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Öğe Airlaid nonwoven panels for use as structural thermal insulation(Taylor & Francis Ltd, 2018) Çerkez, İdris; Koçer, Hasan Basri; Broughton, R. M.Thermal-bonded airlaid nonwoven webs consisting of fiber glass and polyester bicomponent fibers were manufactured, and then multilayer webs were formed into composite panels using compression molding technique. The consolidation process was optimized and the effect of bulk density on air permeabilites, mechanical properties, and thermal resistance was studied. Increasing binder amount and bulk density improved the flexural and tensile strength. Thermal resistance of the panels were found to be very dependent on the bulk density such that the resistance increased exponentially with an initial increase in density, then leveled off and decreased linearly with further increment in density. Depending on the composition and bulk density, the panels provided thermal resistance between 0.52 and 0.88Km(2)/W, tensile strength between 2 and 7MPa, and flexural strength between 600 and 3500kPa. The findings revealed that airlaid nonwoven panels can be designed to use as structural thermal insulation materials in constructions.Öğe Annealing studies on a thermotropic liquid crystalline polyester meltblown fabric(Sage Publications Inc, 2017) Koçer, Hasan Basri; Çerkez, İdris; Broughton, Royall M.Meltblown fabrics composed of a thermotropic liquid crystalline polyester were subjected to heat conditioning at various temperatures. Physical effect of the treatment was investigated by tensile testing of the fabrics and the individual fibers. The fabrics exhibited increased tensile strength by more than 100% after the heat conditioning due to inter-fiber bonding in the fabric structure and morphological reorganization of the thermotropic polymer. The calorimetric behavior of the polymer was further investigated to obtain information about the internal structure. Structural change during the annealing was also visually observed under a polarized light microscope.Öğe Antibacterial polyacrylonitrile nanofibers produced by alkaline hydrolysis and chlorination(Springer, 2017) Aksoy, Oğuz Emre; Ateş, Büşra; Çerkez, İdrisAntibacterial polyacrylonitrile (PAN) nanofibers were developed by alkaline hydrolysis and subsequent chlorination. It was shown that the hydrolyzed nanofibers could serve as an N-halamine precursor through chlorination of the amide groups obtained by partial hydrolysis of the nitrile groups. The hydrolysis conditions were optimized, so that sufficient chlorine for effective antibacterial activities could be obtained on the surfaces. The chemical and physical structural changes were well characterized with FTIR, TGA, DSC and SEM. It was found that even though the hydrolyzed nanofibers cyclized with ionic and free radical mechanisms, the chlorinated nanofibers cyclized with only free radical mechanism as evidenced by its higher onset of cyclization temperature. On the other hand, the hydrolysis and chlorination process significantly improved the mechanical properties of the nanofibers. Moreover, the chlorinated nanofibers showed potent antibacterial activities against S. aureus and E. coli with about 6 logs inactivation. The developed antibacterial PAN nanofibers possess great potential for use in various fields, medical industry in particular.Öğe Antimicrobial functionalization of poly(ethylene terephthalate) fabrics with waterborne N-halamine epoxides(Wiley-Blackwell, 2016) Çerkez, İdris; Koçer, Hasan Basri; Worley, S. D.; Broughton, R. M.; Huang, T. S.A water dispersible terpolymer of [2-(methacryloyloxy)ethyl]trimethylammonium chloride, glycidyl methacrylate and hydantoinyl acrylamide was synthesized and coated on poly(ethylene terephthalate) fabrics through a pad-dry-cure procedure. The coatings were rendered biocidal upon exposure to dilute household bleach solution. The halogenated fabrics exhibited great antimicrobial functionality with about six logs inactivation of S. aureus and E. coli O157: H7 within only two min of contact time. Moreover, the coatings were found to be very stable against repeated washings and UVA light exposure. It was shown that [2-(methacryloyloxy)ethyl]-trimethylammonium monomer is very useful in preparing waterborne N-halamines which can impart rechargeable, effective, and stable antimicrobial coatings to poly(ethylene terephthalate) fabrics. (C) 2015 Wiley Periodicals, Inc.Öğe Antimicrobial surface coatings for polypropylene nonwoven fabrics(Elsevier, 2013) Çerkez, İdris; Worley, S. D.; Broughton, R. M.; Huang, T. S.Anionic and cationic N-halamine polyelectrolytes were synthesized, characterized and then immobilized onto melt-blown polypropylene fabrics having two different basis-weights. The coatings were rendered biocidal upon exposure to dilute sodium hypochlorite solution. The effect of single and multilayer deposition of the polyelectrolytes on the surfaces was investigated in terms of chlorine loadings, rechargeabilities, antimicrobial efficacies, and air permeabilities. It was found that all of the coatings provided remarkable biocidal efficacies with about six log reductions of bacteria within two mm of contact time on filters having higher basis-weight, whereas slower inactivation was observed for lower-basis weight filters due to diminished surface areas and numbers of active halogen atoms. The antimicrobial coatings reduced the air permeabilities of the filters somewhat; however, the air permeabilities of the coated swatches were comparable to those of most protective textiles. (C) 2013 Elsevier Ltd. All rights reserved.Öğe Dual antibacterial functional regenerated cellulose fibers(Wiley, 2017) Ateş, Büşra; Çerkez, İdrisN-[3-(dimethylamino) propyl] methacrylamide monomer was used to impart dual antibacterial functionality to regenerated cellulose fibers. In this regard, the monomer was grafted onto the surfaces by a "grafting from" technique, then the tertiary amine groups were quaternized and the acyclic amide groups were halogenated. Antibacterial activities of the mono-and dual-functional coatings were comparatively evaluated. All the treatments were found to be effective against Staphylococcus aureus and Escherichia coli with about six logs bacterial reduction. It was found that dual-functional coatings provided rapid inactivation as opposed to the monofunctional coatings. FTIR, TGA, and SEM analysis, wash fastness, light stabilities, and the mechanical properties of the coated fabrics were also comparably reported. (C) 2017 Wiley Periodicals, Inc.Öğe Fabrication and characterization of electrospun poly(e-caprolactone) fibrous membrane with antibacterial functionality(Royal Soc, 2017) Çerkez, İdris; Sezer, Ayşe; Bhullar, Sukhwinder KaurThis research study is mainly targeted on fabrication and characterization of antibacterial poly(e-caprolactone) (PCL) based fibrous membrane containing silver chloride particles. Micro/nano fibres were produced by electrospinning and characterized with TGA, DSC, SEM and mechanical analysis. It was found that addition of silver particles slightly reduced onset of thermal degradation and increased crystallization temperature of neat PCL. Silver-loaded samples exhibited higher tensile stress and lower strain revealing that the particles behaved as reinforcing agent. Moreover, addition of silver chloride resulted in beaded surface texture and formation of finer fibres as opposed to the neat. Antibacterial properties were tested against Gram-negative and Gram-positive bacteria and remarkable biocidal functionalities were obtained with about six logs reduction of Staphylococcus aureus and Escherichia coli O157: H7.Öğe Guanine oxidation signal enhancement in single strand DNA with polyacrylonitrile/polyaniline (PAN/PAni) hybrid nanofibers(Wiley, 2018) Cam, Ezginur; Tanik, Nilay Aladag; Çerkez, İdris; Demirkan, Elif; Aykut, YakupPure polyacrylonitrile (PAN) and polyacrylonitrile/polyaniline (PAN/PAni) hybrid nanofibers (NFs) were produced via electrospinning and used to monitor guanine oxidation in single strand DNA (ssDNA) by electrochemical methods. Two different methodologies were conducted. First, pre-synthesized PAni was added into electrospinning PAN solution and electrospun into composite PAN/PAni nanofibrous structure on cylindrical pencil graphite (PGE) surface. In the second route, PAN NFs were electrospun on a PGE surfaces and polymerization of PAni was conducted on the surfaces of the as-spun PAN NFs. NFs were kept at -18 degrees C in a refrigerator for several days. ssDNA was immobilized on the prepared NFs and guanine oxidation signals were observed for each system. The results revealed that use of PAN NFs enhanced signal intensity from 0.92 mu A (PGE) to 1.04 mu A (PAN NFs). Addition of PAni to PAN increased signal intensity to 1.23 mu A. When the PAN NF surfaces were coated with PAni, signal enhancement continued to increase up to 4.19 mu A for fourth day and decreased again when PAni-coated NFs were kept at -18 degrees C in the refrigerator. Since the prepared system is fast and cheap, it is promising for application in DNA biosensor devices. (c) 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45567.Öğe N-(hydroxymethyl) acrylamide as a multifunctional finish to cotton and a tether for grafting methacrylamide for biocidal coatings(Wiley, 2013) Yildiz, Ozkan; Çerkez, İdris; Koçer, Hasan Basri; Worley, S. D.; Broughton, R. M.; Huang, T. S.N-(hydroxymethyl) acrylamide (NMA) was immobilized on cotton surfaces through etherification, and then methacrylamide (MA) was grafted onto the treated surface. The coatings were characterized by ATR-IR spectroscopy and were rendered biocidal upon exposure to dilute household bleach. The treated fabrics were challenged with Gram-negative and Gram-positive bacteria; both NMA and NMA/MA-treated fabrics inactivated about 8 logs of Escherichia coli O157:H7 and Staphylococcus aureus within only 5 min of contact time. The coatings were also quite stable toward ultraviolet (UVA) light exposure and repeated laundering. Moreover, a substantial improvement in wrinkle recovery angle was obtained for the NMA/MA-treated fabrics. The new acyclic acrylamide N-halamine coating should be less expensive to produce and use than previous cyclic N-halamine coatings developed in these laboratories. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013Öğe N-Halamine-Based Antimicrobial Coatings(Elsevier Science Bv, 2017) Çerkez, İdrisN-halamine-based coatings draw great attention in both academia and industry, since they are one of the most effective biocides. These compounds are simply defined as “oxidative halogen stabilizers,” and they possess long-lasting and rechargeable antimicrobial activities. They are suitable to use as biocidal coatings for soft and hard surfaces. Various N-halamine-based coatings are reported in the literature in the last two decades. In this regard, this chapter discusses structure and bioactivity relationship of N-halamine compounds, applications areas of N-halamine-based coatings, the strategies for surface functionalization with N-halamine compounds, and the future trends in N-halamine technology.Öğe N-Halamine-Modified Antimicrobial Polypropylene Nonwoven Fabrics for Use against Airborne Bacteria(Amer Chemical Soc, 2015) Demir, Buket; Çerkez, İdris; Worley, S. D.; Broughton, R. M.; Huang, Tung-ShiDisinfecting, nonbleaching compound 1-chloro-2,2,5,5-tetramethyl-4-imidazolidinone (MC) was uniformly coated onto polypropylene melt-blown nonwoven fabrics having basis-weights of 22 and 50 g/m(2) in order to impart antimicrobial properties via a pad-dry technique. The antimicrobial efficacies of the tested fabrics loaded with MC compound were evaluated against bioaerosols of Staphylococcus aureus and Escherichia coli O157:H7 utilizing a colony counting method. It was determined that both types of coated fabrics exhibited superior antimicrobial efficacy upon exposure to aerosol generation for 3 h. The effect of the coating on air permeability was found to be minimal. Samples were stable for a 6 month time period when they were stored in darkness. However, when the fabrics were exposed to fluorescent light, partial chlorine loss was observed. The MC-coated fabrics exhibited great potential for use in protective face masks and air filters to combat airborne pathogens.Öğe One-Step Synthesis and Characterization of Polyaniline Nanofiber/Silver Nanoparticle Composite Networks as Antibacterial Agents(Amer Chemical Soc, 2014) Poyraz, Selcuk; Çerkez, İdris; Huang, Tung Shi; Liu, Zhen; Kang, Litao; Luo, JujieThrough a facile and effective seeding polymerization reaction via a one-step redox/complexation process, which took place in aqueous medium at ambient temperature, silver nanoparticles (Ag NPs) embedded polyaniline nanofiber (PANI NF) networks were synthesized as antibacterial agents. During the reaction, not only NF morphology formation of the resulting conducting polymers (CPs) but also amplification of the aqueous silver nitrate (AgNO3) solutions oxidative potentials were managed by vanadium pentoxide (V2O5) solgel nanofibers, which acted as well-known nanofibrous seeding agents and the auxiliary oxidative agent at the same time. The PANI/Ag nanocomposites were proven to exhibit excellent antibacterial property against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Antibacterial property performance and average life span of the nanocomposite network were optimized through the homogeneous distribution/embedment of Ag NPs within one-dimensional (1-D) PANI NF matrix. The antibacterial efficacy tests and nanocomposite material characterization results further indicated that the sole components of PANI/Ag have a synergistic effect to each other in terms of antibacterial property. Thus, this well-known catalytic seeding approach via a one-step oxidative polymerization reaction can be considered as a general methodology and a substantial fabrication tool to synthesize Ag NP decorated nanofibrillar PANI networks as advanced antibacterial agents.Öğe PREPERATION AND ANTIBACTERIAL INVESTIGATION OF POLYCAPROLACTONE/CHITOSAN NANO/MICRO FIBERS BY USING DIFFERENT SOLVENT SYSTEMS(Ege Univ, 2018) Tursucular, Omer Firat; Çerkez, İdris; Orhan, Mehmet; Aykut, YakupChitosan (CHI) blended polycaprolactone (PCL) nano/micro fibers were prepared with different CHI content via electrospinning procedure. Two different solvents, acetone and formic acid (FA) were used to dissolve and blend the polymers before electrospinning process. Effect of the solvent on the electrospinability of the blend, final nano/micro fiber morphologies, chemical and thermal properties and antibacterial activities were investigated with SEM, FTIR, DSC, and ASTM 2149 01 Standard Dynamic Contact Conditions. The results revealed that chitosan particles were encapsulated in the as-spun PCL fibers with using acetone as the solvent resulted in reduced antibacterial activities Contrarily, when FA is used as the solvent, CHI and PCL were dissolved and blended very well, and enhanced antibacterial activities were obtained from as-spun PCL/CHI nano/micro fibers.Öğe Swelling Behavior of Hydrogels within Auxetic Polytetrafluoroethylene Jacket(Taylor & Francis Inc, 2015) Bhullar, Sukhwinder Kaur; Çerkez, İdris; Sezer, Ayşe; Jun, Martin B. G.An acrylamide type hydrogel consisting of 2-acrylamido-2-methyl-1-propanesulfonic acid was synthesized using free radical suspension polymerization. Hydrogel particles were then loaded within an auxetic polytetrafluoroethylene jacket. It was found that the swelling ratio of the hydrogels within the jacket can be controlled by changing the loaded particle's amount and size without the wear and tear of jacket due to the auxetic effect. Increasing swelling ratio with finer hydrogel particles was observed due to higher surface area. On the other hand, increasing hydrogel particle amount resulted in a decrease in water absorption due to diminished free volume for swelling within the jacket.Öğe Synthesis, characterization and chlorination of 2-acrylamido-2methylpropane sulfonic acid sodium salt-based antibacterial hydrogels(Elsevier Science Bv, 2017) Hiçyılmaz, Ayşe Sezer; Seçkin, Abdullah Kemal; Çerkez, İdris2-Acrylamido-2-methylpropane sulfonic acid sodium salt-based hydrogels were synthesized by redox polymerization and rendered biocidal by dilute household bleach treatment. The developed hydrogels were characterized by SEM, EDX, FTIR, DSC and TGA. The effect of chlorination parameters on the chlorine loadings and water absorption degree was studied. It was found that depending on the halogenation conditions, the oxidative chlorine loadings could be tuned between 0.10 and 2.82 wt%, and the water absorption degree could be obtained between 10 and 230 g/g. Moreover, the chlorinated hydrogels effectively inactivated about 7 logs of the Gram-positive and Gram-negative bacteria.
