Investigation of carbonization of nanofiber yarns produced by electrospinning

Due to their superior properties, carbon nanofibers are among the advanced materials that attract attention from a technological point of view while the production of PAN-based nanofibrous web surfaces and then their carbonization is among used methods in this field. However, carbonization of nanofiber yarns instead of nanofibrous webs has been relatively a new study field due to the developments in nanofiber yarn spinning methods by electro-spinning in recent years. In this respect, it is aimed to produce carbon nanofibers, which is among today's special materials, in yarn form and analyse their properties in this thesis work. For this aim, firstly spinning of PAN-based twisted nanofiber yarns was carried out by using electrospinning method. Then, stabilization and carbonization processes were applied to the obtained nanofiber yarns. Optimum conditions for stabilized yarns were determined by examining the effect of different temperatures (230 °C, 240 °C and 250 °C) and processing time (1, 2, 3 and 4 hours) during stabilization. In carbonization process, the effect of different temperatures (800 °C, 900 °C and 1000 °C), processing time (1 min, 30 min and 1 hour) and heat ramp (5 °C/min, 7,5 °C/min and 10 °C/min) was investigated. The changes in yarn structure and properties and effect of process parameters were analysed. In addition, positive effect of nanofiber yarn spinning was observed compare to nanofibrous surfaces. The optimum stabilization parameters were determined as 250 °C and 1 hour while maximum carbon element content was obtained following carbonization at 1000 °C, 5 °C/min and 1 hour.