Matematik ve Fen Bilimleri Eğitimi Bölümü Koleksiyonu

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Quark and strange quark matter in f(R) gravity for Bianchi type I and V space-times
(Springer/Plenum Publishers, 2012) Yılmaz, İhsan; Baysal, Hüsnü; Aktaş, Can
Behaviors of quark matter and strange quark matter which exist in the first seconds of the early Universe in f(R) gravity are studied for Bianchi I and V universes. In this respect, we obtain exact solutions of the modified Einstein field equations by using anisotropy feature of Bianchi I and V space-times. In particular, we investigate exact f(R) functions for Bianchi I as the contribution of strange quark and quark matter. Also, we have concluded that quark matter may contribute to the early acceleration of the universe since quark matter behaves like phantom-type dark energy. Furthermore, obtained f(R) solutions represents early eras of the Universe since f(R) solutions for quark matter coincide with f(R) equations for inflation. From this point, we can reach the conclusion that quarks may be source of the early dark energy of the universe or source of little inflation due to their repulsive force.
Domain wall solutions with quark matter in higher dimensional space-times
(Amer Inst Physics, 2007) Aktaş, Can; Yılmaz, İhsan; Baysal, Hüsnü; Aygün, Melis; Demirel, Canan
In this paper, we have examined quark matter in the perfect form attached to domain walls in the higher dimensional spherical symmetric space-time admitting one-parameter group of conformal motions. For this purpose, we have solved Einstein's field equations for higher dimensional spherical symmetric space-time via conformal motions. Also, we have discussed the features of the obtained solutions.
Peroxidase/H2O2 catalyzed oxidative oligomerization of 1-aminopyrene
(Taylor & Francis Inc, 2017) Kaya, İsmet; Bilici, Ali; Tezel, Ruhiye Nilay; Temizkan, Kevser; Doğan, Fatih
A new florescent oligo(aminopyrene) (OAP) was successfully synthesized by enzymatic approach. For this, H2O2 and Horse Radish peroxidase (HRP) were used as catalyst and oxidant, respectively. The structures of monomer and oxidation product were confirmed by NMR, FT-IR and UV-Vis measurements. The oxidation product was characterized by gel permeation chromatography (GPC), thermogravimetry (TG), differential scanning calorimetry (DSC), cyclic voltammetry (CV), photoluminescence (PL) and scanning electron microscopy (SEM) analyses. OAP was soluble in a wide range of organic solvents. UV-Vis spectrum of the OAP showed a dramatic red shift compared to that of the monomer. The optical and electrochemical band gaps of OAP were found to be 1.65 and 1.56 eV, respectively. OAP emitted turquoise color in THF and green color in toluene. SEM observations indicated the presence of a heterogeneous cauliflower like morphology.
Chemical oxidative polymerization, optical, electrochemical and kinetic studies of 8-amino-2-naphthol
(Springer, 2015) Doğan, Fatih; Kaya, İsmet; Bilici, Ali; Yıldırım, Mehmet
Here the polymerization of 8-amino-2-naphthol (AN) is reported without use of an additional external template, surfactants or functional dopants. For this, NaOCl and hydrochloride acid solution (1.0 M) were used as oxidant and reaction medium, respectively. The structure of oligomer was elucidated by FT-IR, UV-vis and H-1-NMR techniques. The number average molecular weight of oligomer was found to be 2200Da with a polydispersity index of 1.4 by size exclusion chromatography. This oligomer exhibited a multicolor emission behavior as it was excited at different wavelenghts. Redox states were clarified by cyclic voltammetry (CV) technique and the relationship between anodic/cathodic peak currents vs. scan rates was determined. Thermal analysis and XRD data assigned that the resulting oligomer was in a semi-crystalline form. The activation energy related to the solid state decomposition was calculated from differential and integral non-isothermal methods and the lowest value using Kissinger procedures was determined to be 79.53 kJ/mol in N-2 atmosphere.
Synthesis, characterization and non-isothermal decomposition kinetic of a new galactochloralose based polymer
(Elsevier Sci Ltd, 2014) Kök, Gökhan; Ay, Kadir; Ay, Emriye; Doğan, Fatih; Kaya, İsmet
A glycopolymer, poly(3-O-methacroyl-5,6-O-isopropylidene-1,2-O-(S)-trichloroethylidene-alpha-D-galactofuranose) (PMIPTEG) was synthesized from the sugar-carrying methacrylate monomer, 3-O-methacroyl-5,6-O-isopropylidene-1,2-O-(S)-trichloroethylidene-alpha-D-galactofuranose (MIPTEG) via conventional free radical polymerization with AIBN in 1,4-dioxane. The structures of glycomonomer and their polymers were confirmed by UV-vis, FT-IR, H-1 NMR, C-13 NMR, GPC, TG/DTG-DTA, DSC, and SEM techniques. SEM images showed that PMIPTEG had a straight-chain length structure. On the other hand, the thermal decomposition kinetics of polymer were investigated by means of thermogravimetric analysis in dynamic nitrogen atmosphere at different heating rates. The apparent activation energies for thermal decomposition of the PMIPTEG were calculated using the Kissinger, Kim-Park, Tang, Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Friedman methods and were found to be 100.15, 104.40, 102.0, 102.2, 103.2 and 99.6 kJ/mol, respectively. The most likely process mechanism related to the thermal decomposition stage of PMIPTEG was determined to be a D deceleration type in terms of master plots results. (C) 2013 Elsevier Ltd. All rights reserved.
Synthesis and characterization of an acrylate polymer containing chlorine-1,3-dioxalane groups in side chains
(Springer, 2012) İlter, Zülfiye; Alhanlı, Ferhat; Doğan, Fatih; Kaya, İsmet
Poly[2-(4-chlorophenyl)-1,3-dioxolan-4-yl]methyl acrylate, poly(CPhDMA), was synthesized with radical polymerization process using 2,2'-azobisisobutyronitrile as radical initiator in 1,4-dioxane at 60A degrees C. The structure of poly(CPhDMA) was confirmed by means of UV-Vis, FT-IR, H-1-NMR, and C-13-NMR spectral techniques. The molecular weight distribution values of the polymer were determined with gel permeation chromatography (GPC). The number-average molecular weight (M (n)), weight-average molecular weight (M (w)) and polydispersity index (PDI) values of poly(CPhDMA) were determined to be 10300, 21600 and 2.097, respectively. The thermal degradation kinetics of the polymer was investigated by using TG/DTG-DTA and DSC analyses at different heating rates in dynamic nitrogen atmosphere. The apparent activation energy values obtained by Flynn-Wall-Ozawa and Friedman methods were found to be 91.68 and 85.23 kJ mol(-1), respectively, for thermal decomposition of poly(CPhDMA). Also, the thermal degradation activation energy value of poly(CPhDMA) was calculated by using the Kissinger method based on the DTG, DTA and DSC data. Then the mechanism function of it was determined by master plots method. Finally, electrical and optical properties of poly(CPhDMA) were determined by four-point probe and UV-Vis techniques, respectively.
Oxidative synthesis of a novel polyphenol having pendant Schiff base group: Synthesis, characterization, non-isothermal decomposition kinetics
(Elsevier, 2011) Dilek, Deniz; Doğan, Fatih; Bilici, Ali; Kaya, İsmet
In here, the facile synthesis and thermal characterization of a novel polyphenol containing Schiff base pendant group, poly(4-{[(4-hydroxyphenyl)imino]methyl}benzene-1,2,3-triol) [PHPIMB], are reported. UV-vis, FT-IR,H-1 NMR, C-13 NMR, GPC, TG/DTG-DTA, CV (cyclic voltammetry) and solid state conductivity measurements were utilized to characterize the obtained monomer and polymer. The spectral analyses results showed that PHPIMB was composed of polyphenol main chains containing Schiff base pendant side groups. Thermal properties of the polymer were investigated by thermogravimetric analyses under a nitrogen atmosphere. Five methods were used to study the thermal decomposition of PHPIMB at different heating rate and the results obtained by using all the kinetic methods were compared with each other. The thermal decomposition of PHPIMB was found to be a simple process composed of three stages. These investigated methods were those of Flynn-Wall-Ozawa (FWO), Tang, Kissinger-Akahira-Sunose (KAS), Friedman and Kissinger methods. (C) 2011 Elsevier B.V. All rights reserved.
A novel shape-controlled synthesis of bifunctional organic polymeric nanoparticles
(Elsevier Sci Ltd, 2015) Doğan, Fatih; Temizkan, Kevser; Kaya, İsmet
A novel shape-controlled bifunctional organic nanoparticle was reported using the facile synthesis of self-stabilized monohydroxy amino naphthol nanoparticles. For this purpose, bifunctional monomer was polymerized by NaOCl as oxidant in aqueous alkaline medium at 70 degrees C. These poly-nanoparticles with molecular weight ca. 5000 Da was obtained by template-free oxidative polymerization (OP) process. The structure of polymer was confirmed by NMR, FT-IR, UV-Vis and X-RD measurements. The chemical and physical properties of polymer were determined size exclusion chromatography (SEC), thermogravimetry (TG), differential scanning calorimetry (DSC), cyclic voltammetry (CV), photoluminescence (PL), dynamic light scattering (DLS), scanning electron microscope (SEM), transmission electron microscope (TEM) and conductivity techniques. The SEM analysis of polymer indicated to be had a nanoparticle structure. The reversible redox behavior of the polymer was attributed to its electroactive nature. In addition, the kinetic parameters related to the solid state decomposition of the poly-nanoparticles were calculated by non-isothermal methods based on multiple heating rates. (C) 2015 Elsevier Ltd. All rights reserved.
Effect of CaCO3 Filler Component on Solid State Decomposition Kinetic of PP/LDPE/CaCO3 Composites
(Taylor & Francis Inc, 2009) Şirin, Kamil; Doğan, Fatih; Balcan, Mehmet; Kaya, İsmet
In this study, the effect of addition Calcium carbonate (CaCO3) filler component on solid state thermal decomposition procedures of Polypropylene-Low Density Polyethylene (PP-LDPE; 90/10 wt%) blends involving different amounts (5, 10, 20 wt%) Calcium carbonate (CaCO3) was investigated using thermogravimetry in dynamic nitrogen atmosphere at different heating rates. An integral composite procedure involving the integral iso-conversional methods such as the Tang (TM), the Kissinger-Akahira-Sunose method (KAS), the Flynn-Wall-Ozawa (FWO), an integral method such as Coats-Redfern (CR) and master plots method were employed to determine the kinetic model and kinetic parameters of the decomposition processes under non-isothermal conditions. The Iso-conversional methods indicated that the thermal decomposition reaction should conform to single reaction model. The results of the integral composite procedures of TG data at various heating rates suggested that thermal processes of PP-LDPE-CaCO3 composites involving different amounts of CaCO3 filler component (5, 10, 20 wt%) followed a single step with approximate activation energies of 226.7, 248.9, and 252.0 kJ.mol- 1 according to the FWO method, respectively and those of 231.3, 240.1 and 243.0 kJ mol- 1 at 5 degrees C min- 1 according to the Coats-Redfern method, the reaction mechanisms of all the composites was described from the master plots methods and are Pn model for composite C-1, Rn model for composites C-2 and C-3, respectively. It was found that the thermal stability, activation energy and thermal decomposition process changed by the increasing CaCO3 filler weight in composite structure.
Thermal Decomposition Kinetics of Azomethine Oligomer and Its Some Metal Complexes
(Wiley, 2010) Doğan, Fatih; Kaya, İsmet; Bilici, Ali; Saçak, Mehmet
In our previous study, we presented the synthesis, characterization, and some physical properties of a new azomethine oligomer and its some metal complexes. This study focuses on the thermal decomposition kinetics of these reported materials. The studied compounds were 1,4-bis[(2-hydroxyphenyl)methylene]phenylenediamine, oligo-1,4-bis[(2-hydroxyphenyl)methylene] phenylenediamine, and oligo-1,4-bis[(2-hydroxyphenyl) methylene]phenylenediamine metal complexes. Several kinetic methods based on a single heating rate such as Coats-Redfern, MacCallum-Tanner, van Krevelen, Horowitz-Metzger, Wanjun-Yuwen-Hen-Cunxin, and Madhusudanan-Krishnan-Ninan were used to elucidate the kinetic parameters of the decomposition processes. The parameters such as activation energy E, frequency factor A, reaction order n, entropy change Delta S*, enthalpy change Delta H*, and Gibbs free energy change Delta G* were calculated by means of the above methods. The activation energy values obtained by each method were in good agreement with each other. An appropriate mechanism for the thermal decomposition process of each material was also determined by means of the thermogravimetric analysis. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 118: 547-556, 2010
Chemical Oxidative Synthesis and Characterization of Poly(8-hydroxyquinoline) Particles
(Taylor & Francis Inc, 2014) Doğan, Fatih; Kaya, İsmet; Temizkan, Kevser
The chemical oxidative polymerization (OP) of 8-hydroxyquinoline (HQ) in an organic medium leaded to the formation of the C-2 and C-4 linking poly (8-hydroxyquinoline) (PHQ). The structure of PHQ was confirmed by UV-Vis, FT-IR, and H-1-NMR. The characterization of polymer was performed by TG-DTA, differential scanning calorimetry, dynamic mechanical analysis, dynamic light scattering, size exclusion chromatography, X-ray diffraction, cyclic voltammetry, atomic force microscope, photoluminescence and solubility tests. The fluorescence spectrum of PHQ exhibited an emission peak at approximately 525nm in DMSO. Accordingly, it was found PHQ emitted green light whereas HQ emitted yellow light in DMSO solvent. Optical band gaps (E-g) of PHQ was calculated to be 3.31eV. The electrical conductivities of iodine doped-PHQ and undoped-PHQ were measured with four-point probe technique. Magnetic particles was prepared by chemical precipitation of mixed Fe(II) and Fe(III) salts and modified with HQ by using an in situ chemical oxidation polymerization method in organic medium.
The synthesis, characterization and effect of molar mass distribution on solid-state degradation kinetics of oligo(orcinol)
(Springer, 2019) Doğan, Fatih; Özdek, Naciye; Acar Selçuki, Nursel; Kaya, İsmet
In this study, the oxidative polymerization of orcinol monohydrate using different oxidants such as NaOCl, H2O2, and air was investigated. Polymerization studies were carried out between 50 and 90 degrees C. The optimum reaction conditions of the polymerization were also established. NaOCl was found to be the most active oxidant. The characterization of oligo(orcinol) was conducted by using FT-IR, H-1-NMR and C-13-NMR, TGA, size exclusion chromatography (SEC) and solubility techniques. At the optimum reaction conditions, the conversion to oligomer of orcinol was found to be 62% (for NaOCl oxidant), 42% (for H2O2 oxidant), and 21% (for air oxidant). According to the SEC analysis, the number-average molecular mass (M-n), mass-average molecular mass (M-w) and polydispersity index (PDI) values of oligo(orcinol) were determined to be 2260, 2540 g mol(-1), and 1.12, using NaOCl, and 2170, 2470 g mol(-1), and 1.14, using H2O2 and 1500, 1770 g mol(-1), and 1.18, using air, respectively. In addition, the relationship between molar mass distributions and activation energies of thermal degradation processes of oligo(orcinol) was investigated by using TG analysis. For this purpose, the methods based on multiple heating rates such as Flynn-Wall-Ozawa [FWO], Tang, and Kissinger-Akahira-Sunose [KAS] were used. The activation energy related to the solid-state decomposition of oligo(orcinol) synthesized with NaOCl oxidant was calculated to be 79.02 kJ mol(-1) by KAS method, 78.74 kJ mol(-1) by Tang method and 81.78 kJ mol(-1) by FWO method in the range of 0.05 < alpha < 0.95. The results obtained show that activation energy increased with an increase in molar mass.
Thermal Degradation Kinetics of Poly(2,7-dihydroxynaphthalene)
(Amer Scientific Publishers, 2015) Doğan, Fatih; Kaya, İsmet
In this paper, the thermal degradation kinetics of 2,7-dihydroxynaphthalene (DHN) was presented. The kinetics of the thermal degradation of PDHN was investigated by means of TGA. TG curves showed that the thermal degradation of poly(2,7-dihydroxynaphthalene) (PDHN) took place in two stages. The apparent activation energies of thermal degradation for PDHN, as determined by the Tang method (TM), the Flynn-Wall-Ozawa method (FWO), the Kissinger-Akahira-Sunose method (KAS), and the Coats-Redfern (CR) method were 136.9, 136.2, 140.1 and 143.7 kJ . mol(-1) for the first stage degradation, 99.4, 98.9, 102.6, and 88.7 kJ . mol(1-) for the second stage degradation, respectively. The mechanism function and pre-exponential factor related to each thermal degradation process were also determined by CR method, master plots. The most likely degradation process for each weight loss stages was deceleration type in terms of the CR and master plots results.
Non-isothermal degradation kinetics of poly (2,2'-dihydroxybiphenyl)
(Springer, 2009) Doğan, Fatih; Kaya, İsmet; Bilici, Ali
Catalytic oxidative polymerization of 2,2'-dihydroxybiphenyl (DHBP) was performed by using Schiff base polymer-Cu (II) complex and hydrogen peroxide as catalyst and oxidant, respectively. According to size exclusion chromatography (SEC) analysis, the number-average molecular weight (M (n)), weight-average molecular weight (M (w)) and polydispersity index (PDI) values of poly (2,2'-dihydroxybiphenyl) (PDHBP) were found to be 37,500, 90,000 g mol(-1) and 2.4, respectively. The thermal degradation kinetics was investigated by thermogravimetric analysis in dynamic nitrogen atmosphere at four different heating rates: 5, 10, 15 and 20 A degrees C min(-1). The derivative thermogravimetry curves of PDHBP showed that its thermal degradation process had one weight-loss step. The apparent activation energies of thermal decomposition for PDHBP as determined by Tang, Flynn-Wall-Ozawa (FWO), Kissenger-Akahira-Sunose (KAS), Coats-Redfern (CR) and Invariant kinetic parameter (IKP) methods were 109.1, 109.0, 110.0, 108.4 and 109.8 kJ mol(-1), respectively. The mechanism function and pre-exponential factor were determined by master plots and Criado-Malek-Ortega method. The most likely decomposition process was a D (n) Deceleration type in terms of the CR, master plots and Criado-Malek-Ortega results.
Regioselective synthesis of polygamma (γ) acid
(Royal Soc Chemistry, 2015) Doğan, Fatih; Temizkan, Kevser; Kaya, İsmet
The oxidative polymerization of 6-amino-4-hydroxy-2-naphthalenesulfonic acid in an aqueous alkaline medium leads to the formation of a polygamma (gamma) acid consisting of regioselective 1-4 oxazine rings. Spectral characterizations were performed by NMR, FT-IR, and UV-Vis techniques. The average molecular weight and polydispersity index of the gamma acid polymer (gamma-AP) were found to be 32 000 Da and 1.42, respectively. gamma-AP also presented an uncommon multicolored emission behavior in dimethylsulfoxide (DMSO). When excited at 405, 480, and 532 nm, gamma-AP emitted blue, green and yellow light, respectively. X-ray diffraction (XRD), differential scanning calorimetry (DSC), dynamic mechanical analyses (DMA), and transmission electron microscopy (TEM) illustrated that gamma-AP is composed of semicrystalline nanofiber structures with different lengths between 10-500 nm. The kinetic parameters related to the solid state thermal decomposition of gamma-AP were determined using differential isoconversional methods (Friedman and Kissenger) and integral isoconversional methods (FWO, KAS, Tang, Starink and Bosewell). By using the Tang, KAS, FWO, Starink, Bosewell, Kissenger and Friedman methods, the average values of the activation energies were calculated to be 184.4, 184.4, 185.4, 188.5, 183.6, 179.7 and 187.1 kJ mol(-1), respectively. The master plot curves also suggested a diffusion-type kinetic model for the solid state thermal decomposition stage of gamma-AP.
6-Hydroxyquinoline Oligomers Emit White Light
(Amer Scientific Publishers, 2014) Doğan, Fatih; Bilici, Ali; Yıldırım, Mehmet; Kaya, İsmet
The 6-hyroxyquinoline (HQ) was shown to undergo an oxidative oligomerization reaction in the alkaline medium. The obtained oligo (6-hyroxyquinoline) (OHQ) was characterized with respect to chemical composition, molecular weight, particle size, thermal stability, morphology and conductivity. FT-IR and H-1-NMR spectral data suggested that the resulting product was mainly C2, C4 and C6-coupled via C-C/C-O-C linkages. OHQ emitted white light upon irradiated at 339 nm. Optical band gap (E-g) of OHQ was determined to be 2.78 eV. The isolated product was amorphous and soluble in common polar organic solvents. The solid state conductivity studies for OHQ were also performed and found to be in the region of semiconductor.
The effect of the oxidant used during polymerization on the solid-state decomposition kinetics of poly(4-methyl catechol)
(Springer, 2013) Doğan, Fatih; Topallar, Harika; Kaya, İsmet; Yürekli, Mehmet
Herein, the oxidative polymerization of 4-methyl catechol using different oxidants including NaOCl, H2O2, and air were reported. Potassium hydroxide solution was used as the reaction solvent and polymerization studies were carried out between 323 and 363 K. Optimum reaction conditions of the polymerization were established and NaOCl was found as the most active oxidant. The structure and characterization of the polymer using FT-IR, ultraviolet-visible (UV-Vis), H-1-NMR, C-13-NMR, thermogravimetry and size exclusion chromatography were confirmed. In addition, the relationship between molar mass distribution of polymer and kinetics parameters such as activation energy, pre-exponential factor of decomposition process was investigated. For this purpose, methods based on multiple heating rates such as Flynn-Wall-Ozawa, Friedman, Tang, Kissinger-Akahira-Sunose, and Kissinger were used. The results obtained show that activation energy increased with an increase of molar mass.
Solid State Decomposition Kinetics of Green Light Emitting Polyphenol Nanoparticles
(Amer Scientific Publishers, 2016) Doğan, Fatih; Kaya, İsmet
The reaction process and kinetic parameters related to the solid state decomposition of green light emitting polyphenol nanoparticles (GLPN) synthesized by oxidative polymerization were investigated by thermogravimetric analysis technique (TG) at different heating rates. TG/DTG-DTA curves showed that the thermal decomposition occurred mainly in one stages. The kinetic parameters related to solid state decomposition stage of GLPN were calculated by using the methods based on multiple heating rates such as Kissinger, Kim-Park (KM), Tang, Flynn-Wall-Ozawa (FWO), Friedman (FR) and Kissinger-Akahira-Sunose (KAS). The activation energies obtained by Kissinger, Kim-Park, Tang, KAS, FWO, and FR methods were found to be 157.5, 158.0, 166.9, 165.8, 167.1 kJ/mol, respectively, in a wide range of conversion. Furthermore the reaction process related to the solid state decomposition stage of GLPN was also determined by using integral procedure Coats-Redfern (CR) and master plots. The analysis of the so-called methods showed that the solid state decomposition mechanism of polyphenol derivatives nanoparticles in N-2 went to the D-n mechanism (dimensional diffusion, n = 6).
Azomethine-based phenol polymer: Synthesis, characterization and thermal study
(Elsevier Science Sa, 2011) Doğan, Fatih; Kaya, İsmet; Bilici, Ali
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 (M(n)), weight-average molecular weight (M(w)) and polydispersity index (PDI) values of PAPIMP were determined to be 33,550, 78,900 g mol(-1) and 2.352, respectively. Also, optical band gaps (E(g)) 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 degrees 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 degrees C min(-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 88.60 kJ mol(-1), respectively; the mechanism function and pre-exponential factor were determined by master plots method. The most likely decomposition process was a D(n) Deceleration type in terms of the Coats-Redfern and master plots results. (C) 2010 Elsevier B.V. All rights reserved.
The influence of CaCO3 filler component on thermal decomposition process of PP/LDPE/DAP ternary blend
(Wiley, 2010) Doğan, Fatih; Şirin, Kamil; Kaya, İsmet; Balcan, Mehmet
Polypropylene-low density polyethylene (PP-LDPE) blends involving PP-LDPE (90/10 wt%.) with (0.06 wt%) dialkyl peroxide (DAP) and different amounts (5, 10, 20 wt%) of calcium carbonate (CaCO3) were prepared by melt-blending with a single-screw extruder. The effect of addition of CaCO3 on thermal decomposition process and kinetic parameters, such as activation energy and pre-exponential factor of PP-LDPE blend with DAP matrix, was studied. The kinetics of the thermal degradation of composites was investigated by thermogravimetric analysis in dynamic nitrogen atmosphere at different heating rates. TG curves showed that the thermal decomposition of composites occurred in one weight-loss stage. The apparent activation energies of thermal decomposition for composites, as determined by the Tang method (TM), the Kissinger-Akahira-Sunose method (KAS), the Flynn-Wall-Ozawa method (FM)), and the Coats-Redfern (CR) method were 156.6, 156.0, 159.8, and 167.7 KJ.mol(-1) for the thermal decomposition of composite with 5 wt% CaCO3, 191.5, 190.8, 193.1, and 196.8 kJ.mol(-1) for the thermal decomposition of composite with 10 wt% CaCO3, and 206.3, 206.1, 207.5, and 203.8 kJ mol(-1) for the thermal decomposition of composite with 20 wt% CaCO3, respectively. The most likely decomposition process for weight-loss stages of composites with CaCO3 content 5 and 10 wt% was an A sigmoidal type. However, the most likely decomposition process for composite with CaCO3 content 20 wt% was an R-n contracted geometry shape type in terms of the CR and master plots results. It was also found that the thermal stability, activation energy, and thermal decomposition process were changed with the increase in the CaCO3 filler weight in composite structure. Copyright (C) 2009 John Wiley & Sons, Ltd.

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