Cyanate ester resins toughened with epoxy-terminated and fluorine-containing polyaryletherketone†
Cyanate ester resins are widely utilized in high-performance printed circuit boards, radar radomes, communication satellites, and other fields. However, the poor toughness after curing due to the highly cross-linked and symmetrical triazine ring structure severely limits their wide application. Herein, a novel epoxy-terminated and fluorine-containing polyaryletherketone (EFPAEK) synthesized from bisphenol AF, difluorobenzophenone, and epichlorohydrin was applied to modify the bisphenol A dicyanate ester (BADCy) resin. The results showed that the EFPAEK/BADCy resin toughened with 20 wt% of EFPAEK displayed the best comprehensive properties. The dielectric constant and the dielectric loss tangent values at 1 MHz were 2.64 and 0.006, respectively, which were much lower than those of the pure BADCy resin (3.09 and 0.008). In addition, the flexural strength and impact strength of the corresponding EFPAEK/BADCy resin increased significantly to 131.8 MPa and 30.6 kJ m−2, respectively, which were 32.5% and 159.3% higher compared to the pure BADCy resin (99.5 MPa and 11.8 kJ m−2). Besides, the modified BADCy resin still maintained high thermal stability, by showing the highest heat resistance index of 219.5 °C, which increased by 4.2% compared with the pure BADCy resin (210.6 °C). Moreover, the addition of EFPAEK improved the bonding strength. The maximum bonding strength of the EFPAEK/BADCy resin was 22.2 MPa, which was 91.4% higher compared to that of the pure BADCy resin (11.6 MPa). Additionally, the EFPAEK/BADCy resin demonstrated improved water resistance as the minimum water absorption rate decreased by 30.9% compared to that of the pure BADCy resin.