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目的:通过时温等效叠加方法预测一种正畸用热压膜材料2周内的应力松弛特征。方法:选用市售正畸用热压膜材料Essix ACE，应用自主改良搭建的恒温系统，测量材料在38.1℃、41.5℃、45.6℃、49.6℃、54.0℃，温度梯度下1000 s拉伸应力松弛。松弛初始应变设定为材料1/4抗拉强度对应应变，为0.92%。通过手动法进行时温等效叠加，得到材料在38.1℃下的应力松弛主曲线。结果:对水平移动因子l g(an T)与温度1/T进行线性关系的检测。并将叠加得到的主曲线与材料在38.1℃下实际测量8 h的松弛结果比较。均证明Essix ACE材料适用于时温等效叠加方法，且叠加后结果与实际测量结果相似。Essix ACE材料在38.1℃下2周后残余应力72.5%，约86.0%的应力松弛在24 h内产生。n 结论:时温等效叠加法可以用来预测正畸用热压膜材料Essix ACE的应力松弛特征。在口腔温度下，Essix ACE材料2周后残余应力72.5%。“,”Objective:To predict 2 weeks stress relaxation properties of an orthodontic thermoplastic material, using time-temperature superposition equivalence method.Methods:Commercially available orthodontic thermoplastic Essix ACE was selected. The constant temperature system was improved to test 1000 s tensile stress relaxation under the temperature gradients of 38.1℃, 41.5℃, 45.6℃, 49.6℃ and 54.0℃. The initial strain of relaxation was set to 0.92%, corresponding to 1/4 tensile strength of the material. Time-temperature equivalent superposition was performed manually to obtain the stress relaxation main curve under 38.1℃.Results:Linear relationship between the horizontal shift factor lg(an T) and temperature 1/T was detected. The superimposed main curve was compared with the actual testing of 8 hours relaxation at 38.1℃. The results proved that Essix ACE was suitable for time-temperature superposition method, and the stress relaxation prediction result was reliable. Residual stress of Essix ACE was 72.5% after 2 weeks under 38.1℃. About 86.0% of the stress relaxation were generated within 24 hours.n Conclusions:Time-temperature superposition method can be used to predict the stress relaxation properties of orthodontic thermoplastic Essix ACE. At oral temperature, the residual stress of Essix ACE was 72.5% after 2 weeks.