Processamento e caracterização de mantas de nanofibras eletrofiadas e orientadas de Poli(fluoreto de vinilideno)
Costa, Ligia Maria Manzine
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In this work was developed a collector to process aligned uniaxially nanofibers mats and with low dimensions suitable for applications such as sensor or transducer. Such nanofibers mats may have applications where control of the orientation of these fibers is important, as membrane filtration, sensors, electrolytes for batteries, electronic or photonic devices, etc. Initially it was determined the minimum concentration of the solution of PVDF/DMF and a mixture of DMF/acetone that limits the processes of electrospray and electrospinning. It was found that in both cases phase formation can not be attributed to the stretch suffered by the polymer during electrospinning. With the introduction of a circular collector of up to 5000 rpm was possible process aligned uniaxially PVDF-nanofibers mats. We changed the processing conditions resulting in randomly oriented fibers, homogeneous and without defects and collector speed resulting in aligned nanofibers mats as molecular alignment of polymer. FTIR, DSC and SEM were used to determine the crystalline phase, molecular orientation, percent crystallinity and morphology of the fibers. The hysteresis curve of aligned nanofibers mats was determined with remanent polarization and coercive field . It was found that the coercive field of nanofibers mats is much smaller than PVDF-samples obtained of stretch PVDF-samples . The dielectric properties (permittivity and loss rate) of nanofibers mats were also obtained and compared with those for PVDFfilms produced with other techniques.