Nanocomposites from lignin-containing cellulose nanocrystals and poly(lactic acid)

Abstract

Utilizing lignin-containing cellulose nanocrystals (HLCNCs) as reinforcing agents to poly(lactic acid) (PLA) for nanocomposites was studied for the first time. The PLA/HLCNCs nanocomposites were prepared by extrusion and injecting molding. The freeze-dried HLCNCs showed micron scale agglomerates. As indicated by the water contact angle measurements, the HLCNCs were more hydrophobic than dealkaline lignin and traditional, lignin-free CNCs derived from high cellulose content wood pulp. Thermogravimetric analysis (TGA) showed that the HLCNCs started to degrade at about 300°C. The thermal stability of nanocomposites was slightly lower than neat PLA. The Young’s modulus of nanocomposites containing 1%, 2% and 5% CNCs was improved by 21.0%, 18.4% and 17.7%, respectively, while the strain at break was improved by 73.2%, 63.4%, and 54.9% compared to neat PLA. The nanocomposites (PLA/2%HLCNC) exhibited increased microductility and plastic deformation over neat PLA during tensile test. No statistically significant changes in the tensile strength were found with HLCNC addition. The results provide some practical and fundamental insight of PLA/HLCNCs nanocomposites to be used for flexible packaging films. Future work to improve the dispersion of HLCNCs in the PLA matrix as well as in the CNC drying approach is suggested.

Citation

Wei, Liqing; Agarwal, Umesh; Stark, Nicole; Sabo, Ronald. 2017. Nanocomposites from lignin-containing cellulose nanocrystals and poly(lactic acid). In: Society of Plastic Engineers, ISBN: 978-0-692-88309-9: Paper prepared for: ANTEC® 2017. 8-10 May 2017. Anaheim, CA. 5 p.