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首页> 外文期刊>Journal of Applied Polymer Science >Shape-Memorized Crosslinked Ester-Type Polyurethane and Its Mechanical Viscoelastic Model
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Shape-Memorized Crosslinked Ester-Type Polyurethane and Its Mechanical Viscoelastic Model

机译：形状记忆的交联酯型聚氨酯及其机械粘弹性模型

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A series of shape-memorized crosslinked ester-type polyurethanes (PUs), based on different compositions of 4,4'-diphenyl methane diisocyanate (MDI), poly(butylene adipate) glycol (PBAG) with differnet molecular weight (MW) and trimethylol propane (TMP), were synthesized. The morphology of samples was investigated by using DSC, WAXD, and dynamic mechanical analysis (DMA). It was found that the morphology of the soft segment, which was PBAG with a different MW, was in an amorphous state and no crystalline domain was found. By increasing the crosslinked density (varying the content of TMP) or decreasing the length of the soft segment (MW of PBAG), the glass transition temperature fo studied samples increased. But the range of transition broadened and the modulus ratio E'(T_g-20deg C)/E'(T_g+20deg C) also decreased. The shape-memory behavior was studied by the bending test method adopted from the shape-memory alloy. The sample with high T_g showed not only a high recovered temperature (T_r) but also a high recovered rate (V_r) with a high modulus ratio. By introducing the chemical crosslinked structure, the deformed samples completely recovered their original shape and rendered shape-memory behavior under the complex deformation. The shape-memorized crosslinked ester-type PUs can be applied at different operating temperatures. A mechanical viscoelastic model is discussed for the shape-memory behavior of PUs, and the modified Bonart's viscoelastic mdoel properly describes the mechanism of the shape memory of PUs.
机译：基于4,4'-二苯基甲烷二异氰酸酯（MDI），具有不同净分子量（MW）的聚己二酸丁二醇酯（PBAG）和三羟甲基酚的不同组成的一系列形状记忆的交联酯型聚氨酯（PU）丙烷（TMP），被合成。通过使用DSC，WAXD和动态力学分析（DMA）研究了样品的形态。发现软段的形态是具有不同MW的PBAG，其处于非晶态并且未发现晶畴。通过增加交联密度（改变TMP的含量）或减小软链段的长度（PBAG的分子量），研究样品的玻璃化转变温度会提高。但是转变范围变宽，模量比E′（T_g-20℃）/ E′（T_g + 20℃）也减小。通过采用形状记忆合金的弯曲试验方法研究了形状记忆行为。具有高T_g的样品不仅显示出高回收温度（T_r），而且还显示出具有高模量比的高回收率（V_r）。通过引入化学交联结构，变形后的样品可以完全恢复其原始形状，并在复杂变形下呈现出形状记忆行为。形状记忆的交联酯型PU可以在不同的操作温度下施加。讨论了用于PU的形状记忆行为的机械粘弹性模型，并且改进的Bonart的粘弹性模型适当地描述了PU的形状记忆的机理。

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