Dear Shima,

Indeed, one of the drawbacks of PLA is its high brittleness (i.e, low impact resistance and low ductility/strain at the break), properties that are much damaged by high filling. Based on my experience with PLA (nano)composites, the composition considered by you is mostly a masterbatch of PLA-graphite/CNT, maybe with bad rheology for 3D printing (did you check?). This MB will require dilution with the neat PLA for further utilization.

Function of the end-use properties required in your application (e.g., thermal, and electrical conductivity, others (?)), traditionally the percentage of CNT or graphite in your PLA composites/3D filaments must be much lower, and the literature is very rich on this subject. Please consider below some references for eventual help. There are also traditional methods to reduce the brittleness of PLA by plasticizing, blending with other (co)polymers, other methods.

Good luck in your R&D project and best regards,

Marius

PS: For eventual help:

Additive manufacturing of multifunctional polylactic acid (PLA)—multiwalled carbon nanotubes (MWCNTs) nanocomposites, Nanocomposites, 7:1, 184-199, DOI: 10.1080/20550324.2021.2000231

https://www.tandfonline.com/doi/full/10.1080/20550324.2021.2000231

Carbon nanotubes and expanded graphite based bulk nanocomposites for de-icing applications

https://doi.org/10.1016/j.compositesb.2020.108583

PLA composites: From production to properties

M. Murariu, P. Dubois / Advanced Drug Delivery Reviews 107 (2016) 17–46

https://doi.org/10.1016/j.addr.2016.04.003

Chapter Carbon Nanotubes and Graphene as Additives in 3D Printing

Marius Murariu Thanks so much for your answer.