Mechanical relaxation of crystalline poly(aryl-ether-ether-ketone) (PEEK) and influence of electron beam irradiation

• Published in: Polymer (Guilford) 1986-06, Vol.27 (6), p.821-826
• Main Authors: Sasuga, Tsuneo, Hagiwara, Miyuki
• Format: Article
• Language: English
• Subjects: Applied sciences; chain scission; crosslinking; crystalline-non-crystalline interface; electron beam irradiation; Exact sciences and technology; molecular motions; Physicochemistry of polymers; Polymers and radiations; Properties and characterization; semicrystalline PEEK
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/0032-3861(86)90288-0

Mechanical relaxation of semicrystalline PEEK and influence of electron beam irradiation on molecular motions were studied by measuring dynamic viscoelastic properties in the temperature range from − 160°C to 350°C. Irradiation caused the glass transition temperature (β relaxation) to shift upwards, and β′ relaxation, related to loosened chain packing, to appear just below the glass transition temperature, and a small shoulder that appeared at − 40°C to 0°C on the γ relaxation peak and disappeared in the first run after irradiation to reappear in the second run. It was concluded that both crosslinking and chain scission take place under irradiation. The shoulder on the γ relaxation was assigned to segmental motion of the chains at the crystalline-non-crystalline interface. The inferior radiation resistance of semicrystalline PEEK with respect to non-crystalline PEEK is ascribed to preferential disintegration of tie-molecules between crystalline and non-crystalline phases.