拉伸速度对ETFE薄膜力学性能的影响

Influence of Extension Speed on Mechanical Properties of ETFE Foil

对厚度为250μm的长条形ETFE(乙烯-四氟乙烯共聚物)薄膜试样进行了6种定速(应变速率分别为10%/min,25%/min,50%/min,100%/min,200%/min,500%/min)单向拉伸试验,得到了相应的抗拉强度、断裂延伸率、屈服应力以及弹性模量等力学参数的变化规律.结果表明:ETFE薄膜的抗拉强度随拉伸速度的增加略有增加,而断裂延伸率随拉伸速度的增加略有减小;ETFE薄膜的屈服强度随拉伸速度的增加而有所增加,但第二屈服强度增加不大;ETFE薄膜的屈服应变随拉伸速度的增加略有增加,第二屈服应变则略有减少;ETFE薄膜的切线弹性模量以及第二弹性模量随拉伸速度的增加呈下降趋势,割线弹性模量和第三弹性模量则没有明显的变化.通过分析,给出了以应变速率对数为变量的线性拟合公式,可用于计算在不同应变速率下ETFE薄膜的相关力学参数.

Abstract： Uniaxial extension tests of ethylene tetrafluoroethylene（ETFE） foil specimens （thick- ness： 250/~m） were carried out by using six kinds of extension speed （tensile strain rate： 10 ~/min, 25%/min, 50~/min, 100%/min, 200%/min, 500%/rain）. The tensile strength, the tensile strain at break, the yield stress and the Young＇s modulus under different extension speed were obtained from the tests. According to the results of the tests with the increase of the exten- sion speed the tensile strength of ETFE foil increases slightly while the tensile strain at break de- creases; the yield stress of ETFE foil increases a little but the second yield stress increases little; the yield strain of ETFE foil increases too but the second yield strain decreases slightly. It is also found that the tangent and the second Young＇s modulus of ETFE foil exhibit a descending trend while the secant and the third Young＇s modulus have no notable change when the extension speed increases. By analyzing the results of the tests, the linear fitting formulas to calculate the mechanical parameters of ETFE foil through using the logarithm of tensile strain rate as the variable are proposed.