Synthesis and Characteristics of Composite Material with a Plant-Based Filler

The article presents the results of synthesis of polymeric composite material based on epoxy binder and plant-based filler. Pre-dried and powdered wheat straw was used as a plant-based filler. The wheat straw content in the composite varied from 10 to 50 wt.%. Thermal, mechanical, and surface properties of composites depending on the wheat straw content were researched. In addition, the samples were studied for resistance to corrosive environments. The hydrophobic–hydrophilic surface balance of composites was evaluated, and their free surface energy was studied. Introduction of wheat straw in small amounts (up to 30 wt.%) increases bending strength of polymer from 18.65 ± 1.12 MPa to 22.61 ± 0.91 MPa; when the content is more than 40 wt.%, reduction of strength is observed. Even with a wheat straw powder content of 50 wt.%, the bending strength is 11.52 ± 1.03 MPa, which corresponds to the strength of the construction material. The upper limit of working temperature for the epoxy binder is 306 °C, and for the composite with the wheat straw content of 30 wt.%—264 °C. The surface of the pure polymer shows a hydrophilic character. The average value of the water wetting contact angle of the pure epoxy sample is 84.96 ± 9.03°. The introduction of 30 wt.% of wheat straw powder filler transforms the surface into hydrophobic one (average value of water wetting contact angle is 96.69 ± 5.71°). The developed composites can be applied in furniture production including tabletops or panels for floors. Future research will focus on expanding the types of plant-based fillers for polymer composites.