Fused Deposition Modeling of Poly (lactic acid)/Nutshells Composite Filaments: Effect of Alkali Treatment

In this work, four kinds of nutshells (including walnut, almond, macadamia and wild almond shell powder (WSP, ASP, MSP and WASP) were composed with poly (lactic acid) (PLA). Fused deposition modeling technology was used to prepare the PLA/nutshell composite filaments. Nutshells were investigated by means of Fourier transform infrared spectroscopy regardless of the treatment with alkali. The composites were characterized by using: differential scanning calorimetry, thermogravametric, scanning electron microscopy. Meanwhile, the water-resistance and tensile properties were examined. The results showed that the thermal stability, water-resistant ability and tensile properties of untreated composites got worse comparing with that of PLA, but were enhanced dramatically after NaOH treatment. PLA/treated WASP has the highest degradation temperature. The crystallization degree of PLA/treated MSP and PLA/treated WASP was improved, when compared with that of PLA. The tensile strengths of PLA/MSP-Na and PLA/WASP-Na were almost close to that of PLA. PLA/MSP composite was the most water-resistant regardless of surface treatment. Those results indicated that the four kinds of composites have a potential application to manufacture structural parts with lighter weight.