The production of biobased carbonaceous powder from bioethanol coproduct lignin for use as a substitute for fossil fuel-derived conductive carbon black filler is examined. The synthesis procedure used for the formation of biobased carbon black is studied in order to obtain properties similar to conventional carbon black. Characterization of the carbon material after varying carbonization temperatures and ball milling times was investigated to optimize carbon size, surface area, and thermal and electrical conductivity. The optimized carbonized ball milled lignin had a carbon content greater than 90% with the majority of the carbon atoms in the sp² hybridized state. The carbonized ball milled lignin exhibited a surface area 882% larger and a thermal conductivity 36% greater in comparison to the conductive carbon black tested, while the electrical conductivity was 9.5 S m^–1 lower for the carbonized ball milled lignin. This research has demonstrated the possibility of producing biobased carbon black as a potential substitute for commercial carbon black by using lignin as a precursor material.

Polypropylene (PP) is an attractive polymer for use in automotive parts due to its ease of processing, hydrophobic nature, chemical resistance and low density. The global shift towards eliminating non-renewable resource consumption has promoted research of sustainable biocarbon (BioC) filler in a PP matrix, but this material often leads to reduction in composite strength and requires additional fillers. Graphene nano-platelets (GnPs) have been the subject of considerable research as a nanofiller due to their strength, while maleic anhydride grafted polypropylene (MA-g-PP) is a commonly used compatibilizer for improvement of interfacial adhesion in composites. This study compared the thermo-mechanical properties of PP/BioC/MA-g-PP/GnP composites with varying wt.% of GnP. Morphological analysis revealed uniform dispersion of BioC, while significant agglomeration of GnPs limited their even dispersion throughout the PP matrix. In the optimal blend of 3 wt.% GnP and 17 wt.% BioC biocontent, tensile strength and modulus increased by ~19% and ~22% respectively, as compared to 20 wt.% BioC biocomposites. Thermal stability and performance enhancement occurred through incorporation of the fillers. Thus, hybridization of fillers in the compatibilized matrix presents a promising route to the enhancement of material properties, while reducing petroleum-based products through use of sustainable BioC filler in composite structures.

To increase the biobased content of poly(ethylene terephthalate) (PET), up to 30 wt % poly(lactic acid) (PLA) was blended with PET using twin-screw compounding and injection molding processes. Multifunctional epoxide compatibilizers including a chain extender and an impact toughening agent were used as blend modifiers to improve the poor mechanical properties of PET/PLA blends. The mechanical and thermodynamic performances were investigated along with the morphological features through scanning electron microscopy, atomic force microscopy, and interfacial tension determination. From rheological and differential scanning calorimetry results, it was observed that the molecular weight of both PET and PLA increased with compatibilizers because of epoxide reactions. The toughening agent, poly(ethylene-n-butylene-acrylate-co-glycidyl methacrylate) (EBA–GMA), provided a 292% increase in impact strength over the blend but reduced modulus by 25%. In contrast, 0.7 phr addition of the chain extender, poly(styrene-acrylic−co-glycidyl methacrylate) (SA−GMA), yielded comparable performance to that of neat PET without sacrificing the tensile and flexural properties. When both compatibilizers were present in the blend, the mechanical properties remained relatively unaltered or decreased with increasing EBA–GMA content. The differences in mechanical performance observed were considered in relation to the strengthening mechanism of the two differing compatibilizers and their effects on the miscibility of the blend.

The incorporation of poly(lactic acid) (PLA) and poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) as a partial biobased polymer substitute for polypropylene (PP) was investigated. The ternary blends were prepared through melt compounding extrusion followed by injection molding techniques with a constant biopolymer ratio of 30 wt %. Further addition of pyrolyzed miscanthus-based carbon was carried out to establish a contrast between talc-filled PP. When the morphology of the biopolymer minor phase was analyzed theoretically using contact angle for interfacial tension and spreading coefficient values along with solubility parameter calculations and via scanning electron microscopy imaging, the core–shell architecture was found with the PHBV encasing the PLA phase. Mechanical testing of the materials showed that only the tensile properties were reduced for all samples, whereas the impact strength was increased above the neat PP. With inclusion of the biobased carbon filler into the blend system, the thermomechanical properties were elevated above that of the PP matrix. The final properties of the multiphase polymeric composites are found to be related to the morphology obtained and inherent properties of the individual constituents.

PLA composites containing sustainable biocarbon providing wear resistance and flame-retardant capabilities on par or superior to conventional talc filler.