Lee Jang-Gun, Jeong Jin-Oh, Jeong Sung-In, Park Jong-Seok
Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup-si 56212, Korea.
Polymers (Basel). 2021 Aug 23;13(16):2832. doi: 10.3390/polym13162832.
Crosslinking of polyolefin-based polymers can improve their thermal and mechanical properties, which can then be used in various applications. Radiation-induced crosslinking can be done easily and usefully by irradiation without a crosslinking agent. In addition, polymer blending can improve thermal and mechanical properties, and chemical resistance, compared to conventional single polymers. In this study, high-density polyethylene (HDPE)/ethylene vinyl acetate (EVA)/polyurethane (PU) blends were prepared by radiation crosslinking to improve the thermal and mechanical properties of HDPE. This is because HDPE, a polyolefin-based polymer, has the weaknesses of low thermal resistance and flexibility, even though it has good mechanical strength and machinability. In contrast, EVA has good flexibility and PU has excellent thermal properties and wear resistance. The morphology and mechanical properties (e.g., tensile and flexure strength) were characterized using scanning electron microscopy (SEM) and a universal testing machine (UTM). The gel fraction, thermal shrinkage, and abrasion resistance of samples were confirmed. In particular, after storing at 180 °C for 1 h, the crosslinked HDPE-PU-EVA blends exhibited ~4-times better thermal stability compared to non-crosslinked HDPE. When subjected to a radiation dose of 100 kGy, the strength of HDPE increased, but the elongation sharply decreased (80%). On the other hand, the strength of the HDPE-PU-EVA blends was very similar to that of HDPE, and the elongation was more than 3-times better (320%). Finally, the abrasion resistance of crosslinked HDPE-PU-EVA was ~9-times better than the crosslinked HDPE. Therefore, this technology can be applied to various polymer products requiring high heat resistance and flexibility, such as electric cables and industrial pipes.
聚烯烃基聚合物的交联可以改善其热性能和机械性能，进而可用于各种应用。通过辐照无需交联剂即可轻松且有效地实现辐射诱导交联。此外，与传统的单一聚合物相比，聚合物共混可以改善热性能、机械性能和耐化学性。在本研究中，通过辐射交联制备了高密度聚乙烯（HDPE）/乙烯-醋酸乙烯酯（EVA）/聚氨酯（PU）共混物，以改善HDPE的热性能和机械性能。这是因为HDPE作为一种聚烯烃基聚合物，尽管具有良好的机械强度和可加工性，但存在耐热性低和柔韧性差 的缺点。相比之下，EVA具有良好的柔韧性，PU具有优异的热性能和耐磨性。使用扫描电子显微镜（SEM）和万能试验机（UTM）对形态和机械性能（如拉伸强度和弯曲强度）进行了表征。确认了样品的凝胶分数、热收缩率和耐磨性。特别是，在180°C下储存1小时后，交联的HDPE-PU-EVA共混物的热稳定性比未交联的HDPE高约4倍。当受到100 kGy的辐射剂量时，HDPE的强度增加，但伸长率急剧下降（80%）。另一方面，HDPE-PU-EVA共混物的强度与HDPE非常相似，伸长率提高了3倍以上（320%）。最后，交联的HDPE-PU-EVA的耐磨性比交联的HDPE高约9倍。因此，该技术可应用于各种需要高耐热性和柔韧性的聚合物产品，如电缆和工业管道。
