Study On Preparation And Properties Of Polyimide/SiO₂ Hybrid Materials

Polyimide as a high-performance polymer materials are widely used in various fields,while polyimide has excellent comprehensive performance but there are some drawbacks.Polyimide has significant water absorption and thermal expansion,because of the spinning process,which makes the polyimide fiber strength,modulus and thermal properties significantly decreased.In this paper,we synthesized PI matrix with pyromellitic dianhydride?PMDA?and 4,4'-diaminodiphenyl ether?ODA?as monomer materials.We obtain the polyimide film hybrid and hybrid fibers by sol-gel method and in situ dispersion method,The hybrid materials were characterized and analyzed by Scanning electron microscopy?SEM?,Fourier transform infrared spectroscopy?FR-IR?,UV-visible spectrometer?UV-VIS?,thermal gravimetric analyzer,x-ray diffractometer?XRD?,electronic universal testing machine,electronic yarn strength tester and so on.Nano-silica uniformly dispersed in the PI/SiO₂ hybrid films,particle size is uniform and two-phase compatibility is good.For the optical properties of hybrid film,the transmittance of the film prepared by in situ dispersion method is better than the film prepared by sol gel method.When the silica content is 5%,the moisture absorption resistance of the film is preferably.The tensile strength and elastic modulus of hybrid films prepared by sol-gel method is better than the pure polyimide film increased by 200MPa and 3.2GPa at 7wt%silica content.When the silica content is 9%,the 10%weight loss temperature increased nearly 50?than the pure polyimide film.When silica content is at 7wt%in the hybrid film prepared by in situ dispersion method,tensile strength and elastic modulus is up to 192MPa and 4.8GPa.Polyimide/SiO₂ hybrid fiber is dense inside and there is on holes inside.When the silica content is 7%,the tensile strength and elastic modulus of pure polyimide fibers were increased by nearly 400MPa and2GPa.When the silica content is 9%,the 10%heat loss temperature of hybrid fiber increased nearly 40?than pure polyimide fibers.The tensile strength and elastic modulus of hybrid films prepared by by in situ dispersion method is better than the pure polyimide film increased by140MPa and 4GPa.When the silica content of 9wt%,the 10%weight loss temperature reaches 600?,improved by 37?than pure polyimide.The results show that it can effectively improve the tensile strength,elastic modulus,heat resistance and moisture absorption resistance of polyimide by organic-inorganic hybrid way.