Preparation Of Polyimides With Flexible Chain In The Main Chain And The Groping Application In Fabric

Polyimide is a special and excellent polymer. As a kind of macromolecule material, polyimide has marked thermal stability, excellent mechanical strength, electrical property, solvent-resistance and radiation-proof property, moreover, it can be prepared by many ways. Therefore, it is being widely used in many fields, such as aviation, spaceflight, electric, machine, chemistry industry and micro-electronics.This dissertation is based on the outstanding heat-resistant and radiation-proof properties of polyimide. In this dissertation, the Polyamide acids prepared were coated to the proper fabric successfully, through heating process, completed the cyclization. Finally, the anti-UV property, thermal behaviour and the mechanical property of the treated aramid fiber 1414 fabric were tested.At first, three diamines which contain flexible chain in the main chain, including 1,2-di(4-aminophenoxy)ethane, l,3-di(4-aminophenoxy)-propane and l,4-di(4-aminophenoxy)butane, were designed and synthesize. The synthesis can be performed through two phases. Firstly, the preparation of 1,2-di(4-nitrophenoxy)ethane, l,3-di(4-nitrophenoxy) -propane and 1,4-di(4-nitrophenoxy)butane through Williamson reaction;secondly, deoxidizing the compounds which contain two nitro-groups by hydrazine hydrate method. The three compounds were confirmed by !H NMR, MS and IR.Protected by nitrogen at room temperature, Polyamide acids were prepared by the condensation of 1,2-di(4-aminophenoxy)ethane, l,3-di(4-aminophenoxy)propane, 1,4-di(4-aminophenoxy)butane and diphenylether 3,3',4,4'-tetracarboxylic acid dianhydride, followed by the solution imidation, Polyimides thus obtained are insoluble in normal strong polar solvents. Prepare polyimide membrane by the Polyamide acids thermal-cyclization. It was observed that the polyimide membrane obtained have good thermal property and mechanical character.Coated aramid fiber 1414 foundation fabric with the polyamide acids and followed by a thermal imidization. The mechanical property, thermal behaviour and the anti-UV property of the treated aramid fiber 1414 fabric were tested, it was observed that the strength decreased, thermal resistance improved, and the anti-UV property obviously improved.