形状记忆聚氨酯是一种热致型功能高分子材料,可以通过感知外界温度刺激而改变其分子结构并回复到初始设定形状.通过在不同温度下的单调拉伸实验,获取了形状记忆聚氨酯在玻璃态和橡胶态下力学性能参数;通过不同峰值应变下的热机械循环实验获知,在降温过程中应力升高幅度随着加载峰值应变的增加而减小,应变回复率随循环周次的增加而增加,回复比随着循环周次的增加而降低,呈现出功能退化的现象;通过机械循环和热机械循环交互作用实验发现,热机械循环和机械循环的交互作用有助于提高形状记忆聚合物的应变回复率和回复比,从而提高形状记忆聚氨酯形状记忆能力的稳定性.
Shape memory polyurethane is a kind of thermotropic functional polymer materials, which can be stimulated by the external temperature and recover to initial state by changing its molecular structures.Firstly, monotonic tensile experiments were carried out to obtain the mechanical properties of glass and rubber states at different temperatures.Moreover, the thermo-mechanically cyclic experiments under different peak strains show that the increased stress amplitude decreases with the increased peak strain during the cooling process.The recovery rate increases but the recovery ratio decreases with the increased number of cycles, which implies a functional degradation of shape memory.Finally, it was found that the interaction between mechanical and thermo-mechanical cycles can increase the rate and ratio of recovery, resulting in the stability improvement of shape memory polyurethane.
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