Enhanced toughness and lowered dielectric loss of reactive POSS modified bismaleimide resin as well as the silica fiber reinforced composites

Inherent brittleness is the most weakness of bismaleimide resin, which adversely affects the performance and application of the terminal fiber reinforced bismaleimide composites. In this study, polyhedral oligomeric silsesquioxane (POSS) with glycidyl group (G-POSS) and methacryloxy propyl group (MA-POSS) are utilized to toughen diallyl bisphenol-A/N, N′-4,4′-diphenylmethane bismaleimide (BD resin) to obtain hybrid resins named BDGP and BDMP. The results of hybrid resins show that the two series hybrid resins perform higher toughness, strength, water resistance as well as lower dielectric constant and loss comparing with pristine BD resin, and BDMP perform better than BDGP due to that MA-POSS can react with BD resin while G-POSS cannot. In specific, the BDMP₃ in which 3 wt% MA-POSS is added performs the highest impact strength of 19.0 KJ/m², increased by 102.1% comparing with pristine BD resin, and it also performs the lowest dielectric constant of 3.04 as well as lowest dielectric loss of 0.006 at 1 MHz. In addition, the silica fiber reinforced BDMP composites (SF/BDMP) are fabricated, and the results show that the bending strength and interlaminar shear strength of SF/BDMP₃ composite are enhanced to 290.2 and 32.5 MPa, 32.0% and 38.4% higher than those of SF/BD composite, and the corresponding dielectric loss (0.025) at 8.2 GHz is reduced by 45.9%. This research displays that reactive POSS can improve the toughness and reduce the dielectric loss of resin, which is benefit to obtain a high performance and functional resin-based composites with excellent mechanical properties and low dielectric properties.