Synthesis And Modification Study Of Terpolymer Polyamide-imide Adhesive

Polyamide-imide（PAI）adhesives have broad prospects in microelectronics,aerospace and other fields due to their excellent comprehensive properties.However,the PAI adhesive prepared by the traditional diisocyanate method has the problems of insufficient adhesive strength and strong water absorption,which restrict its application in high-end fields.Based on this,three dianhydrides containing biphenyl,ether bonds and ketone groups in the structure are used in this paper:3,3’4,4’-biphenyltetracarboxylic dianhydride（BPDA）,4,4’-diphenylether dianhydride（ODPA）and 3,3’4,4’-benzophenone tetracarboxyl Acid dianhydride（BTDA）.They were introduced into the polymerization system respectively,and terpolymerized with 4,4’-methylene diisocyanate（MDI）and 1,2,4-mellitic anhydride（TMA）to prepare PAI adhesive.The effects of three dianhydrides on the adhesive properties were investigated.In order to further improve the bonding strength,organic sericite modified PAI adhesive was used on this basis.The main conclusions are as follows:（1）BPDA/TMA-MDI type PAI has advantages in thermal properties and hydrophobicity,but the adhesive properties remain basically unchanged and the damping properties decrease;ODPA/TMA-MDI type PAI can slightly improve the adhesive performance and hydrophobicity of the adhesive,but the damping performance is basically unchanged and the thermal performance is decreased;BTDA/TMA-MDI type PAI has significant advantages in improving the adhesive properties of adhesives,and at the same time can slightly improve the thermal properties,damping properties and hydrophobicity of the adhesives.（2）The content of the three dianhydrides has a certain influence on the tensile properties,thermal properties,damping properties,water absorption properties and adhesive properties of PAI.After comparison,it is found that when the molar ratio of BTDA:TMA:MDI is 0.05:0.95:1.05,the T₅ of PAI is 471℃,T₁₀ is 498℃,Tg is 270℃,the water absorption rate is 1.77%,and the adhesive strength is 18.81 MPa.Compared with binary copolymer PAI,it has an increase of 34.2%,and has good adhesion performance.（3）Intercalation modification can expand the interplanar spacing of sericite to 3.27 nm,so that the PAI molecular chain is successfully inserted into the lamellar structure of sericite,and the organic sericite modified PAI adhesive with good dispersibility is prepared.Organic sericite can effectively improve the bonding properties of PAI adhesives.When the content of organic sericite is 5wt%,the bonding strength of modified PAI adhesives is 23.12 MPa,which is 22.9%higher than that of BTDA/TMA-MDI type PAI.Compared with binary copolymer PAI,it is 64.9%higher,T₅ is 472℃,T₁₀ is 504℃,water absorption rate is 1.79%,and it has good comprehensive performance.39 figures,17 tables and 92 references...