PEER-REVIEWED ARTICLE bioresources.com Rodriguez et al. (2010). “Modeling corn fiber strength,” BioResources 5(4), 2535-2546. 2535 DETERMINATION OF CORN STALK FIBERS’ STRENGTH THROUGH MODELING OF THE MECHANICAL PROPERTIES OF ITS COMPOSITES Manuel Rodriguez, a Alejandro Rodriguez, b Jordi Bayer R., c Fabiola Vilaseca, d Jordi Girones, d,e* and Pere Mutje d Worldwide cultivation of corn is expanding, due in part to the increasing production of bioethanol. In consequence, huge amounts of corn stalks residues are been produced. Instead of incineration, we transformed the corn stalks into a semichemical pulp and successfully applied it as reinforcement in polypropylene composites. PP composites reinforced with 40% wt corn stalk single fibers were prepared, and their mechanical properties were evaluated. Through mechanical properties modeling of the composites, the intrinsic tensile strength of the cellulosic fibers that constitute the corn stalk have been determined. Keywords: Intrinsic tensile strength; Corn stalks; Composites; Modeling Contact information: a: Pulp&Paper Consultant; b: Universitat de Cordoba; c: Modified Cellulosic Fibres SL, C/Pic de la Peguera 15, Girona 17003, Spain; d: Group LEPAMAP, Universitat de Girona, Campus Montilivi, Girona 1707, Spain; e: Instituto de Ciencia y Tecnologia de Polimeros (ICTP-CSIC), Juan de la Cierva 3, Madrid 28006. *Corresponding author: jgirones@ictp.csic.es INTRODUCTION The determination of the intrinsic mechanical properties of natural strands (hemp, sisal, jute, etc.) as well as lignocellulosic fibers from wood and agro-forestry (wood pulp, thermomechanical pulp, semichemical pulp, recycled fibers, etc.) is a matter of controversy. Bibliographic data for the tensile strength of most lignocellulosic fibers presents big disparities. For instance, the tensile strength of flax fibers has been reported to be between 345 and 1100 MPa (Bledzki and Gassan 1999; Oksman et al. 2009). In the case of mechanical pulps, to our knowledge, there is only one report establishing its tensile strength as 750MPa (Sanadi et al. 1994), although it does not mention the true nature of the pulp (hardwood, softwood) or type (ground wood, thermomechanical pulp, etc.). Meanwhile, the tensile strength of a kraft-bleached fiber has been reported by some researchers to be in the neighborhood of 300 MPa (Beg and Pickering 2008), whilst other reports suggest a tensile strength of over 1000 MPa (Michel and Willis 1978). For fibers obtained from crop plants, the disparity in the tensile strength values reported can be easily understandable due to the influence of climatic conditions on plants. Besides, tensile strength of fiber strands can be empirically measured be means of single fiber analysis and, due to the naturally occurring imperfections on the fiber structure, the strength at break of the cellulosic fibers diminishes with fiber length. For this reason, typical protocols imply the analysis at variable gauge length. Then, the intrinsic strength of the fiber is extrapolated to a hypothetical zero gauge length, thus