Mechanical characterization and design of hybrid reinforced polypropylene composites with talc fillers and cellulose fibers

Hybrid reinforced polypropylene composites (PPCs) were fabricated via injection molding, and tensile tests were conducted. The results showed that the addition of cellulose nano-fibers (CNFs) and maleic-anhydride-modified polypropylene enhanced the PPC elastic constant and tensile strength. The nonlinear properties of the composites were analyzed via two-step asymptotic homogenization. After confirming that the numerical simulation can predict the experimental results well, a new strain-energy-based indicator was introduced to quantify the filler addition effect. The mechanical properties of PPCs can be linearly approximated using the indicator, named filler contribution proportion, and a simple composite design based on this relationship was proposed. As verification examples, the elastic constant and maximum tensile stress of unknown PPCs were predicted within a 5% error.