Study On Synthesis And Application Of Polyimide From By-product Of Chlorination Of Phthalic Anhydride

Polyimide(PI)is heat-resistant,acid-alkali-resistant,radiation-resistant,and does not produce toxic substances,so it has no "three wastes" pollution to the social environment;it is widely used in aerospace,electronic machinery,circuit components and precision manufacturing and other high-tech fields.But there are also many disadvantages of PI,such as insoluble in organic solvents,high melting point,high forming pressure,complex synthesis process and harsh conditions.Its application is limited in many aspects.Therefore,finding a suitable synthesis method and modification of PI has become the main research direction.Based on the related research work at home and abroad,a new route to synthesize polyimide was put forward.Polyimide was synthesized from chlorinated by-product of phthalic acid(4-chlorophthalic anhydride)through salt formation,melting and polymerization in aqueous phase.The first key step was to replace high boiling point organic solvent with water to save cost and reduce reaction conditions.In order to achieve maximum utilization of resources.Polyimide was synthesized from halogenated aromatic rings,focusing on the improvement of synthesis process,the improvement of conversion and product selectivity,the improvement of purity of polymer products,the reduction of impurities in the reaction on products and equipment,and the further optimization of reaction conditions to promote the realization of efficient and green chemical industry.In addition,two kinds of polyimide-biphenyl polyimide and thioether polyimide were designed in this paper.The influencing factors of the synthetic route were explored and the optimum technological conditions were obtained.The structure and properties of the monomers were characterized by infrared,aggregated structure,thermal properties,molecular weight,viscosity and solubility.The obtained monomers conform to the design criteria.The thermal weight loss temperatures of 5%biphenyl polyimide and thioether polyimide were 390 ~425 ~C,the glass transition temperatures were 244 ~C and 198 ~C,the dispersion coefficients of PDI measured by GPC were 1.68 and 2.3 respectively,and the intrinsic viscosities measured by viscometry were 0.36 and 0.41,respectively.And the solubility is improved,the thermal stability is stable,which broadens a new path for the synthesis of polyimide in thefuture.