Rheology Modulation and Melt Strength Enhancement Enable Continuous Melt Spinning of PEK-C Fibers

Phenolphthalein poly (aryl ether ketone) (PEK-C) is highly compatible with epoxy resin, which is applied in epoxy resin-based composites to improve their strength. Solution spinning and electrospinning techniques are often used to produce PEK-C fibers, but these techniques pollute the environment and are not productive. To address the above challenges, melt spinning may be employed, but due to the high degree of molecular chain entanglement and poor melt fluidity of PEK-C, melt spinning remains difficult. Herein, this study presents the continuous melt spinning of PEK-C fibers through rheology modulation and melt strength enhancement. A series of PEK-C samples with different molecular weights were prepared by adjusting the molar ratio of monomers. The influence of molecular weights on rheological properties was investigated via capillary rheology tests. PEK-C with molecular weight (2.01 × 10⁴ g/mol) was chosen, and the optimal spinning temperature was determined to be 370 °C. The as-polymerized PEK-C powder was compounded into pellets; subsequently, the PEK-C pellets with enhanced melt strength were continuously processed into fiber through melt spinning. The obtained PEK-C fibers possess high tensile strength (0.56 cN/dtex) and breaking strength (1.06 cN/dtex). The mechanical properties and molecular chain orientation of PEK-C fibers were also optimized by spinning process parameters. This work presents continuous melt spinning of PEK-C fibers via rheology modulation and melt strength enhancement, which resolve the environmental and low productivity issues.