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Pekcan, Mehmet Önder
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Name Variants
Mehmet Onder Pekcan
Mehmet Onder, Pekcan
Mehmet Önder Pekcan
Pekcan ö.
P., Mehmet Önder
Pekcan, MEHMET ÖNDER
Pekcan,Mehmet Onder
Pekcan, M. Ö.
Mehmet Önder PEKCAN
P., Mehmet Onder
PEKCAN, Mehmet Önder
Pekcan, Mehmet Onder
Pekcan,M.Ö.
M. Ö. Pekcan
MEHMET ÖNDER PEKCAN
M. Pekcan
Pekcan, M.
PEKCAN, MEHMET ÖNDER
PEKCAN Ö.
Pekcan N.
Pekcan Ö.
Pekcan, Mehmet Önder
Pekcan O.
P.,Mehmet Onder
Pekcan,M.O.
Pekcan, Önder
Pekcan, Onder
Pekcan, Oonder
Mehmet Onder, Pekcan
Mehmet Önder Pekcan
Pekcan ö.
P., Mehmet Önder
Pekcan, MEHMET ÖNDER
Pekcan,Mehmet Onder
Pekcan, M. Ö.
Mehmet Önder PEKCAN
P., Mehmet Onder
PEKCAN, Mehmet Önder
Pekcan, Mehmet Onder
Pekcan,M.Ö.
M. Ö. Pekcan
MEHMET ÖNDER PEKCAN
M. Pekcan
Pekcan, M.
PEKCAN, MEHMET ÖNDER
PEKCAN Ö.
Pekcan N.
Pekcan Ö.
Pekcan, Mehmet Önder
Pekcan O.
P.,Mehmet Onder
Pekcan,M.O.
Pekcan, Önder
Pekcan, Onder
Pekcan, Oonder
Job Title
Prof. Dr.
Email Address
pekcan@khas.edu.tr
Main Affiliation
Molecular Biology and Genetics
Status
Former Staff
Website
ORCID ID
Scopus Author ID
Turkish CoHE Profile ID
Google Scholar ID
WoS Researcher ID

Scholarly Output
116
Articles
98
Citation Count
0
Supervised Theses
0
14 results
Scholarly Output Search Results
Now showing 1 - 10 of 14
Article Citation - WoS: 7Citation - Scopus: 8Elastic Properties of a Swollen Paam-Nipa Copolymer With Various Nipa Contents(Taylor & Francis, 2014) Evingür, Gülşen Akin; Pekcan, Mehmet Önder; Pekcan, ÖnderCopolymer based on cross-linked polyacrylamide (PAAm) having N-isopropylacrylamide (NIPA) was prepared and their elastic properties were studied as a function of NIPA contents. NIPA content dependency of the shear modulus S of the PAAm-NIPA copolymers due to volume phase transition was measured using tensile testing technique at 30 degrees C. It was observed that its shear modulus and toughness were found to be strongly dependent on NIPA content. It is understood that the shear modulus was found to increase with NIPA contents keeping constant temperature at 30 degrees C. Elastic properties of the PAAm-NIPA copolymers show compositional dependence.Article Citation - WoS: 4Citation - Scopus: 5Kinetic Models for the Dynamical Behavior of Polyacrylamide (paam)-Kappa (kappa C) Composite Gels(Springer, 2015) Evingür, Gülşen Akın; Pekcan, Mehmet Önder; Pekcan, ÖnderA fluorescence method was employed for studying the drying and swelling of PAAm-kappa C composite gels which were formed from acrylamide (AAm) and N N'- methylenebisacrylamide (BIS) with various kappa-carrageenan (kappa C) contents by free radical crosslinking copolymerization in water. Composite gels were prepared at 80 A degrees C with pyranine (Py) as a fluorescence probe. Scattered light I (sc) and fluorescence emission intensities I (em) were monitored during drying and swelling of these gels. The fluorescence intensity of pyranine increased and decreased as drying and swelling time are increased respectively for all gel samples. The Stern-Volmer equation combined with moving boundary and Li-Tanaka models were used to explain the behavior of I (em) during drying and swelling processes respectively. It is found that the desorption coefficient D (d) decreased as kappa C contents were increased for a given temperature during drying. However the cooperative diffusion coefficient D (s) presented exactly the opposite case. Conventional gravimetrical and volumetric experiments were also carried out during drying and swelling of PAAm-kappa C composite gels. It was observed that D (d) and D (s) values measured with the fluorescence method were found to be much larger than they were measured with the conventional methods.Article Citation - WoS: 3Citation - Scopus: 3Temperature Effect on the Elasticity of Acrylamide-N Copolymers(Taylor & Francis Inc, 2018) Evingür, Gülşen Akin; Pekcan, Mehmet Önder; Pekcan, ÖnderAcrylamide (AAm) - N-isopropylacrylamide (NIPA) copolymers were prepared via free radical crosslinking copolymerization with various weight percentages (wt%) of AAm and NIPA. The temperature dependence of the compressive elastic modulus G and toughness U-TU- of the PAAm- NIPA copolymers due to a volume phase transition was found using a compressive testing technique. It was observed that the compressive elastic modulus increased comprehensively when the temperature was increased between 30 degrees C and 60 degrees C. The PAAm- NIPA copolymers presented higher values of the compressive elastic modulus than pure NIPA above the lower critical solution temperature (LCST) (NIPA exhibits a volume phase transition from hydrophilic to hydrophobic in water at 31 degrees C) and their compressive elastic modulus and toughness had a strong temperature dependence.Article Citation - WoS: 6Citation - Scopus: 6Drying of Polyacrylamide Composite Gels Formed With Various Kappa- Carrageenan Content(Springer/Plenum Publishers, 2011) Evingür, Gülşen Akın; Pekcan, Mehmet Önder; Pekcan, ÖnderDrying of polyacrylamide (PAAm)-kappa-carrageenan (kappa C) composite gels were monitored by using steady-state fluorescence technique. Disc shaped gels were formed from acrylamide (AAm) and N N'- methylenebisacrylamide(Bis) with various kappa- carrageenan (kappa C) contents by free radical crosslinking copolymerization in water. Pyranine (P) was doped as a fluorescence probe and scattered light I (sc) and fluorescence intensities I were monitored during drying of these gels. It is observed that fluorescence intensity of pyranine increased as drying time is increased for all samples. The increase in I was modeled using Stern- Volmer equation and diffusion with moving boundary. It is found that desorption coefficient D decreased as kappa C contents were increased. Supporting gravimetrical and volumetric experiments were also carried out during drying of PAAm- kappa C composite gels.Article Citation - WoS: 3Citation - Scopus: 3Fractal Dimension and Phase Transition of Graphene Oxide (go) Doped Polyacrylamide(ELSEVIER SCI LTD, 2020) Evingür, Gülşen Akın; Pekcan, Mehmet Önder; Pekcan, ÖnderGraphene Oxide (GO)- Polyacrylamide composites prepared between 5 and 50 mu l GO were performed by Fluorescence Spectroscopy. The phase transition performed on the composites was measured by calculating the critical exponents, beta and gamma, respectively. In addition, fractal analysis of the composites was calculated by a fluorescence intensity of 427 nm. The geometrical distribution of GO in the composites was calculated based on the power law exponent values using scaling models. While the gelation proceeded GO plates first organized themselves into a 3D percolation cluster with the fractal dimension (D-f) of the composite, D-f = 2.63, then After it goes to diffusion limited clusters with D-f = 1.4, its dimension lines up to a Von Koch curve with a random interval of D-f = 1.14.Article Citation - WoS: 2Citation - Scopus: 3Gelation of Paam-Pvp Composites: a Fluorescence Study(World Scientific, 2014) Evingür, Gülşen Akin; Pekcan, Mehmet Önder; Kaygusuz, Hakan; Erim, F. Bedia; Pekcan, ÖnderHybrid hydrogels are a new class of composite materials. Polyacrylamide (PAAm) hydrogels are mainly produced by free radical crosslinking copolymerization (FCC) of AAm in the presence of N N'-methylene bis (acrylamide) (BIS) as the crosslinker. Pyranine doped PAAm-poly (N-vinyl pyrrolidone) (PVP) composite were prepared with different amounts of PVP varying in the range between 0.0015 and 0.1 gr. It was observed that pyranine molecules as a fluoroprobe bind to AAm and PVP chains upon the initiation of the polymerization causing the fluorescence spectra of the bonded pyranines shift to the shorter wavelengths. The sol-gel phase transition and its universality were monitored and tested as a function of PVP contents. Observations around the critical point show that the gel fraction exponent beta agreed with the percolation result for below 0.025 gr PVP contents. However classical result was observed above 0.0125 gr PVP content.Article Citation - WoS: 12Citation - Scopus: 14Elastic Percolation of Swollen Polyacrylamide (paam)-Multiwall Carbon Nanotubes Composite(Taylor & Francis Ltd, 2012) Evingür, Gülşen Akin; Pekcan, Mehmet Önder; Pekcan, ÖnderPolyacrylamide (PAAm)-multiwalled carbon nanotube (MWNT) composites were prepared via free radical cross-linking copolymerization with different amounts of MWNTs varying in the range between 0.1 and 50 wt%. The mechanical properties of swollen PAAm-MWNT composites were characterized by the tensile testing technique. A small content of embedded nanotubes dramatically changes the compressive elastic modulus of the composites. Compressive elastic modulus dramatically increases up to 1wt% MWNT on increasing nanotube content and then decreases presenting a critical MWNT value indicating that there is a sudden change in the material elasticity. The critical exponent y of elasticity below the critical MWNT content 1 wt% is found to be 0.58 which is consistent with the suggestions of percolation in the superelastic percolation network for PAAm-MWNT composite.Article Citation - WoS: 13Citation - Scopus: 14Superelastic Percolation Network of Polyacrylamide (paam)-Kappa Carrageenan (kappa C) Composite(Springer, 2013) Evingür, Gülşen Akin; Pekcan, Mehmet Önder; Pekcan, ÖnderThe elasticity of the polyacrylamide (PAAm)-kappa carrageenan (kappa C) composite was determined as a function of (w/v-%) kappa C content at 40 A degrees C. The gel composites studied contained various percentages (w/v-%) of kappa C. The elasticity of the swollen PAAm-kappa C composite was characterized by using the tensile testing technique. This study investigated the elasticity and the percolation threshold of PAAm-kappa C composite as a function of kappa C content. It is understood that the compressive elastic modulus decreases up to 1 (w/v-%) of kappa C and then increases at contents above 1(w/v-%) of kappa C. The critical exponent of elasticity y was determined between 1 and 1.6 (w/v-%) of kappa C and found to be 0.68. The observed elastic percolation threshold is consistent with the suggested values of the superelastic percolation network.Article Citation - WoS: 4Citation - Scopus: 3Drying of Polyacrylamide-Multiwalled Carbon Nanotube (mwnt) Composites With Various Mwnts Contents: a Fluorescence Study(Walter De Gruyter Gmbh, 2013) Evingür, Gülşen Akin; Pekcan, Mehmet Önder; Pekcan, ÖnderWe studied the drying of polyacrylamide (PAAm)-multiwalled carbon nanotube (MWNT) composites prepared by free radical crosslinking copolymerization in water with a steady state fluorescence technique. Composite gels were prepared at room temperature with pyranine (Py) doped as a fluorescence probe. Drying experiments were performed in air at various MWNT contents by real time monitoring of the Py fluorescence intensity (I) which increased as the drying proceeded. The Stern-Volmer equation combined with the moving boundary diffusion model was used to explain the behavior of I during drying. It was observed that the desorption coefficient (D) increased as the temperature increased. Drying energies (Delta E) were measured for the drying processes for each MWNT content gel by using fluorescence gravimetrical and volumetric methods. It is understood that Delta E values decrease by increasing MWNT content until 1 wt % MWNT and then increase above the level of this threshold value. The energy of drying is strongly correlated with the MWNT content in the composite. Delta E drops to its lowest value at which conducting cluster starts to appear.Article Citation - WoS: 22Citation - Scopus: 23Critical Exponents of Gelation and Conductivity in Polyacrylamide Gels Doped by Multiwalled Carbon Nanotubes(Taylor & Francis Ltd, 2010) Aktas, Demet Kaya; Pekcan, Mehmet Önder; Evingür, Gülşen Akin; Pekcan, ÖnderPolyacrylamide (PAM) doped by multiwalled carbon nanotube (MWNT) gels were prepared with different amounts of MWNTs varying in the range between 0.1 and 15 wt%. The PAM-MWNT composite gels were characterized by the steady state fluorescence technique (SSF). The alternative electrical conductivity (AC) of PAM-MWNT composite gels was measured by the dielectric spectroscopy technique. Observations around the gel point t(gel) for PAM-MWNTs composite gels showed that the gel fraction exponent beta obeyed the percolation result. The critical exponent r of AC electrical conductivity for the composite PAM-MWNT gel was also measured and found to be about 2.0 which agrees with a random resistor network. (C) Koninklijke Brill NV Leiden 2010