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The influence of formation temperature on the ultradrawing properties of ultrahigh‐molecular‐weight polyethylene/carbon nanotube (UHMWPE/CNT) fiber specimens is investigated. Gel solutions of UHMWPE/CNT with various CNT contents were gel‐spun at the optimum concentration and temperature but were cooled at varying formation temperatures in order to improve the ultradrawing and tensile properties of the UHMWPE/CNT composite fibers. The achievable draw ratio (Dra) values of UHMWPE/CNT as‐prepared fibers reach a maximum when they are prepared with the optimum CNT content and formation temperature. The Dra value of UHMWPE/CNT as‐prepared fibers produced using the optimum CNT content and formation temperature is about 33% higher than that of UHMWPE as‐prepared fibers produced using the optimum concentration and formation temperature. The percentage crystallinity (Wc) and melting temperature (Tm) of UHMWPE/CNT as‐prepared fiber specimens increase significantly as the formation temperature increases. In contrast, Wc increases but Tm decreases significantly as the CNT content increases. Dynamic mechanical analysis of UHMWPE and UHMWPE/CNT fiber specimens exhibits particularly high α‐transition and low β‐transition, wherein the peak temperatures of α‐transition and β‐transition increase dramatically as the formation temperature increases and/or CNT content decreases. In order to understand these interesting drawing, thermal and dynamic mechanical properties of the UHMWPE and UHMWPE/CNT as‐prepared fiber specimens, birefringence, morphological and tensile studies of as‐prepared and drawn fibers were carried out. Possible mechanisms accounting for these interesting properties are proposed. Copyright © 2010 Society of Chemical Industry

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The influences of the dispersion level of carbon nanotubes (CNTs) and functionalized CNTs on the transmittance properties of ultrahigh‐molecular weight polyethylene (UHMWPE) gel solutions and on ultradrawing properties of their as‐prepared fibers are reported. The transmittance properties suggest that the dispersion level of functionalized CNTs in UHMWPE/functionalized CNTs gel solution is significantly better than plain CNTs in UHMWPE/CNTs gel solutions. The orientation factors, achievable draw ratios, tensile strength (σf), and modulus (E) values of UHMWPE/CNTs (FxCy) and UHMWPE/functionalized CNTs (FxCf‐y) as‐prepared fiber specimens reached a maximum value as their CNT and functionalized CNT contents approached optimum contents at 0.00015 and 0.0001 wt%, respectively. The σf and E values of both FxC0.0012 and FxCf‐0.001 series fiber specimens prepared at their optimum CNT and functionalized CNT contents reached another maximum as their UHMWPE approached optimum UHMWPE concentration of 1.7 wt%. Possible reasons accounting for these interesting properties are proposed. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers