| Low-density polyethylene(LDPE)is an insulating plastic widely used in cables.It has been widely used due to its excellent electrical properties and processing properties.In particular,it is a cross-linked polyethylene produced as a base material and is widely used in DC cables.Because of the long transmission distance and large transmission capacity,medium and direct-current cables have been used more and more widely.Antioxidants are indispensable additives in low-density polyethylene,which has the effect of retarding the aging and oxidation of low-density polyethylene.Can significantly improve the life of low-density polyethylene,the addition of antioxidants will affect the space charge and conductance characteristics of low-density polyethylene,at present,under the same antioxidant effect,which antioxidant can be added There is no systematic assessment of the good space charge distribution and conductivity properties of LDPE.Based on the above reasons,an antioxidant/LDPE composite medium was prepared by melt blending.The antioxidant effect of antioxidant 300,antioxidant 1010,antioxidant 1035,and antioxidant 1010/168 was evaluated by oxidation induction period.Measure the oxidation induction period of different antioxidants at different concentrations,and perform nonlinear fitting using the ExpAssoc fitting formula to obtain a continuous change in the induction period of oxidation,and ensure that the oxidation induction period is at the same time.The proportions of different antioxidants were added.Under the new additive ratio,the oxidation induction period was ensured to be 50 min and 90 min.The space charge and conductance characteristics of the composite media were measured and evaluated.The results showed that the addition of antioxidants would make The increase of space charge accumulation,the higher the concentration of antioxidants,the higher the space charge accumulation.Among them,the increase of antioxidant 300 is the smallest and the increase of compound antioxidant 1010/168 is the largest.The addition of antioxidants will increase the conductivity of LDPE.The higher the content of antioxidants,the higher the increase of conductance.The addition of antioxidants will increase the activation energy of the composites,and the composite medium containing antioxidant 300 will increase.With a small degree,the addition of antioxidants will increase the conductivity activation energy of LDPE materials,in which the addition of antioxidant 300 has little effect on the activation energy of LDPE,and the activation energy of LDPE with the addition of composite antioxidant 1010/168.most influential.The experimental results obtained in this paper have certain practical significance for the selection and addition of antioxidant additives in UHVDC cables. |
