Electrochemically Obtained Insulating and Conducting Polymers and Composites of Acrylonitrile

Electrochemically obtained polyacrylonitrile and a commercial polyacrylonitrile were heat treated to improve their conductivities. The parameters chosen for heat treatment conditions were the temperature, treatment medium (vacuum or air) and, doping agent. The conductivity of all heat treated polymers was measured. The characterization of the heat treated polymers was made by IR analysis. The composite films of polyacrylonitrile with polypyyrole and polythiophene were electrochemically prepared at different compositions. The change in the conductivity of composites was analyzed as a function of the percent composition of the insulating component. IR, DSC, TGA and SEM analyses were used to characterize the polymer composites

A CONDUCTING COMPOSITE OF POLYPYRROLE .1. SYNTHESIS AND CHARACTERIZATION

A conducting composite of polypyrrole was prepared via electrochemical methods. A polyamide was used as the insulating matrix polymer. The characterization of the composite was done by FT-IR, SEM, TGA, DSC and pyrolysis studies. Conductivity and solubility studies together with spectroscopic methods reveal that H bonding exists between the two polymers and a possible grafting to a certain extent

POLYMERIZATION OF MALEIC-ANHYDRIDE INITIATED BY IMIDAZOLE

Imidazole was employed as an anionic initiator for the homopolymerization of maleic anhydride in various solvents. Polymerization was very rapid and the obtained products have different colours varying from white to dark brown. The colour of the product was found to depend on the quantity of imidazole added, and the solvent of polymerization. Darkness of polymers are thought to be due to cross-conjugation displaying paramagnetic character. The ESR signals of dark brown polymers were more intense than the lighter ones whereas the white products had no ESR signal

POLYESTER FILM STRIPS COATED WITH PHOTOGRAPHIC GELATIN CONTAINING IMMOBILIZED GLUCOSE-OXIDASE HARDENED BY CHROMIUM(III) SULFATE

Glucose oxidase was immobilized into photographic gelatin hardened by chromium(III) sulphate. The enzyme-gelatin mixture was coated on polyester film strips which allowed easy and simple handling during assays. The effect of gelatin and cross-linker concentrations on water content and enzymatic activity was studied. The effect of pH during immobilization and that of incubation temperature on maximum activity were examined- Enzyme leakage tests were carried out during reuse number studies. Consecutive use of strips followed by washing and resting between uses were found to affect the reuse number. A maximum immobilization of 68% was reached under optimal conditions. Mechanical stability and leakage were found to be functions of gelatin and cross-linker concentrations. Photographic gelatin was found to have many capabilities with extraordinary characteristics as a carrier on immobilization

IMMOBILIZATION OF BETA-GALACTOSIDASE ONTO GELATIN BY GLUTARALDEHYDE AND CHROMIUM(III) ACETATE

Beta-Galactosidase (EC 3.2.1.23) was immobilised onto a gelatin carrier system by crosslinking. Glutaraldehyde and chromium(III) acetate were used as crosslinking agents. The effect of pH on enzyme activity, kinetic parameters and reusability of the immobilised enzyme were investigated. To obtain a better relative activity, a method was developed and further modified to increase the surface area of the support system by using polyacrylamide. Relative activity enhancement of 68% was achieved in the gelatin-glutaraldehyde system

ELECTROINITIATED POLYMERIZATION OF MALEIC-ANHYDRIDE BY DIRECT ELECTRON-TRANSFER

Controlled potential electrolysis was employed to accomplish homopolymerization of maleic anhydride, by direct electron transfer. The solvent used in the polymerization studies was acetonitrile-dimethylformamide mixture (1:1) with the supporting electrolyte tetrabutylammonium tetra fluoroborate. A brown paramagnetic polymer was obtained from the catholyte, upon electroreduction of monomer

Flaş ve indirekt piroliz sistemlerinin geliştirilmesi ve uygulanması

TÜBİTAK TBAG Proje28.02.1998Polimerlerin ısıl davranımı ile ilgili bilgi elde etmek için uygulanan tekniklerden olan piroliz kütle spektrometre teknikleri, bu tekniklerle bozunum ürünlerinin de tanımlanabilmesinden dolayı diğer termal analiz teknikleri arasında özel bir yere sahiptirler. Bu yöntemlerin uygulanmasıyla ısıl kararlılığın, bozunum mekanizmasının ve bozunum ürünlerinin belirlenebilmesinin yanında yapısal karakterizasyonun yapılabilmesine ve hatta polimerleşme mekanizmasının saptanabilmesine olanak elde edilmektedir. Uygulanan piroliz sistemi elde edilen bilgilerin içeriğini değiştirmektedir. Indirekt piroliz tekniği uygulandığında kararlı gaz faz ürünler gözlenebilmekteyken direkt piroliz tekniğiyle kararsız araürünler de saptanabilmekte ve böylece incelenen polimerin yapısına ışık tutabilecek önemli veriler elde edilmektedir. Flaş piroliz tekniğinde ise direkt piroliz tekniğinde olduğu gibi kararsız araürünler de gözlenebilmektedir. Bunun yanında sıcaklığın çok kısa sürede artırılabilmesi ve deney boyunca sabit tutulabilmesi sıcaklık kontrolünün daha sağlıklı yapılabilmesini sağlanmaktadır. Isıl davranımın güvenilir ve yeterli bir şekilde belirlenebilmesi çoğu kez bir kaç tekniğin bir arada uygulanması ile gerçekleşmektedir. Bu çalışmamızda laboratuvarımızda bulunan kütle spektrometresiyle birlikte kullanılabilecek flaş ve indirekt priloz sistemleri geliştirilmiş ve optimize edilmiştir. Geliştirilen sistemler kullanılarak çeşitli polimerlerin termal analizleri yapılmıştır

ELECTROINITIATED POLYMERIZATION OF BUTADIENE SULFONE

Electroinitiated polymerization of butadiene sulfone was achieved by direct electron transfer in acetonitrile-tetrabutylammonium fluoroborate system by controlled potential electrolysis technique. High conversions were obtained at reasonable temperatures and polymerization times. The polymer was found to be composed of linear segments along with some cyclic units. The effect of monomer concentration, temperature, and polymerization potential on the rate of polymerization was investigated. Temperature and polymerization potential have positive effects on the rate of polymerization. The effect of ultrasonic vibration was also investigated by conducting electrolyses at different monomer concentrations in the presence and absence of ultrasonic vibration. It was observed that the rate of polymerization increases significantly in the presence of ultrasonic vibration. The inverse relationship between the rate of polymerization and monomer concentration was observed in presence and absence of ultrasonic vibration