用时温等效叠加法预测一种正畸用热压膜材料2周内的应力松弛  

Stress relaxation prediction of a thermoplastic material in two weeks using time-temperature superposition method

作　　者：李凤茹 江久汇[1] Li Fengru;Jiang Jiuhui(Department of Orthodontics,Peking University School and Hospital of Stomatology,Beijing 100081,China)

机构地区：[1]北京大学口腔医学院·口腔医院正畸科,北京100081

出　　处：《中华口腔正畸学杂志》2020年第4期212-215,共4页Chinese Journal of Orthodontics

摘　　要：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(aT)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。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(aT)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.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.

关 键 词：热压膜材料 应力松弛 时温等效叠加 

分 类 号：R783.5[医药卫生—口腔医学]