Barbier Maxime, Le Guen Marie Joo, McDonald-Wharry John, Bridson James H, Pickering Kim L
Scion, Rotorua, New Zealand.
Faculty of Science and Engineering, University of Waikato, Hamilton, New Zealand.
3D Print Addit Manuf. 2021 Jun 1;8(3):193-200. doi: 10.1089/3dp.2020.0166. Epub 2021 Jun 2.
A biobased composite material with heat-triggered shape memory ability was successfully formulated for three-dimensional (3D) printing. It was produced from cellulose nanocrystals and cellulose micro-powder particles within a bioderived thermally cured polyester matrix based on glycerol, citric acid, and sebacic acid. The effect of curing duration on the material's shape memory behavior was quantified by using two thermo-mechanical approaches to measure recovery: (1) displacement in three-point bending and (2) angular recovery from a beam bent at 90° in a single cantilever setup. Extending curing duration increased the material's glass-transition temperature from -26°C after 6 h to 13°C after 72 h of curing. Fourier-transform infrared spectroscopy confirmed the associated progressive conversion of functional groups consistent with polyester formation. Slow recovery rates and low levels of shape recovery (22-70%) were found for samples cured less than 24 h. Those results also indicated a high dependence on the measurement approach. In contrast, samples cured for 48 and 72 h exhibited faster recovery rates, a significantly higher recovery percentage (90-100%) and were less sensitive to the measurement approach. Results demonstrated that once a sufficient curing threshold was achieved, additional curing time could be used to tune the material glass-transition temperature and create heat-triggered 3D-printed products.
一种具有热触发形状记忆能力的生物基复合材料被成功制备用于三维（3D）打印。它由纤维素纳米晶体和纤维素微粉颗粒在基于甘油、柠檬酸和癸二酸的生物衍生热固化聚酯基体中制成。通过两种热机械方法测量回复来量化固化持续时间对材料形状记忆行为的影响：（1）三点弯曲中的位移和（2）在单悬臂装置中从90°弯曲的梁的角度回复。延长固化持续时间使材料的玻璃化转变温度从固化6小时后的-26°C升高到固化72小时后的13°C。傅里叶变换红外光谱证实了与聚酯形成一致的官能团的相关逐步转化。发现固化少于24小时的样品回复速率慢且形状回复水平低（22 - 70%）。这些结果还表明对测量方法高度依赖。相比之下，固化48小时和72小时的样品表现出更快的回复速率、显著更高的回复百分比（90 - 100%）并且对测量方法不太敏感。结果表明，一旦达到足够的固化阈值，额外的固化时间可用于调节材料的玻璃化转变温度并制造热触发的3D打印产品。
