The recent increases in plastic pollution and consumption have put bioplastics in a strong position to expand. However, better understanding is needed for bio-fillers and their effect on popular bioplastics, such as poly (lactic acid) (PLA), in order for this to occur. Biochar (BC), a stable form of carbon derived from high temperature conversion of organic material, has potential application as a plastic filler. Although biochar’s effect on petroleum-based plastics has been widely studied, there are still major gaps in the literature surrounding biochar use as a filler in PLA/starch composites. Biochar particle size and loading are two factors that greatly affect a composites’ mechanical properties. Thus, in this work, the effects of biochar particle size and biochar loading were examined when paired with a PLA/starch matrix. Mechanical and thermal testing was performed on composites that varied in filler loading (0-20 wt.%), as well as biochar filler particle size. At 20 wt.% biochar, the finer biochar particles produced a drop in the viscosity, which could be attributed to degradation within the composite at higher loadings. Mechanical characterization showed that increasing the BC filler loading, increased the modulus of elasticity. Decreasing the particle size also increased the modulus of elasticity, and therefore made the composite stiffer. The most prominent finding showed that through a combination of decreasing the particle size and identifying an ideal filler loading (5wt.%), we were able to double the tensile strength and slightly increased the elongation, thereby increasing the composites toughness. These results indicate that particle size and loading are important design consideration when using biochar as a filler.

Library of Congress Subject Headings

Fillers (Materials); Polylactic acid--Mechanical properties; Biochar

Publication Date


Document Type


Student Type


Degree Name

Packaging Science(MS)

Department, Program, or Center

Packaging Science (CET)


Carlos Diaz-Acosta

Advisor/Committee Member

Thomas Trabold

Advisor/Committee Member

Alexis Rich


RIT – Main Campus

Plan Codes