Mechanical, thermal and morphological properties of unsaturated polyester/chemically treated woven kenaf fiber/AgNPs@PVA hybrid nanobiocomposites for automotive applications

Abstract

One of the major problems of the natural fiber reinforced composites is the inadequate interfacial bonding between the fibers and the polymer matrix. This problem can be overcome by removing the lignin and related materials from the fiber by chemical treatments. Besides nanoparticles are drawing more attention in the past two decades as they enhance the mechanical properties of polymers and composites. Hence, in the present work silver nanoparticles (AgNPs@PVA) were prepared and nanobiocomposites were made using unsaturated polyester resin, woven kenaf fiber (untreated and treated with NaOH, formic acid, acetic anhydride, hydrogen peroxide and KMnO4) and 2% AgNPs@PVA. In the FT-IR spectrum the band at 1736 cm−1 due to lignin disappeared completely for the fiber treated with 5% NaOH. The intensity of the above band was found to decrease in the order of KMnO4 > H2O2 > Ac2O > Untreated > HCOOH > NaOH treated fibers. The same trend was also observed in the mechanical properties of the nanobiocomposites. The tensile strength decreased in the order KMnO4 (40.76 N/mm2)>H2O2 (39.88 N/mm2)>untreated (35.04 N/mm2)>HCOOH (35.73 N/mm2)>Ac2O (34.6 N/mm2)>NaOH (26.80 N/mm2) treated nanobiocomposites. Both NaOH and HCOOH treated fibers were damaged as confirmed by the surface morphological studies. KMnO4 treated KF + PE + AgNPs@PVA nanobiocomposite showed better mechanical properties and less water uptake when compared to other nanobiocomposites. So addition of AgNPs@PVA and chemical treatment of the fibers together significantly increased the mechanical properties and reduced the water absorption properties of nanobiocomposites. This study, suggests that the material studied here could be good replacement for automotive interior (side panels, seat frames, central consuls) and exterior parts (door panels, dash boards).