Water‐tree aging characteristics of chloroacetic acid allyl ester grafted crosslinked polyethylene

Abstract

To investigate the inhibition effect of chloroacetic acid allyl ester (CAAE) grafting modification on water‐tree aging in crosslinked polyethylene (XLPE), CAAE grafted XLPE (XLPE‐g‐CAAE) with different CAAE contents are prepared by melt blending and grafting modification method. The accelerated water‐tree aging experiments are carried out by the water‐blade electrode method. It is found that XLPE‐g‐CAAE has a great inhibitory effect on the water‐tree aging compared to XLPE, and XLPE‐g‐CAAE with 1.0 phr CAAE has the most significant effect on the water‐tree growth in the scope of the study. The microstructure of XLPE and XLPE‐g‐CAAE is investigated by thermal elongation, gel content, and static water contact angle, respectively. The results show that the grafting of CAAE containing polar groups can enhance the polarity of XLPE and improve the hydrophilicity, which has a dispersing effect on the polar water molecules entering the polymer. Thus, the water molecules are not easy to gather, inhibiting the water‐tree growth. Meanwhile, although the mechanical properties of XLPE‐g‐CAAE decrease to a small extent, and the relative dielectric constant and dielectric loss factor increase slightly, but the performance still meet the requirements of water‐tree resistance XLPE cable insulation.Highlights CAAE with polar groups was successfully grafted onto XLPE. The polar groups can enhance the polarity of XLPE to improve the hydrophilicity. CAAE grafting can inhibit the water‐tree growth in XLPE. The dielectric properties meet the requirements of water‐tree resistance XLPE.