为了降低直流电缆绝缘材料的电导率,并提升电导率及直流击穿场强的温度稳定性,同时改善绝缘的高温力学性能,文中引入低交联度线性低密度聚乙烯(linear low density polyethylene,LLDPE)作为直流电缆绝缘材料。文中对比添加不同含量过氧...为了降低直流电缆绝缘材料的电导率,并提升电导率及直流击穿场强的温度稳定性,同时改善绝缘的高温力学性能,文中引入低交联度线性低密度聚乙烯(linear low density polyethylene,LLDPE)作为直流电缆绝缘材料。文中对比添加不同含量过氧化二异丙苯(dicumyl peroxide,DCP)的LLDPE和低密度聚乙烯(low density polyethylene,LDPE),通过热延伸、动态热机械测试及拉伸试验分析其力学性能,并测试直流电导率和直流击穿场强。结果表明,DCP质量分数为0.7%~2.0%范围内,交联LLDPE具有更低的热延伸率,DCP质量分数为0.7%即可满足高压直流电缆对交联聚乙烯(crosslinked polyethylene,XLPE)热延伸率的要求。由此结果,结合减少副产物的目的,选出DCP质量分数为0.7%的LLDPE作为传统XLPE(DCP质量分数为2.0%的LDPE)的对比及替代绝缘材料。动态热机械测试(dynamic mechanical analysis,DMA)及拉伸试验验证了DCP质量分数为0.7%的LLDPE比传统XLPE拥有更高的杨氏模量及断裂伸长率;电导率及直流击穿实验表明前者在30~90℃拥有更低的电导率及更优的电导率和直流击穿场强的温度稳定性。由于实际电缆中的交联副产物难以脱尽且分布不均,严重影响电缆长期安全运行,可考虑将DCP质量分数为0.7%的低交联度LLDPE用作直流电缆绝缘材料,从而在满足高温机械性能的同时降低直流电导率并增强电导率的温度稳定性。展开更多
The oxygen-contained groups such as C—O,C—OH,CO,C(O)O and C(O)OH are introduced onto the molecular chains of linear low density polyethylene(LLDPE) through ultraviolet irradiation at environmental temperature of 70 ...The oxygen-contained groups such as C—O,C—OH,CO,C(O)O and C(O)OH are introduced onto the molecular chains of linear low density polyethylene(LLDPE) through ultraviolet irradiation at environmental temperature of 70 ℃ in air without adding any additives.The concentration of these groups increases with the iucrease of irradiation time.The gel appears in irradiated LLDPE,the gel content increases with the iucrease of irradiation time.The melt flow index decreases and reach minimum when the irradiation time is 24 h,and then increase.The interfacial adhesion between irradiated LLDPE and polyamide 66(PA66) and the mechanical properties of the PA66/irradiated LLDPE(80/20) blends are improved owing to the oxygen-contained polar groups introduced.Compared with those of PA66/LLDPE(80/20) blends,the tensile strength,Young′s modulus,bending strength and notch impact strength of PA66/irradiated LLDPE(80/20) blends for 24 h are increased from 48.3,908,64.8 MPa and 31 J/m\ to 62.0,984,83.1 MPa and 85 J/m,respectively.展开更多
文摘为了降低直流电缆绝缘材料的电导率,并提升电导率及直流击穿场强的温度稳定性,同时改善绝缘的高温力学性能,文中引入低交联度线性低密度聚乙烯(linear low density polyethylene,LLDPE)作为直流电缆绝缘材料。文中对比添加不同含量过氧化二异丙苯(dicumyl peroxide,DCP)的LLDPE和低密度聚乙烯(low density polyethylene,LDPE),通过热延伸、动态热机械测试及拉伸试验分析其力学性能,并测试直流电导率和直流击穿场强。结果表明,DCP质量分数为0.7%~2.0%范围内,交联LLDPE具有更低的热延伸率,DCP质量分数为0.7%即可满足高压直流电缆对交联聚乙烯(crosslinked polyethylene,XLPE)热延伸率的要求。由此结果,结合减少副产物的目的,选出DCP质量分数为0.7%的LLDPE作为传统XLPE(DCP质量分数为2.0%的LDPE)的对比及替代绝缘材料。动态热机械测试(dynamic mechanical analysis,DMA)及拉伸试验验证了DCP质量分数为0.7%的LLDPE比传统XLPE拥有更高的杨氏模量及断裂伸长率;电导率及直流击穿实验表明前者在30~90℃拥有更低的电导率及更优的电导率和直流击穿场强的温度稳定性。由于实际电缆中的交联副产物难以脱尽且分布不均,严重影响电缆长期安全运行,可考虑将DCP质量分数为0.7%的低交联度LLDPE用作直流电缆绝缘材料,从而在满足高温机械性能的同时降低直流电导率并增强电导率的温度稳定性。
文摘The oxygen-contained groups such as C—O,C—OH,CO,C(O)O and C(O)OH are introduced onto the molecular chains of linear low density polyethylene(LLDPE) through ultraviolet irradiation at environmental temperature of 70 ℃ in air without adding any additives.The concentration of these groups increases with the iucrease of irradiation time.The gel appears in irradiated LLDPE,the gel content increases with the iucrease of irradiation time.The melt flow index decreases and reach minimum when the irradiation time is 24 h,and then increase.The interfacial adhesion between irradiated LLDPE and polyamide 66(PA66) and the mechanical properties of the PA66/irradiated LLDPE(80/20) blends are improved owing to the oxygen-contained polar groups introduced.Compared with those of PA66/LLDPE(80/20) blends,the tensile strength,Young′s modulus,bending strength and notch impact strength of PA66/irradiated LLDPE(80/20) blends for 24 h are increased from 48.3,908,64.8 MPa and 31 J/m\ to 62.0,984,83.1 MPa and 85 J/m,respectively.
