Mechanical and thermal properties of epoxy/silicon carbide nanofiber composites Poornima Vijayan P a , Debora Puglia b , Agnieszka Dąbrowska c , Pournami Vijayan P d , Andrzej Huczko c , Jose M. Kenny b and Sabu Thomas a,e,f * The silicon carbide (SiC) nanofibers (0.1, 0.25, and 0.5 phr), produced by self-propagating high-temperature synthe- sis (SHS), are used to reinforce the epoxy matrix cured with an anhydride hardener. Morphological studies reveal a better dispersion of SiC nanofibers and a good level of adhesion between nanofiber and the matrix in composites with lower (0.1 and 0.25 phr) nanofiber loading. The flexural studies show that a maximum increase in flexural prop- erties is obtained for composites with 0.25 phr SiC nanofiber. The fracture toughness of epoxy is found to increase with the incorporation of SiC nanofibers, and 0.25 phr SiC nanofiber loading shows maximum fracture toughness value. The possible fracture mechanisms that exist in epoxy/SiC nanofiber composites have been investigated in de- tail. Thermogravimetric analysis reveals that SiC nanofibers are effective fillers to improve the thermal stability of epoxy matrix. Copyright © 2014 John Wiley & Sons, Ltd. Keywords: epoxy composite; SiC nanofiber; flexural properties; fracture toughness; thermal properties INTRODUCTION Silicon carbide (SiC) exhibits many excellent properties such as good thermal conductivity, high mechanical strength and hard- ness, high thermal stability, and superior chemical stability to ox- idation in extreme conditions. Recently, much work has been focused on production of SiC one-dimensional nanostructures, such as nanofibers, nanowires, nanorods, and nanowhiskers, due to their potential applications. [1–3] The outstanding mechan- ical properties of SiC nanofibers make this material a promising candidate for the reinforcing element in ceramic-, metal-, and polymer–matrix composites. Epoxy represents one of the most important engineering poly- mers and has found wide applications in adhesives and electronics encapsulation materials. Epoxy composites are used as structural parts in aerospace, automobile, and civil engineering applications due to their high mechanical strength. [4–6] Nanoscaled materials such as nanoclay, carbon fibers, graphites, carbon blacks, and car- bon nanotubes (CNTs) are now considered as filler material to pro- duce high performance epoxy composite structures with further enhanced properties. [7–11] The development of epoxy composite based on β-SiC nanoparticles having the best combination of ther- mal and mechanical properties was reported. [12] Recently, Alamri et al. [13] studied the synthesis and properties of epoxy hybrid com- posites filled with cellulose fibers and nano-SiC particles. Few stud- ies related to the enhancement of the mechanical properties of an epoxy matrix by the introduction of SiC nanowires have been con- ducted [14] so far. We have already reported the effectiveness of ul- tra sonication process over high shear mixing for the dispersion of SiC nanofibers in epoxy. [15] One of our authors recently prepared and studied the mechanical properties of epoxy nanocomposites using SiC purified fibers and raw SiC branches. [16] It is well recognized that, to take full advantage of the en- hanced properties of nanoreinforcements, it is necessary that they are homogeneously dispersed in the polymeric matrix. [17– 21] The fiber–matrix interfacial adhesion also plays an important role in determining the mechanical properties of fiber/polymer composites. Stronger interfacial bonding imparts high degrees of nanofiber wettability and better dispersion and enhances the mechanical and other properties of the resulting composite material. [22,23] Prolongo et al. [24] showed that the combination of sonication technique and high shear mechanical stirring seems to be effec- tive enough to separate carbon nanofiber bundles in the epoxy * Correspondence to: Sabu Thomas, School of Chemical Sciences, Mahatma Gandhi University, Priyadarshini Hills P.O., Kottayam, Kerala 686560, India. E-mail: sabupolymer@yahoo.com a P. Vijayan P, S. Thomas School of Chemical Sciences, Mahatma Gandhi University, Priyadarshini Hills P.O., Kottayam, Kerala, 686560, India b D. Puglia, J. M. Kenny University of Perugia, Materials Engineering Centre, Department of Civil and Environmental Engineering, Strada di Pentima 4, 05100, Terni, Italy c A. Dąbrowska, A. Huczko Department of Chemistry, Warsaw University, 1 Pasteur str., 02-093, Warsaw, Poland d P. Vijayan P Department of Physics, St. Berchmans College, Changanacherry, Kerala, 686001, India e S. Thomas International and Interuniversity Centre for Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam, Kerala, 686560, India f S. Thomas Universiti Teknologi MARA, Faculty of Applied Sciences, 40450, Shah Alam Selongor, Malaysia Research article Received: 14 August 2014, Accepted: 11 November 2014, Published online in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/pat.3437 Polym. Adv. Technol. (2014) Copyright © 2014 John Wiley & Sons, Ltd. 1