超级隔热纳孔聚合物泡沫的传热机理及其二氧化碳发泡成形方法研究

The super-insulating materials have very important practical application values for conserving energy and reducing emissions. The nanocellular polymer foam fabricated by carbon dioxide foaming has the potential super-insulating properties, and thus it has been getting a high level of attention in recent years. At present, the structure-function relationship between the micro structure and the macro heat transfer property of the nanocellular polymer foam is not clear. At the same time, the expansion ratio of the nanocellular polymer foam fabricated by current methods is still very small, and it cannot meet the requirement for super-insulating performance. Moreover, although the radiative heat transfer in the nanocellular polymer foam is significant, there is currently little research on how to shield the radiative heat transfer passing through the nanocellular foam. To this end, this project will create a heat transfer mathematical model to clarify the relationship between the micro structure and the macro heat transfer property of the nanocellular polymer foam, through an in-depth study of the micro-nano heat transfer mechanisms. Based on the mathematical model, the cellular structure of the super-insulating nanocellular foam will be created and optimized. Furthermore, new foaming technologies will be developed for fabricating the nanocellular foam with a high expansion ratio based on studying the cell nucleation and growth behavior, and its regulation methods. Moreover, effective methods will be developed for reducing the radiative heat transfer in the nanocellular polymer foam. Finally, the nanocellular foam with a super-insulation property will be fabricated. This project not only has important practical value for reducing energy consumption and improving energy efficiency, but also has important scientific significance for enriching the micro-nano heat transfer theory.

超级隔热材料对于“节能减排”具有重要应用价值。基于二氧化碳发泡成型的纳孔聚合物泡沫因具有潜在的超级隔热性能而受到高度重视。目前，纳孔聚合物泡沫的微观结构与宏观传热性能之间的构效关系尚不清楚，现有方法制备的纳孔聚合物泡沫的发泡倍率还很小，无法实现超级隔热性能，高发泡倍率纳孔聚合物泡沫存在显著辐射传热，但尚未开展针对其辐射传热屏蔽方法的研究，严重阻碍了超级隔热纳孔聚合物泡沫的开发。为此，本项目拟深入研究纳孔聚合物泡沫的传热机理，建立描述微观结构与宏观传热性能之间构效关系的数学模型，优化设计超级隔热纳孔聚合物的泡沫结构，研究泡孔成核与长大行为及其调控方法，研发高发泡倍率纳孔聚合物泡沫制备技术，研究建立纳孔聚合物泡沫辐射传热屏蔽方法，最终制备具有超级隔热性能的纳孔聚合物泡沫。本研究不仅对于减少能源损耗、提升能源效率具有重要的实际应用价值，而且对于丰富微纳结构热传递理论具有重要的科学意义。

超级隔热微纳孔聚合物泡沫对于“节能减排”具有重要应用价值，有助于加快“双碳”战略目标的达成。目前，微纳孔聚合物泡沫的传热机制尚不清晰，同时缺少制备高孔隙率微纳孔聚合物泡沫的有效手段，这极大限制了超隔热微纳孔聚合物泡沫的开发。为此，本项目深入研究了微纳孔聚合物泡沫的传热行为，揭示了微纳孔聚合物泡沫传热的微观尺度机制，建立了考虑固体传热声子散射效应、气体传热克努森效应和辐射传热薄膜干涉效应的微纳孔聚合物泡沫传热数学模型，探明了泡孔结构与传热性能之间的构效关系，实现了微纳孔聚合物泡沫传热性能的准确预测，综合预测精度优于90%，掌握了具有超级隔热性能的微纳孔聚合物泡沫结构，为超隔热微纳孔聚合物泡沫的开发奠定了理论基础。结合材料屈服理论和经典泡孔成核理论，推导建立了粘弹性泡孔成核理论模型，深入揭示了应变能、异相成核剂等对泡孔成核的影响机理，首次开展了拉伸辅助和压缩辅助微孔发泡工艺实验研究，验证了所提出的粘弹性泡孔成核理论模型的有效性，利用创建的双向拉伸辅助微孔发泡方法，制备了具有亚微米级尺度泡孔的聚合物薄膜泡沫。基于粘弹性泡孔成核理论模型，提出了一系列利用异相诱发的应变能促进泡孔成核的微孔发泡方法，成功制备了孔隙率高达0.875且泡孔尺寸小于200nm的超隔热微纳孔聚合物泡沫材料，其热导率低至24.8 mW/(m·K)；研究发现，对于弱红外辐射吸收能力的聚合物，其高孔隙率泡沫存在显著的辐射传热，严重恶化了泡沫的隔热性能，通过混入碳纳米管、碳纳米纤维、纳米石墨片等碳材料对聚合物进行改性，能够显著增强聚合物泡沫对红外电磁波的屏蔽能力，从而增强聚合物泡沫的隔热性能。本研究不仅对于减少能源损耗、提升能源效率具有重要的实际应用价值，而且对于丰富微纳结构热传递理论具有重要的科学意义。