Effective reinforcement of engineered sustainable biochar carbon for 3D printed polypropylene biocomposites

Abstract

Carbon materials derived from sustainable biomass are widely being used as reinforcement fillers to alleviate the use of fossil fuel derived carbon materials in composites. However, high loading percentages of biochar carbons are required for effective reinforcement, because biochar derived traditionally are of low quality. In current study, high quality biochar was synthesized from sustainable starch based packaging waste using a high temperature/pressure pyrolysis reaction. Thus, obtained biochar was further modified using ultrasonication to reduce the particle sizes and increase active surface area making it more compatible for dispersion and 3D Printing. The BET surface area of ultrasonicated carbon was 185.08 m2/g; it was also observed that the modified biochar developed nanoscale morphology due to effect of ultrasound on surface of carbon. XRD and Raman analysis revealed that the carbon obtained was highly graphitized. SEM and TEM micrographs revealed that the carbon obtained has graphitic regions with nano surface morphologies. The modified biochar was used as an effective reinforcement filler with polypropylene polymer at a relatively low loading of 0–1 wt.%. The tensile modulus and strength increased by 34% and 46% respectively with a loading of just 0.75 wt.%. Thermal stability of the composite material also improved by delay of 51⁰ C in onset of decomposition temperature and 40 ⁰ C in maximum rate of decomposition temperature at 0.75 wt.%. Failure analysis of fractured surface revealed that ultrasonicated biochar was effective in reinforcing the material due to improved available surface area and nanosize defects formed on the surface of biochar carbon.