Modification of poly(lactic acid) filament with expandable graphite for additive manufacturing using fused filament fabrication (FFF): effect on thermal and mechanical properties

Abstract

Fused Filament Fabrication, better known as Fused Deposition Modeling®, is currently the most widespread 3D Printing Technology. There has been a significant demand for developing flame-retardant filaments. Thereby enabling them, for example, in electronics and automotive applications. In this study, commercial PLA filament was modified by the addition of 1, 3 and 5% (%wt.) of expandable graphite. The composites were reprocessed, via extrusion, into filaments for Fused Filament Fabrication. Thermal properties of the filament composites were evaluated by thermogravimetric analysis and differential scanning calorimetry. Mechanical properties of thermo-pressed specimens indicated that no strong adhesion was promoted between the filler and matrix. This is a challenge with expandable graphite reported by many authors. All composites with expandable graphite achieved the V-2 rating of UL-94 flammability test. In spite of this, the results indicated that flammability of the PLA was reduced. All composite filaments were printable and prototypes were successfully 3D printed.

Effect of amine‐reactive elastomer on the properties of poly(lactic acid) films obtained by solvent‐cast3Dprinting

“…While economically feasible for applications in, for example, disposable packaging, PLA has a high glass transition temperature (Tg) and brittleness, which limits its use when toughness and/or flexibility are required [ 2–5 ] or in electronics and automotive applications due to its high ignitability. [ 6 ] A possible route for overcoming these limitations is to blend PLA with conventional elastomers such as natural rubber, [ 2 ] terpolymer elastomers such as ethylene/n‐butyl acrylate/glycidyl methacrylate (EBA‐GMA), [ 4 ] acrylate copolymer with a core–shell structure, [ 7 ] or flexible polymers such as poly(butylene succinate) (PBS) [ 8 ] or poly(butylene adipate co‐terephthalate) (PBAT). [ 9,10 ] PBAT, for example, has been employed to result in dispersed‐phase morphology, where particles absorb fracture energy by increasing the toughness of brittle matrices.…”