Purification And Structure Research Of UHV Polyethylene Cable Materials

Widely used in industrial production and daily life,cable which plays a very important role in the infrastructure construction refers to a kind of cable product that is used to transmit electricity and distribute power.However,the key technology of the ultra-high voltage cable with the range of 110-750kV is currently controlled by foreign companies which means impossible to fully make this cable in China although the demand of this cable is large and the usage is widespread.Especially,due to the technical limitation,the super clean XLPE insulant for ultra-high voltage cables is all imported and little research in China has been done.What’s more,foreign companies have blockaded the information of raw materials fabricating ultra-high cable,so we cannot get the basic resins for research except for the product.Therefore,the first step of this work was to wash and purify five purchased high-voltage cable products.Two cleaning methods were designed.Method A was the general alcohol washing step and method B added one smashing step in addition to method A.The test of weight,melting index,gel content and DSC of the washing products showed that only method B can remove the additives and obtain pure raw materials.Next,we studied the microstructure of the cleaned and washed cable material.Firstly,GPC results showed that the number-average molecular weight(Mn)of the five samples was close but the molecular weight distribution was quite different.And D sample,made in China,had little difference with the foreign mainstream products on molecular weight and distribution.Then,the DSC curves of five kinds of samples were made.The short branched structure was analyzed by investigating the crystallization behavior of the polymer,and it was found that the crystallization ability was worst for the samples made in China.Continuous self-nucleation and annealing classification method was used to correlate the thermal behavior of materials and their short branched chain structure.SSA thermal classification experiment was performed to obtain the details of the short branched chain structure based on the result of self nucleation experiment.The thermal classification parameters showed that the crystallization performance of the samples made domestically was the worst with the lowest melting point of the main melting peak while the crystallization ability of the imported samples(C-2)was the best,with lower short chain content and more regular chain structure.And this sample was selected for subsequent detailed structural analysis.