Preparation And Application Of Series Of Aromatic Polyimides

Aromatic polyimides have been proverbially accepted for their excellent chemicalstability and high mechanical properties, along with their eximious thermal stability andelectrical properties, compared to traditional polyamides (such as polyamide66). Because ofthese outstanding properties, their application in automobiles, precision machinery, medicaldevices, flexible printed circuit boards, adhesives, thin films, atomic energy industry, spaceindustry, military field.In this paper, a series of poly(amic acid)(PAA) has been synthesized from polymerizingpyromellitic dianhydride (PMDA),4,4’-oxydiphthalic dianhydride (ODPA) and1,4-pheny-lenediamine (PDA),4,4’-oxydianiline (ODA), respectively, by two-step method. Studies areconcentrated on the effects of the reaction conditions, such as order of added reagent,monomer ratio, reaction temperature, mass fraction of reaction system, reaction time, storageconditions on viscosity of the poly(amic acid), and the optimum synthesis conditions. Theexperimental results show that the optimum order of added reagent is positive feeding method,the optimum monomer ratio is1.00, the optimum reaction temperature is-15℃, the optimummass fraction of reaction system is13%, the optimum reaction time is4h. At the same time,the viscosity of poly(amic acid)s decreased with the increased storage time and storagetemperature.A series of poly(amic acid)s are imidization. Series of poly(amic acid) and polyimidemake test by FT-IR. The results showed that: polymer have been synthesized at the molecular.A series of poly(amic acid)(PAA) and polyimide (PI) thin film were compared andanalyzed for mechanical properties. Experimental data from this paper can be seenmechanical properties of polymer materials were influenced on their chain of elementalcomposition and spatial patterns. Polyimides which have the structure of aether and smallerangle are better mechanical properties, for the aptotic relative molecular weight of thematerial. The effect of both reaction time and temperature on imidization also was studied bydetection with FT-IR. The process of imidization was studied by detection with FT-IR. Theisothermal imidization shows a better effeciency of polyimides. And a series of poly(amic acid) used in electrospinning, using scanning electron microscopy test, is the series nanofibers.The poly(amic acid) solution, by using the high voltage electrospun device, posses excellentnanostructures. The poly(amic acid) nanofibers show smooth surface and uniform diameter.