Synthesis Of Poly(Imide-Benzoxa Zole) And Analysis Of Their Fiber's Structures And Properties

Poly(imide-benzoxazole) is a kind of heterocyclic polymers that exhibit excellent thermal stability and superior chemical resistance. Besides these, they also have high mechanical properties and good electrical properties. They are widely used in high-performance applications, such as butter coatings and interlayer dielectric materials in the semiconductor industry. They are also used for matrix resins, high modulus fibers, and structural adhesives in the aerospace industry.In this paper, three kinds of poly(imide-benzoxazole) were synthesized respectively after three kinds of diamine which contain benzoxazole unit were synthesized in PPA in a one-pot reaction respectively. Three kinds of diamine were characterized with FT-IR, 1H-NMR, 13C-NMR, elemental analysis. It has been showed that three kinds of diamine were synthesized with high purity and yield. The study of PIBO polymerization was conducted widely in which many factors influencing PIBO polymerization were discussed, and FT-IR, elemental analysis and viscosity methods were used to characterize structure and molecular weight of PIBO. It has been made clear that the temperature and the concentration of P2O5 in the PPA were the key factors determining whether PIBO polymer with high molecular weight could be obtained successfully or not. Moreover PIBO thermal resisting property was evaluated by means of thermogravimetric analysis. It has been showed that the thermal decomposing temperature was up to 615℃, which suggested that it have excellent thermal stability.The solution of poly(imide-benzoxazole) in PPA was used for a spinning dope, fibers were prepared by dry-jet wet spinning. Mechanical properties of PIBO fiber were characterized by means of tensile property measurements. It has been showed that tensile strength of PIBO fiberⅠ, PIBO fiberⅡ, PIBO fiberⅢup to 2.2GPa, 2.4GPa,0.7GPa respectively. In addition, the SEM was used to analyze the surface and the lateral section of the fiber, which has been showed that the surface is quietly smooth, and a skin-core structure and some insoluble monomer were observed.