This study proposes a thorough investigation, especially based on thermodynamics, to predict phase separation in a linear thermoplastic polyurethane, denoted TPU, prepared from fatty acid-based soft segments and MDI (4,4′-methylene bis(phenyl isocyanate))/BDO (1,4-butanediol) hard segments and specially designed for bitumen modification. Hansen’ solubility parameters (HSP) of both segments are evaluated to predict their compatibility. The later ones are evaluated either individually from the corresponding segment synthesized separately or from a decomposition of the solubility diagram of the TPUs into two distinct spheres. In a second step, phase separation is experimentally analyzed by combining differential scanning calorimetry, microscopy techniques, and small angle X-ray scattering (SAXS). The microstructure of the TPUs is described considering one soft phase made of polyol chains and short miscible hard segments and a hard phase organized as semi-crystalline nanodomains either dispersed or assembled as ramified (nano)objects within the soft phase. The dynamic mechanical properties of the TPUs can be explained by the presence of such well-defined hard domains in the structure of the TPU, acting as reinforcing fillers while maintaining a thermoplastic elastomer mechanical behavior to the TPU above the glass transition of the continuous soft phase.

这项研究提出了一项彻底的研究，尤其是基于热力学的研究，以预测由脂肪酸基软链段和MDI（4,4'-亚甲基双（苯基异氰酸酯））/ BDO制备的线性热塑性聚氨酯（TPU）的相分离（1,4-丁二醇）硬链段，专为沥青改性而设计。对两个链段的汉森溶解度参数（HSP）进行评估，以预测其相容性。从单独合成的相应链段或将TPU的溶解度图分解为两个不同的球体中分别评估后一个。第二步，通过组合差示扫描量热法，显微镜技术和小角度X射线散射（SAXS），对相分离进行实验分析。描述了TPU的微观结构，其中考虑了一个由多元醇链和短的可混溶硬链段组成的软相，以及一个组织为半结晶纳米域的硬相，该半相分散或组装为在软相中的分枝（纳米）物体。TPU的动态机械性能可以通过在TPU结构中存在明确定义的硬域来解释，这些硬域可以用作补强填充剂，同时在连续软相的玻璃化转变温度以上，保持热塑性弹性体对TPU的机械性能。