Polyethylene (PE) is a widely used thermoplastic valued for its low cost, chemical resistance, recyclability, and good mechanical properties. PE makes up about one-third of the global plastic production. Recent advances in the field of additive manufacturing, especially material extrusion (MEX), have initiated interest in incorporating PE. However, using PE in such applications is challenging due to the polymer's semicrystalline nature, which causes significant shrinkage when cooled and limits chain diffusion, affecting the adhesion between the deposited layers. PE's non-polar character can also reduce the adhesion of the 3D-printed part to the printing bed. This paper analyzes the current progress in using PE in MEX, attempts to correlate PE's thermo-rheological properties with its 3D printability, and discusses the challenges associated with PE within the nozzle, post-deposition on the bed, and in the stand-off region between them. Additionally, the paper highlights the strategies to overcome these challenges to improve PE's printability in MEX by modulating the physicochemical properties of PE via incorporating fillers and nanofillers and blending with other polymers. Finally, future research directions are proposed to aid the design of PE-based feedstocks, which could also enhance plastic recycling.

中文翻译：

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聚乙烯材料挤出 (MEX) 综述 - 挑战、机遇和未来前景


聚乙烯 (PE) 是一种广泛使用的热塑性塑料，因其低成本、耐化学性、可回收性和良好的机械性能而受到重视。 PE 约占全球塑料产量的三分之一。增材制造领域的最新进展，尤其是材料挤出 (MEX)，引发了人们对掺入 PE 的兴趣。然而，由于聚合物的半结晶性质，在此类应用中使用 PE 具有挑战性，这会导致冷却时显着收缩并限制链扩散，从而影响沉积层之间的粘附力。 PE的非极性特性也会降低3D打印部件对打印床的粘附力。本文分析了目前在 MEX 中使用 PE 的进展，尝试将 PE 的热流变特性与其 3D 打印适性关联起来，并讨论了与喷嘴内、床上沉积后和隔离区域中的 PE 相关的挑战它们之间。此外，本文还重点介绍了克服这些挑战的策略，通过掺入填料和纳米填料以及与其他聚合物共混来调节 PE 的物理化学性质，从而提高 PE 在 MEX 中的印刷适性。最后，提出了未来的研究方向，以帮助设计基于聚乙烯的原料，这也可以增强塑料的回收利用。