Abstract: Due to the unique structural characteristics of ultra-high molecular weight polyethylene (UHMWPE) fibers, fiber materials possess several excellent properties including lightweight, high strength, low temperature resistance, resistance to UV radiation, chemical corrosion resistance, high energy absorption, low dielectric constant, high electromagnetic wave transmittance, low friction coefficient, and outstanding performance in terms of impact resistance and cut resistance. The melting point of UHMWPE fibers is higher than that of ordinary polyethylene fibers at 134 ℃. However, compared to other high-performance fibers such as aramid and carbon fibers, UHMWPE fibers have poor high-temperature resistance, which limits their application range. Currently, research on the thermal stability of UHMWPE fibers in both domestic and international contexts mainly focuses on fiber spinning, low-temperature composites, and application environments. These studies are of importance in analyzing the thermodynamic properties of UHMWPE fibers. Recent studies have shown that UHMWPE fibers can be composite with thermoplastic polyurethane, polyvinyl chloride, and other resins to produce lightweight and high-strength membrane materials. However, in the process of hot-pressing composite processing, UHMWPE fibers need to withstand short-term high-temperature and high-pressure conditions. The processing environment temperature in these processes is high, reaching or exceeding the melting point of the material. As for the impact of transient high temperature in the thermal processing process on fiber structure and mechanical properties, no research reports have been found.
In response to the shortcomings of low melting point and easy creep of UHMWPE fibers, the mechanical stability performance of UHMWPE fibers under different hot-pressing temperatures and times was studied under the testing conditions of composite material hot-pressing processing environment. Through instruments such as differential scanning calorimeter, thermogravimetric analyzer, scanning electron microscope, X-ray diffractometer, Fourier transform infrared spectrometer and mechanical performance tester, the thermal stability performance and microstructure of UHMWPE fibers were characterized and analyzed. The results showed that the hot-pressing temperature and time had a significant impact on the performance of UHMWPE fibers. Under hot-pressing treatment of 150 ℃ or below, the mechanical properties of UHMWPE fibers changed little with the increase of hot-pressing time; under hot-pressing treatment of 160 ℃ or above, the long-term heat treatment led to a significant decrease in the mechanical properties of UHMWPE fibers. When the yarns were treated at 160 °C for 40 s, the breaking strength was 153 N, and the strength loss was 46.50%. When the hot-pressing temperature was higher than the melting point of the fibers, their strength dropped rapidly. When they were treated at 170 ℃ for 10 s, the strength dropped to 121 N, and the strength loss reached 57.80%.
The research on the effects of molding temperature and molding time during the processing of UHMWPE fibers on fiber structure, surface morphology, and mechanical properties has clarified that the temperature and time during the composite processing have a significant impact on the performance of UHMWPE fibers. Suitable composite processing techniques can promote the application of UHMWPE fibers in various fields. The research findings provide necessary references for determining the composite processing technology of UHMWPE fiber materials.

Key words: UHMWPE fiber, thermal stability, breaking strength, elongation at break, high-performance fiber

摘要： 针对超高分子量聚乙烯（UHMWPE）纤维熔点低、易蠕变的缺点，以复合材料热压加工环境为测试条件，通过分析不同热压温度和热压时间下的力学稳定性能，研究UHMWPE纤维的耐高温性能。采用差示扫描量热仪、热重分析仪、扫描电子显微镜、X射线衍射仪、红外吸收光谱分析仪和力学性能测试仪等仪器设备，表征并分析了UHMWPE纤维的力学性能、热稳定性能和微观结构。结果表明：热压温度及时间对UHMWPE纤维性能有着重要的影响。在150 ℃及以下热压处理时，纤维力学性能随着热压时间的增加而变化不大；在160 ℃及以上热压处理时，长时间的热处理导致纤维力学性能下降明显，在160 ℃处理40 s时丝束断裂强力为153 N，强力损失为46.50%；当热压温度大于纤维熔点时，纤维强力出现急速下降，在170 ℃热压处理10 s时强力下降到了121 N，强力损失达到了57.80%。研究结果可为UHMWPE纤维复合材料的加工及应用提供参考。

关键词: 超高分子量聚乙烯纤维, 热稳定性能, 断裂强力, 断裂伸长, 高性能纤维