Polyurethane (PU) elastomers are among the most used rubberlike materials due to their combined merits, including high abrasion resistance, excellent mechanical properties, biocompatibility, and good processing performance. A PU elastomer exhibits pronounced hysteresis, leading to a high toughness on the order of 10⁴ J/m². However, toughness gained from hysteresis is ineffective to resist crack growth under cyclic load, causing a fatigue threshold below 100 J/m². Here we report a fatigue-resistant PU fiber–matrix composite, using commercially available Spandex as the fibers and PU elastomer as the matrix. The Spandex fibers are stiff, strong, and stretchable. The matrix is soft, tough, and stretchable. We describe a pullout test to measure the adhesion toughness between the fiber and matrix. The test is highly reproducible, showing an adhesion toughness of 3170 J/m². The composite shows a maximum stretchability of 6.0, a toughness of 16.7 kJ/m², and a fatigue threshold of 3900 J/m². When a composite with a precut crack is stretched, the soft matrix causes the crack tip to blunt greatly, which distributes high stress over a long segment of the Spandex fiber ahead the crack tip. This deconcentration of stress makes the composite resist the growth of cracks under monotonic and cyclic loads. The PU elastomer composites open doors for realistic applications of fatigue-resistant elastomers.

聚氨酯 (PU) 弹性体因其综合优点而成为最常用的橡胶类材料之一，包括高耐磨性、优异的机械性能、生物相容性和良好的加工性能。PU 弹性体表现出显着的滞后，导致10 ⁴ J/m ²数量级的高韧性。然而，从滞后获得的韧性无法有效抵抗循环载荷下的裂纹扩展，导致疲劳阈值低于 100 J/m ². 在这里，我们报告了一种抗疲劳的 PU 纤维-基体复合材料，使用市售的氨纶作为纤维和 PU 弹性体作为基体。氨纶纤维坚硬、坚固且可拉伸。基质柔软、坚韧且可拉伸。我们描述了一种拉拔试验来测量纤维和基体之间的粘附韧性。该测试具有高度可重复性，显示出 3170 J/m ²的粘附韧性。该复合材料的最大拉伸性为 6.0，韧性为 16.7 kJ/m ²，疲劳阈值为 3900 J/m ². 当具有预切裂纹的复合材料被拉伸时，软基体导致裂纹尖端大大变钝，从而将高应力分布在裂纹尖端之前的氨纶纤维的长段上。这种应力分散使复合材料在单调和循环载荷下抵抗裂纹的增长。PU 弹性体复合材料为抗疲劳弹性体的实际应用打开了大门。