辐照交联低烟无卤阻燃电缆受潮后性能研究

Study on Performance of Moistened Irradiation Crosslinking Low-smoke Halogen-free and Flame-retardant Cable

为了研究光伏电缆用辐照交联低烟无卤阻燃绝缘层和护套层受潮前后的性能变化,对不同浸水时间的电缆绝缘层和护套层进行了力学性能、热延伸率、动态热机械分析(DMA)、傅里叶变换红外光谱(FTIR)和体积电阻率测试。结果表明:长期的浸水会造成材料内部的分子链水解,分子链间的缠结作用减弱,导致试样的力学性能下降;浸水后,绝缘层和护套层试样的起始储能模量减小,填料微粒与基体树脂间粘附力降低,绝缘层试样的力学损耗峰呈现双峰特征;随着受潮程度的不断加深,聚烯烃基体中EVA吸水溶胀,自由体积增大,部分阻燃填料脱离基体的束缚,充当了杂质离子,使载流子浓度增大,迁移率提高,导致体积电阻率持续降低。

In order to study the performance changes of irradiation crosslinking low-smoke halogen-free flameretardant insulation layer and sheath layer for photovoltaic cables before and after getting moistened, the insulation layer and sheath layer of photovoltaic cable with various water-immersion time were conducted mechanical properties, thermal extensibility, dynamic thermomechanical analysis(DMA), Fourier transform infrared spectroscopy(FTIR), and volume resistivity tests. The results show that the long-term water-immersion causes hydrolysis of molecular chains in the material, and the entanglement of molecular chains weakens, which lead to decrease of tensile properties of samples. After water-immersion, the initial storage modulus of the insulation layer and sheath layer samples decreases, the adhesion force between filler particles and matrix resin decreases, and the mechanical loss peak of the insulation layer presents double peaks characteristic. With the increase of moistening degree, the EVA in the polyolefin matrix swells, and the free volume increases. Some flame retardant fillers are separate from the binding of matrix and become impurity ions, making the carrier concentration and mobility increase, which leads to continuous decrease of volume resistivity.