Material Properties The effect of post-consumer PET particles on the performance of flexible polyurethane foams Darlan de Mello a , Se ´ rgio H. Pezzin b , Sandro C. Amico a, * a PPGEM, Federal University of Rio Grande do Sul, UFRGS P.O. Box 15010, 91501-970 Porto Alegre/RS, Brazil b Center of Technological Sciences, Santa Catarina State University, 89223-100 Joinville/SC, Brazil article info Article history: Received 17 April 2009 Accepted 27 May 2009 Keywords: Polyurethane Flexible foams Post-consumer PET Physical properties abstract In this work, the use of post-consumer PET (polyethylene terephthalate), PET pc , as rein- forcement filler in flexible polyurethane foams was studied, with the aim of finding alternatives for the recycling of polymer packaging. Density, number of cells per linear centimeter, tensile resistance, strain at break and tear resistance of standard foams were compared to those of foams with PET pc in the formulation, using 1.5 parts per hundred of polyol of PET pc (granulometric range 0–297 mm). The produced foams were sectioned into top, mid-top, mid-bottom and bottom layers. Tensile resistance, strain at break and tear resistance of the reinforced foam surpassed those of the standard foam for all layers. The number of cells was constant but density increased towards the base of the block. In addition, the filled foams yielded better wear, compression set and compression resistance than the standard foam, whereas no significant variation in morphology (cell shape) was found. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction Flexible polyurethane foams, produced from the poly- condensation of polyols with isocyanate, are formed by open cells and have high gas permeability, low density and limited mechanical strength [1,2]. Due to their reversible deformation, among others positive aspects, flexible PU foams are widely used and have many commercial appli- cations (e.g. mattresses, automotive and furniture cushions, cleaning products) [3]. The network structure of a typical polyurethane foam is comprised of both chemical cross- links, since polyols with functionality greater than two are used, and physical crosslinks, derived from the phase segregation of rigid urea segment domains. The two main classes of polyols for PU foam processing are polyesterols and polyetherols, the latter being currently responsible for 80–90% of the production of PU foams [4]. The use of traditional raw materials for the production of PU foams implies in a high consumption of non-renewable oil derivatives. Part of these derivatives could be replaced by fillers, as long as the desired characteristics of the foams are retained, and reinforcements could be used to yield a combined set of physical properties to the foams. The production of foams reinforced by fibers or particles can lead to an increase in the mechanical properties of the polymer matrix, enhancing its energy absorption ability [5]. A variety of particulate or fibrous fillers for cost reduction or mechanical properties improvement, among other benefits, have been reported in the literature, including: silica, glass fibers, aluminum hydroxide or starch [6], Ca 3 (PO 4 ) 2 [7], CaCO 3 [8], CaSO 4 [9] and talc [10], and even nanostructured fillers, such as carbon nanotubes [11] and nanoclays [12]. Granulometry, surface state, dispersion and filler type and amount are critical parameters to define foam architecture and mechanical properties [5]. The substitution of virgin resins by recycled ones is a worldwide tendency, endorsed by the fluctuation of oil prices and the competitiveness of the recycling market. * Corresponding author. Tel.: þ55 51 3308 9419; fax:þ55 51 3308 9414. E-mail addresses: darlan.mello@uol.com.br (D. de Mello), pezzin@ joinville.udesc.br (S.H. Pezzin), amico@ufrgs.br (S.C. Amico). Contents lists available at ScienceDirect Polymer Testing journal homepage: www.elsevier.com/locate/polytest 0142-9418/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.polymertesting.2009.05.014 Polymer Testing 28 (2009) 702–708