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对当前高分子材料蠕变持久性的测定方法进行了总结,指出了半对数和双对数作图直线外推法的局限性。根据高聚物处于不同力学状态具有不同断裂机理,提出了三种蠕变持久性表征方法:1)准脆性状态下粘弹性蠕变持久性表征作图法;2)受迫高弹状态下银纹和屈服断裂表征作图法;3)高弹状态下蠕变塑性流动断裂表征作图法。并以三种不同类型高聚物(半晶态、玻璃态和弹性体)大量的蠕变断裂力学性能实验数据加以验证,讨论了它们的适用范围。最后提出了一种适用于较宽应力和断裂时间范围的蠕变持久性直线外推的新方法,该法能较好地预测具有粘弹性断裂特征的高密度聚乙烯蠕变持久性。
The current methods for determining the creep persistence of polymeric materials are summarized, and the limitations of linear extrapolation of semi-logarithms and double-logarithmic plots are pointed out. According to different fracture mechanism of polymer in different mechanical states, three permanent creep characterization methods are proposed: 1) Persistence of viscoelastic creep under quasi-fragile state; 2) Grain and yield fracture characterization mapping method; 3) high elastic state creep plastic flow fracture characterization mapping method. The experimental data of a large number of creep rupture mechanical properties of three different types of polymers (semi-crystalline, glassy and elastomeric) were also validated and their applicability was discussed. Finally, a new method of long-term linear extrapolation for creep strain, which is suitable for a wide range of stress and fracture time, is proposed. This method can better predict the creep persistence of high density polyethylene with viscoelastic fracture characteristics.