Preparation and Characterization of Five Amino-Modified Hyper-Crosslinked Polymers and Performance Evaluation for Aged Transformer Oil Reclamation

Adsorption is intensively considered to be the most feasible and economical option for aged transformer oil treatment. In this work, five aminated hyper-crosslinked polymers were prepared from chloromethylated polystyrene–co-divinylbenzene (Cl-PS-DVB) through a two-stage modification of crosslinking and five different reagents aminating. After modification, the specific surface area (SBET) and nitrogen content (CN) of prepared resins were greatly improved. To evaluate the reclamation performance of resins for removing oxides and contaminants from aged transformer oils, the total acid number (TAN) and color of oils were mainly examined. The results shown that the prepared resins have superior oil reclamation capacity compared to commercial resin XAD-4 due to their higher microporous specific surface area (Smic) and surface polarity. Among them, the NHC-R3, which used dimethyltriamine (DETA) as an aminating agent, had the best deacidification and decolorization performance. A series of experiments were designed to investigate the optimal regeneration program conditions for NHC-R3, and the additional electrical characteristics of the reclaimed oil, including breakdown voltage, dielectric dissipation factor (DDF), and interfacial tension, were measured as evidence that aged oil was successfully reclaimed.