Tran Ngon T, Patterson Brendan A, Harris Douglas E, Napadensky Eugene, Lenhart Joseph L, Knorr Daniel B, Bain Erich D
Materials & Manufacturing Sciences Division, U.S. Army Research Laboratory Aberdeen Proving Ground, Maryland 21005, United States.
ACS Appl Mater Interfaces. 2020 Nov 25;12(47):53342-53355. doi: 10.1021/acsami.0c16280. Epub 2020 Nov 15.
Polymers formed by ring-opening metathesis polymerization (ROMP) such as poly(dicyclopentadiene) (pDCPD) exhibit a technologically desirable combination of high toughness, high glass transition temperature, and outstanding low-temperature performance. However, because of their nonpolar molecular structure, they tend to suffer from relatively low elastic moduli and poor adhesion to common fillers, fibers, and substrates, limiting their utility as adhesives and composite binders without specialized bonding agents. Here, we investigate the mechanical properties of a pDCPD-based copolymer filled with well-defined spherical microparticles having four distinct surface chemistries capable of strong, moderate, or weak bonding to the matrix with surfaces ranging from polar to nonpolar. Measurements in uniaxial tension, quasi-static fracture, and high-velocity impact are complemented by digital image correlation (DIC), scanning electron microscopy (SEM) fractography, and X-ray computed tomography (X-μCT) of subcritically loaded crack tips, yielding insight into the complex roles played by interfacial bonding in strength, stiffness, and toughening mechanisms of an already tough polymer. Analysis using quantitative fracture and impact mechanism models provided valuable guidelines for designing heterogeneous systems that combine structural and tough performance.
通过开环易位聚合（ROMP）形成的聚合物，如聚（二环戊二烯）（pDCPD），展现出高韧性、高玻璃化转变温度和出色的低温性能等技术上理想的性能组合。然而，由于其非极性分子结构，它们往往具有相对较低的弹性模量，并且与常见的填料、纤维和基材的粘附性较差，在没有专用粘合剂的情况下，限制了它们作为粘合剂和复合粘合剂的用途。在此，我们研究了一种填充有具有四种不同表面化学性质的明确球形微粒的基于pDCPD的共聚物的力学性能，这些微粒能够与极性到非极性的表面与基体形成强、中或弱的键合。单轴拉伸、准静态断裂和高速冲击测量通过数字图像相关（DIC）、扫描电子显微镜（SEM）断口分析以及亚临界加载裂纹尖端的X射线计算机断层扫描（X-μCT）得到补充，从而深入了解界面键合在一种本已坚韧的聚合物的强度、刚度和增韧机制中所起的复杂作用。使用定量断裂和冲击机制模型进行的分析为设计兼具结构性能和坚韧性能的非均相体系提供了有价值的指导。
