Potential of Biodegradable Polyhydroxyalkanoates for the Construction of Sustainable Polymer Composite Materials

The article presents the results of a study of constructed composites based on degradable poly(3-hydroxybutyrate) (P(3HB)) filled with plant materials of 30, 50, and 70% of different origin-wood flour (WF) from birch (<i>Betula pendula</i>), hemp hurds (HH) or hemp fiber (HF) (<i>Cannabis sativa</i>). Composite bar samples were obtained by hot pressing homogeneous mixtures of polymer and fillers at 170 °C and a specific pressure of 6.13 MPa. The influence of the filler type and the polymer/filler ratio on the temperature characteristics of the samples, density, microstructure, surface properties, water absorption, physical and mechanical properties, and degradability in soil was determined. The Young's modulus of the samples ranged from 2640 to 3715 MPa, depending on the composition. The maximum degradation of the composites after 120 days of exposure to soil was recorded at 70% WF, HH, or HF filling, amounting to 77.4, 63.5, and 38.6%, respectively. Perspective biodegradable composites based on P(3HB) filled with various plant-based fillers were obtained and characterized, along with new knowledge about their properties, the lack of which currently hinders the active development and commercialization of such in-demand materials.