Bio-composites based on polylactic acid and argan nut shell: Production and properties

The aim of this work is to develop a new bio-composite based on polylactic acid (PLA) reinforced with argan nut shells (ANS). In this study, the effect of ANS chemical surface treatments on the morphological, mechanical, thermal, and rheological properties of PLA was investigated. In particular, a comparison between three chemical treatments (alkali, bleaching, and silane) is made for two filler concentrations (8 and 15% wt.). Scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, dynamic mechanical analysis, and tensile measurements were used to determine the morphology (particle distribution/dispersion/adhesion), thermal stability, mechanical behavior and rheological properties of the bio-composites compared with neat PLA. The results showed that the highest Young's modulus improvement (16%) was obtained with 15% of bleached ANS particles, while the highest tensile strength (1%) and strain at yield (8.5%) improvements were obtained with a silane treatment. These results were associated with good ANS-PLA interfacial adhesion and distribution in the matrix. Nevertheless, lower thermal stability (onset degradation temperature) for all the bio-composites was observed when compared to neat PLA. To complete the characterizations, water absorption and water contact angle were determined indicating better resistance of the bio-composites when ANS surface treatment was applied.