Industrial Crops and Products 55 (2014) 180–186 Contents lists available at ScienceDirect Industrial Crops and Products jo u r n al homep age: www.elsevier.com/locate/indcrop Unconventional plasticization threshold for a biobased bisphenol-A epoxy substitution candidate displaying improved adhesion and water-resistance Pierre Verge ∗ , Valérie Toniazzo, David Ruch, João A.S. Bomfim Centre de Recherche Public Henri Tudor, Advanced Materials & Structures, 5 Rue Bommel, Z.A.E. Robert Steichen, Kaërjeng-Hautcharage L-4940, Luxembourg a r t i c l e i n f o Article history: Received 22 August 2013 Received in revised form 20 January 2014 Accepted 30 January 2014 Available online 12 March 2014 Keywords: Epoxy Adhesive Plasticization Water resistance CNSL a b s t r a c t Toxicity concerns over bisphenol A (BPA) based materials like polycarbonates or diglycidyl ether of bisphenol A (BADGE) lead to their progressive substitution in food packaging and can coating applications, even if the eventual release of BPA in food remains debatable. In this paper, we study the adhesive, water resistance and thermo-mechanical properties of a bio-based BADGE substitution candidate issued from Cardanol (CardDE). Different formulations with increasing ratio of BADGE substitution were evaluated, highlighting a real prospect for BPA-based epoxy substitution. During these studies, an unconventional relationship between water uptake by the biobased adhesive and property loss due to plasticization was evidenced. The water resistance of CardDE adhesives was investigated in detail revealing a plasticization threshold at elevated water content, attributed to their hydrophobic structure. While the adhesive prop- erties of conventional BADGE networks are prematurely affected, the deterioration of CardDE adhesives is delayed. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Bisphenol A [2,2-bis(4-hydroxyphenyl)propane or BPA] is an important industrial chemical that is primarily used as an interme- diate in the production of polycarbonate (PC) plastics and epoxy resins (Staples et al., 1998). Products of BPA range from PC bot- tles to the inner coating of cans and from dental sealants to cell phone casings. Controversy surrounding BPA mainly involves its potential human health risk due to its estrogenic activities (Maffini et al., 2006; Tsai, 2006). As the release of BPA from coatings has been evidenced (Nam et al., 2010), a strong urgency appears to its substitution in sensitive applications by more eco and human friendly compounds. Renewable resources can provide an interesting sustainable platform to substitute, partially or totally, petroleum-based polymers through the design of bio- based polymers that can compete or even surpass the existing petroleum-based materials on a cost-performance basis with high eco-friendliness values (Raquez et al., 2010). Literature review reveals several attempts to obtain bio- based epoxy resins from isosorbide (Chrysanthos et al., 2011; Lukaszczyk et al., 2011) or from vegetable oils. Many vegetable ∗ Corresponding author. Tel.: +352 42 5991 4943. E-mail address: pierre.verge@tudor.lu (P. Verge). oils display high levels of unsaturated fatty acids that can be converted into epoxy fatty acids by conventional double-bond oxidation reactions. Nowadays, epoxydized vegetable oils are receiving a great deal of attention as they are obtained from sustainable and renewable natural resources and are environmen- tally friendly. Nevertheless, as these oils are obtained from food resources, or as their production would need farmlands other- wise dedicated to growing food resources and despite a potentially positive environmental balance, biosourced materials which can compete with food resources are deemed unethical raw mate- rials (Pimentel et al., 2009). Clearly, truly sustainable, societally acceptable bio-sourced materials should rely on non-alimentary resources, focusing as much as possible on waste materials or by-products. In this paper, we explore the potential of a derivative of cashew nutshell liquid (CNSL) as an alternative to BPA-derived epoxy. CNSL, which main constituent is Cardanol – an unsaturated meta-alkylphenol, is a by-product from the processing of cashew nutshells and thus does not compete with the production of food resources (Mele et al., 2010). Few works treat of the use of Cardanol- based products for the conception of thermosets, in spite of the non-allergenic, non-estrogenic and non-toxic properties of Car- danol and even it is considered for the development of anti-cancer drugs (Hemshekhar et al., 2012). In (Aggarwal et al., 2007), the anti- corrosive properties of a mono-epoxidized Cardanol chemical is 0926-6690/$ – see front matter © 2014 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.indcrop.2014.01.048