Article Influence of halloysite nanotubes on physical and mechanical properties of cellulose fibres reinforced vinyl ester composites AM Alhuthali and IM Low Abstract Natural fibres are generally added to polymer matrix composites to produce materials with the desirable mechanical properties of higher specific strength and higher specific modulus while at the same time to maintain a low density and low cost. The physical and mechanical properties of polymer composites can be enhanced through the addition of nanofillers such as halloysite nanotubes. This article describes the fabrication of vinyl ester eco-composites and eco- nanocomposites and characterizes these samples in terms of water absorption, mechanical and thermal properties. Weight gain test and Fourier transform infrared analysis indicated that 5% halloysite nanotube addition gave favourable reduction in the water absorption and increased the fibre–matrix adhesion leading to improved strength properties in the eco-nanocomposites. However, halloysite nanotube addition resulted in reduced toughness but improved thermal stability. Keywords Vinyl ester, halloysite nanotubes, recycled cellulose fibre, water uptake, mechanical properties, thermal properties Introduction Halloysite nanotubes (HNTs) are derived from natur- ally deposited alumino-silicate (Al 2 Si 2 O 5 (OH) 4 H 2 O) and are chemically similar to kaolin. 1 Structurally, due to mismatch between tetrahedral and octahedral inter- nal components, HNTs take on a cylindrical shape forming the tubes which are typically between 1 and 15 mm in length. 2 These tubes have dimensions of between 50 and 70 nm for the outer diameters and between 10 and 30 nm for the inner diameters. As the tubes are hollow, they allow HNTs to have very high surface area with a high aspect which promotes excel- lent interaction between the filler and matrix. 3 Tensile, fracture and impact strength as well as other mechan- ical and thermal properties are believed to be dramat- ically improved when HNTs are added to epoxy, polystyrene, polypropylene, polyvinyl alcohol and other polymers. 4 Natural fibres are eco-friendly, commercially viable fillers, that have excellent modulus to weight ratios and are capable of forming polymer composites with excel- lent toughness properties. 5 Natural fibres are bio- degradable, unlike plastics, and are energy efficient and often less expensive than the synthetic counter- parts. 6,7 Natural fibres are lighter than synthetic mater- ials, and having an excellent modulus to weight ratio, are ideal for stiffness-critical designs needed in con- struction, automotive and even aerospace industries. 7 Acoustic damping properties of natural fibres make them suitable for use in components in the internal areas of automobiles. 8 Compared to synthetic fibres, Department of Imaging and Applied Physics, Curtin University, Perth, Australia Corresponding author: IM Low, Department of Imaging and Applied Physics, Curtin University, GPO Box U1987, Perth, WA 6845, Australia. Email: j.low@curtin.edu.au Journal of Reinforced Plastics and Composites 32(4) 233–247 ! The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0731684412467392 jrp.sagepub.com