The Preparation Of High Tensile Strength Of Biphenyl Polyimide By Tape Casting And The Surface Modification Research

Polyimide(PI) is one of the superior overall performance polymer materials. Because of the outstanding mechanical property, high temperature resistance, chemical resistance, radiation resistance, low dielectric constant, low thermal expansion coefficient, and so on, PI has been widely used in many special fields, such as aircraft and aerospace industries, machinery, electronics, chemistry and other fields.This paper selects 3,3’,4,4’-Biphenyldianhydride(BPDA) and phenylene diamine(p-PDA) as monomers, and synthesizes the BPDA-p-PDA PI precursor polyamic acid (PAA) solution through polymerization at room temperature, ultrasound-assisted polymerization at room temperature, ultra-low temperature polymerization these three ways, then imidizes PAA into biphenyl PI film by heating process. In order to enhance the application performance of the optimal performance of high tensile strength of biphenyl PI film synthesized via ultra-low temperature polymerization, we modify their surface using alkaline and acidic solution, ethylene diamine/methanol solution, and hexamethylenediamine/ethylene glycol solution. The modified effect are studied by surface performance test, and compare peel strength of modified PI films to copper foils for flexible copper clad laminates(FCCL). The structure, the thermal property, the crystallization behavior, the surface, and the mechanical property of PAA, unmodified and modified PI films, and peel strength of FCCL are characterized by fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS), thermogravimetric(TG), polarizing microscopy, X-radial diffractometer(XRD), scanning electron microscopy(SEM), atomic force microscopy(AFM), static contact angle measurement, and tensile tests.The results show that:of the three ways synthesized BPDA-p-PDA PI, the ultra-low temperature synthesized PI film has the superior overall performance. The PI derived from PAA which is reacted at -15℃ for 6h is particularly prominent, and the apparent viscosity of this PAA is 471000cp. Moreover, the PI film has good thermal stability, and the 5%,10% and 50% decomposition temperature are 611 ℃,629℃ and 652℃ in a nitrogen atmosphere. The tensile strength is 403.83MPa, and the crystallinity reaches 28.73%. In addition, surface property of PI film modified by hexamethylenediamine/ethylene glycol is perfect. And hexamethylenediamine 40min modified PI has the best adhesion property, has reserved the best thermal and mechanical properties, and the 180° peel strength of corresponding FCCL reaches 0.40 KN·m-1.