The effect of nanoparticles shape on the mechanical properties of poly lactic acid matrix

In this research, mechanical properties of poly lactic acid (PLA)-based nanocomposites were investigated. The nanocomposites were fabricated by adding of three types of nano-materials including multi-walled carbon nanotubes (MWCNT), carbon black (CB) nanoparticles and graphene nano-platelets (GnPs) in four levels from 0 to 3 wt.% to PLA matrix by an internal mixer. Tensile and impact tests were performed to obtain the mechanical properties of nanocomposites. Moreover, field-emission scanning electron microscopy (FESEM) was used to observe the state of nano-fillers dispersion. The FESEM images showed that CB nanoparticles and MWCNT are well distributed in the matrix, but that GnPs are agglomerated. The results of the tensile tests showed that the addition of MWCNT and CB nanoparticles increased the tensile strength by 36% and 76% and the elastic modulus by 10% and 68%, respectively. Also, the presence of all three types of carbon fillers at low loading increased the elongation at break of PLA matrix, and this increase was more significant for GnPs by 55% in the 1 wt.% loading. Finally, the PLA polymer become more brittle with the addition of nanotubes and nano-platelets, and its impact strength was reduced. While, the CB nanoparticles increased the absorbing energy and impact strength.