Effect of saline and alkaline solution aging on the properties of jute/poly(lactic acid) composites

In this paper, jute/PLA composites were prepared by using twin-screw extrusion, and injection molding with weight percent of jute fibers was 10%. A saline solution (pH = 7.48 +/- 0.1) was prepared adding 0.05 g/mL of sodium chloride. A solution of NaOH with pH = 8.53 +/- 0.1 was also prepared. Its water absorption, pH value, and mechanical properties were measured and differential scanning calorimetry, gel permeation chromatography, scanning electron microscopy were performed to analyze the aging mechanism of jute/PLA composite in saline and alkaline solution at 23 degrees C. The results showed that the weight gain for jute/PLA composite immersed in alkaline solution was higher than that immersed in saline solution. The pH of alkaline solution declined faster than saline solution due to the neutralization of alkali and lactic acid, which produced from the hydrolysis of PLA. All the aged composites have a decline on mechanical properties in both solutions due to the degradation of jute fiber, PLA, and the interface between fiber and matrix. Mechanical strength of the composites under alkaline environment was lower than that of the composites under saline environment after aging.