In our earlier contribution, it was shown that with the addition of 1 wt% functionalized multiwall carbon nanotube (f-MWNT), an unprecedented 152% increase in PP impact strength without a significant loss in stiffness and ductility can be achieved. In the context of these observations, this work examined the impact fracture mechanism of such PP/f-MWNT nanocomposite, in which the PP interphase was tailored by the same co-solvent solution process. The nanotube-matrix stress transfer efficacy in PP/f-MWNT as compared to that of PP/pristine MWNT (p-MWNT) was determined by Raman spectroscopy. The calculated interfacial shear strength (τ_i) is 17.8 MPa in PP/f-MWNT and 2.2 MPa in PP/p-MWNT, suggesting improved matrix-CNT adhesion in the former. This strong interfacial adhesion allows CNTs to bridge the opening crack, absorb fracture energy and promote local plastic deformation of the polymer matrix. Such process was demonstrated using SEM fractography where breakage/pull out of the CNTs, microcracks, and the intensive fibril formation accompanied with the extension of the PP matrix were captured at the impact fracture surface. Both the interfacial shear strength and the SEM fractography supported the hypothesis that better matrix-CNT adhesion can be achieved through interphase engineering.

在我们的早期贡献中，我们发现，添加1 wt％的功能化多壁碳纳米管（f-MWNT），PP的冲击强度将达到前所未有的152％，而不会显着降低刚度和延展性。在这些观察的背景下，这项工作研究了这种PP / f-MWNT纳米复合材料的冲击断裂机理，其中PP间相是通过相同的助溶剂溶液工艺定制的。通过拉曼光谱法确定了与PP /原始MWNT（p-MWNT）相比，PP / f-MWNT中的纳米管基质应力转移功效。所计算出的界面剪切强度（τ_我）在PP / f-MWNT中为17.8 MPa，在PP / p-MWNT中为2.2 MPa，表明前者中基体与CNT的粘合性得到了改善。这种强大的界面附着力使CNT能够弥合开口裂缝，吸收断裂能并促进聚合物基体的局部塑性变形。使用SEM断层照相术证明了该过程，其中在冲击断裂表面捕获了CNT的断裂/拉出，微裂纹以及伴随PP基体延伸的强烈原纤维形成。界面剪切强度和SEM形貌均支持以下假设：通过相间工程可以实现更好的基体与CNT的粘合。