Industrial Crops and Products 51 (2013) 415–424 Contents lists available at ScienceDirect Industrial Crops and Products journal h om epage: www.elsevier.com/locate/indcrop Green nanocomposites of natural rubber/nanocellulose: Membrane transport, rheological and thermal degradation characterisations Eldho Abraham a,b , Merin S. Thomas c , Cijo John d , L.A. Pothen b,∗ , O. Shoseyov a , S. Thomas c a R.H. Smith Institute of Plant Sciences and Genetics, Hebrew University of Jerusalem 76100, Israel b Research Department of Chemistry, CMS College, Kottayam 690110, Kerala, India c School of Chemical Sciences, Mahatma Gandhi University, Kottayam 686560, Kerala, India d Central Forensic Science Laboratory, Govt. of India, Chandigarh 160 036, India a r t i c l e i n f o Article history: Received 23 June 2013 Received in revised form 5 September 2013 Accepted 13 September 2013 Keywords: Natural rubber Nanocellulose Biocomposite Membrane transport Thermal stability Rheology a b s t r a c t The membrane transport, rheological and thermal degradation properties of nanocomposites based on natural rubber (NR) latex reinforced with nanocellulose is clearly discussed with theoretical explanations. The concentration of the nanocelluloses in the composites was 2.5, 5, 7.5 and 10 wt%. The cross-linking agents like ZnO, sulphur etc. were used during the composite preparation stage. The existence of the three dimensional network of Zn/cellulose complex in the nanocomposite and its influence on the diffusion, rheological and thermal properties were also discussed. The V rf value of the composite shows an increase from 0.74 (NR) to 0.80 (10% composite) which gives the evidence of the reinforcement of the filler in the matrix. The polarity and the tortuosity of the nanocellulose make the composites resistant to non-polar organic solvents and this behavior is increased with increasing the nanofibre content. The remarkable decrease in the diffusion coefficient and the equilibrium solvent absorption with the addition of nanocel- lulose is also discussed. Kraus empirical equation was used to ascertain the extent of reinforcement and found the percolation threshold value of the filler is in the range of 4.5–5.9 wt% of nanocellulose. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Nanocomposites based on polymeric matrices successfully inte- grate the concepts of composites and nanometer sized materials. It is well known that the term ‘nanocomposite’ describes a class of two-phase materials where one of the phases has at least one dimension lower than 100 nm. Scientific reports shown that the commercial interest in fillers for nanocomposites has mainly focused on clay, silica (Pavlidou and Papaspyrides, 2012) and other inorganic based materials. Tremendous works were reported in the last decade about carbon nanotubes (CNTs) reinforced nanocom- posites (Lau et al., 2006) and most recently the research works are concentrated in graphene reinforced composites (Nabarun et al., 2012). But in the recent decades, the polymers reinforced with cellulose nanofibres or with its derivatives have attracted many scientists owing to the green environmental issues (Abraham et al., 2012) and the enhanced mechanical, electrical and biodegrada- tion properties because of the nanomeric size of the cellulose. The biodegradability, high mechanical properties, low density, and availability from renewable resources and diversity of the sources ∗ Corresponding author. Tel.: +91 479 2301730; fax: +91 481 2590357. E-mail addresses: eldhoabraham@gmail.com, eldhoabraham1@gmail.com (E. Abraham), lapothan@gmail.com (L.A. Pothen). (Abraham et al., 2011) of the nanocelluloses have posted them as a competing candidate for polymeric green filler. Nano reinforced polymer composites are widely used in many engineering applications and hence the study of transport of sol- vent molecules through these membranes and their flow properties along with the thermal degradation analysis are very important. Diffusion in the composite membrane is a kinetic process depend- ing on the free volume within the material, segmental mobility of polymer chains, tortuosity on the moving path because of the presence of the filler, polarity of the reinforced phase and the size of the penetrant molecule (Smith and Peppas, 1985). The trans- port properties of various rubber/rubber, thermoplastic elastomers, interpenetrating networks and natural fiber and particulate filled composites have been studied by various researchers (Mathew et al., 2002; Prasanthakumar and Thomas, 2001; Visakh et al., 2012). Transport properties of rubber composites are strongly dependent on the cross-linking, the nature of filler and additives, penetrant size, etc. The hydrophilic OH groups in the surface of the nanocellulose has the ability to improve the barrier properties of rubber composite materials toward organic solvents according to a tortuous path model in which a small amount of nanocellulose significantly reduces permeant diffusion. In the dispersed system, the individual nanofibre will have very high surface area and as a result the barrier and flow properties get changed. Angellier et al. (2005) have investigated the swelling behavior of natural rubber 0926-6690/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.indcrop.2013.09.022