Highly conductive graphite/carbon fiber/cellulose composite papers Lara Jabbour ⇑ , Didier Chaussy, Benoit Eyraud, Davide Beneventi UMR 5518 CNRS-Grenoble-INP, Domaine Universitaire, 461 rue de la Papeterie, BP 65, 38402 St. Martin d’Hères, France article info Article history: Received 19 July 2011 Received in revised form 10 January 2012 Accepted 11 January 2012 Available online 20 January 2012 Keywords: A. Carbon fibers A. Functional composites B. Electrical properties Cellulose fibers abstract Papermaking techniques were used to produce graphite/carbon fiber/cellulose fiber composite papers with tunable electrical conductivity and good mechanical properties. The obtained conductive papers are easy to handle, flexible and have an extremely good conductivity, up to 964 S m 1 . Furthermore the proposed production process is low cost and can be easily scaled up in the perspective of disposable and recyclable device production. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Papermaking is a well established production process, still very relevant in today’s economy. Paper, cardboard, and other wood- based products are used in communication, packaging and numer- ous other aspects of modern life. The basic papermaking process involves the use of cellulose fibers in aqueous suspension, their fil- tration on a forming fabric and the subsequent generation of a ran- domly interwoven fiber mat. The final paper sheet is obtained by removing the residual water in the fiber mat by pressing and heat-drying. In the production of traditional printing/writing papers, filler addition either during the fiber mat formation or by deposition on the surface of the dry paper sheet is a very common practice. Usually fillers are used to obtain cost and energy savings [1], and/or to improve the optical properties, sheet formation ability, dimensional stability, printability and writability of the base cellu- losic paper [2,3]. By incorporating specific fillers, paper with magnetic [4], photo- luminescent [5], catalytic [6,7], flame retardant [8] and conductive [9–11] properties and mechanical resistance comparable to that of conventional paper have been obtained, thus opening the door to a broad range of new potential applications. Among these new functional papers, conductive papers are of particular interest owing to their efficiency in electromagnetic interference shielding [12,13], potential use in electronic circuits, active matrix displays and static electrical dissipation [14,15]. In the recent past, some studies demonstrated the possibility to produce carbon nanotubes (CNTs)/cellulose composite paper [8,10,11,13,16]. However a large scale use of CNTs remains ques- tionable since they are suspected carcinogens and may have asbestos-like effects on the lungs [17]. Moreover, CNTs production process is still expensive and the properties of the obtained papers strongly depend on the CNTs dispersion which is not easy to obtain and requires further treatments such as surfactant addition [18] or CNTs functionalization [19]. Other studies involved cellulose fibers coating with polypyrrole [20–22] or layer-by-layer deposition of conductive polymers onto cellulose fibers [23,24] to produce conductive papers. However, the inherent instability of conductive polymers came across thus showing that carbon remains the material of election for the elab- oration of conductive paper. In this study we report a simple method to produce conductive papers by incorporating graphite particles (GPs) and carbon fibers (CFs) using a conventional paper sheet formation process. CFs and GPs were selected as conductive particles thanks to their relatively low cost (if compared to CNTs) and high availability. A preliminary study on the dispersion of CFs in water was performed, in order to overcome their poor wettability [25] and pre- vent agglomeration. Carboxymethyl cellulose (CMC) was selected as dispersing agent. CMC is a bio-sourced anionic polyelectrolyte de- rived from cellulose, commonly used in papermaking as wet-end additive to improve paper sheet dry strength and uniformity, i.e. it promotes the formation of a homogeneous fibers network during the sheet formation process, by depressing fibers flocculation [26]. The aim of this work was to demonstrate that conventional papermaking practices can be used to produce high conductivity graphite/carbon fiber/cellulose fiber composite sheets while pre- serving good mechanical properties. 0266-3538/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.compscitech.2012.01.006 ⇑ Corresponding author. E-mail addresses: lara.jabbour@lgp2.grenoble-inp.fr, jabbour.lara@yahoo.it (L. Jabbour). Composites Science and Technology 72 (2012) 616–623 Contents lists available at SciVerse ScienceDirect Composites Science and Technology journal homepage: www.elsevier.com/locate/compscitech