Improvement of Mechanical and Viscoelastic Properties of Polypropylene with Wood and Wollastonite Fillers

In recent years, polypropylene has become one of the most popular thermoplastic polymers due to its excellent properties, chemical resistance, affordability, and easy processing. When reinforced with glass fibers, wood fibers, or mineral fillers, polypropylene composites exhibit enhanced mechanical strength, stiffness, and durability. This makes them suitable for applications where high performance and specific mechanical properties are required, such as in automotive interior parts, building materials, and consumer goods. This research analyzes the effects of wood fibers as an organic filler and wollastonite mineral as an inorganic filler on the mechanical and viscoelastic properties of polypropylene. Various weight ratios of these fillers were added into polypropylene to produce hybrid biocomposites using a laboratory-type high-speed thermokinetic mixer and a heated-cooled hydraulic press. The mechanical properties were determined by tensile and three-point bending tests, and viscoelastic properties were analyzed using dynamic mechanical analysis. The test results indicated that the polypropylene composite sample containing 7% by weight of silane-treated wollastonite and 3% by weight of wood fibers showed the best results among all samples. The storage and loss moduli of the sample are approximately 25% and 22% higher than those of the polypropylene, respectively. Overall, hybrid biocomposites filled with silane-treated wollastonite exhibited enhanced mechanical and viscoelastic properties compared to those filled with untreated wollastonite, as supported by the experimental data.