Please cite this article in press as: C.F. Escobar, L.A. dos Santos, New eco-friendly binder based on natural rubber for ceramic injection molding process, J Eur Ceram Soc (2015), http://dx.doi.org/10.1016/j.jeurceramsoc.2015.06.006 ARTICLE IN PRESS G Model JECS-10160; No. of Pages 9 Journal of the European Ceramic Society xxx (2015) xxx–xxx Contents lists available at www.sciencedirect.com Journal of the European Ceramic Society journal homepage: www.elsevier.com/locate/jeurceramsoc New eco-friendly binder based on natural rubber for ceramic injection molding process C.F. Escobar ∗ , L.A. dos Santos Departamento de Engenharia de Materiais, Federal University of Rio Grande do Sul, Av. Bento Gonc ¸ alves 9500, setor 4 prédio 74 sala 118, Agronomia, Porto Alegre, RS, Brazil a r t i c l e i n f o Article history: Received 20 April 2015 Received in revised form 31 May 2015 Accepted 6 June 2015 Available online xxx Keywords: Eco-friendly binder Ceramic injection molding (CIM) Natural rubber (NR) a b s t r a c t The binder composition used for ceramic injection molding plays a crucial role on the final properties of sintered ceramic and to avoid defects on green parts. This study proposes a new eco-friendly binder based on natural rubber as a backbone polymer for ceramic injection molding of alumina. Three binders with different content of natural rubber and paraffin wax have been investigated. The powder volume fraction was kept constant. Physical properties were analyzed and four thermal debinding cycles on molded sam- ples were applied for investigation of the influence of temperature and heating rate of sintered samples. All binders showed good rheological properties and yield stress was changed with homogeneity between powder-binder suspension. Thermal debinding affected the sintered properties of alumina samples. In result it was found that, between the binders used, the better binder components for injection process was obtained for 40% wt of natural rubber and 60% wt of paraffin wax. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction Ceramic injection molding (CIM) is a near-net shape processing technique that allows manufacturing of complex components in large scale industry. The CIM process involves the traditional shape- making capacity of plastic injection molding and the flexibility of materials employed in powder technology. The fabrication starts by compounding a polymeric binder and powder mixture, known as feedstock, followed by injection molding, binder removal and sintering [1,2]. The binder is a complex mixture comprising of several com- ponents, which is carefully selected to promote good injection molding properties and be easy for removal of molded parts. The primary component is a high molecular weight polymer which pro- vides the adequate strength molded parts. The secondary binder component generally is a wax or low molecular weight polymer and acts to improve the rheological properties of feedstock, as well as easy removal of the binder. In this binder system, an excess of primary component may cause poor rheological properties, which increases the feedstock viscosity and implicates incomplete mold ∗ Corresponding author. Fax: +55 51 3308 9424. E-mail address: camila.escobar@ufrgs.br (C.F. Escobar). filling. On the other hand, low concentration of primary component can also lead loss of mechanical strength of molded parts. Several binder systems were developed in the few last decades and the more traditional ones are based on thermoplastics, such as polypropylene (PP) and polyethylene (PE) blend for alumina injec- tion molding [3], polyoximethilene for PIM of stainless steel 316L powder (POM) [4]. Thermosetting binders based on epoxy were patented by Nishimura and Yoshino [5]. More recently binders based on water-soluble polymers have been developed. Weil et al. [6] developed the ethylene vinyl acetate (EVA) binder for injection molding of Ti–6Al–4V alloy, giving a max- imum powder loading of 65% vol. The starch-based binder and low density polyethylene (LDPE) was used with stainless steel 316L by Abolhasani and Muhammad [7]. An eco-friendly binder com- posed by polyethylene glycol (PEG) and cellulose acetate butyrate (CAB) for zirconia injection molding was developed by Abajo et al. [8]. This paper proposes the development of a new eco-friendly binder for the powder injection molding (PIM) process based on natural rubber latex as backbone polymer and paraffin wax as a secondary component. The aim of development of this binder is the study of natural rubber as a backbone binder component for CIM process. This is obtained from the Hevea brasiliensis tree, a renewable natural source, and has not been used yet as binder in http://dx.doi.org/10.1016/j.jeurceramsoc.2015.06.006 0955-2219/© 2015 Elsevier Ltd. All rights reserved.