Reinforcement of poly(ether ketone) by introducing fluorene groups and their effect on thermal and mechanical properties

A series of novel poly(ether ketone) copolymers with different contents of fluorene groups were synthesized. The effects of fluorene group content on the thermal and mechanical properties of poly(ether ketone) copolymers were investigated. The introduction of a low content of fluorene groups can lead to an increase in glass transition temperature, thermal stability and heat deflection temperature. Among them, the heat deflection temperature of 10% fluorene‐containing poly(ether ketone) copolymers (PEK‐FD10) increases from 178 °C (pure poly(ether ketone)) to 196 °C, which means that the material has a higher heat resistance rating. Compared with poly(ether ketone)s, these copolymers have excellent mechanical properties. When the content of fluorene groups is only 2% (PEK‐FD2), the strength is significantly improved. And the flexural strength of PEK‐FD2 is 149.3 MPa, which is 12% higher than that of poly(ether ketone). It is worth noting that the fracture toughness and impact toughness are also increased significantly. The strain at break of PEK‐FD2 is up to 88% and the impact toughness of PEK‐FD2 is 54.6 J m−1. This suggests that the introduction of minute contents of fluorene groups can simultaneously increase the strength and toughness. © 2020 Society of Industrial Chemistry Introducing 2% fluorene groups into poly(ether ketone) can simultaneously improve the strength and toughness of the material.