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Polyimides, high-performance polymers with superior properties such as high temperature stability, resistance to solvents and high strength, can be used in high-tech applications of the aerospace and aviation, medical or electronics industry in different forms (film, fiber, nanofiber, membrane, foam, adhesive or coating). Among these applications, coating has a special place and is used to develop advanced structures having high temperature resistance, flame retardancy and etc. for high tech industries via an economical and feasible way. Therefore, in this review, we aimed to report the broad application status of polyimide coatings by reviewing publications, patents and commercial products. Thus, this study can assist in selecting suitable polyimide types and production methods for polyimide coating applications and in understanding their applicability for future products.

DOI:  https://doi.org/10.1007/s42452-021-04362-5

 

In recent years, graphene has attracted the attention of scientists and industry due to its superior electronic, thermal and mechanical properties and has been used in different fields and advanced applications. Graphene and its derivatives have also attracted great interest in the field of polymer composites, since the use of graphene as a small amount of additive brings about advanced properties to the polymers. Therefore, in this study, graphene was added to the epoxy at certain rates (0.05%, 0.1%, 0.25%, 0.5% and 1%) to obtain nanocomposites with improved electrical conductivity and mechanical properties. The properties of obtained nanocomposite films were examined by fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), mechanical test, scanning electron microscope (SEM), UV-Vis-NIR spectrophotometer and electrical conductivity measurements. 1% graphene additive caused a 28.2% decrease in the volumetric resistance and 9.7% in the surface resistance of the nanocomposite films. The maximum tensile value of graphene/epoxy nanocomposites was obtained as ~ 20 MPa by increasing 33.84% in 1% graphene additive compared to neat epoxy-based nanocomposites. As a result, it has been observed that as the amount of graphene added to the epoxy increases, the electrical conductivity, tensile values and light absorption of nanocomposite films increase. The nanocomposite films obtained can be used in industrial applications thanks to the improved electrical conductivity and mechanical properties.

Keywords: Graphene, nanocomposite, epoxy, composite, polymer nanocomposite

DOI: https://doi.org/10.2339/politeknik.689424

Turkish Scientific and Technological Research Council (TÜBİTAK) introduces a new European Commission Horizon 2020 Marie Sklodowska-Curie Actions Cofund program “Co-Funded Brain Circulation2 Scheme (CoCirculation2)”. CoCirculation2 is the follow up project of the “Co-funded Brain Circulation Scheme (Co-Circulation)”, which has been funded under the FP7-PEOPLE-2011-COFUND call of the 7th Framework Programme.
CoCirculation2 is a 5-year project aiming to invite experienced researchers to both academic and non-academic research performing organizations located in Turkey. Within this context, 100 experienced researchers of any nationality who wish to engage in incoming mobility and to implement a research project in Turkey will be able to apply for a fellowship. 4 calls for proposals will be published, fellowships for calls 1 – 3 will last 24 months, fellowships for call 4 will last 12 months.
The objective of CoCirculation2 is toenhance the career development of 100 Experienced Researchers wishing to diversify their individual competence through advanced training, international and intersectoral mobility opportunities through incoming mobility into Turkey. The triple ‘i’ dimension is applied to the program, with the objective to strengthen the effect of the fellowship on the researchers’ careers. All fellowships must have an international component, and intersectoral and interdisciplinary elements in each project are highly encouraged.
TÜBİTAK is the leading agency for management, funding and conduct of research in Turkey. The Council is an autonomous institution and is governed by a Executive Council whose members are prominent scholars selected from universities, industry and research institutions. More than 2,500 researchers work in 20 different institutes of TÜBİTAK to carry out cutting-edge and applied research. TÜBİTAK also acts as an advisory agency to the Government of Turkey on science and research related issues and is responsible for the secretariat of the Supreme Council for Science and Technology (SCST), the highest S&T policy making body which is headed by the Prime Minister. The programme will be executed by TÜBİTAK-BİDEB, the Science Fellowships and Grant Programmes Department within TÜBİTAK.

 

You can reach the announcement from the link: http://cocirc2.org.tr

Polyacrylonitrile (PAN) nanofibers are one of the primary precursors in the production of carbon nanofibers. The nanofiber morphology is significantly affected by the process parameters such as polymer concentration, distance, applied voltage and feed rate during the production of PAN nanofibers obtained by the solution-based electrospinning method, and these parameters should be optimized properly. In this study, firstly PAN nanofiber production parameters were optimized, and then homogeneous and thin PAN nanofibers produced in optimum conditions were used as the precursor in the production of carbon nanofibers. PAN nanofibers with a diameter of 233 nm were obtained at 7.5% PAN concentration in N,N-dimethylformamide (DMF), 28 kV applied voltage, 17.5 cm nozzle to collector distance, 2 ml/h feed rate and 500 rpm rotation speed of the aluminum drum. The carbon nanofiber diameters produced after the stabilization and carbonization processes were measured as 200 and 140 nm, respectively. The morphological, chemical and thermal properties of the produced nanofibers were characterized by field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR), thermogravimetric analyzer (TGA). Carbon nanofibers, which are made from optimized electrospun PAN nanofibers, can be used to construct supercapacitors in future studies.

Keywoeds: Carbonization, Carbon Nanofiber, Electrospinning, PAN Nanofiber, Supercapacitor

First published: 30 July 2020             DOI: http://jise.btu.edu.tr/tr/pub/issue/56253/726792

Recently, piezoelectric nanogenerators have received great interest as they can convert waste mechanical and radiative energy to electricity and can be used in self‐energy generating systems and sensor technologies. In this study, electrospun poly(vinylidene fluoride) (PVDF) nanofiber‐based piezoelectric nanogenerators with reduced graphene oxide (rGO), polyaniline (PANI), and PANI‐functionalized rGO (rGOPANI) have been developed. Two different types of nanofiber mats were produced: First, rGO‐ and rGOPANI‐doped PVDF nanofiber mats and second, rGO, PANI and rGOPANI‐spray‐coated PVDF nanofiber mats that have worked as nanogenerators’ electrodes. Then, characterizations of samples were performed in terms of piezoelectricity, Fourier transform infrared (FTIR) spectrophotometric, X‐ray diffractions (XRD), and scanning electron microscopy analyses. FTIR and XRD results confirmed that piezoelectric β‐crystalline phase of PVDF occurred after the electrospinning process. Besides, maximum output voltages were obtained as 7.84 and 10.60 V for rGO‐doped PVDF and rGOPANI‐coated PVDF nanofiber mats, respectively. As a result, the doped nanofibers were found to be more successful due to the higher device accuracy in sensor technologies compared with spray‐coated samples. However, spray‐coating method proved to be more suitable technique for the production of nanogenerators on an industrial scale in terms of fast and large‐scale applicability.

Keywords: Coatings, Conducting Polymers, Electrospinning, Nanotubes, Graphene and Fullerenes, Sensors and Actuators

Keywords Wearable electronics, flexible photovoltaics, solar textiles, organic photovoltaics, conductive fabric

First Published: February 12, 2020 | DOI: https://doi.org/10.1177/1528083720904053

 

Mahmut Tas, Yasin Altin, Ayse Bedeloglu, Graphene and graphene oxide-coated polyamide monofilament yarns for fiber-shaped flexible electrodes, Journal of the Textile Institute, online published in Apr 2018.