacrylate (MMA) was carried out in 1,4‐dioxane at 65 ± 1°C. The copolymers were analyzed by Fourier transform infrared spectroscopy, 1H‐NMR, 13C‐NMR, and gel permeation chromatography (GPC). Elemental analysis was used to determine the molar fractions of NBOEMA and MMA in the copolymers and for the characterization of the compounds. The monomer reactivity ratios were calculated according to the general copolymerization equation with the Kelen–Tudos and Fineman–Ross linearization methods. The polydispersity indices of the polymers, determined with GPC, suggested a strong tendency for chain termination by disproportionation. The thermal behaviors of the copolymers with various compositions were investigated by differential scanning calorimetry and thermogravimetric analysis. The glass‐transition temperature of the copolymers increased with increasing NBOEMA content in the copolymers. Also, the apparent thermal decomposition activation energies were calculated by the Ozawa method with a Shimadzu TGA 60H thermogravimetric analysis thermobalance. All of the products showed moderate activity against different strains of bacteria and fungi. The photochemical properties of the polymers were investigated by UV spectroscopy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Synthesis and characterization of novel methacrylate copolymers based on sulfonamide and coumarine: Monomer reactivity ratios, biological activity, thermal stability, and optical properties

AbstractThe free radical copolymerization of 2‐oxo‐2‐[(4‐sulfamoylphenyl)amino]ethyl‐2‐methylpropenoate (SAEMA) with 4‐methyl‐2‐oxo‐2H‐chromen‐7‐yl‐2‐methylpropenoate (MCMA) has been carried out in 1, 4‐dioxane at 65 °C ± 1 °C and the copolymers were analyzed by Fourier‐transform infrared, 1H‐NMR, 13C‐NMR and gel permeation chromatography. 1H‐NMR and elemental analysis was used to determine the molar fractions of SAEMA and MCMA in the copolymers. The monomer‐reactivity ratios were calculated according to the general copolymerization equation using Kelen‐Tüdõs and Fineman‐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 MCMA 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. The photochemical properties of the polymers were investigated by UV spectra. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4323–4334, 2010

Synthesis of Organo Cobalt−Aluminum Layered Double Hydroxide via a Novel Single-Step Self-Assembling Method and Its Use as Flame Retardant Nanofiller in PP

Synthesis of polypropylene/organo-layered double hydroxide (PP/OLDH) has been carried out based on self-assembled organocobalt-aluminum LDH (O-CoAl-LDH). The novel method of synthesizing self-assembled CoAl-LDH and its characterization have also been reported in details. This method is proven to be very efficient way of producing OLDH in a single step with homogeneous composition and structure. As flame-retardant nanofiller, O-CoAl-LDH shows significant decrease in heat release rate (HRR), the total heat release (THR) and the heat release capacity (HRC) of the PP composites, though the thermal stability of the compounds decreases slightly compared to the base polymer. Morphological analyses show that the LDH particles are dispersed in PP matrix in a partially exfoliated form. The activation energy calculation based on the Kissinger method reveals that O-CoAl-LDH has a positive effect on the activation energy of thermal decomposition of PP. However, in the presence of this filler, decomposition of the composites starts at an earlier stage than that of pure PP.

Thermal and morphological analysis of thermoplastic polyurethane–clay nanocomposites: Comparison of efficacy of dual modified laponite vs. commercial montmorillonites

Thermoplastic polyurethane (TPU)–clay nanocomposites were studied with respect to thermal properties and morphology. Different types of clay, e.g. modified laponite (ionic followed by covalent modification using different silanes) and montmorillonites (e.g. Cloisite 30B and Nanomer I.30E) were used. Activation energies ( E) for thermal decomposition of nanocomposites were determined by Flynn and Wall technique. The changes in ‘ E’ value with the level of conversion suggest a complicated degradation rate. Lifetime of composites was estimated by Toop's equation revealing higher lifetime for montmorillonite based composites. It was found that dual modification of laponite was sometimes more effective/equivalent to commercial montmorillonites regarding viscoelastic properties and thermo-dimensional stabilities of nanocomposites. Phase morphology, filler dispersion, RMS roughness obtained from SEM (including X-ray dot mapping), AFM analyses revealed the role of aggregates in degradation of properties of composites. Moreover, thermo-physical properties were dependent on the aspect ratio, polarity, and aggregation characteristics of clay into TPU.

Formation of bisphenol A by thermal degradation of poly(bisphenol A carbonate)

The thermal decomposition of poly(bisphenol A carbonate) (PoC) results in the formation of the endocrine disruptor bisphenol A (BPA). In the present work, we investigated the kinetics of the thermal decomposition of PoC, and the subsequent decomposition of BPA, under pyrolysis conditions and in the presence of oxygen by using infrared image furnace-ion attachment mass spectrometry. The decomposition of PoC obeyed Arrhenius kinetics, which allowed us to determine the activation energy ( E a) for thermal decomposition to BPA from Arrhenius plots. From the selected ion monitoring curves for BPA, E a for thermal decomposition in a nitrogen atmosphere was calculated to be 133.2 kcal mol −1, whereas E a for oxidative thermal decomposition was calculated to be approximately 35% lower (86.5 kcal mol −1).