Thermal transport in 3D printed shape memory polymer metamaterials
Thermal transport in 3D printed shape memory polymer metamaterials
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DOI：
10.1063/5.0094036
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发表时间：
2022-08
期刊：
影响因子：
6.1
通讯作者：
Shiva Farzinazar;Yueping Wang;Charles Abdol-Hamid Owens;Chen Yang;Howon Lee;Jaeho Lee
中科院分区：
文献类型：
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作者：
Shiva Farzinazar;Yueping Wang;Charles Abdol-Hamid Owens;Chen Yang;Howon Lee;Jaeho Lee
形状记忆聚合物作为新兴 4D 打印领域的主要构成材料之一，引起了人们的广泛关注。虽然具有形状记忆聚合物的 3D 打印超材料表现出独特的热机械行为，但其热传输特性受到的关注相对较少。在这里，我们表明，3D 打印形状记忆聚合物中的热传输强烈依赖于形状、固体体积分数和温度，并且热辐射起着关键作用。我们的红外热成像测量揭示了形状记忆聚合物的热传输机制，形状记忆聚合物的形状从块状到八角桁架和开尔文泡沫微晶格，体积分数为 4%–7%，温度范围为 30–130 °C。本体形状记忆聚合物的热导率在玻璃化转变温度附近从 0.24 W m−1 K−1 增加到 0.31 W m−1 K−1，其中主要机制是热传导的相依赖变化。相反，热辐射在微晶格中主导传热，在相同温度范围内，其对开尔文泡沫结构的贡献范围为 68% 至 83%，对八角桁架结构的贡献范围为 59% 至 76%。我们将热辐射的这种重要作用归因于形状记忆聚合物微晶格中高红外发射率和高表面积与体积比的独特组合。我们的工作还提出了一种有效的介质方法来解释实验结果并模拟不同形状、体积分数和温度的热传输特性。这些发现为理解 4D 打印形状记忆聚合物中的热传输机制和探索热机械超材料的设计空间提供了新的见解。
Shape memory polymers are gaining significant interest as one of the major constituent materials for the emerging field of 4D printing. While 3D-printed metamaterials with shape memory polymers show unique thermomechanical behaviors, their thermal transport properties have received relatively little attention. Here, we show that thermal transport in 3D-printed shape memory polymers strongly depends on the shape, solid volume fraction, and temperature and that thermal radiation plays a critical role. Our infrared thermography measurements reveal thermal transport mechanisms of shape memory polymers in varying shapes from bulk to octet-truss and Kelvin-foam microlattices with volume fractions of 4%–7% and over a temperature range of 30–130 °C. The thermal conductivity of bulk shape memory polymers increases from 0.24 to 0.31 W m−1 K−1 around the glass transition temperature, in which the primary mechanism is the phase-dependent change in thermal conduction. On the contrary, thermal radiation dominates heat transfer in microlattices and its contribution to the Kelvin-foam structure ranges from 68% to 83% and to the octet-truss structure ranges from 59% to 76% over the same temperature range. We attribute this significant role of thermal radiation to the unique combination of a high infrared emissivity and a high surface-to-volume ratio in the shape memory polymer microlattices. Our work also presents an effective medium approach to explain the experimental results and model thermal transport properties with varying shapes, volume fractions, and temperatures. These findings provide new insights into understanding thermal transport mechanisms in 4D-printed shape memory polymers and exploring the design space of thermomechanical metamaterials.