STRUCTURE-PROPERTIES RELATIONSHIP OF POLYIMIDES DERIVED FROM DIFFERENT COMPOSITION OF DIAMINES AND DIANHYDRIDES

摘要

As the most popular high performance, high temperature polymers, polyimides, such as poly (pyromellitic dianhydride-oxydianiline) (PMDA-ODA), are widely used as adhesives, coatings, composite matrices, films, fibers, foams, and membranes in a variety of applications due to their high glass transition temperature (T_g), low coefficient of thermal expansion (CTE), low dielectric constant and good mechanical properties. In this work, polyimide films with different composition of pyromellitic dianhydride (PMDA), benzophenonetetracarboxylic dianhydride (BTDA), 4,4-oxydianiline (ODA) and 1.4-phenylenediamine (PDA) are investigated. Aromatic polyamic acids (PAA) were synthesized from the aforementioned dianhydrides and diamines in polar aprotic solvent - N, N-dimethylacetamide (DMAc). The resulting PAAs were used to prepare films by thermal cyclo-dehydration of the amide-acid in a high temperature oven. The structure-property relationship of said polyimide films was studied with differential scanning calorimetry (DSC), Thermogravimetric Analysis (TGA), dynamicmechanical analysis (DMTA) and Thermomechanical Analysis (TMA). Mechanical property was then investigated by tensile tests.