Investigation On Electrical Treeing Spreading Characteristics In Polyethylene By Nano-montmorillonite Modulation

The phenomenon of electrical trees in polymeric affects application rangeand ageing life of insulation material seriously, which has been widely paidattention to treeing cause in domestic and international researchers. A variety ofmethods inhibiting the inception and spreading of electrical trees in polymericinsulating material are attempted in order to improve its insulation properties.Adding nano particles into polymer insulation could improve its dielectricproperties, meanwhile electrical aging causing by electrical trees will be retarded.The modulation mechanism of interface is taking as the core elements,intercalation process and surface modification are used to treat theMontmorillonite (MMT). Under acidic conditions, using intercalation agent andcoupling agent in union to treat the MMT. Nano montmorillonite/polyethylene(MMT/PE) composites are prepared via melting intercalation method while lowdensity polyethylene (LDPE) is as polymer matrix.Infrared spectroscopy, space charge testing and PLM are utilized to studythe modulation effect of MMT on micro-domain structure and electricalproperties, electrical trees test is utilized to study the performance of electricaltrees in different content of organic montmorillonite samples, the picoammetertest system is used to study the conductance changes of current situation beforeand after the electrical trees generation simultaneously. Experimental resultsshow that the performance of resistance to electrical treeing in compositematerial of MMT/PE adding appropriate montmorillonite has improved, becauseof uniformly dispersed of MMT and good interfacial bonding with polyethylene.The length of electrical tree branches is short in composite that0.5wt%and1wt%content of montmorillonite, as well as the density and fractal dimension is increase. The length of electrical tree branches and the dispersion of the fractaldimension and shape is increase, since montmorillonite produce reunion in thecomposite material with3wt%and5wt%content. The conductive current insample of polyethylene containing electrical trees decreases, because ofconductive characteristics of electrical trees and shielding effect of the spacecharge. The changing of the shape and conductive characteristics of the electricaltrees, make the conductive current increases after electrical trees produce inMMT/PE composite. The D/L and the fractal dimension of electrical trees affectthe changing of conductive current in material.