MCBÜ Açıkerişim Sistemi :: Browsing by Author "Şirin K."

Browsing by Author "Şirin K."

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Effect of CaCO3 filler component on solid state decomposition kinetic of PP/LDPE/CaCO3 composites
(2009) Şirin K.; Doǧan F.; Balcan M.; Kaya I.
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 5C 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 CaCO 3 filler weight in composite structure.
The influence of CaCO3 filler component on thermal decomposition process of PP/LDPE/DAP ternary blend
(2010) Doǧan F.; Şirin K.; Kaya I.; Balcan M.
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 (FWO), 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 An sigmoidal type. However, the most likely decomposition process for composite with CaCO3 content 20 wt% was an Rn 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. © 2009 John Wiley & Sons, Ltd.
Mechanical properties and thermal analysis of low-density polyethylene + polypropylene blends with dialkyl peroxide
(2010) Şirin K.; Balcan M.
Polypropylene + low density polyethylene (PP + LDPE) blends involving 0, 25, 50, 75 and 100wt% of PP with dialkyl peroxide (DAP) were prepared by melt blending in a single-screw extruder. The effects of adding dialkyl peroxide on mechanical and thermal properties of PP + LDPE blends have been studied. It was found that at lower concentrations of peroxide (e.g., 0-0.08wt% of dialkyl peroxide) LDPE component is cross-linked and Polypropylene (PP) is degraded in all compositions of PP + LDPE blends. Mechanical properties (Tensile strength at break, at yield and elongation at break),Melt flow index (MFI), hardness, Scanning Electron Microscope (SEM) and thermal analyses (DSC) of these blends were examined. Because of serious degradation or cross-linking the mechanical properties and the crystallinty (%) of those products were decreased as a result of increasing peroxide content. © 2009 John Wiley & Sons, Ltd.
Improving the mechanical, physical, thermal, and morphological properties of isotactic polypropylene with dialkylperoxide
(PRINTS PUBLICATIONS PVT LTD, 2013) Şirin K.; Yavuz M.; Çanli M.; Avci A.; Doǧan F.
In this study, the influence of the visbreaking agent (DAP) on mechanical, physical, thermal and morphological properties of PP has been studied. For this reason, isotactic polypropylene (PP) matrices containing 0.01, 0.02, 0.04, 0.06, 0.08, and 0.1 wt% of dialkylperoxide [2, 5dimethyl-2,5-di (tert-butyl peroxy)-hexane, (DAP)] were prepared by using a single-screw extruder. As a result of DAP addition, the crystallinity ratio of the PP matrices has changed between 2.67-7.80%. Mechanical properties of the matrices have been improved. Particularly, the mechanical tests of PP have given Interesting results when compounded with 0.02 wt.% dialkyl peroxide. The microstructure of isotactic polypropylene matrix was investigated by scanning electron microscopy (SEM). From SEM analysis, it was observed that the surface disorder increased by the increasing amount of DAP. Thermal analyses of the matrices were investigated using thermogravimetry in dynamic nitrogen atmosphere at different heating rates. The Flynn-WallOzawa (FWO), Kissinger and master plots method were employed to determine the kinetic model and kinetic parameters of the decomposition processes under non-isothermal conditions. It was found that the thermal stability, activation energy and thermal decomposition processes were all changed by increasing amount of DAP in the matrix structure. © MD Publications Pvt. Ltd.
Mechanical properties of polypropylene (PP)+high-density polyethylene (HDPE) binary blends: Non-isothermal degradation kinetics of PP+HDPE (80/20) Blends
(2013) Şirin K.; Doǧan F.; Çanli M.; Yavuz M.
In this study, the mechanical properties and non-isothermal degradation kinetics of polypropylene (PP), high-density polyethylene (HDPE) with dilauroyl peroxide and their blends in different mixture ratios were investigated. The effects of adding dilauroyl peroxide (0-0.20wt%) on the mechanical and thermal properties of PP+HDPE blends have been studied. On the other hand, the kinetics of the thermal degradation and thermal oxidative degradation of PP+HDPE (80/20wt%) blends were studied in different atmospheres, to analyze their thermal stability. The kinetic and thermodynamic parameters such as the activation energy, Ea, the pre-exponential factor, A, the reaction order, n, the entropy change, the enthalpy change, and the free energies of activated complex related to PP, HDPE, and blend systems were calculated by means of the several methods on the basis of the single heating rate. A computer program was developed for automatically processing the data to estimate the reaction parameters by using different models. Most appropriate method was determined for each decomposition step according to the least-squares linear regression. © 2013 John Wiley & Sons, Ltd.
Synthesis of poly(cyclohexene oxide)-montmorillonite nanocomposite via in situ photoinitiated cationic polymerization with bifunctional clay
(2013) Bayram I.; Oral A.; Şirin K.
Poly(cyclohexene oxide) (PCHO)/clay nanocomposites were prepared by means of in situ photoinitiated cationic polymerization with initiator moieties immobilized within the silicate galleries of the clay particles. Diphenyliodonium molecules were intercalated via cation exchange process between Cloisite Ca and diphenyliodonium. The polymerization of CHO through the interlayer galleries of the clay can provide a homogenous distribution of the clay layers in the polymer matrix in nanosize and results in the formation of PCHO/clay nanocomposites. The rates of clay loadings were changed to 1%, 3%, and 5% so as to investigate the effect of clay and initiator amount on polymer. X-ray diffraction (XRD) spectroscopy, thermogravimetric analysis (TGA), and transmission electron microscopy (TEM) methods were used for the characterization of modified clay and nanocomposite materials. Thermal stability of PCHO/MMT nanocomposites was also studied by both differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). © 2013 Işil Bayram et al.
Thermal, fluorescence, and electrochemical characteristics of novel poly(urethane-imide)s
(2014) Avc A.; Şirin K.
In this study, the novel thermally stable poly(urethane-imide)s (PUIs) were synthesized. The structures of the obtained polymers were confirmed by FT-IR and NMR techniques. The molecular weight distribution parameters of the synthesized PUIs were determined by the size exclusion chromatography (SEC). The synthesized PUIs were also characterized by solubility tests, solution viscosity, TG-DTA, and DSC analyses. Cyclic voltammetry measurements were carried out, and HOMO-LUMO energy levels and electrochemical band gaps () were calculated from their absorption edges. Additionally, optical band gaps (Eg) were determined by using UV-vis spectra of the materials. Fluorescence measurements were carried out in various concentrated DMSO solutions to determine the optimum concentrations to obtain the maximal PL intensities. Also, morphological characterizations were made by scanning electron microscopy technique. © 2013 Taylor & Francis.
Fluorescence, thermal, electrochemical, and morphological properties of new poly(Urethane-İmide)s: Synthesis and characterization
(Taylor and Francis Inc., 2014) Avci A.; Şirin K.
New thermally stable poly(urethane-imide)s (PUIs) were synthesized to investigate aliphatic and aromatic group effects on various properties such as thermal stability and electrochemical properties. Thermal characterizations were carried out by TG-DTA and DSC techniques. TGA results showed that the PUIs derived from aromatic diisocyanates had relatively higher thermal stabilities as compared to the aliphatic diisocyanate. They have between 223-245°C onset temperature and above 37% char at 1000°C. Also, thermal degradation values show that PUIs have higher stability than conventional PU. DSC results showed that the new PUIs have Tg values between 134 and 138°C. Fluorescence measurements were performed using dimethyl sulfoxide solutions and also, the optimization of the concentrations maximal emission intensity was investigated in dimethyl sulfoxide. As a result, the remarkable properties related to the fluorescence and thermal measurements of the polymers were obtained. Therefore, these polymers could be used in various application fields because of the fluorescent and thermal properties. © Taylor & Francis Group, LLC.
Influence of dilauroyl peroxide on mechanical and thermal properties of different polypropylene matrices
(Polymer Society of Korea, 2015) Şirin K.; Yavuz M.; Çanli M.
In this study, the influence of dilauroyl peroxide on mechanical and thermal properties of different polypropylene (PP) matrices was investigated. Polypropylene matrices, different molecular weight isotactic PP containing 0.01, 0.02, 0.04, 0.06, 0.08, and 0.1 wt% of dilauroyl peroxide (DLP) were prepared by using a single-screw extruder. The effect of the visbreaking agent (DLP) on mechanical, physical, thermal and morphological properties of different molecular weight PP had been studied. Mechanical properties (tensile strength at break point, at yield and elongation at break point), melt flow index (MFI), scanning electron microscope (SEM) and differential scanning calorimetric (DSC) analyses of these matrices were examined. Melting (Tm) and crystallization (Tc) temperatures, crystallinity ratio (%) and enthalpies were determined. The microstructure of isotactic polypropylene matrix was investigated by scanning electron microscopy (SEM). From SEM analysis, it was observed that the surface disorder increased by the increasing amount of DLP. As a result of DSC analyses, the crystallinity ratio of the PP matrices has varied between 1.64-7.27%. Mechanical properties of the matrices have been improved. Particularly, the mechanical tests of PP have given interesting results when compounded with 0.06-0.08 wt% dilauroyl peroxide (DLP). Mechanical properties and thermal decomposition processes were all changed by increasing the amount of DLP in the matrix structure. © 2015 The Polymer Society of Korea. All rights reserved.
The radioluminescence and optical behaviour of nanocomposites with CdSeS quantum dot
(Elsevier B.V., 2017) Keskin İ.Ç.; Türemiş M.; Katı M.İ.; Kibar R.; Şirin K.; Çipiloğlu M.A.; Kuş M.; Büyükçelebi S.; Çetin A.
In this work, highly luminescent alloyed CdSeS QDs are successfully synthesized by two phase route method by using oleic acid (OA) as a surfactant. OA capped CdSeS QDs prepared in two different synthesis duration were compared in terms of luminescence and optical properties. The nanocomposites blended with CdSeS QDs which have highly luminescent efficiency in different ratios by Low Density Polyethylene (LDPE) and these nanocomposites were mainly investigated radioluminescence (RL) and optical properties (UV/VIS absorption). Structural, morphological, thermal properties of the nanocrystal and nanocomposites were examined using; XRD, FT-IR, TEM, SEM, TG-DTA techniques. OA capped CdSeS and also nanocomposites were showed two RL spectrum peaks in green and red region at around 528 nm and 710 nm respectively. Also, it is seen that the radioluminescence intensity changes linearly with the particle size of the QDs and about 12% size change of quantum dot led to a threefold increase in RL intensity. The luminescence glow curves are in compliance with absorption and fluorescence spectra. The absorption bands showed a significant blue shift for the nanocomposites as compare to powder CdSeS. The optical band gap of the OA capped CdSeS calculated as 1.77 eV. It was observed that the optical band gap of LDPE was decreased by the adding ratio of CdSeS from 3.71 eV to 2.25 eV. © 2017 Elsevier B.V.
Conducting polymer composites based on LDPE doped with poly(aminonaphthol sulfonic acid)
(Elsevier B.V., 2018) Doğan F.; Şirin K.; Kolcu F.; Kaya İ.
The paper presents the mechanical, morphological, thermal and the electrostatic charge dissipative (ESD) properties of binary blends of low-density poly (ethylene) (LDPE) blended with poly (1-amino-2-hydroxy naphthalene-4-sulfonic acid) (PANSA). Blends were prepared by loading 0.5, 1.0 and 3 wt% of PANSA into LDPE matrix in the twin-screw micro extruder. The interaction between PANSA and LDPE was then characterized by FT-IR, DSC, TG, DMA, AFM, SEM and X-RD techniques. The resulting polyolefin-based blends were also investigated by stress-strain curves in order to analyze some physico-mechanical properties. Percentages of the crystallinity of the blends were calculated by FT-IR, DSC and X-RD analyses. The conductivity of PANSA/LDPE blends was determined to be in the range of 10−11- 10−12 S cm−1 using ESD applications. The antistatic decay time of blend films was found to be of the order of 0.103–1.721 secat corona voltages between −3 kV and 3 kV, concluding that PANSA can be used as an effective ESD material for antistatic coatings of LDPE. © 2018 Elsevier B.V.
Optimizing Optical and Structural Properties of Nanocomposites by ZnO and BP-3
(Pleiades Publishing, 2018) Türemiş M.; Keskin I.Ç.; Katı M.I.; Kibar R.; Şirin K.; Çanlı M.; Çorumlu V.; Çetin A.
This study aims to find out usage of zinc oxide (ZnO) and 2-hydroxy-4-methoxybenzophenone (BP-3) for getting better optical and structural properties of nanocomposites. Polymer nanocomposites were prepared by adding zinc oxide for minimizing UV rays effects of the sun with the particle size of nanometer in different ratios to a low density polyethylene (LDPE). The polymer mixtures were synthesized by mixing nanocomposite samples with BP-3 featuring UV stabilizer. Besides making tensile testing measurements, in order to find out the optical, structural, mechanical and thermal changes, the new polymer nanocomposites were characterized by XRD, TG-DTA spectra, and SEM images. The samples with zinc oxide which show luminescent properties were examined in terms of radioluminescence features. Radioluminescence spectrum showed characteristic peaks of zinc oxide dispersed nanocomposites prepared with LDPE. The intensity of the characteristic peaks at 530 and 390 nm (exciton) increased by increasing rates of nanopowder zinc oxide while adding BP-3 to the composites caused a decrease in intensity of radioluminescence. © 2018, Pleiades Publishing, Ltd.
Preparation and characterization of dialdehyde cellulose/polylactic acid blends; [Dialdehit selüloz/polilaktik asit blendlerinin hazırlanması ve karakterizasyonu]
(TUBITAK, 2021) Şirin K.; Seziş Ü.G.; Ay E.
In recent years, the demand for naturally derived synthetic materials to protect the environment has increased. Cellulosic polymers are renewable, biodegradable, eco-friendly, and possess high strength and stiffness. As a result of the researches, the use of polylactic acid (PLA) instead of petroleum-based polymers stands out as an alternative. In this study, dialdehyde cellulose (DAC)/polylactic acid (PLA) mixtures were prepared. DAC was prepared by peroxide oxidation from microcrystalline cellulose. Firstly, DAC was blended with PLA. In addition to having hydrophilic properties of DAC, polyethylene glycol (PEG) was added to increase compatibility between PLA and DAC, as PLA was known to have hydrophobic properties.The blends were characterized by infrared spectroscopy (FT-IR) and thermal analysis (TGA and DTG) techniques. Besides, scanning electron microscopy (SEM) images of the polymer blends obtained were interpreted. © 2021, TUBITAK. All rights reserved.
Preparation, characterization and thermal properties of polypropylene/polyethylene/zinc borate composites: investigation of thermal degradation kinetics
(Springer Science and Business Media B.V., 2023) Saltan F.; Şentürk S.; Al A.M.; Özkan A.N.; Şirin K.
In this study, polypropylene/polyethylene/zincborate composites (PP/HDPE/Zinc Borate) were prepared using high-density polyethylene, isotactic polypropylene, and a certain percentage of zinc borate. The composites were characterized using by X-Ray Diffraction (XRD), Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDX), Fourier Transform Infrared (FT-IR) spectroscopy analyses. The thermal behavior of the materials was investigated using thermogravimetric analysis (TG), Differential Thermal Analysis (DTA), and Differential Thermogravimetry (DTG). The thermal degradation kinetics of the PP/HDPE/Zinc Borate15% composite was investigated. The apparent activation energies (Ea) were obtained following the differential and integral methods of Kissenger and Flynn-Wall-Ozawa (FWO). Using Kissinger's and Flynn–Wall–Ozawa methods to define thermal degradation of PP/HDPE/Zinc Borate%15, their activation energies were 233.3 kJ/mol and 189.3 kJ/mol, respectively. The mechanism of the studied conversion range was found to be the R3 deceleration model using the Coats–Redfern. The viscosity and shear stress of PP/HDPE/Zinc Borate15% were determined using a cone-plate type rheometer. PP/HDPE/Zinc Borate15% composite shows plastic-type fluidity, according to rheological analysis. © 2023, The Polymer Society, Taipei.
Preparation and characterization of novel boron containing nanocomposites with neutron radiation shielding properties
(John Wiley and Sons Inc, 2023) Saltan F.; Şirin K.; Aydin S.; Yildirim Y.
PVA/PEO/PVP-B4C and PVA/PEO/PVP-BN polymer nanocomposites were prepared using boron nitrite (BN), boron carbide (B4C), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and polyethylene oxide (PEO). B4C and BN nanopowders were added to the mixture at three different percentages: 5%, 10%, and 20%. Thermal characterization was performed by differential scanning calorimetry, differential thermal analysis and thermogravimetry. Scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction were used for surface analysis and crystal structure characterization. The atomic distribution was determined by elemental analysis. Neutron shielding properties were performed at three different gamma peak areas, 1293.56 keV, 1097.33 keV, 416.86 keV, and calculated total macroscopic cross-section ∑T and half-value layer. The ∑T values were found to be in the range of 7.99–14.37 for all synthesized composites. B4C-doped composites show higher protection efficiency against slow thermal neutrons than BN-doped samples. Highlights: Poly(vinyl alcohol)/poly(ethylene oxide)/polyvinylpyrrolidone composites containing boron nanoparticles are flexible and workable. Nanocomposites were prepared with a simple, cheap, and fast method. Prepared boron nanocomposites exhibit slow thermal neutron stopping even at 3 mm thickness. PVA90/PEO5/PVP5-BN and PVA90/PEO5/PVP5-B4C composites are good candidates for demanding military applications such as vehicle and body armor. © 2023 Society of Plastics Engineers.
Boron containing polyvinyl alcohol/ polyethylene oxide/polyvinyl pyrrolidone composites: Preparation, characterization, gamma radiation shielding and gamma radiation effect on it's thermal properties
(Elsevier Ltd, 2024) Saltan F.; Şirin K.; Aydın S.; Taşköprü C.; Yıldırım Y.
The production of PVA/PEO/PVP-B4C and PVA/PEO/PVP-BN nanocomposites is presented in this study by adding certain proportions of boron nitride (BN) and boron carbide (B4C) to the polyvinyl alcohol(PVA)/polyethylene Oxide (PEO)/polyvinyl pyrrolidone (PVP) blend. The percentages of BN and B4C nano powder in the PVA/PEO/PVP blend have been determined as 5%, 10% and 20%. Thermal characterizations were carried out with different techniques such as Differential scanning calorimetry (DSC), Differential Thermal Analysis (DTA), Thermogravimetry (TG). Surface, crystal structure and atomic percentage distribution analyzes of the obtained composites were performed by X-ray Photoelectron Spectroscopy (XPS), X-Ray Diffraction Analysis (XRD), Scanning Electron Microscopy-Energy Dispersive X-Ray (SEM-EDX), and elemental analysis. 10 kGy gamma irradiation was performed on PVA/PEO/PVP-B4C and PVA/PEO/PVP-BN composites. The thermal behavior of the composites at this dose level was investigated. In addition, the radiation shielding properties of composite films obtained at 10 cm distances using Am-241 beam source were examined. © 2023 Elsevier Ltd
Thermal decomposition kinetics and mechanical analysis of boron carbide-reinforced polymer nanocomposites
(John Wiley and Sons Inc, 2025) Yildirim Y.; Saltan F.; Şirin K.; Küçük V.A.
In the present study, the mechanical properties and thermal degradation kinetics of PVA/PVP/PEO (polyvinyl alcohol/polyvinyl pyrrolidone/polyethylene oxide) blend, along with their composites containing various percentages of boron carbide (B4C), are examined. The solvent-casting method is used for preparing the composites. Thermal degradation is analyzed using both Kissinger and FWO (Flynn-Wall-Ozawa) methods to determine the activation energies (Ea). The Ea varied with the B4C content, with higher B4C percentages leading to increased thermal stability. Dynamic mechanical analysis (DMA) was employed to evaluate the mechanical properties, revealing that B4C addition enhances the Young's modulus (E) while decreasing strain. The highest strain (ε) was observed in the PVA/PEO/PVP blend, reaching 184%. The ε values for PVA/PEO/PVP-B4C%5, PVA/PEO/PVP-B4C%10, and PVA/PEO/PVP-B4C%20 composites were determined as 45.30%, 29.15%, and 16.48%, respectively. The E was measured as 0.12 MPa for PVA/PEO/PVP, while the highest E value of 0.64 MPa was observed in the PVA/PVP/PEO-B4C20% composite. Additionally, chemometric analysis using FTIR data and clustering algorithms confirmed the homogeneity of the blends. These findings indicate that B4C-reinforced PVA/PVP/PEO composites could serve as alternatives to conventional polymers, particularly in applications requiring enhanced thermal and mechanical stability. Highlights: B4C addition increases the thermal stability of the PVA/PVP/PEO blend. DMA analysis shows that B4C addition increases the elastic modulus. Activation energies were calculated by the Kissinger and FWO methods. PVA/PVP/PEO-B4C composites offer superior mechanical resistance. © 2025 Society of Plastics Engineers.

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