Influence of epoxy resin species on the curing behavior and adhesive properties of cyanate Ester/Poly(aryl ether nitrile) blends

In this study, four different bisphenol A glycidyl ether epoxy resins (E06, E12, E20, and E44) with varying epoxide equivalents were utilized to investigate their effect on the curing behavior, mechanical, thermal, and adhesive properties of bisphenol A cyanate ester (ACE)/fluorinated poly(aryl ether nitrile) (PFPEN) blends. The differential scanning calorimetry (DSC) results revealed that the use of epoxy resin reduced the curing temperature and activation energy of the modified resin system. The hydroxyl and epoxy groups in the EP resin respectively facilitated the polymerization of cyanate group and the formation of oxazoline and oxazolidone structures, instead of rigid triazine rings. This, in turn, improves the toughness of the cross-linked network structure. Rheological analysis showed that the EP resin could reduce crystallinity in the modified resin and improve low-temperature processing performance. Comparatively, E20/PFPEN/ACE showcased a significant increase in both tensile and impact strength, reaching 74.6 MPa and 19.35 kJ/m2, respectively. Likewise, shear strength and peel strength at room temperature showed an improvement by 18.7% and 20.7%, respectively, when compared to the pure PFPEN/ACE system. Overall, this modified resin exhibits relatively good comprehensive properties and could be used for high-performance adhesives and resin matrix composites.