Effect of microstructure on the tensile and fracture properties of sisal fiber/starch based composites.

VERA ALVAREZ; ANALÍA VÁZQUEZ; CELINA BERNAL

JOURNAL OF COMPOSITE MATERIALS

Sage

Año: 2006 vol. 40 p. 21 - 35

0021-9983

In this work, the effect of microstructure on the tensile and fracture properties of injection-molded biocomposites consisting on starch based matrix and short sisal fibers was investigated. Tensile tests were carried out on samples cut in longitudinal (L) and transverse (T) directions respect to the melt flow direction. An increasing trend on Young’s modulus and tensile strength with fiber content was found, irrespective of the sample orientation. In addition, this reinforcing effect was more pronounced for L samples with many fibers mainly oriented longitudinally to the loading direction. Quasi-static fracture tests were also performed on SENB specimens with cracks propagating both parallel and perpendicular to the melt flow direction. The stress intensity factor was found to increase with fiber content, and it also depends on fiber orientation. The observed trend in fracture toughness with fiber content and microstructure could be explained in terms of the fiber pull-out mechanism. On the other hand, puncture tests were carried out for all compositions. Injection-molded composites exhibited higher values of total fracture energy than neat matrix. Furthermore, fiber orientation induced different patterns in the damage zone. Finally, several theoretical models were used in this work to predict elastic properties of these composites.