This study investigates the foaming behavior of TPU samples with three different soft segment (SS) molecular weights of 1000, 2000, and 3500 g/mol. The variation of SS length did not only enhance the flexibility of the TPU samples but could also ease the hard segment (HS) crystallization with various size/closed packed structure with much wider HS crystal melting peak. Such broadened melting peak expanded the foam processing window in TPUs with higher SS length. Moreover, the results showed that the increase in SS length could not only enhance the foam expansion behavior but could also enhance the heterogeneous cell nucleation and more importantly minimize the shrinkage of the TPU foams as a result of broadened HS crystallization. The saturation temperature, pressure, and time could also differently influence the formation of HS crystals in each TPU with different structure which could eventually differently affect the TPUs’ foaming behavior.

这项研究调查了三种分子量分别为1000、2000和3500 g / mol的TPU样品的发泡行为。SS长度的变化不仅增强了TPU样品的柔韧性，而且还缓解了具有各种尺寸/密堆积结构且HS晶体熔融峰更宽的硬链段（HS）的结晶。这种加宽的熔融峰扩大了具有较高SS长度的TPU中的泡沫加工窗口。此外，结果表明，SS长度的增加不仅可以增强泡沫的膨胀行为，而且可以增强异质泡孔的成核作用，更重要的是，由于HS结晶的扩大，TPU泡沫的收缩率最小。饱和温度，压力