Pantano Maria F, Pavlou Christos, Pastore Carbone Maria Giovanna, Galiotis Costas, Pugno Nicola M, Speranza Giorgio
Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, 38123 Trento, Italy.
Institute of Chemical Engineering Sciences, Foundation of Research and Technology-Hellas (FORTH/ICE-HT), Stadiou Street, Platani, 26504 Patras, Greece.
ACS Omega. 2021 Mar 19;6(12):8308-8312. doi: 10.1021/acsomega.1c00016. eCollection 2021 Mar 30.
Poly(methyl methacrylate) (PMMA) is a glassy engineering polymer that finds extensive use in a number of applications. Over the past decade, thin films of PMMA were combined with graphene or other two-dimensional materials for applications in the area of nanotechnology. However, the effect of size upon the mechanical behavior of this thermoplastic polymer has not been fully examined. In this work, we adopted a homemade nanomechanical device to assess the yielding and fracture characteristics of freestanding, ultrathin (180-280 nm) PMMA films of a loaded area as large as 0.3 mm. The measured values of Young's modulus and yield strength were found to be broadly similar to those measured in the bulk, but in contrast, all specimens exhibited a quite surprisingly high strain at failure (>20%). Detailed optical examination of the specimens during tensile loading showed clear evidence of craze development which however did not lead to premature fracture. This work may pave the way for the development of glassy thermoplastic films with high ductility at ambient temperatures.
聚甲基丙烯酸甲酯（PMMA）是一种玻璃态工程聚合物，在许多应用中都有广泛用途。在过去十年中，PMMA薄膜与石墨烯或其他二维材料相结合，用于纳米技术领域的应用。然而，尺寸对这种热塑性聚合物力学行为的影响尚未得到充分研究。在这项工作中，我们采用自制的纳米力学装置来评估自由支撑的、超薄（180 - 280纳米）且加载面积高达0.3毫米的PMMA薄膜的屈服和断裂特性。发现测得的杨氏模量和屈服强度值与在本体中测得的值大致相似，但相比之下，所有试样在失效时都表现出相当惊人的高应变（>20%）。在拉伸加载过程中对试样进行的详细光学检查显示出明显的银纹发展迹象，然而这并未导致过早断裂。这项工作可能为在环境温度下开发具有高延展性的玻璃态热塑性薄膜铺平道路。
