Utilising bio-based plasticiser castor oil and recycled PLA for the production of conductive additive manufacturing feedstock and detection of bisphenol A

Abstract

The production of electrically conductive additive manufacturing feedstock from recycled poly(lactic acid) (rPLA), carbon black (CB), and bio-based plasticiser castor oil is reported herein. The filament was used to print...

Mixed Graphite/Carbon Black Recycled PLA Conductive Additive Manufacturing Filament for the Electrochemical Detection of Oxalate

“…The onset temperature of thermal degradation and conductive filler contents, where applicable, are presented in Table S1. It can be seen that the rPLA used throughout this study had an average onset of degradation temperature of 304 ± 4 °C, which showed good agreement with previous work. , As previously reported, castor oil produced an onset temperature of 250 ± 3 °C . The bespoke graphite/CB filament produced an average onset of degradation temperature of 283 ± 4 °C, which indicated that the conductive carbon fillers provided a stabilizing effect by acting as a barrier for gas diffusion out of the polymer, slowing the rate of decomposition .…”

“…The graphite/CB filament exhibited excellent printability, as shown for the lollipop-shaped AMEs, Figure D, where no additional extrusion rate was required to get a high-quality print. In comparison, the CB-only filament required increased extrusion rates to achieve a nonporous print surface …”

“…Initially, the as-printed graphite/CB AMEs were tested using cyclic voltammetric scan rate studies against the near-ideal outer-sphere redox probe [Ru­(NH 3 ) 6 ] 3+ (1 mM in 0.1 M KCl), Figure A. This allows for the best determination of the heterogeneous electrochemical rate constant, k 0 , and the real electrochemical surface area of the AME, A e . , A comparison of the CV response to [Ru­(NH 3 ) 6 ] 3+ at 25 mV s –1 from the bespoke graphite/CB filament, the commercially purchased CB/PLA filament, and a bespoke, previously published, CB/rPLA filament is presented in Figure B. It is important to compare to a bespoke filament of the same conductive filler wt % comprising only CB to elucidate the effect the graphite has on the system.…”

“…To help improve the sustainability of AM electrochemistry, Sigley et al produced bespoke conductive FFF filament from recycled coffee machine plastic pod feedstock that later was successfully applied for the electrochemical detection of caffeine. Further improvements in the sustainability of conductive filament production were made through the introduction of castor oil as a biobased plasticizer . Additionally, it has recently been shown how used AM electroanalytical sensing platforms can be recycled into a new filament (both conductive and nonconductive) for the production of sensors …”

“…Further improvements in the sustainability of conductive filament production were made through the introduction of castor oil as a biobased plasticizer. 21 Additionally, it has recently been shown how used AM electroanalytical sensing platforms can be recycled into a new filament (both conductive and nonconductive) for the production of sensors. 22 Within the work above, carbon black (CB, Super P), was added as a conductive filler with a loading of ∼25 wt %, increasing the amount found in the commercial conductive filament by ∼4.5 wt %.…”