Preparation of novel low-κ polyimide fibers with simultaneously excellent mechanical properties, UV-resistance and surface activity using chemically bonded hyperbranched polysiloxane

摘要: High-strength and high-modulus fibers with low dielectric constants (low-κ) play an important role in newly-developed wave-transparent composites. Herein, a method was developed to prepare novel low-κ polyimide simultaneously ultrahigh mechanical properties, excellent UV-resistance surface activity using chemically bonded hyperbranched polysiloxane. The constant of PI/HBPSi composites conspicuously decreases increasing HBPSi loadings, namely, from 3.6 pure PI 2.6 the composite containing 20 wt% HBPSi, along loss decreasing 0.047 0.01 at 1 GHz, mainly owing confinement effect increased free volume polymer chains. These functionalized nanoparticles were further proved effectively enhance properties fibers, leading maximum 19% increase tensile strength (3.44 GPa, ca. 27.3 g per denier) 37% modulus (115.2 914.2 relative fiber, which are better than those typical high fiber-Kevlar 49. Attributed potential crosslinking reaction between carbonyl groups chains methyl under UV irradiation, retain (94–96)% strengths after exposure light source for 168 h, meanwhile, moduli irradiated by (2–23)% compared un-irradiated showing resistances. Additionally, roughness introduced amino fiber produce higher interfacial adhesion interactions epoxy matrix. single-fiber pullout test indicates that shows 30% shear strength. Accordingly, such multiscale reinforced show great be likely applied new generation stronger more durable