关键词: PET中空纤维, 熔融纺丝, DTY, 非等温结晶动力学, 张力在线检测

Abstract: Polyethylene terephthalate (PET) hollow fibers have significant application value in thermal insulation materials, bionic fibers, and composite materials due to their unique characteristics of low density, high specific surface area, and directional transport capability. Currently, PET hollow fibers account for over 50% of the global synthetic fiber market, with 99% produced via the melt-spinning process. However, existing research predominantly focuses on isolated analyses of individual process parameters, lacking systematic investigation into the synergistic effects of key parameters such as spinning temperature, winding speed, and draw ratio. Moreover, studies on complex processes like draw-textured yarn (DTY) remain insufficient. Additionally, traditional detection methods struggle to achieve precise quantification of critical parameters, hindering in-depth analysis of the process-performance correlation mechanisms. This study aims to elucidate the influence of melt-spinning parameters on the crystallization behavior and hollow structure of PET hollow fibers through multi-parameter synergistic regulation and advanced online monitoring technology, providing a theoretical foundation for the industrial production of high-performance fibers. This study systematically investigates the synergistic effects of spinning temperature, winding speed, drawing process (ratio and stages), and tension on fiber properties. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were employed to analyze crystallization behavior. The results reveal that merely reducing spinning temperature (295→285 °C) significantly increases hollowness (5.69%→26.39%), but excessively low temperatures lead to uneven wall thickness and reduced shape retention. Increasing winding speed (500→2,000 m/min) enhances crystallinity (17.9%→22.2%) and orientation (0.03→0.16). Innovatively, Doppler laser-based online tension measurement is introduced to dynamically quantify tension during drawing. The findings demonstrate that single-stage drawing improves crystallinity but high tension (~166 cN) reduces hollow shape retention (increased CV). In contrast, two-stage drawing effectively controls tension (<66 cN) through stepwise heat setting, stabilizing hollowness above 20% with CV <10% and achieving 6% higher crystallinity than single-stage drawing at the same draw ratio (3×), exceeding 39% at higher ratios (3.5× and 4.0×), alongside optimized mechanical properties. Multi-parameter analysis indicates that spinning temperature influences hollow structure via melt fluidity, while the synergy between tension and draw ratio is key to balancing hollow structure, crystallization, and mechanical performance. Multi-stage drawing enables high crystallinity, shape retention, and reliability. This study establishes a quantitative model linking melt-spinning process parameters to PET hollow fiber properties, offering a novel strategy for industrial production of fibers with high crystallinity and shape retention. Future research may explore synergistic optimization of spinneret design and melt rheology, as well as the application of multi-stage drawing in specialty hollow fibers. The findings provide critical guidance for advancing PET hollow fibers in textiles and composite materials.

Key words: PET hollow fiber, melt spinning, DTY, nonisothermal crystallization kinetics, tension online detection