线性低密度聚乙烯及其紫外光辐照交联材料老化特性研究

发布时间：2018-08-07 15:42

【摘要】：聚乙烯与交联聚乙烯由于其杰出的电学和力学特性而普遍应用于电缆绝缘领域,在现实运行过程中,电缆容易遭受热、电、机械、水等多种因素的影响使其绝缘性能逐渐劣化而产生绝缘老化,最终致使绝缘丧失。因此,研究电缆绝缘材料的老化因子作用下性能的变化,对检测、评估电缆运行状态及合理建立有效的评判方式来判断绝缘老化等方面具有重要的意义。本文以线性低密度聚乙烯(LLDPE)与紫外光交联聚乙烯(UV-Light XLPE)两种绝缘材料作为实验研究对象,以热、电作为单因子老化应力,探究实验材料在热、电老化因子作用下,其击穿场强、电导率、介电常数、损耗因数、断裂伸长率、拉伸强度等性能的变化,并根据实验结果分别建立合理的热、电老化模型。实验结果表明:在热老化实验初期,两种绝缘材料的击穿场强、电导率与力学性能出现较小程度的降低,介电常数、损耗因数出现微量的增大;随老化时间增加,原本稳定的大分子链断裂,产生许多小分子基团和氧化产物,导致击穿场强与力学性能出现显著下降,电导率、介电常数、损耗因数出现明显增大,电学性能与力学性能都受到严重的破坏作用,老化温度越高、时间越长遭受破坏越严重;两种实验材料性能参数变化规律基本一致的,存在一定程度的差异。根据两种材料的热老化数据分别建立热老化模型,校验发现UV-Light XLPE的耐热老化性能较好。电老化实验结果表明:在本文设定的电老化实验条件下,实验材料的击穿场强均下降;电导率、介电损耗均增大;断裂伸长率、拉伸强度出现微小的变化,可能电老化时间较短对力学特性的影响较小。结果发现UV-Light XLPE耐电老化性能较好,这一点可从建立的电老化模型得到验证。
[Abstract]:Polyethylene and crosslinked polyethylene are widely used in the field of cable insulation because of their outstanding electrical and mechanical properties. In the process of practical operation, cables are vulnerable to heat, electricity and machinery. The influence of water and other factors make its insulation performance deteriorate gradually and cause insulation aging, and eventually lead to insulation loss. Therefore, it is of great significance to study the change of performance under the action of aging factor of cable insulation material, which is of great significance in detecting, evaluating the running state of cable and establishing an effective evaluation method to judge insulation aging. In this paper, two kinds of insulating materials, linear low density polyethylene (LLDPE) and ultraviolet light crosslinked polyethylene (UV-Light XLPE), are used as experimental objects, and heat and electricity are used as single factor aging stress to investigate the breakdown field strength of the experimental materials under the action of thermal and electric aging factors. The electrical conductivity, dielectric constant, loss factor, elongation at break, tensile strength, and so on are changed. According to the experimental results, reasonable thermal and electric aging models are established respectively. The experimental results show that the breakdown field strength, conductivity and mechanical properties of the two kinds of insulating materials decrease slightly, the dielectric constant and loss factor increase slightly at the beginning of the thermal aging experiment, and with the aging time, the dielectric constant and the loss factor increase slightly. The previously stable macromolecular chain breaks, resulting in many small molecular groups and oxidation products, resulting in a significant decrease in breakdown field strength and mechanical properties, and a significant increase in electrical conductivity, dielectric constant and loss factor. The electrical properties and mechanical properties are seriously damaged, the higher the aging temperature, the longer the time is damaged, and the variation of the two experimental materials' properties parameters is basically the same, there is a certain degree of difference. According to the data of heat aging of two kinds of materials, the thermal aging model was established, and it was found that the heat aging property of UV-Light XLPE was better. The results show that the breakdown field strength decreases, the electrical conductivity and dielectric loss increase, the elongation at break and tensile strength change slightly. It is possible that the short time of electric aging has little effect on mechanical properties. The results show that UV-Light XLPE has better resistance to electric aging, which can be verified by the established model.
【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM215.1

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