Simultaneously Strengthening and Toughening Poly(lactic acid) by Co-Additions of Poly(ɛ-caprolactone), Tributyl Citrate Plasticizer and Functionalized Multiwall Carbon Nanotube

In order to strengthen and toughen poly(lactic acid) (PLA), poly(ɛ-caprolactone) (PCL), tributyl citrate (TBC) plasticizer and sodium dodecylbenzene sulfonate (SDBS) modified multi-walled carbon nanotubes (s-MWCNTs) were melt compounded with PLA materials for the first time. The effect of s-MWCNTs on the morphology, as well as mechanical and thermal properties of PLA/PCL blends (containing 8 wt% TBC) was investigated. By co- additions of PCL, TBC, and s-MWCNTs at an optimized composition (containing 10 phr∼PCL, 8 phr∼TBC, 3 phr∼s-MWCNTs (phr∼parts per hundred)), simultaneously strengthening and toughening of PLA could be achieved, where the tensile strength and elongation at break of the nanocomposites were greatly enhanced by 8% and 147.9%, respectively, as compared to the neat PLA. The toughening mechanism was attributed to the synergistic effect of the flexibility of PCL and plasticizer effect of TBC, and the strengthen mechanism was attributed to the reinforcing effect of s-MWCNTs. In addition, the s-MWCNTs could be served as a nucleation agent and promote the growth rate of PLA crystallization. Overall, we proposed a simple and effective method to fabricate high-performance PLA materials with balanced mechanical properties.