Crosslinkable poly(aryl ether ketone)s containing pendant phenylethynyl moieties: Synthesis, characterization and properties

Design and Synthesis of PET-Based Copolyesters with Flame-Retardant and Antidripping Performance

Poly(ethylene terephthalate) (PET) is a fiber-forming polymer with the largest output and widest usage. Its flame retardation is well-achieved via a mechanism of promoting the melt dripping while ignited. However, the melt dripping leads to secondary damage and an immediate empyrosis during fire. How to address the contradiction between the flame retardation and the melt-dripping behavior of PET via an inherent flame-retardant approach becomes a real challenge. This feature article highlights the design and synthesis of novel PET-based copolyesters with flame-retardant and antidripping performance. Three approaches are used to design these copolyesters: "ionic aggregation," "smart self-cross-linking," and "rearrangement at high temperatures." Some new conceptions are proposed accordingly. The synthesis, structure characterization, and properties of those copolyesters are discussed together with the ongoing challenges and limitations at this frontier.

Development of a high-performance poly(ether ether ketone) copolymer with extremely low melt viscosity

The conventional poly(ether ether ketone) (PEEK) and two other PEEK copolymers (PEEEKK-PEK and PEEEKK-PEEEK) were successfully synthesized and investigated on their thermal stabilities, mechanical properties, and rheological behaviors. Both of the PEEEKK-PEK and PEEEKK-PEEEK were composed of the same chemical components with conventional PEEK (phenyl–ether–ketone equals 3:2:1), but the sequences of their components (phenyl, ether, and ketone) were different. Differential scanning calorimetry analysis and dynamic mechanical analysis indicate that PEEEKK-PEK and PEEEKK-PEEEK have extremely close glass transition temperatures and melting points with conventional PEEK, which suggests their similar operating temperatures. They also process similarly high mechanical properties based on their stress–strain tests. However, PEEEKK-PEK, PEEEKK-PEEEK, and PEEK exhibit significant differences in their rheological behaviors; PEEEKK-PEK even shows an excessively low melt viscosity (51% of PEEK). These results reveal the effects of sequence distribution on polymer properties and thereby demonstrate the processing viscosity of PEEK could be decreased without sacrificing its operating temperature or material performances.