Study On The Corrosion Behavior Of Polymer Materials In AlCl₃-EMIC Ionic Liquid

Ionic liquid shows a promising prospect in the fields of materials,chemistry,and biotechnology for its favorable physicochemical propties,such as negligible vapor pressure,low melting point,low viscosity and wide range of chemical processes.Polymer materials are expected to be used in the contact environment with ionic liquids due to their good mechanical properties and properties.Therefore,it is important to study the corrosion behavior of polymer materials in ionic liquid.In the present paper,the corrosion behavior of polymer materials,such as plastic,rubber and adhesive in AlCl3-EMIC was firstly studied by means of macroscopical examination and weight loss method,combined with SEM,ATR-FTIR and other characterization methods.Secondly,in order to explore the physical corrosion mechanism,the corrosion process of PP and UPE in AlCl3-EMIC ionic liquid was investigated through the change of weightlessness curve and corrosion morphology with time.At last,the cracking behavior of welded PP in AICI3-EMIC ionic liquid was studied,and the reason was analyzed.The results showed that PTFE did not corrode in AlCl3-EMIC ionic liquid.PP,HDPE,UPE,PEEK,PC and GFEP physically corroded in AlCl3-EMIC ionic liquid.PVC,CPVC and PVDF chemically corroded in AlCl3-EMIC ionic liquid.According to the classification of corrosion grade,PTFE was completely resistant.PC and GFEP were very corrosion resistant.PEEK and PVDF were corrosion resistant.PP,HDPE,UPE,PVC and CPVC were still corrosion resistant.Among the rubber,NBR had good resistance,while butyl rubber and silicone rubber had poor resistance.Among the adhesive,expoxy adhesive had better resistance,while adhesive tape,insulating adhesive and 502 adhesive had worse corrosion resistance.PP and UPE were both physical corrosion processes that swelled first and then dissolved in AlCl3-EMIC ionic liquid.The corrosion of PP in AlCl3-EMIC was divided into two linear stages:the corrosion rate was about 0.086mm/a within 14 days,the corrosion rate was approximately 0.174mm/a afer 14 days.The change of corrosion morphology was as follows:firstly appeared holes,then appeared flaky warps,and finally mainly appeared as pits.The corrosion of UPE in AlCl3-EMIC was also divided into two linear stages:the corrosion rate was about 0.033mm/a within 14 days,the corrosion rate was approximately 0.13 mm/a after 14 days.The change of corrosion morphology was as follows:firstly the holes appeared,then the flaky warps appeared,and finally the fiber morphologies appeared.Welded PP would would undergo cracking during immersion in the ionic liquid.The cracks perpendicular to the weld direction originated in the heat affected zone and were distributed along the welding joint and in the heat affected zone.The cracking was a type of environment stress cracking caused by the joint action of physical corrosion and welding inernal stress.The main stress causing the cracking was the flow induced residual stresses arise during welding.The cracking of welded PP would not occur after heat treatment at 110 ? for 1 h.