Radiation resistant polypropylene blended with mobilizer, antioxidants andnucleating agent

Post-irradiation storage of medical disposables prepared from isotactic pol ypropylene renders them brittle due to degradation. To avoid this, isotacti c polypropylene [(is)PP] was blended with a mobilizer, dioctyl pthallate (D OP), three antioxidants (hindered amines and a secondary antioxidant) and b enzoic acid to obtain radiation-resistant, thermally-stable and transparent material. Different formulations prepared were subjected to gamma radiatio n to doses of 25 and 50 kGy. Tests of breakage on bending after ageing in a n oven at 70 degrees C up to 12 months have shown that the addition of DOP and the antioxidants imparts improved radiation and thermal stability as co mpared to (is)PP alone or its blend with DOP, All the formulations irradiat ed or otherwise demonstrated excellent colour stability even after accelera ted ageing at 70 degrees C for prolonged periods. (C) 2000 Elsevier Science Ltd. All rights reserved.