Institute for Materials Chemistry and Engineering, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
Soft Matter. 2018 Feb 28;14(9):1659-1664. doi: 10.1039/c7sm01842h.
It is desirable to establish a method for evaluating mechanical properties, such as modulus and strength, of micrometer and sub-micrometer thick polymer films. Bulge tests, where bulge deformation is imposed on films by the pressure of an inert gas, are suitable for satisfying this demand. However, very few studies on polymer films exist in the literature. In this study, bulge testing equipment for in situ synchrotron radiation wide-angle X-ray diffraction (WAXD) measurements is designed and used to study the relationship between the molecular aggregation structure and the mechanical properties of a crystalline nylon 12 (Ny12) film during bulge testing. Isothermally crystallized and quenched Ny12 films exhibited stress-strain curves similar to those obtained by conventional uniaxial elongation. In situ WAXD measurements during bulge testing revealed that the lattice extension of the crystallites is clearly dependent on crystallinity. Concretely, crystallites in the isothermally crystallized film show higher elastic properties than those in the quenched one. The results of the molecular aggregation structure, including the crystal structure and the amorphous chain surrounding the crystallites, of the films during bulge deformation firstly obtained in this study must be useful for designing toughened polymer films.
建立一种评估微米和亚微米厚聚合物薄膜机械性能（如模量和强度）的方法是可取的。鼓胀试验通过惰性气体的压力对薄膜施加鼓胀变形，适合满足这一需求。然而，文献中关于聚合物薄膜的研究很少。在这项研究中，设计了用于同步辐射广角 X 射线衍射（WAXD）原位测量的鼓胀试验设备，用于研究在鼓胀试验过程中结晶尼龙 12（Ny12）薄膜的分子聚集结构与力学性能之间的关系。等温结晶和淬火的 Ny12 薄膜表现出与常规单轴拉伸获得的相似的应力-应变曲线。在鼓胀试验过程中的原位 WAXD 测量表明，晶粒的晶格延伸明显依赖于结晶度。具体来说，等温结晶薄膜中的晶粒表现出比淬火薄膜更高的弹性性能。本研究首次获得的薄膜在鼓胀变形过程中的分子聚集结构（包括晶体结构和围绕晶粒的非晶链）的结果对于设计增韧聚合物薄膜必定是有用的。
