Influence of compatibilizers on the water-tree property of Montmorillonite / Cross-linked polyethylene nanocomposites

In this paper, a series of Montmorillonite / Cross-linked polyethylene (MMT/XLPE) nano-composites were prepared though melting blend method, before which the MMT had been modified by Octadecyl ammonium. Two types of organic modifiers (EEA and EVA) were used to control the dispersion state of MMT in XLPE. X-ray diffraction (XRD) and scanning electron microcopy (SEM) were used to represent different influences of two organic modifiers on the dispersion of MMT Nano-additions in XLPE. The result shows the interlayer spacing of MMT has increased from 2.5nm to 3.6nm and 3.7nm by adding EEA and EVA, respectively, which devotes to the melt intercalation of MMT in XLPE. Accelerating water tree aging tests were performed on the nanocomposites and water trees were observed by a microscope. According to the result, it can be concluded that with the same addition of MMT, composites using EEA as organic modifier have an obvious decrease in water tree length (58.9% along the electrical field direction and 19.9% in vertical) compared with the XLPE sample. Besides, water tree length of composites using EVA as organic modifier has a decrease of 65.0% along the electrical field direction and 37.1% in vertical, which means EVA has a more remarkable contribution to the water tree retardant property of MMT/XLPE nanocomposites.