Study On The Molecular Structure Of Acid Anhydride On The Insulation Performance In Epoxy Resin-Anhydride System

Basin-type insulators are key insulation components in GIS systems,a few of flashover accidents of such basin-type insulators happened,the safety of the power grid was threatened.Basin-type insulators are made by casting and curing epoxy resin composite materials,the insulation performance is determined by this material.The electrical epoxy resin materials are usually prepared with epoxy resins,acid anhydride curing agents,and some additives.The cross-linked network structure of epoxy resin materials with different molecular structures is very different,resulting in differences in insulation and other properties.In addition,curing defects such as bubbles,contraction cavities are one of the main reasons for insulators causing surface flashover failures.Study the insulation properties of EP/acid anhydride systems with different molecular structures,and prepare epoxy resin materials with low curing defects,are closely matched the current development requirements for insulation safety in electrical industry.The main researches of this paper are as follows:?1?To study the influence of anhydride molecular structure on the insulation performance of epoxy materials,several anhydride curing agents with different molecular structures were used to prepare several epoxy resin/acid anhydride systems,and the insulation performance of these systems was tested.The results show that in the molecular structure of MNA,Me-THPA,and Me-HHPA,the-CH₃ and the carbon atom of carboxylic acid are close to each other,the steric hindrance was increased.So epoxy resin materials prepared by these curing agents have a compact structure.It is benefit to form deep traps in epoxy materials multi-action zone model,and the insulation performance is better.?2?To study the effect of the dosages of anhydride curing agent on the insulation performance of epoxy/anhydride system,several epoxy resin materials prepared with different dosages Me-THPA,the insulation and other properties were tested.The result show that epoxy resin/Me-THPA materials prepared with the amount of Me-THPA was90%,100%?calculated value?,and 110%,has the best Tg,insulation performance and mechanical strength.The reason was-CH₃ account was large in the molecular structure of epoxy resin materials prepared by these amounts of Me-THPA.?3?In this paper,Me-THPA was used to extend the molecular chain of a liquid epoxy resin to prepare epoxy resin composite materials with low curing exothermic rates,and the insulation and other properties were tested.The results showed that chain-extended epoxy resin had low curing exothermic rates were due to the generation of-C=O in the molecular structure of the chain-extended resin.The curing exotherm rate of the chain-extended EP reduced.The insulation performance of chain-extended EP/Al₂O₃systems was effectively improved.With the increase of the chain extension molar ratio of EP/Me-THPA,the insulation performance was further improved.FTIR show that the content of–C–O in the chain-extended epoxy resin composite materials was decreased.The-C-O is unstable structure,the contents reduction are benefit to improve the insulation performance.SEM show that the curing defects forming in the composite materials were inhibited.