“110th Anniversary:” Interactions of Bis(1-methyl-1-phenylethyl) Peroxide with the Secondary Antioxidant Bis(octadecyloxycarbonylethyl) Sulfide: Mechanistic Studies Conducted in Dodecane as a Model System for Polyethylene

Abstract

Cross-linked polyethylene (XLPE) is an important class of materials with critical applications including pipes and high voltage electric cables. An organic peroxide such as bis(1-methyl-1-phenylethyl) peroxide (BMPEP) is a commonly used radical initiator in the cross-linking process along with a secondary antioxidant such as bis(octadecyloxycarbonylethyl) sulfide (BOCES). Herein is described a detailed investigation into the complex interactions of the radical initiator BMPEP and the secondary antioxidant BOCES in dodecane solvent–a model for the polyethylene polymer. Kinetic and spectroscopic experiments along with DFT calculations provide the foundation for a detailed mechanistic description for the roles of BMPEP, BOCES, atmospheric oxygen, and trace amounts of water in the overall process.