MECHANICAL PROPERTIES OF HYBRID TALC-CELLULOSE NANOFIBRIL-FILLED POLYPROPYLENE COMPOSITES Douglas J. Gardner, Yousoo Han University of Maine, Advanced Structures and Composites Center Alper Kiziltas, Debbie Mielewski Ford Motor Company Abstract There is considerable interest in the automotive industry towards light-weighting vehicles through the application of new material technologies, and polymer matrix composites are of primary importance in meeting the goals of light-weighting. In addition, the application of renewable materials like wood and plant fibers is of interest in meeting sustainability goals and replacement of petroleum-derived feedstocks. This paper presents results of a study examining novel hybrid polypropylene composites using a combination of cellulose nanofibrils and talc for potential use in automobile applications. The composites were compounded using a laboratory scale co-rotating extrusion system, and test samples were prepared by injection molding tensile, flexure and impact test specimens. The tensile and flexural properties of the hybrid composites were determined using an Instron testing machine and the Izod impact strength was determined on Ceast Impact tester. Cellulose nanofibrils can replace a portion of the talc which produces PP composites with improved mechanical properties and lower density. Background The concept of utilizing hybrid or mixed fillers in polymer matrix composites has been explored in the research arena for several decades (Zhang et al. 2006; Yang et al. 2010; Gaciua et al. 2005; Mittal et al. 2015). Combinations of fillers can provide enhanced material property performance in polymer matrix composites. For example, filler combinations might be chosen to provide improved mechanical properties and reduced water permeability or enhanced electrical conductivity and lighter weight, etc. Addition of fillers can also typically reduce the cost of the resulting composite especially with the application of nature-derived fillers such as cellulose or clay. The use of filled polymer composites is common in the automotive industry. Many manufacturers utilize glass-, cellulose-, or talc-filled polypropylene, glass-filled nylon to mention a few. However, manufacturers are looking at automotive composites for lighter weight materials to provide better fuel economy and lower carbon dioxide emissions (Stewart 2010). There is also a significant interest in green composites for automotive applications (Koronis et al. 2013). In many instances, the traditional filled polymer matrix composites are limited in material behavior were the combination of strength and reduced weight are needed. Thus the impetus for the work presented here.