Hybrid cellulose-inorganic reinforcement polypropylene composites: Lightweight materials for automotive applications

Cellulose fibers are attracting considerable attention within the transportation industry as a class of reinforcing agents for polymer composites owing to their low cost, low density, high mechanical properties, and considerable environmental benefits. The objective of this study was to develop hybrid composites combining cellulose fiber with long glass fiber (LGF), short glass fiber (SGF), or talc in a polypropylene (PP) matrix to optimize the overall composite properties. Tensile, flexural, and notched Izod impact tests revealed that in general the mechanical properties decreased with increasing cellulose content, however, adding an optimum concentration of the cellulose fiber is a promising alternative to reduce or replace the utilization of inorganic fibers. Hybrid composites with 15 wt% LGF and 15 wt% Cellulose A exhibited an increase of 86% and 252% in tensile stress and Young's modulus, respectively, compared to neat PP X. Regarding the impact strength and the temperature at the maximum rate of decomposition, hybrid composites with 15 wt% SGF and 15 wt% Cellulose B exhibited 23% and 17% increase, respectively, compared to neat PP Z. The crystallization temperature (T-c) of all the composites increased compared to neat PP, revealing the fibers ability to act as nucleating agents and speed rate of part production which will result in lowering the manufacturing cost. For applications in automotive under-the-hood and body interior components, the hybrid cellulose-inorganic reinforcement composite approach not only leads to superior weight and cost savings, but also environment benefits over the inorganic reinforced composites.