Elaboration and properties of novel biobased nanocomposites with halloysite nanotubes and thermoplastic polyurethane from dimerized fatty acids Juliano Marini a, b, * , Eric Pollet a , Luc Averous a , Rosario Elida Suman Bretas b a BioTeam/ECPM-ICPEES, UMR CNRS 7515, Universit e de Strasbourg, 25 Rue Becquerel, 67087 Strasbourg, Cedex 2, France b Department of Materials Engineering, Universidade Federal de S~ ao Carlos, Rodovia Washington Luís, Km 235, 13565-905 S~ ao Carlos, Brazil article info Article history: Received 3 May 2014 Received in revised form 27 July 2014 Accepted 19 August 2014 Available online 30 August 2014 Keywords: Nanocomposites Halloysite nanotubes Biobased thermoplastic polyurethane abstract Nanocomposites of biobased thermoplastic polyurethane (TPU) from dimer fatty acids and halloysite nanotubes (HNT) were elaborated by different melt processing routes such as direct mixing (1 step process) and masterbatch/dilution (2 steps process), at different temperatures (150 and 180  C). Rheo- logical and transmission electron microscopy (TEM) analyses indicated that the HNT distribution and dispersion were dependent on the processing conditions: the 2 steps process produced well dispersed nanocomposites and the masterbatch dilution at 180  C improved the HNT distribution through the TPU. Consequently, a high reinforcement was achieved, with a 40% increase in the elastic modulus and 8  C increase in the relaxation temperature related to the glass transition of the TPU soft segments. Furthermore, a percolated network was attained, even if a large extent of HNT breaking was observed during processing, suggesting that a synergistic effect between the HNT particles and the TPU's hard segments in the molten state occurred. Thus, HNT nanotubes can be seen as highly reinforcing nanofillers when good dispersion and distribution are achieved through the polymeric matrix. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction In recent years, the production of polymeric materials from renewable sources has become a major focus of study and the basis for the development of new materials due to environmental con- cerns, low cost and non-availability of some petrochemical raw materials. Polyurethanes (PU) are one of the most produced and consumed polymers, being widely used in automotive, domestic, construction and biomedical applications. The use of polyols ob- tained from natural renewable sources for the synthesis of poly- urethanes is largely known and the industry has moved towards the replacement of fossil resources, allowing the production of biobased PU materials in large scale [1]. Thermoplastic polyurethanes (TPU) are block copolymers with hard (HS) and soft segments (SS) that separate into microphases or domains. The SS are formed of amorphous domains generally constituted by long chain polyols. However, the HS form domains mainly composed by a rigid diisocyanate and a short chain extender. Recently, the synthesis of innovative TPUs (with different HS contents) based on long chain polyols from dimer fatty acids of rapeseed oil was reported by some of us [2]. The dimer of fatty acids was obtained by a DielseAlder reaction between two different fatty acids, mainly linoleic acids. The structure, morphology, mechanical properties and degradation behavior of these TPU were studied [2,3]. By tuning the HS content, and consequently the structure of the TPU, it was possible to obtain efficient materials with adjustable properties for a large range of application. The use of nanoparticles (NP) to improve specific properties of polymeric materials has been extensively studied during the last decade [4e11]. In general, the achieved reinforcement is dependent on the NP intrinsic characteristics (aspect ratio, shape, surface area, rigidity …), on a proper NP's dispersion and distribution through the polymeric matrix (to form a percolated structure) and on the compatibility/affinity between the two main components (nano- filler and polymer). The dispersion and distribution state of the NP's (and thus its percolation concentration) can be altered by the processing conditions [10,12], while the compatibility with the matrix can be improved by surface modification of the NP and/or the use of compatibilizers such as surfactants [10,13e15]. More * Corresponding author. Present address: Universidade Federal de Itajub a, Campus Itabira, Rua Irm~ a Ivone Drumond, 200, 35903-087 Itabira, Brazil. Tel.: þ55 31 3839 0877. E-mail address: juliano.marini@unifei.edu.br (J. Marini). Contents lists available at ScienceDirect Polymer journal homepage: www.elsevier.com/locate/polymer http://dx.doi.org/10.1016/j.polymer.2014.08.049 0032-3861/© 2014 Elsevier Ltd. All rights reserved. Polymer 55 (2014) 5226e5234