Zhang Ni, Pan Zhouzhou, Lei Jincheng, Liu Zishun
International Center for Applied Mechanics, State Key Laboratory for Strength and Vibration of Mechanical Structure, Xi'an Jiaotong University Xi'an 710049 China
RSC Adv. 2018 Sep 3;8(54):31048-31054. doi: 10.1039/c8ra06518g. eCollection 2018 Aug 30.
As an excellent model material for fundamental studies on temperature-sensitive hydrogels, poly(-isopropylacrylamide) (NIPA) hydrogel has been applied in drug delivery, tissue engineering, and soft robotics. However, the lack of study on fracture and fatigue hinders further development of hydrogels for applications where cyclic loading-unloading is unavoidable. In this study, the fracture and fatigue damage of the NIPA hydrogel were studied for the first time by pure shear tests at different temperatures. Fracture behaviors were investigated under monotonic load from 31 °C to 39 °C. It is found that the fracture energy increases with the increase in temperature. The fracture energy is approximately 20 J m near the volume phase transition temperature. Temperature also significantly influences the fatigue life. By fitting the experimental data, the fatigue limit is determined. The results obtained from the experimental tests would be important for the engineering applications of the NIPA hydrogels.
作为温度敏感水凝胶基础研究的优良模型材料，聚（N-异丙基丙烯酰胺）（NIPA）水凝胶已应用于药物递送、组织工程和软体机器人领域。然而，由于缺乏对断裂和疲劳的研究，阻碍了水凝胶在不可避免地承受循环加载-卸载的应用中的进一步发展。在本研究中，首次通过在不同温度下的纯剪切试验研究了NIPA水凝胶的断裂和疲劳损伤。在31℃至39℃的单调载荷下研究了断裂行为。发现断裂能随温度升高而增加。在体积相变温度附近，断裂能约为20 J/m²。温度也显著影响疲劳寿命。通过拟合实验数据，确定了疲劳极限。实验测试所得结果对NIPA水凝胶的工程应用具有重要意义。
