不同硬段结构TPU物理发泡行为及弹性性能的影响研究

Study on the influence of on the physical foaming behavior different and elastic properties of TPU with different hard segment structures

摘要:

以超临界CO₂物理发泡技术制备了一系列具有可调泡孔结构的TPU泡沫材料,研究了TPU泡沫的泡孔结构、硬段化学结构与弹性性能之间的关系。研究发现,泡孔尺寸和泡孔密度主要由饱和压力决定,膨胀倍率主要取决于饱和温度。随着饱和温度的增加,泡孔尺寸先增大后减小,但是温度对泡孔尺寸的影响较小。TPU泡沫的压缩强度随着泡孔尺寸的减小而逐渐增大,TPU泡沫的压缩回弹性随着泡孔尺寸的减小而增大。泡沫的压缩强度随着膨胀倍率的增大而明显降低,而泡沫的压缩回弹性随着膨胀倍率的增大先增大后降低。TPU硬段分子结构的对称性,最终导致脂肪族TPU泡沫的压缩强度高于芳香族TPU泡沫,最高提高了60%,脂肪族TPU泡沫的回弹性相比芳香族TPU泡沫最高提高了45%。

Abstract:

A series of TPU foams with tunable cellular structures were prepared by supercritical carbon dioxide physical foaming technology. The relationships between cellular structure, hard segment chemical structure, and elastic properties of TPU foams were investigated. The study revealed that cell size and cell density of TPU foams are primarily determined by saturation pressure, while the expansion ratio is mainly depended on temperature. With increasing temperature, the cell size initially increases and then decreases, although the temperature has little effect on cell size. The compression strength of TPU foams gradually increases with decreasing cell size, and the compression resilience of TPU foams increases with decreasing cell size. The expansion ratio is a key structural parameter determining the compression strength of TPU foam. The compression strength of the foams significantly decreases with increasing expansion ratio, while the compression resilience of TPU foams initially increases and then decreases with increasing expansion ratio. The symmetry of the TPU hard segment molecular structure eventually leads to the higher compression strength of H-TPU foams than M-TPU foams, up to 60% higher, and the resilience of H-TPU foams up to 45% higher than that of M-TPU foams.