Study on Preparation and Breakdown Performance of Acetylated SEBS/PP

Abstract

Polypropylene (PP) is a kind of potential environmentally friendly insulation material with excellent heat resistance. However, due to its low temperature impact strength, it cannot be directly used in the production of high voltage cables. By filling the PP with elastomer, the problem can be improved, but the poor insulation properties of the elastomer significantly reduce the insulation performance of the composite system. The previous experimental results have showed that the voltage stabilizer can improve the electrical resistance of the insulating material. In this paper, through the acetylation reaction, under the premise of not destroying the SEBS macromolecular chain, using its inherent chemical structure, the acetyl group was introduced at the terminal styrene para-position to modify the acetophenone unit to make it a voltage stabilizer, so as to improve the breakdown field strength of the composite system. And the acetophenone molecule is fixed on the SEBS molecular chain, which avoids the migration of small acetophenone molecules in the polymer system, while maintaining the toughening function of SEBS. The infrared spectra showed that acetylated SEBS (Ac-SEBS) after acetylation had the functional group of acetophenone. The number of functional units in the Ac-SEBS was measured by <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> H NMR. PP was fused with Ac-SEBS to prepare PP/Ac-SEBS composites. The alternating current (AC) breakdown field strength and direct current (DC) breakdown field strength were tested to study the effect of the acetylation degree of Ac-SEBS on its compatibility with PP. The results showed that mixing Ac-SEBS into PP could effectively improve the Ac breakdown field strength and DC breakdown field strength of PP/SEBS. However, excessive acetylation would make the compatibility of PP/Ac-SEBS worse and the breakdown field strength would therefore decrease. In addition, when Ac-SEBS with an acetylation degree of 4.6% was fused with PP, the AC breakdown field strength and DC breakdown field strength were both the highest and slightly higher than that of pure PP. This work provides a new approach for the application of aromatic compounds as voltage stabilizers in insulation materials.