Stone-Ground Wood Pulp-Reinforced Polypropylene Composites: Water Uptake and Thermal Properties

Abstract

Two of the drawbacks of using natural-based composites in industrial applications are thermal instability and water uptake capacity. In this work, mechanical wood pulp was used to reinforce polypropylene at a level of 20 to 50 wt. %. Composites were mixed by means of a Brabender internal mixer for both non-coupled and coupled formulations. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to determine the thermal properties of the composites. The water uptake behavior was evaluated by immersion of the composites in water until an equilibrium state was reached. Results of water absorption tests revealed that the amount of water absorption was clearly dependent upon the fiber content. The coupled composites showed lower water absorption compared to the uncoupled composites. The incorporation of mechanical wood pulp into the polypropylene matrix produced a clear nucleating effect by increasing the crystallinity degree of the polymer and also increasing the temperature of polymer degradation. The maximum degradation temperature for stone ground wood pulp-reinforced composites was in the range of 330 to 345 ºC.

Effect of particle size, coupling agent and DDGS additions on Paulownia wood polypropylene composites

“…Other studies have shown this trend. 18,19,26,27,[29][30][31] Tensile strength is a measure of the stress load a material can support before generating voids that lead to crazing of the material and ultimate failure. The u increase is attributed to better transfer of stress between the hydrophobic wood fiber and the hydrophilic PP matrix due to the chemical coupling.…”

Orange Wood Fiber Reinforced Polypropylene Composites: Thermal Properties

“…One of the limitations related with the use of natural fibers is the low range of temperature allowed to process the composite to avoid fiber degradation (López et al 2012a). To avoid this problem, it is important to determine the melting and degradation temperatures of the composite material.…”

Macro and micromechanics analysis of short fiber composites stiffness: The case of old newspaper fibers–polypropylene composites

“…In recent years, wood fiber and natural fibers have gained a significant interest as a reinforcing material for commercial thermoplastics [1][2][3][4][5][6]. Some advantages of natural fibers as opposed to other reinforcing materials are their high availability, their biodegradability, and their relative low cost and density.…”