Effect of electron beam radiation on the polypropylene/ polyethylene blends: Radiation stabilization of polypropylene C.V. Chaudhari a, * , K.A. Dubey a , Y.K. Bhardwaj a , G. Naxane b , K.S.S. Sarma a , S. Sabharwal a a Radiation Technology Development Section, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India b College of Engineering and Technology, Akola, Maharashtra, India Received 6 February 2007; received in revised form 27 June 2007 Available online 10 July 2007 Abstract The effect of incorporation of polyethylene in the polypropylene matrix, on the radiation sensitivity of polypropylene, has been inves- tigated. The changes in the properties such as tensile strength, elongation at break, Shore D hardness, density and melt flow index were monitored as function of polyethylene content and electron beam radiation dose. A correlation between the mechanical properties and morphology of the irradiated polymeric blends has been observed, which has been explained on the basis of Fourier-transform infrared spectroscopy, scanning electron microscope and X-ray diffraction studies. Improvement in the mechanical properties of the polypropyl- ene, irradiated to an optimum electron beam dose, could be achieved by blending it with polyethylene >20%. The optimum radiation dose was found to be dependent on blend composition and morphology, however, an absorbed dose of 250 kGy found to be effective enough to ensure good mechanical properties of the polypropylene/polyethylene blends. Ó 2007 Elsevier B.V. All rights reserved. Keywords: Polyolefins; Free volume; Electron beam irradiation; Mechanical properties; Polymer blends 1. Introduction Polyolefins are widely used as structural materials because of their relatively low cost and general availability [1]. Radiation processing of polyolefins is an economically viable and versatile way to produce materials with enhanced chemical, mechanical, physical properties [2–5]. However, the radiation processing of polypropylene (PP) is of limited use as it undergoes predominantly chain scis- sion when subjected to high-energy radiation. In addition to poor radiation resistance of PP, its poor impact resis- tance at low temperature further restricts its utilization in industrial domain [6]. The toughness and radiation resistance of PP is expected to increase via the addition of PE, as it undergoes predom- inantly cross-linking on high-energy irradiation [7,8]. How- ever, it is known that PP and polyethylene (PE) are immiscible and incompatible; consequently the mechanical properties of PP–PE blends are inferior to those of pure component. Several studies have been reported to enhance the compatibilization between PP and PE by the addition of interfacial agents or compatibilizers [9]. The present study presents the investigation done on effect of electron beam irradiation on PP–PE blends. The objective was to find suitable blend composition and radiation dose for significant improvement in the mechanical properties of the blends and improve upon radiation resistance of PP. 2. Experimental 2.1. Preparation of PP–PE blends Different proportions of LDPE (density 0.915 g/cm 3 and melt flow index 1.5 g/10 min) and PP (density 0.904 g/cm 3 0168-583X/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2007.06.027 * Corresponding author. Tel.: +91 022 25590175; fax: +91 022 25515050. E-mail address: chaaudhari@yahoo.com (C.V. Chaudhari). www.elsevier.com/locate/nimb Nuclear Instruments and Methods in Physics Research B 263 (2007) 451–457 NIM B Beam Interactions with Materials & Atoms