Effect of Sample Preparation on Water TreeResistance of XLPE/SEBS Blends

The effects of an aromatic polymer, such as poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS), and its preparation processes on water tree resistance,morphology, crystallinity, dielectric constant and dielectric loss tangent of crosslinkedpolyethylene (XLPE)/SEBS and XLPE/SEBS/ethylene vinyl acetate (EVA)blends were investigated. The XLPE/SEBS samples were characterized by means ofdifferential scanning calorimetry, scanning electron microscopy, dielectric spectralanalysis and the accelerated water treeing experiment. The results clearly showed thatalthough SEBS was partially compatible with LDPE and it was dispersedevenly in XLPE matrix, the blends demonstrated excellent dielectric performances,such as dielectric constant and dissipation factor. The crystallinity of XLPE/SEBSblends was decreased with increase in SEBS content and it was further decreased withthe addition of EVA. SEBS could effectively improve the water-tree resistance of XLPEand both SEBS and EVA were found to improve the water tree resistance of XLPEsynergistically as expected. The differences in sample preparation processes couldchange the phase morphology and dielectric performance of the blends, and could alsoinfluence the dispersion of SEBS in XLPE matrix as well as the crystallinity of theblends. Different preparation processes led to different water tree resistancebehaviours of the samples. The improvement of SEBS dispersion in XLPE matrixhelped to improve the water tree resistance of XLPE.