Study Of The Carbonization Behavior Of Polyimide Materials

Polyimide(PI)is well known in the field of high performance plastic materials and been studied intensively for its excellent thermal and mechanical properties.It has been used in a variety of industrial applications such as,aircraft parts,aerospace,electronic packaging,and matrix materials for composites.Polyimide and polyimide-based composites have been used for different high temperature applications and recently proposed to be used as secondary structures in space applications under high temperature.Motivated by the possibility of using polyimide composite/matrix,this work will focus on the study of the carbonization behavior of polyimide materials as follow:1.Characterization of the carbonization of polyimide/metal composite nfilms has been executed by the blending of iron complex with polyimide in a solution pre-prepared by poly(amic acid)(PAA)derived from pyromellitic dianhydride(PMDA)and 4,4-oxydianiline(ODA),in N,N-dimethylacetamide(DMAc)with incorporation of iron(Ⅲ)acetylacetonate(AAI).The carbonization was conducted in a temperature range of 600-1600 ℃.The carbonization process and the properties of the carbon films were carefully investigated and analyzed by X-ray diffraction technique(XRD),and scanning electron microscopy(SEM).2.Preparation,characterization,and thermal degradation of Polyimide(PMDA/ODA)/Fe composite films after the synthesis of the polyimide and the formation of Fe particles in the polyimide matrix.Kinetic parameters and thermal stability of the degradation process for the prepared polyimide/Fe composite films were investigated by TGA in N2 atmosphere.3.Characterization of the carbonization process of pol)imide/metal composite films,together with chemical structure change and formation of different metal catalyst in polyimide/metal composite films is executed by blending iron or nickel compound with polyimide in the pre-prepared solution by PAA derived from 3,3’,4,4’-biphenyltetracarboxylic dianhydride(BPDA)and p-phenylenediamine(PDA),in DMAc with incorporation of iron(Ⅲ)AAI or nickel acetate tetrah)drate and by subsequent carbonization.The carbonization process and the properties of the carbon films were also closely tracked and analyzed by X-ray diffraction technique(XRD)and scanning electron microscopy(SEM).The growth of ferrum complex and nickel clusters in the film occurs substantially during carbonization in the temperature range of 600 ℃-1600 ℃.4.Studying the behavior of the polyimide carbonization type by measuring the changes of properties(weight,size,and electrical conductivity,etc.).It was found that the metal complexes in the polyimide films promote the carbonization of polyimide matrix and also increase the electrical conductivity of the films.The combination of metal particles and carbon films was successfully acquired by the blending of polyimide and metal complexes.The change of iron complex and nickel clusters in the film occurred remarkably during carbonization in the temperature range of 600-1600 ℃,which is approved by SEM observations on the same films.The presence of the metal catalyst promoted the carbonization of polyimide matrix and resulted in high electrical conductivity.After treatment at 1600℃,there was almost the same conductivity for both the iron-and the nickel-containing carbon films,and carbon films derived from pure PI as a result of the improvement of the cry stallinity due to the reduction of iron compounds.The carbon films presented a ferromagnetic behavior with the help of iron during the carbonization process.Meanwhile,the strong interaction between Fe particles and polyimide matrix has obvious effect on the thermal transition behavior and magnetic properties of composites.To improve the properties of composites,it is important to control the uniform phase dispersion in polymer matrix as well as the interaction between different hybrid materials.Metal particles in carbon films bring about a transition behavior from paramagnetic to ferromagnetic.The composite films maintain the basic mechanical properties of the pristine polyimide film.The integration of iron particles in the carbon films was successfully obtained using polyimide and iron complexes,along with the structural change.This material can serve as a building block for the preparation of polyimide hybrid materials.