Modeling of the tensile moduli of mechanical, thermomechanical, and chemi‐thermomechanical pulps from orange tree pruning

Stiffness is one of the most relevant properties of composite materials. Although fiberglass has been traditionally used as reinforcement, natural fibers are seen as possible replacements due to concerns for environmental protection. In this work fibers from orange tree prunings were prepared and converted into mechanical, thermomechanical and chemi-thermomechanical pulps, to be used as reinforcement for polypropylene. Polypropylene composite materials with 20–50% of reinforcing fibers were prepared and mechanically characterized. The intrinsic Young's modulus of the fibers was back calculated by means of the Hirsch model. The moduli were also obtained by Halpin-Tsai equations with Tsai-Pagano methods and then compared to establish the influence of the aspect ratio. Finally, a fiber tensile modulus factor was defined in order to characterize the contribution of the fibers to the Young's moduli of the composites. POLYM. COMPOS., 34:1840–1846, 2013. © 2013 Society of Plastics Engineers