Effect of electron beam irradiation on the properties of poly(tetramethylene oxide) and a poly(tetramethylene oxide)-based polyurethane

• Published in: Radiation physics and chemistry (Oxford, England : 1993) England : 1993), 2020-09, Vol.174, p.108905, Article 108905
• Main Authors: Navarro, R., Rubio Hernández-Sampelayo, A., Adem, E., Marcos-Fernández, A.
• Format: Article
• Language: English
• Subjects: Biomedical materials; Chain scission; Covalent bonds; Crosslinking; Crystallization; Degradation mechanism; Electron beam irradiation; Electron beams; Electron irradiation; Ionizing radiation; Mechanical properties; NMR; Nuclear magnetic resonance; Oxidation; Physical properties; Poly(tetramethylene oxide); Polytetrahydrofuran; Polyurethane; Polyurethane resins; Radiation therapy; Sterilization; Surgical implants; Tensile properties
• ISSN: 0969-806X; 1879-0895
• DOI: 10.1016/j.radphyschem.2020.108905

Polyurethanes (PUs) based on poly(tetramethylene oxide) (PTMO) used in the biomedical sector can be exposed to ionizing radiation in vivo as implants during diagnosis (X-ray) or during radiotherapy treatment (gamma), or ex vivo for sterilization purposes (gamma, electron beam). This ionizing radiation can, at certain levels, cause degradation of the polymer. To understand the effect on those PUs, a high molecular weight PTMO (pTHF) and one PU based on PTMO (pTHF-MDI) were irradiated with electron beam and the changes in their chemical structure and physical properties with the dose were evaluated. Electron beam irradiation produced crosslinking and chain scission without significant predominance of one mechanism over the other in pTHF and predominance of crosslinking for pTHF-MDI. New saturated hydrocarbon species were detected in irradiated pTHF by proton NMR. These species were consistent with a mechanism where radicals were formed at alpha methylenes and chain scission took place at C–C bonds without significant oxidation, in disagreement with the mechanism proposed in literature. Crosslinking decreased significantly the crystallization and melting temperatures of pTHF and pTHF-MDI. Tensile properties of pTHF decreased rapidly with the increase in dose due to chain scission. •Crosslinking/chain scission in PTMO were produced in similar proportion by e-beam.•Crosslinking predominated in PTMO-based polyurethanes.•E-beam produced new saturated species in PTMO without significant oxidation.•Mechanical properties decreased rapidly with dose in PTMO due to chain scission.