Melt-Electrospinning of Poly(ether ether ketone) Fibers to Avoid Sulfonation

We have successfully electrospun un-sulfonated fibers of poly(ether ether ketone), PEEK, from the molten state. A high temperature furnace was used to melt electrically grounded PEEK pellets at 350 °C, and the electric force caused fibers to be deposited onto the high voltage collector. Whereas solution electrospinning of PEEK results in sulfonation of the polymer chain and reduction of thermal stability, direct melt electrospinning produced PEEK fibers which are chemically unaltered from as-received pellets, as shown by their Fourier transform infrared spectra. Thermogravimetry demonstrated electrospun PEEK fibers have similar thermal decomposition temperature, T_d = 600 °C as the pellets. Melt electrospun fibers had a large range of diameters, ranging from 1.5 μm to 8.5 μm, and were smooth, defect-free, and round in cross-section. As-spun amorphous fibers, with thicknesses less than 10 μm and masses ~200 ng, were selected for fast scanning calorimetry (FSC) experiments. Using heating and cooling rates from 50 to 2000 K/s, FSC studies were made of the glass transition, melting and crystallization behavior of electrospun PEEK fibers.