Dielectric and mechanical properties of polyimide fiber reinforced cyanate ester resin composites with varying resin contents

Polyimide (PI)/ bisphenol A dicyanate esters (BADCy) composite laminates with varying resin contents were prepared by filament winding and autoclave molding process. The laminates exhibited ultralow dielectric constant (epsilon of 3.15-3.25) and dielectric loss (tan delta of 0.004-0.006) as well as excellent mechanical properties. When the resin content was 35.6%, the composite achieved outstanding comprehensive properties with tensile strength and modulus equal to 1485.1 MPa and 80.9 GPa, respectively, and the inter-laminar shear strength (ILSS) up to 66.2 MPa. The failure mode of laminates followed an explosive gage middle (XGM) mechanism, which suggested a favorable interface between fiber and resin. According to the mixed law equation, PI fiber at a frequency of 10.2 GHz exhibited dielectric constant of 3.41 +/- 0.03 and dielectric loss of about 0.002-0.004. The successful preparation of PI fiber reinforced BADCy composite with low dielectric constant provides new ideas for material design and selection of lightweight high-strength structural-functional integrated composites.