The study focuses on the fabrication of semicrystalline polyethylene oxide (PEO) composite nanofibers using electrospinning method, incorporating ionic liquid (1-Butyl-3-methylimidazolium Trifluoromethanesulfonate [BMIM TFSI]) and lithium salts (Lithium bis(trifluoromethanesulfonyl)imide [LiTFSI]). The crystallization and rigid amorphous fraction (RAF) of pure PEO and its composites were analyzed using Flash Differential Scanning Calorimetry (FDSC). Electrospinning of PEO nanofiber and PEO composites with Ionic liquid and Li ion salt were carried out using the Nanoscience Electrospinning machine. FDSC measurements were performed under nitrogen atmosphere with cooling rates varying from 1 to 2000 K/s over a wide temperature range of -90 to 90oC. At lower cooling rates pure PEO nanofibers exhibited a crystallinity of 24%, which is significantly lower than the bulk PEO. Following cold crystallization, the crystallization factor (CF), RAF, and mobile amorphous fraction (MAF) of PEO and its composites were determined based on heat capacity information obtained from FDSC analysis using Star E software. As CF decreased with increasing cooling rate, RAF increased from 76 ~ 84% for pure PEO corresponding to a CF decline from 24 to ~ approximately 10%. However, with the addition of ionic liquid and Li ion salt, RAF increased from ~76 ~ 90% while CF decreased from ~17 to ~ 6%. Notably, no significant changes in RAF development as a function of thermal processing were observed in highly crystallizable semi-crystalline PEO polymer when IL and Li-ion salt were added to the PEO composite nanofibers. The presence of higher RAF suggests that a significant portion of the material remains in amorphous state. In conclusion, this study provides valuable insights into the crystallization behavior of PEO and highlights the role of RAF in cold crystallization, particularly in relation to material composition and thermal processing conditions.
