The dwindling petroleum supply along with climate change brought on by accelerating release of carbon into the atmosphere give rise to the demand for commodity plastic materials made from renewable resources. While several crop-based polymers are available on the market today, their full potential has yet to be realized due to thermomechanical property limitations. Nanocomposites offer the ability to control the polymer molecular interactions and thereby the bulk properties. Specifically, poly(L-lactic acid) (PLLA), produced from fermentation of corn sugars, is limited for packaging applications by its low heat distortion temperature and brittleness. PLLA is also slow to crystallize, which adds cost to processing operations.

Novel carbon nanospheres (CNS) derived from cellulose are a renewable nanomaterial that, when compounded with PLLA results in nanocomposites that are almost 100% renewables-based. In this study, various treatments of the CNS surface are compared in order to enhance the filler compatibility with the PLLA matrix. Chemically modified CNS show reversed solubility in non-polar solvents compared with the polar CNS as-received. The surface chemistries are characterized using thermogravimetric analysis, Fourier transform infrared spectroscopy, Raman spectroscopy and x-ray photoelectron spectroscopy. Performance of CNS as a nanofiller in PLLA is compared with common mineral fillers using a solution blending compounding technique. The resulting composites are characterized using thermal analysis and various mechanical testing techniques. Crystallization kinetics are explored in both the renewable PLLA and conventional polypropylene. The addition of CNS to the polymer matrices leads to faster crystallization and shows promise for improved thermal and mechanical stability. The resulting materials can be considered a new class of ecologically responsible biopolymer nanocomposites.