Processing and Characterization of Polypropylene Nanocomposite Films Reinforced with Hexagonal Boron Nitride Nanosheets

In this study, we synthesized hexagonal boron nitride nanosheets (h-BNN) via the molten hydroxide exfoliation method which results in small flakes and nanoscrolls. The resultant h-BNNs can be dispersed in various solvents such as water, ethanol, and acetone, and form a stable dispersion. The morphological and structural analysis of h-BNNs were performed with Fourier Transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), and scanning electron microscopy (SEM). The masterbatch (MB) method was used to incorporate the h-BNNs into the polypropylene (PP) matrix via melt mixing. Dilution and film production processes were performed using a twin screw extruder. Nanocomposite films having an h-BNN weight ratio of 1%, 2%, 3%, and 5% were prepared. Thermogravimetric analyzer (TGA) and differential scanning calorimetry (DSC) were used to investigate the thermal stability. Crystallization (Tc) temperatures were increased with the increased amount of h-BNNs and h-BNNs nucleating agent behavior on the PP crystallization was observed. Oxidation induction time (OIT) of the pure PP was increased from 8.84 min to 17.82 min. The results show a considerable effect of the h-BNN content on the thermo-oxidative stability of the nanocomposites studied. The rheological and mechanical properties of the PP-hBNN nanocomposite films were also determined depending on the particle loading ratio. Optimum particle content providing the best thermal, mechanical, and rheological properties were found to be 3% wt

Immobilization of Candida rugosa Lipase on Magnetic Biosilica Particles: Hydrolysis and Transesterification Studies

Biodiesel is a renewable fuel used mainly in diesel engines. At the present time, biodiesel is largely produced by acid or alkali transesterification reactions. A hot spring water algae isolate “Kamptonema formosum” was cultivated at three different temperatures, and the algae oil was extracted using chloroform and methanol (v/v, 1/1 ratio) as the solvent. The maximum amount of algal biomass (1.86 g/L) was obtained at 25°C, and the extracted oil was found to be 48.7% of the total dry biomass. Diatomic earth particles (Biosilica) were magnetized via thermal co-precipitation reaction, and then it was grafted with polydopamine (MBioSi@PDA). The lipase was covalently immobilized on the surface of the MBioSi@PDA via Schiff’s base reaction. The immobilization conditions were optimized and 3.0 mg/mL as the initial lipase concentration in the immobilization medium was found to be the most favorable. At this lipase concentration, the amount of the immobilized lipase on the MBioSi@PDA particles and immobilization yield were found to be 81.9 mg/g and 67.9%, respectively. The MBioSi@PDA@lipase particles were used for conversion of K. formosum oil into biodiesel, and the conversion yield was found as 91.2% under optimum conditions. The fatty acid methyl ester (FAME) compositions of the alga oil were identified using a gas chromatography-mass spectrometry (GC-MS). K. formosum oil mainly composed of the required fatty acids (i.e., 16 and 18 carbon long-saturated and unsaturated fatty acids) for biodiesel synthesis, and these were advantageous for synthesis of biodiesel from the algal oil. © 2021, The Korean Society for Biotechnology and Bioengineering and Springer

Preparation of effective green sorbents using O. Princeps alga biomass with different composition of amine groups: Comparison to adsorption performances for removal of a model acid dye

In the present study, various green biosorbents based on Oscillatoria princeps biomass were developed for removal of dyes from wastewaters. For this, alga biomass was modified with three different amine containing ligands [i.e., tetraethylene tetramine (TETA), para-amino benzamidine (PAB) and polydopamine (PDA)]. These modified algal biomasses were used for removal of Reactive Red 120 dye (RR-120). The prepared biosorbents were characterized using Fourier transform infrared spectroscopy, zeta seizer, and contact angles studies. The zeta potential values of the TETA, PAB and PDA modified biosorbents were varied from 42.3 to −18.4 mV, 36.7 to −14.8 mV and 30.7 to −12.6 mV, in the pH range of 2.0–11.0, respectively. Batch experiments were performed to determine the effect of operational parameters on the biosorption of RR-120 dye on the biosorbents (i.e., pH: 2.0–8.0, biosorbent dose: 0.1–1.0 g/L, initial dye concentration: 25–500 mg/L, temperature: 15–35 °C, and contact time: 0–120 min). The biosorption capacities of the native, TETA, PAB, and PDA modified algal biomasses for RR-120 dye were found to be 148.7, 687.1, 451.8, and 260.3 mg/g, respectively, at pH 3.0, at 25 °C in 120 min. These results showed that the biosorption of the RR-120 dye on the algal biomass preparations was achieved by hydrogen bonding, ion-exchange, electrostatic, and π-π interactions. The biosorption process of the RR-120 by algal biomasses was well described by the Langmuir isotherm model and pseudo-second-order kinetic model. The adsorption enthalpies for the biosorption of dye on the biomass preparations had been found to be between 21.5 and 90.3 kJ/mol. Furthermore, the modified algal biomasses displayed good regeneration capabilities, and the modification of the algal biomass with different ligands remarkably increased the RR-120 dye biosorption performances compared to native algal biomass. © 202

İzosiyanatoetil metakrilat modifiye, biyoparçalanabilir, enjekte edilebilir, UV ışınları ile hazırlanan biyopolimerlerin sentezi ve hücre kültür çalışmaları

Yapılan çalışmanın ilk kısmında dallanmış, metakrilat modifiye poli(propilen glikol-ko-laktik asit) (PPG-PLA-IEM) ve selüloz asetat bütirat (CABIEM) kopolimerleri sentezlenmiştir. Sentezlenen polimerlerin kimyasal yapıları, molekül ağırlıkları, çapraz bağ yoğunlukları üzerinde çalışmalar yapılarak en üstün performansı sağlayan malzeme belirlenmiştir. Sentezlenen polimerlere çeşitli oranlarda poli(etilenglikol) diakrilat, su ve fotobaşlatıcı ilave edilerek farklı içerikte hidrojel formülasyonları hazırlanmıştır. Hidrojellerin hücre etkileşimlerini arttırmak üzere kolojen yapısına akrilat fonksiyonalitesi kazandırılarak hidrojel formülasyonu içerisine ilave edilmiş, bu ilavenin hücre çoğalması üzerine etkisi in vitro olarak incelenmiştir. İkinci kısımda ise yapılan ilk çalışmalara paralel olarak, amin grubu ile sonlandırılmış asit poliester (polikaprolakton) sentezlenerek, dallanmış yeni bir metakrilat modifiye poli(kaprolakton-ko-laktik asit) (PC-PLA-IEM) kopolimeri ve metakrilat modifiye poli(tetrahidrofuran) (PTHF-IEM) oligomeri sentezlenmiştir. Sentezlenen polimerler poli(etilen glikol) diakrilat, su ve fotobaşlatıcı ve ilk çalışmada sentezlenen PEGMA-Kolojen ile farklı oranlarda karıştırılarak çeşitli hidrojeller kompozisyonları hazırlanmıştır. Elde edilen hidrojeller karakterize edilerek hücre etkileşimleri çalışmalarında kullanılmıştır. Yapılan hücre çalışmaları sonucu her iki gruba ait hidrojel içerisindeki akrillenmiş kolojen içeriğinin artmasıyla hücre çoğalmasının da arttığı görülmüştür. ABSTRACT In the first stage of this study, a new branched methacrylated poly(propylene glycol-co-lactic acid) (PPG-PLA-IEM), and methacrylated cellulose acetate butyrate resin (CAB-IEM) were synthesized. The chemical structures, molecular weights, cross-link densities of the synthesized polymers were investigated to determine the best material with desired performance. With the addition of poly(ethylene glycol) diacrylate, water and photoinitiator in various ratios to the synthesized polymers, different hydrogel formulations were prepared. Collagen attached PEG-monoacrylate (PEGMA-collagen) was prepared and supplemented to hydrogel formulation in order to enhance cell affinity and the effect of PEGMA-Collagen on cell proliferation was investigated in vitro. In the second stage, parallel to the first studies, by preparation of amine terminated acid polyester (polycaprolacton) a new type branched methacrylate modified poly(caprolakton-co-lactic acid) (PC-PLA-IEM) and methacrylate modified poly(tetrahyrofurane) (PTHF-IEM) were synthesized. The synthesized polymers were mixed with various amounts of poly(ethylene glycol) diacrylate, water, photoinitiator and collagen attached PEG-monoacrylate that was previously synthesized in first study and different hydrogel formulations were prepared. Prepared hydrogels were characterized and used for cell growth experiments. The cell growth experiments showed that with the increasing amount of PEGMA-Collagen content in hydrogels cell proliferation was increased

Plexiglass türü malzemelerin UV ışınları ile sertleşebilen SOL-GEL tekniği kullanılarak yüzey özelliklerinin modifiye edilmesi

Çevre ve halk sağlığı kuruluşları, kaplama endüstrisine çok düşük ya da sıfır uçucu organik emisyona sahip kaplama ürünleri geliştirmeleri ve üretmeleri konusunda büyük baskılar uygulamaktadır. Bu baskılar ve 1970' ler de ortaya çıkan petrole dayalı enerji sorunlarının etkisiyle farklı boyut kazanmış ve kaplama endüstrisinde yeni tekniklerin geliştirilmesine neden olmuştur. Bu gelişmelerden en önemlisi şüphesiz ki UV ışınları ile sertleşebilen kaplamaların üretilmesidir. UV ışınları ile sertleşen kaplamalar %100 katı içeriğine sahip, daha düşük enerji tüketimine neden olan, daha kaliteli ve en önemlisi çevre dostu kaplamalardır. Bu tür kaplamaların Pazar payı uluslararası çevre korunması antlaşmalarının da etkisi ile her yıl %5-7 oranında artmaktadır.Sol-jel yöntemi, metal-alkoksitlerin hidroliz ve kondenzasyonu ile bir inorganik ağ oluşturulması, ardından inorganik ağın bağlı olduğu polimerize olabilen grupların termal ya da yüksek enerjili ışıma yardımıyla reaksiyon vermesine dayanır. Organik polimer kaplamalarla kıyaslandığında, hibrit sol-jel filmleri yüksek kimyasal ve mekanik dayanıklılık, yüksek optik özellikler, farklı kaplama yüzeylerine karşı daha iyi uyumluluk gösterirler. Bunların dışında hibrit malzemeler düşük su absorbsiyonu ve su buharı geçirgenliğine de sahiptirler.Bu çalışmada, UV-ışınları ile sertleşebilen üretan modifiye epoksi akrilat (UMEA) oligomeri sentezlenmiştir. Bu oligomerde hem hibrit malzeme hem deüretan grupları oluşturmak için IPTMS kullanılmıştır. Bu amaçla ilk adımda akrillenmiş epoksi oligomeri sentezlenmiş, ikinci adımda ise oligomer üzerindeki oksiran halkalarının açılması ile oluşan hidroksil grupları teorik olarak belirli oranlarda IPTMS ile reaksyona sokularak üretan modifiye epoksi akrilat oligomeri elde edilmiştir. Daha sonra elde edilen farklı modifikasyon derecelerine sahip UMEA oligomeri, hekzandioldiakrilat, PhotomerÒ-4006F ve fotobaşlatıcı içeren standart bir karışım hazırlanmıştır. Hazırlanan bu formülasyonların bir kısmı camdan hazırlanmış kalıp üzerine dökülerek mekanik testler için serbest film, diğer kısmı yüzeyi modifiye olmuş cam plakalara kaplanarak TGA (Termal Gravimetrik Analiz) ve GC-MS analizlerinde kullanılacak serbest filmler üretilmiştir. Hazırlanan formülasyonlardan arda kalan kısım ise Pleksiglas plakalar üzerine pleksiglasın yüzey özelliklerinin dış etkenlere karşı iyileştirilmesi sağlanmıştır. Daha sonra tüm örnekler UV lambası altında 60 saniye süre ile sertleştirilmiştir.Böylece bu polimerik filmlerin yüzey kaplama malzemesi olarak göstermiş oldukları özellikler ASTM ve DIN yöntemleri ile incelenmiştir.Haziran 2005 Gülay Environment and public health concerns have forced the coating industry to develop and produce bening coating products with low or zero volatile organic compound (VOC) emissions. These constraints and energy problems leaning against petrolum that occured in 1970's; caused developments of new techniques in coating industry. Undoubtedly, the most important development is, the production of UV curable coatings. UV curable coatings have % 100 solid content, lower energy consumption, beter quality skills and cause less environmental pollution. With the effect of international environment protection deals, market of these kind of coatings is being increased %5-7 in each year.Sol-gel method depends on, formation of inorganic network with hydrolysis and condensation of metal alkoxides followed by a reaction of polymerisable groups on inorganic network with thermal or high energy radiation. Compared with organic polymer coatings, the hybrid sol-gel films also manifest some advantages such as low optical propagation loss, high chemical and mechanical stabilities as well as good compability with different surfaces to be coated. Besides that hybrid materials have low water absorption and water vapor permeability.In this study, UV curable urethane modified epoxy acrylate oligomer (UMEA) was synthesized. In this oligomer, 3-isosiyanatopropyltrimetoxysilan (IPTMS) was used for both synthesis of urethane groups and hybrid materials. First of all, acrylated epoxy oligomer was synthesized and than -OH groups, which were formed by opening of oxirane ring on oligomer; were reacted with different theoric ratios of IPTMS. By this way, UMEA oligomer was synthesized.Than, standard mixtures that consist of UMEA oligomer with various amount silicate content, hexanedioldiacrylate (HDDA), PhotomerÒ-4006F and photoinitiator ( Irgacure-184) were prepeared. By pouring of a little part of these mixtures on a glass mold, free films for mechanical tests; by pouring of a little part of these mixtures on a surface-modified glass plates, free films for TGA (Thermal Gravimetry Analyse) and GC-MS analysis were obtained. The remainders of these mixtures were applied on plexiglass plates for developing surface properties of plexiglass against exterior effects. All these samples irradiated for 60 seconds from one side with a UV lamp.By this way, properties of these polymeric films as surface coating materials are investigated with ASTM and DIN standards.June 2005 Gülay BAYRAMOĞL

Polystrene- PhosphineOxideModifiedClay Nanocomposites

Nanoteknoloji ve nanobilim kimya ile fizik bilimlerini bir araya getiren multidisipliner bir bilim alanıdır. Günümüzde bu alanda gerçekleştirilen çalışmalardan çoğu nano boyutta tanecikler içeren malzemeler hakkındadır. En yaygın çalışma alanı bulan nanokompozitler, en az bir bileşenini nano boyutta olduğu çok fazlı malzemeler olarak tanımlanırlar. Başta tıp, elektronik, tekstil, kataliz, bilişim ve uzay sektörleri olmak üzere oldukça yaygın ticari kullanım alanlarına sahiptirler. Bu uygulama alanları nano boyuttaki malzemelerin makro boyuttaki hallerine göre farklı özellikler göstermesine bağlı olarak artmaktadır. Bu çalışmanın temel amacı yanma geciktirici özelliği arttırılmış polimer-kil nanokompozitlerinin hazırlanmasıdır. Öncelikle montmorillonit kil (MMT) kuaternizeBis (3-aminofenil)-fenilfosfin oksit (BAPPO) kullanılarak sulu bir ortam içinde BAPPO katyonları ile kildeki Na+ iyonları arasındaki iyon değişimi reaksiyonu sonucunda modifiye edilmiştir. Polistiren-kil nanokompozitler, dağılmış kil ihtiva eden stirenin serbest radikal polimerizasyonu ile hazırlanmıştır. Elde edilen nanokompozitler, X-ışını difraksiyonu (XRD) ve taramalı elektron mikroskobu (SEM) ile karakterize edilmiştir. Kompozit içerisindeki nano-dolgu miktarının artışına bağlı olarak termal özelliklerdeki değişim termogravimetrik analizi (TGA) ve diferansiyel taramalı kalorimetre (DSC) ile incelenmiştir. Nanokompozitlerin alev geciktirici özellikleri ise kısıtlayıcı oksijen indeksi (LOI) ve UL 94 testleri kullanılarak belirlenmiştir.Nanotechnology and nanoscience are multidisciplinary fields that combines chemistry and physics. Nowadays, most of the studies conducted in this area, are about materials containing nano- sized particles. Nanocomposites that have widespread utilization are defined as multiphase materials where at least one of the phases has a dimension in the nano-scale. They have variety of commercial application fields such as medical, electronic, textile, catalysis, informatics and space sectors. Due to the fact that matter at the nano-scale has different properties as compared with macro-scale, these application fields are increasing. The main aim of this study is to preparation of polymer/clay nanocomposites with improved flame retardancy. Montmorillonite clay (MMT) was pre-modified using quaternized derivative of Bis(3-aminophenyl) phenyl phosphine oxide (BAPPO) via ion exchange between Na+ ions in the clay and BAPPO cations in aqueous medium. Polystyrene–clay nanocomposites were prepared by free radical polymerization of styrene containing dispersed clay. The resultant nanocomposites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect of increased nanofiller loading in thermal properties of the nanocomposites was investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Flame retardancy properties were investigated by Limiting Oxygen Index and UL 94 flammability test

Preparation of ion-exchange beads based on poly (methacrylic acid) brush grafted chitosan beads: Isolation of lysozyme from egg white in batch system

Poly(methacrylic acid) brush grafted crosslinked-chitosan (chitosan-g-poly(MAA)) beads were prepared in two sequential steps: in the first step, chitosan beads were prepared by phase-inversion technique and then were crosslinked with epichlorohydrin under alkaline condition; in the second step, the graft copolymerization of methacrylic acid onto the chitosan beads was initiated by ammonium persulfate (APS) under nitrogen atmosphere. The chitosan-g-poly(MAA) beads were first used as an ion exchange support for adsorption of lysozyme (LYZ) from aqueous solution. The influence of pH, equilibrium time, ionic strength and initial LYZ concentration on the adsorption capacity of the chitosan-g-poly(MAA) ion-exchange beads has been investigated in a batch system. Maximum LYZ adsorption onto chitosan-g-poly(MAA) beads was found to be 65.7 mg/g at pH 6.0. The experimental equilibrium data obtained LYZ adsorption onto chitosan-g-poly(MAA) ion-exchange beads fitted well to the Langmuir isotherm model. Kinetics parameters of this adsorption system were also analyzed by using the equilibrium experimental data. The result of kinetic analyzed for LYZ adsorption onto ion-exchange beads showed that the second order rate equation was favourable. Finally, the chitosan-g-poly(MAA) ion-exchange beads were used for the purification of LYZ from egg white in batch system and the purity of the eluted LYZ from ion-exchange chitosan-g-poly(MAA) beads was determined as 94% by HPLC from single step purification