Optimum Volume Fraction of Short Sisal Fibers in Pectin Composites

N. A. OCHOA; M. G. GARCÍA; F. CRUCES

San Carlos de Bariloche

Congreso; 18° Congreso Internacional de Metalurgia y Materiales SAM-CONAMET 2018; 2018

CNEA

Short Sisal fiber composites (SSFC) based on a pectin matrix were prepared and characterized mechanically and optically. The lowest experimental L/d aspect ratio reported before was studied as a function of mechanical parameters. Different concentrations of sisal fiber within the pectin matrix were proved. Higher elastic modulus and tensile strength were observed as the amount of fiber content increases in the composite from 1 to 30 wt. %, proving a reinforcement effect. Optical microscopy and ImageJ software were used to analyze sisal fiber aspect ratio and fiber length and diameter distributions. It was found a maximum L/d = 2.8, L = 0.11 mm and d = 0.044 mm. Theoretical models were studied in order to calculate the maximum packing fraction (max) of randomly orientated short fibers and its relationship with mechanical parameters of the composite. Experimental volume fractions (exp) were range from 0.036 to 0.993 for 1 to 30 wt. % of fiber contents, respectively. Interestingly, an optimum volume fraction (opt) equal to 0.662 was observed at 20 wt. % SSFC. This composite also depicted best reinforced property agreeing with the theoretical predictions of the maximum packing fraction (max) for randomly orientated short fibers. It was also observed that higher fiber contents might promote orientation of fibers within the composite due to a lowering of mechanical parameters.