ETFE薄膜低温单向拉伸性能

Uniaxial Tensile Properties of ETFE Film at Low-Temperature Condition

在20^-100℃下进行ETFE(乙烯-四氟乙烯共聚物)薄膜单向拉伸性能试验.结果表明:当温度降低至-40℃以下时,ETFE薄膜应力-应变曲线在强化前由明显的两折线几乎变成连续的曲线.随着温度的降低,ETFE薄膜第一屈服点应力、第一屈服点应变、第二屈服点应力和抗拉强度均呈近似线性升高趋势,破断延伸率呈近似线性降低趋势,而第二屈服点应变变化幅度不大.与常温(20℃)相比,低温下ETFE薄膜的抗拉强度有较大提高,而延性则明显降低.在温度从20℃降低至-100℃过程中,ETFE薄膜割线模量变化幅度在10%以内,因此工程设计中可以忽略低温温度变化对ETFE薄膜割线模量的影响.

Uniaxial tensile properties tests of ETFE film were carried out from 20 ℃ to --100 ℃. The test results show that the stress-strain curve of ETFE film is nearly a continuous curve before the second yield point at low temperature （≤ -- 40 ℃） while it is two straight lines at normal temperature（20 ℃）. The stress at the first yield point, the strain at the first yield point, the stress at the second yield point and the tensile strength of ETFE film show a nearly linear increase with decreasing temperature. The breaking e longation of ETFE film shows a nearly linear decrease with decreasing temperature. The strain at the sec- ond yield point changes a little with decreasing temperature. Compared with that at normal temperature （20 ℃）, the tensile strength of ETFE film has improved greatly and the ductility of ETFE film has de- creased obviously at low-temperature. When temperature changes from 20 ℃ to --100 ℃ ,the change am- plitude of secant elastic modulus of ETFE film is less than 10℃ and can be ignored for engineering design.