Title: Effect of fiber treatments on tensile and thermal properties of starch/ethylene vinyl alcohol copolymers/coir biocomposites Authors
|Rosa, Morsyleide - EMBRAPA, BRAZIL|
|Mattoso, Luiz - EMBRAPA, BRAZIL|
Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 12, 2009
Publication Date: November 1, 2009
Citation: Rosa, M.F., Chiou, B., Medeiros, E.S., Wood, D.F., Williams, T.G., Mattoso, L.H., Orts, W.J., Imam, S.H. 2009. Effect of fiber treatments on tensile and thermal properties of starch/ethylene vinyl alcohol copolymers/coir biocomposites. Bioresource Technology. 100(21):5196-5202. Interpretive Summary: The cior fibers treated by washing, mercerization and bleaching were incorporated in starch/polymer (EVA )matrix to develop composite. All the treatments removed surface impurities on fibers, producing modifications on the surface and improving thermal stability of both fibers and fiber-reinforced composites. Composites made from treated fiber had much improved physical and mechanical properties than those made from the untreated fibers The composites made with mercerized fibers showed a considerable 33% improvement in tensile strength and a 75% improvement in tensile modulus over that of the neat starch/polymer blend. Results indicate a better wettability of treated coir fibers with matrix and corroborated the role of treated coir fiber as a reinforcing agent.
Technical Abstract: The effects of different fiber treatments, namely washing with water, alkali treatment (mercerization) and bleaching, on mechanical and thermal properties of starch/EVA/coir biocomposites were evaluated by tensile tests and thermogravimetry (TG), respectively. Additionally, the fiber/matrix interface was characterized by scanning electron microscopy (SEM). All treatments produced surface modifications and improved the thermal stability of the fibers and consequently of the composites. The best results were obtained for mercerized fibers where the tensile strength (TS) increased by about 53% compared to composites with untreated fibers, and 33.3% compared to composites without fibers (Starch/EVOH). The results indicated that the mercerization conditions promoted a better fiber-matrix adhesion, allowing an efficient stress transfer from the matrix to the fibers. The increased adhesion between fiber and matrix was also shown by scanning electron microscopy. Treatment with water also produced improved values of Young’s modulus (E) which increased by 75% compared to starch/EVOH blends without fibers. Thus, starch/EVA blends reinforced with treated coconut fibers have superior properties than neat starch/EVA.