TENSILE PROPERTIES AND MORPHOLOGY OF PLA/KENAF FIBER COMPOSITES TOUGHENED WITH ETHYLENE ACRYLIC COPOYMER

R. Mat Taib* and H. M. Hasan

Abstract

TENSILE PROPERTIES AND MORPHOLOGY OF PLA/KENAF FIBER COMPOSITES TOUGHENED WITH ETHYLENE ACRYLIC COPOYMER

1. Mat Taib ¹ and H. M. Hasan¹

1School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia

ABSTRACT

Composites from poly(lactic acid) (PLA) and kenaf bast fiber (KF) were prepared using an internal mixer and compression molding. The weight percent of the fiber was fixed at 40 wt %. The biodegradable composites were prepared with different amounts (0 to 40 wt %) of a commercially available ethylene acrylate copolymer impact modifier (IM). The tensile properties of the composites were examined in relation to their morphology. With increasing IM content, the PLA/KF composites showed some improvements in the elongation at break indicating the toughening effects of the impact modifier. In contrast, the tensile strength and tensile modulus decreased with the increase in the IM content. Scanning electron microscopy (SEM) examination on the composite fractured surfaces revealed the formation of a ductile material (flexible interface) partially around the embedded fiber. In addition, matrix drawing or shear yielding was also observed. Formation of the flexible interface and improved deformability of the PLA matrix may have contributed to the positive improvement in the elongation at break impact but negative improvements in the tensile strength and modulus of the composites. Other toughening mechanisms observed via SEM were fiber debonding and fiber pull-out.

Key words: Poly(lactic) acid, kenaf bast fiber, impact modifier, mechanical properties, morphology.