The modification of ultra-high-molecular-weight polyethylene supramolecular structures induced by irradiation and thermal treatment

• Published in: Polymers for advanced technologies Vol. 14; no. 11-12; pp. 802 - 806
• Main Authors: Nevoralová, M., Mikešová, J., Baldrian, J., Horák, Z.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.11.2003
• Subjects: crystallinity; irradiation; rheological characteristics; UHMWPE
• ISSN: 1042-7147; 1099-1581
• DOI: 10.1002/pat.398

The effect of γ‐radiation and subsequent thermal treatment on the crystallinity and rheological characteristics of ultra‐high‐molecular‐weight polyethylene (UHMWPE) has been investigated. Irradiation of the polymer was performed using a 60Co γ‐emitter at laboratory temperatures. Five irradiation doses (25, 50, 100, 150 and 200 kGy), two dose rates (0.25 and 2.5 kGy/h) and two (atmosphereic environments) (air and nitrogen) were used. Some irradiated samples were thermally treated at 190°C. The crystallinity changes were determined using wide‐angle X‐ray diffraction (WAXS), while the rheological characteristics were measured with a rotation rheometer. In addition to the expected effect of γ‐rays on the structural changes and rheological behaviour of UHMWPE at higher radiation doses (from about 50 kGy), two interesting results were obtained. First, a minimum on the dependence of the radiation dose as a function of crystallinity was found for all of the measured samples. The crystallinity decrease in UHMWPE is also associated with substantial changes in its rheological properties at temperature above the melting point. Secondly, a remarkable effect of the dose rate on the measured characteristics has been proved. Copyright © 2003 John Wiley & Sons, Ltd.