耦合温度效应的纳米橡胶改性环氧树脂动态断裂机理研究

Abstract: Epoxies are the main resin matrix for advanced composite，the significant brittle feature of epoxies could lead to fracture failure of advanced composite, herein, how to improve fracture toughness of epoxies has been a research focus for advanced composite. With the development of Nano technology, Nano-rubber particles are widely filled in the epoxies to become toughened epoxy adhesive because of its excellent toughening ability. However, the mechanical properties of rubber materials are often affected by the impact loading and variable temperatures, which could seriously influence the nano-rubber toughening ability in epoxies. Hence, the temperature effect on dynamic fracture behaviour of nano-rubber modified epoxies will be investigated based on dynamic fracture experiments using hopkinson bar, in addition, utilized the SEM and TEM microstructure analysis technique, the changing law of microstructure characteristics with loading rate and temperature will be investigated, and the microstructure fracture mechanisms of nano-rubber modified epoxies will be revealed, finally, based on strain energy density theory, fracture energy release rate of nano-rubber modified epoxies considering loading rate and temperature will be developed. The research achievements of the project are helpful to better understand the nano-rubber toughening mechanism under extreme environment, and can also provide reference for safe application and design for nano-rubber composites.

环氧树脂是先进复合材料的主要基体树脂，其高度脆性特征容易引发先进复合材料断裂失效，因此对环氧树脂的增韧改性一直是先进复合材料研究的热点。随着纳米技术的发展，纳米橡胶颗粒以其高效的增韧能力被广泛填充在环氧树脂中形成高韧性环氧胶，但橡胶材料的力学性能往往受到加载率和温度变化等极端环境的影响，这将严重影响纳米橡胶对环氧树脂的断裂特性。对此，本项目拟通过霍普金森压杆动态断裂实验，研究不同温度作用下纳米橡胶改性环氧树脂的动态断裂力学行为；通过SEM和TEM等微观分析，探究纳米橡胶改性环氧树脂微观组织特征随加载率与温度的变化规律，继而揭示纳米橡胶改性环氧树脂的动态断裂机制；基于应变能密度理论，最终建立计及加载率和温度依赖性的纳米橡胶改性环氧树脂断裂能量释放率理论模型。项目研究成果有助于深入理解极端环境下纳米橡胶颗粒对环氧树脂的增韧机制，同时为纳米橡胶先进复合材料的安全使用与设计提供参考。

环氧树脂的脆性特征导致树脂基纤维增强复合材料易于分层，因此，如何提高环氧树脂的断裂韧性是亟待解决的问题。随着纳米技术的发展，纳米橡胶颗粒以其高效的增韧能力被广泛填充在环氧树脂中形成高韧性环氧胶，但橡胶材料的力学性能往往受到温度和加载率的双重影响，这将严重影响纳米橡胶对环氧树脂的增韧特性。对此，本项目拟通过霍普金森压杆动态断裂实验，研究发现纳米橡胶改性环氧树脂断裂韧性随温度的升高而提高，但是高温或者低温都会导致纳米橡胶对环氧树脂的增韧效率降低；通过SEM和TEM等微观分析，发现纳米橡胶随着加载率的提高或者温度的降低其空穴扩展和基体变形会显著降低，最后基于应变能密度理论，建立了计及率和温度依赖性的纳米橡胶改性环氧树脂断裂能量释放率理论模型。项目研究成果有助于深入理解加载率与温度耦合作用下纳米橡胶颗粒对环氧树脂的增韧机制，同时为纳米橡胶改性环氧胶在极端环境下的安全使用与设计提供参考。