Research on 3D/4D printing has seen significant growth in recent years due to the immense potential for applying these techniques across various fields. Polyethylene terephthalate glycol (PETG) and thermoplastic polyurethane (TPU) are commercially utilized polymers in 3D printing, holding promise for application in 4D printing as well. PETG demonstrates excellent shape fixity at room temperature but limited recovery capacity, while TPU exhibits good recovery but poor shape fixity. Hence, this study aims to investigate the shape memory effect (SME) of PETG/TPU blends. The blends were prepared through melt blending, extruded into filaments, and then molded using 3D printing. Chemical, rheological, morphological, and mechanical characterizations were conducted, and the shape memory effect was assessed in a water bath under bending mode and using a rheometer under torsion mode. All compositions demonstrated a more balanced SME compared to individual polymers. For instance, the PETG/TPU (50/50) blend showcased a fixity ratio of approximately 97 % and a recovery ratio of around 93 % in bending mode, while under torsion mode, it exhibited a fixity ratio of approximately 100 % and a recovery ratio of about 87 %. To optimize printing parameters for achieving the best SME, an experimental design was employed, which involved assessing nozzle temperature, printing speed, and layer height. The study revealed that, within defined limits, the most favorable SME outcomes were attained at lower levels of nozzle temperature, printing speed, and layer height.

中文翻译：

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形状记忆聚对苯二甲酸乙二醇酯/热塑性聚氨酯 (PETG/TPU) 共混物的 4D 打印

近年来，由于 3D/4D 打印技术在各个领域应用的巨大潜力，有关 3D/4D 打印的研究取得了显着增长。聚对苯二甲酸乙二醇酯 (PETG) 和热塑性聚氨酯 (TPU) 是 3D 打印中商业化使用的聚合物，也有望在 4D 打印中得到应用。 PETG在室温下表现出优异的形状固定性，但恢复能力有限，而TPU表现出良好的恢复性，但形状固定性较差。因此，本研究旨在研究 PETG/TPU 共混物的形状记忆效应 (SME)。共混物通过熔融共混制备，挤出成长丝，然后使用 3D 打印成型。进行了化学、流变、形态和机械表征，并在弯曲模式下的水浴中和在扭转模式下使用流变仪评估了形状记忆效应。与单个聚合物相比，所有组合物均表现出更平衡的 SME。例如，PETG/TPU (50/50) 共混物在弯曲模式下表现出约 97% 的固定率和约 93% 的恢复率，而在扭转模式下表现出约 100% 的固定率和约 100% 的恢复率。比例约为87%。为了优化打印参数以实现最佳 SME，采用了实验设计，其中包括评估喷嘴温度、打印速度和层高。研究表明，在规定的限度内，最有利的中小企业结果是在较低水平的喷嘴温度、打印速度和层高下获得的。