Rheological Properties of Polyether Ether Ketones Containing Multi‐Walled Carbon Nanotubes

ABSTRACT In this study, the rheological and melt‐flow behavior of polyether ether ketone (PEEK) filled with multi‐walled carbon nanotubes (MWCNTs) was investigated to evaluate its melt‐spinnability. A rheological percolation threshold was detected below 1 wt% MWCNT, accompanied by a significant increase in storage modulus (G′) and loss modulus (G″), as well as a decrease in complex viscosity ( η *), indicating the formation of a nanotube network and a transition from viscous to elastic behavior. Neat PEEK ( n = 0.09, m = 1.16) and PEEK containing 1 wt% MWCNT ( n = −0.33, m = 0.66) exhibited stable flow behavior and remained within the spinnable range due to moderate shear‐thinning characteristics. At 2 wt% MWCNT, increased elasticity and partial network formation ( n = −0.89; m = 0.39) resulted in reduced spinnability. Above 2 wt%, the materials were not spinnable due to their highly elastic behavior ( m < 0.3) and thread breakage during spinning. Van Gurp–Palmen and Cole–Cole analyses confirmed that PEEK/MWCNT blends with phase angles δ > 40° and MWCNT contents below 2 wt% are spinnable. The optimum MWCNT content for stable melt spinnability was determined to be 1 wt%, though 2 wt% was also spinnable under certain spinning conditions.