Ionizing radiation influence on the morphological and thermal characteristics of a biocomposite prepared with gelatin and Brazil nut wastes as fiber source Patricia Y. Inamura a , Felipe H. Kraide a , Walker S. Drumond b , Nelson B. de Lima a , Esperidiana A.B. Moura a , Nelida L. del Mastro a,n a Energy and Nuclear Research Institute, IPEN-CNEN/SP, Av. Prof. Lineu Prestes, 2242, 05508-000 S ~ ao Paulo, Brazil b Department of Metallurgical and Materials Engineering, Polytechnic School, University of Sao Paulo, SP, Brazil article info Article history: Received 1 January 2011 Accepted 1 January 2012 Keywords: Electron beam irradiation Brazil nut fiber Composite Gelatin abstract Composites of acrylamide, glycerin, gelatin and Brazil nuts shell fiber have been prepared by the solution/suspension casting technique. The effect of two doses of electron beam (EB) irradiation on the structural properties of the polymeric composites has been investigated by X-ray diffraction, thermo- gravimetric analysis (TG), scanning electron microscope (SEM), gel content and the swelling behavior. Gel content increased with the radiation dose. The results obtained by X-ray diffraction analysis suggest that crystallinity decreases with increasing dose. The gelatin/fiber composites, before and after irradiation, showed to be poorly stable against thermal decomposition. & 2012 Elsevier Ltd. All rights reserved. 1. Introduction Natural fibers can be classified as vegetables, animals and minerals materials. All the vegetal fibers have cellulose in com- position, while the fibers of animal origin consist basically of proteins (Saheb and Jog, 1999). The structure and properties of biodegradable polymer were studied at several laboratories, using natural proteins or other compounds (Qiu et al., 2004; Jo et al., 2005; Ciesla et al., 2006; Mishra et al., 2008). There are also examples from the literature of the development of new composites materials from biodegrad- able polymers and lignocellulosic materials Mortain et al. (2004). Although the Brazil nuts market growths continuously the nut shell fiber residues have no further application. The search for alternative technologies is crucial for the utilization of by-pro- ducts from Brazil nuts processing, with the aim of developing new products with higher added value. Primary organic components of any nutshells are cellulose, hemicellulose and lignin. This sort of material could be used as reinforcement to enhance polymer mechanical properties, as other natural fibers, piassava fiber for instance, employed with the same objective showed encouraging results (Schuchardt et al., 1995; Moura et al., 2010). Gelatin is the partially renatured collagen, which consists of triple helical superstructure of extended polypeptide chains. It has been widely used as binder or coating materials in the pharmaceutical, biomedical and photographic industries. Gelatin is an interesting material because when dehydrated it is a partially crystalline polymer and has a relatively low melting point (Daı ´ and Liu, 2006). At approximately 40 1C, gelatin aqueous solutions are in the sol state and form physical, thermoreversible gels on cooling. During gelation, the chains undergo a conformational disorder– order transition and tend to recover the collagen triple-helix structure (Ross-Murphy, 1992; Sobral and Habitante, 2001). Gelatin films with plasticizer have sufficient stability, strength and flexibility to allow them to be used as support and packaging materials. The radiation induced ionization of a material gives rise to radicals and the subsequent alteration of the structure of the material via radical chemical action. High energy ionizing radiation cannot only cause alterations to the chemical structure of a polymer through mechanisms like cross-linking, chain scission, oxidation, change in the number and nature of double bonds but can also give rise to the presence of trapped charge within the material, the trapping characteristics of which may be influenced by the radia- tion-induced structural alterations (Kacarevic-Popovic et al., 2004) Ionizing radiation is able to induce cross-linking of collagen gelatin (Cataldo et al., 2008). Some authors found that the thermal and functional properties of gelatin-based films depend on the type and concentration of the plasticizers being employed (Vanin et al., 2005). The sol–gel analysis of irradiated polymers allows to estimate important radiation parameters as yield of cross-linking and degradation, gelation dose, etc., and to correlate these with some physical–chemical properties (Rosiak, 1998). The acknowledged versatility of polymeric materials, which are widely used in the form of plastics, films, coatings and fibers, Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/radphyschem Radiation Physics and Chemistry 0969-806X/$ - see front matter & 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.radphyschem.2012.06.043 n Corresponding author. Tel.: þ55 11 3133 9829; fax: þ55 11 3133 9765. E-mail address: nlmastro@ipen.br (N.L. del Mastro). Please cite this article as: Inamura, P.Y., et al., Ionizing radiation influence on the morphological and thermal characteristics of a biocomposite prepared with gelatin and.... Radiat. Phys. Chem. (2012), http://dx.doi.org/10.1016/j.radphyschem.2012.06.043 Radiation Physics and Chemistry ] (]]]]) ]]]–]]]