Multiple‐stage drawn ultrahigh molecular weight polyethylene/activated carbon fibers prepared with the assistance of supercritical CO₂

Abstract Remarkable improved achievable draw ratios (DRs) and tensile strengths (σ_ts) of multiple‐stage drawn ultrahigh molecular weight polyethylene (UHMWPE)/functionalized activated carbon (FAC) fibers prepared with the aid of supercritical carbon dioxide (scCO₂) were first reported. The achievable DRs and σ_ts of single‐ and multiple‐stage drawn scCO₂UHMWPE/FAC fibers were considerably higher than those achievable DRs and σ_ts found for the corresponding single‐ and multiple‐stage drawn UHMWPE/FAC fibers spun from gel solutions gelatinized in nitrogen atmosphere. It is worth noting that the largest achievable DR obtained for the most proper five‐stage drawn scCO₂UHMWPE/FAC fiber approached 688, which is approximately 40% larger than the achievable DR found for the single‐stage drawn scCO₂F₁₀₀FAC^13.5_0.1 fiber. The σ_t found for the most proper five‐stage drawn scCO₂UHMWPE/FAC fiber reached an extraordinarily high value of 13.4 GPa, which is ∼4.6, ∼1.6 and, ∼1.4 times of those σ_ts found for the optimal single‐stage drawn UHMWPE, UHMWPE/FAC and scCO₂UHMWPE/FAC fibers, respectively. Considerably smaller lamellar thicknesses and dynamic transition temperatures were detected for scCO₂UHMWPE and scCO₂UHMWPE/FAC as‐prepared fibers compared with the equivalent UHMWPE and UHMWPE/FAC as‐prepared fibers, respectively. Specific surface area, morphological, and Fourier transform infrared analyses of the FAC particles and orientation factor analyses of the single‐ and multiple‐stage drawn UHMWPE, UHMWPE/FAC, scCO₂UHMWPE, and scCO₂UHMWPE/FAC fibers were performed. Possible reasons accounting for the remarkable improved achievable DRs and σ_ts found for the proper single‐ or multiple‐stage drawn scCO₂UHMWPE/FAC fibers are proposed.