Tensile Properties of Kenaf/Unsaturated Polyester Composites Filled with a Montmorillonite Filler H. D. Rozman, 1 L. Musa, 2 A. A. Azniwati, 1 A. R. Rozyanty 1 1 School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang, Malaysia 2 School of Material Engineering, Universiti Malaysia Perlis, Perlis, Malaysia ABSTRACT: Kenaf/unsaturated polyester composites filled with montmorillonite (MMT) filler were produced. Overall, the study showed that, for samples with kenaf fil- ler only, the strength properties decreased as the kenaf fil- ler loading was increased from 40 to 60%. The increase in the kenaf filler loading reduced the amount of matrix ma- terial. This subsequently lowered the ability of the sample to absorb energy or distribute stress efficiently. However, with MMT, the tensile properties improved because of the high aspect ratio and surface area of the MMT. The study of the effect of kenaf filler size on the tensile properties showed that the samples with the smallest size (74 lm) displayed the lowest tensile properties compared to the larger ones. This was attributed to the agglomeration of the kenaf fillers. The addition of MMT resulted in an over- all increase in the tensile strength of the composites com- pared to those without MMT. V C 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 2549–2553, 2011 Key words: composites; mechanical properties; polyesters INTRODUCTION Recently, the use of lignocellulosic materials to make composites has received considerable attention. This has been attributed to several advantages offered by lignocellulosic fillers, such as a lower density, greater deformability, lower abrasiveness to equip- ment, biodegradability, and lower cost. However, to produce a polymer composite with acceptable me- chanical and physical properties, the main obstacle to be resolved is the compatibility between the ligno- cellulosic material and the polymer matrix. Gener- ally, there are two types of interaction at the interfa- cial region, that is, covalent and hydrogen bonding. In thermoplastic–wood composites, covalent bond- ing at the interfacial region can be created with the incorporation of a coupling agent. Kenaf has gained research interest as a lignocellu- losic filler in polymer composites. One of its advan- tages is the absence of silica content, which is critical in the reduction of abrasiveness to processing equip- ment. 1 The density of kenaf (0.1–0.2 g/cm 3 ) 2 is much lower than that of glass fiber (2.55 g/cm 3 ), 3 carbon fiber (1.77 g/cm 3 ), 3 oil palm empty fruit bunch (0.7– 1.55 g/cm 3 ), 3 and hemp (1.48 g/cm 3 ). 4 This low den- sity gives the kenaf core an advantage to be used in applications, such as automotive interior paneling, to reduce fuel consumption. 5 The market price for lignocellulosic filler is much cheaper than conventional fillers, such as Kevlar, glass fibers, and carbon fibers. 6 However, the incor- poration of a lignocellulosic filler has been shown to adversely affect the strength of composites. 7–11 This situation may outweigh the importance of economy posed by lignocellulosic composites. From various studies in nanocomposites, nanofiller addition into a polymer matrix increases the strength and the mod- ulus of the composites. 12–16 With their high surface area and aspect ratio, nanofillers are expected to bal- ance the adverse effect of the irregularities of the lignocellulosic fillers. Thus, in this study, we focused on the effect of a nanofiller on the tensile properties of kenaf/unsaturated polyester composites (USPs). The nanoclay was a montmorillonite (MMT), a lay- ered aluminosilicate that comes from the smectite group. It has individual platelets that measure on the order of the micrometer scale diameter; this gives them an aspect ratio of about 1000 : 1, and the surface area of this clay can approach up to 760 m 2 /g. 17 Although it naturally forms stacks of platelike structure, it can still exhibit a high aspect ratio. EXPERIMENTAL Materials Unsaturated polyester resin (P9728) was purchased from Euro Chemo-Pharma Sdn. Bhd. Pte. Ltd., Correspondence to: H. D. Rozman (rozman@usm.my). Journal of Applied Polymer Science, Vol. 119, 2549–2553 (2011) V C 2010 Wiley Periodicals, Inc. Pre print of Tensile Properties of Kenaf/Unsaturated Polyester Composite Filled with a Montmorillonite Filler (2010) Journal of AppliedPolymer Science. , Vol. 119, 2549-2553