Benefits of Low Kenaf Loading in Biobased Composites of Poly(L-lactide) and Kenaf Fiber Sunny M. Ogbomo, 1 Kent Chapman, 2 Charles Webber, 3 Robert Bledsoe, 4 Nandika A. D’Souza 1 1 Department of Materials Science and Engineering, University of North Texas, Denton, Texas 76203 2 Department of Biological Sciences, Biology Building 210, University of North Texas, Denton, Texas 76203 3 USDA, ARS, SCARL, Highway 3 West Lane, Oklahoma 74555 4 Kenaf International Association, 101 Depot, Ladonia, Texas 75449 Received 14 May 2008; accepted 15 October 2008 DOI 10.1002/app.29519 Published online 30 January 2009 in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: Bast fibers from stems of kenaf (Hibiscus cannabinus, L.), a warm-season tropical herbaceous annual plant, were dispersed into poly-L-lactide (PLLA) matrix by melt-mixing followed by compression molding. Low fiber fractions (1–5%) were investigated. The composites showed a slight lowering of thermal stability when eval- uated by thermogravimentric analysis. X-ray diffraction and differential scanning calorimetry indicated an influ- ence of kenaf on the crystallization of PLLA. The fiber dis- persion in the polymer matrix was established by polarized optical microscopy. Scanning electron micros- copy showed good fiber–matrix adhesion as revealed by the combination of dispersion, interaction, and crystallin- ity, which enabled an increase in the mechanical proper- ties of the composite that scaled with concentration. V V C 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112: 1294–1301, 2009 Key words: poly-L-lactide (PLLA); renewable resources; green and biocomposites; kenaf; crystallization; dynamic mechanical analysis INTRODUCTION The need to replace fossil-based materials has led to an increased interest in biopolymer composites. Reinforcement of polymers with natural fibers has also been of interest. 1–6 A primary benefit is the improvement in mechanical properties. Kenaf (Hibis- cus cannabinus, L.; family Malvaceae) is a tropical- season herbaceous annual plant, related to cotton, okra, and hibiscus that can be produced across a large range of cultural conditions and locations, and has excellent potential as a commercial crop for industrial applications. 7–9 It is grown widely for cor- dage in Asia. Products from kenaf have many uses that include animal litter, a fiberglass substitute, ani- mal forage, cellulose fiber, potting mix, pulp and pa- per making, sacs, canvasses, and carpets. 7,10–14 Applications of kenaf fibers have received renewed attention because of their lightweight, low combusti- bility, nontoxicity, biodegradability, and low cost. 15–17 In the past few decades, increased use of fiber- reinforced composites for various structural and semi- structural applications has resulted in the development of synthetic fibers for such applica- tions. 18–25 In the automobile industry, an increased need to replace fossil-based materials with renew- able resources has led to the interest in reinforcing polymers with natural fibers. 4,26 For example, Toyota Motor Corporation recently used some of these properties in their production of door panels from polypropylene/kenaf blends. 26–29 Incorporating kenaf in the manufacture of automotives not only increased their biodegradability but also reduced their weight and enhanced their noise absorbent ability. Parikh et al. 30 found that nonwovens made of retted kenaf blended with cotton fibers, recycled polyester, and off-quality polypropylene could meet industry specifications of flammability, odor, mil- dew, and strength. Mueller and Krobjilowski 31 have studied the formation of composites by using flax fibers and biodegradable melt-blown polymeric materials as the matrix. It was observed that the nat- ural fiber-based composites possessed many of the required properties that are comparable with the polypropylene-based composites. Poly-L-lactide (PLLA) is one of the most important biodegradable polymers and has been the focus of many studies in recent years. 32–37 PLLA has a melt- ing temperature of 160  C and good tensile proper- ties. 38 As such, PLLA possesses wide applications as a raw material in industrial applications 39 and in medical applications 36,40 (suture materials and ortho- pedic fixation devices). Serizawa et al. 39,41 investi- gated the development of fiber-reinforced polylactic acid for use in electronic products. In their studies, high-performance biomass-based plastics consisting of polylactic acid were added to kenaf, which fixes carbon dioxide efficiently. They discovered that the Journal of Applied Polymer Science, Vol. 112, 1294–1301 (2009) V V C 2009 Wiley Periodicals, Inc. Correspondence to: N. A. D’Souza (ndsouza@unt.edu).