Effects of modified SWCNT on the mechanical and thermal properties of PLA/PHB bio-composites

Humic acid (HA) was first loaded on single-walled carbon nanotubes (SWCNTs) and then the HA-loaded SWCNTs (FSWCNTs) were further incorporated into polylactic acid/poly-β-hydroxybutyrate (PLA/PHB) composites (with a weight ratio of 60/40) to synthesize the FSWCNT/PLA/PHB blend, which is designed to prepare a fully biodegradable film. Further research to assess the morphological, mechanical, barrier, and hydrophobic properties of blends was carried out. HA was successfully attached to SWCNTs by investigating the microstructure of FSWCNTs and SWCNTs. Meanwhile, the samples showed two different melting peaks, which demonstrates that the blend was immiscible. Interestingly, the crystallization of PHB was gradually accelerated by increasing the content of FSWCNTs. The blend also exhibited an effect on the oxygen barrier. Most importantly, a small amount of the FSWCNT could greatly improve the ductility of the FSWCNT/PLA/PHB composite, with the maximum tensile strength increased by 236% and the elongation at break improved by 790%. Additionally, the tensile strength, compatibility, thermal stability, and barrier abilities of the films were improved for an FSWCNT content within the range of 0.1 wt. %–0.2 wt. %. From this study, it can be observed that PLA/PHB blended with small portions of FSWCNTs may further expand the application of environmentally friendly resources to diverse applications such as flexible films, agricultural films, and so on.