Effects of temperature, packaging and electron beam irradiation processing conditions on the property behaviour of Poly (ether-block-amide) blends Kieran A. Murray a , James E. Kennedy a , Brian McEvoy b , Olivier Vrain b , Damien Ryan b , Richard Cowman b , Clement L. Higginbotham a, ⁎ a Materials Research Institute, Athlone Institute of Technology, Dublin Road, Athlone, Co. Westmeath, Ireland b Synergy Health, IDA Business & Technology Park, Sragh, Tullamore, Co. Offaly, Ireland abstract article info Article history: Received 17 December 2013 Received in revised form 6 February 2014 Accepted 7 March 2014 Available online 16 March 2014 Keywords: Electron beam irradiation Poly (ether-block-amide) Crosslinking and chain scission Mechanical, thermal, structural and surface properties Stabilisers Packaging and processing conditions The radiation stability of Poly (ether-block-amide) (PEBA) blended with a multifunctional phenolic antioxidant and a hindered amide light stabiliser was examined under various temperatures, packaging and electron beam processing conditions. FTIR revealed that there were slight alterations to the PEBA before irradiation; however, these became more pronounced following irradiation. The effect of varying the temperature, packaging and processing conditions on the resultant PEBA properties was apparent. For example, rheology demonstrated that the structural properties could be enhanced by manipulating the aforementioned criteria. Mechanical testing exhibited less radiation resistance when the PEBA samples were vacuum packed and exposed to irradiation. MFI and AFM confirmed that the melting strength and surface topography could be reduced/increased depending on the conditions employed. From this study it was concluded that virgin PEBA submerged in dry ice with non- vacuum packaging during the irradiation process, provided excellent radiation resistance (20.9% improvement) in contrast to the traditional method. © 2014 Published by Elsevier B.V. 1. Introduction Poly (ether-block-amides) (PEBAs) are thermoplastic elastomers which are composed of linear chains of rigid polyamide segments linked to flexible polyether segments via ester groups [1–3]. PEBAs were first introduced by Atochem in the early 1980s, which are sold under the trade name PEBAX®. There are many types of polyamides that are used to synthesise PEBAX, including nylon 6, nylon 66, nylon 11, nylon 6/11, nylon 12 and nylon 6/12. In terms of polyethers, these include poly (propylene glycol), poly(tetramethylene ether glycol) and poly(ethylene glycol) [4]. These block copolymers are synthesised via a metallic Ti(OR)4 catalyst which helps the melt polycondensation of carboxylic acid terminated amide blocks with polyoxyalkylene glycols. This polymerisation reaction is performed at elevated tempera- tures and under high vacuum [5–7]. Due to the invaluable properties that the PEBA material has to offer, for instance elasticity and thermal stability at body temperatures, this material is extensively used in the biomedical industry for a range of ap- plications from catheter bodies to angioplasty balloons [8]. For this reason it is important that these end products are sterilised before use. Converse- ly, such sterilisation processes like high energy irradiation, dry steam and heat can have unfavourable effects on medical grade polymers such as plastic deformation and extensive material degradation [9–11]. Sterilising techniques can either act physically or chemically leading to modifica- tions of the structure or function of macromolecules which can result in crosslinking, chain scission, oxidation, melting and hydrolysis. With regards to high energy radiation, it is vital that the material properties are not impaired by the sterilisation process [12]. Radiation exposure can result in both chain scission and crosslinking; however, one generally predominates over the other [13]. The dominance of one process over an- other is determined by the overall structure of the polymer [17] and the irradiation processing conditions [18]. Chain scission can consequently lead to a reduction in the molar mass, whereas crosslinking increases the molar mass leading to a less flexible product [15]. The yield of oxidative products plays an important role in the extent to which crosslinking and chain scission processes affects the polymer properties. Earlier work performed on polyethylene oxide identified that chain scission predominates when electron beam irradiation is carried out in air whilst crosslinking predominates when irradiated in vacuum [14]. While with polyamides, crosslinking has been proposed as the main consequence of damage leading to the loss of crystallinity Materials Science and Engineering C 39 (2014) 380–394 ⁎ Corresponding author. E-mail addresses: kmurray@research.ait.ie (K.A. Murray), jkennedy@ait.ie (J.E. Kennedy), Brian.Mcevoy@synergyhealthplc.com (B. McEvoy), Olivier.Vrain@synergyhealthplc.com (O. Vrain), Damien.Ryan@synergyhealthplc.com (D. Ryan), Richard.Cowman@synergyhealthplc.com (R. Cowman), chigginbotham@ait.ie (C.L. Higginbotham). http://dx.doi.org/10.1016/j.msec.2014.03.021 0928-4931/© 2014 Published by Elsevier B.V. Contents lists available at ScienceDirect Materials Science and Engineering C journal homepage: www.elsevier.com/locate/msec