This paper was devoted to the technological process of manufacturing a biocomposites tube made of low-density polyethylene and barley straw fibers. 50% of HDPE, 42% barley straw, 5% of shungite (mineral filler), 2% Maleid F (N, N-metaphenylenediamine) as coupling agent, and 1% Hexol CLA as lubricant were pre-mixed before compounding. The compounding of the raw materials was carried out on a co-rotating twin-screw extruder. The resulting granules were fed into the single screw extruder to obtain thermoplastic composite tubes. The temperature regime for the HDPE/barley straw composite processing was in the range of 145-160 °C and the screw rotation speed was 50 rpm. The tensile strength and modulus were found to be 27.7 MPa and 1687 MPa, respectively. The water absorption (24-h) and density of the specimens were 1.43% and 1.158 g/cm3, respectively. Based on the findings obtained from the present study, it can be said that the barley straw can be efficiently used in the production of tube formed HDPE composites.

The paper is devoted to the properties of the wood-polymer composite based on polyethylene and barley straw. The effect of a mineral additive, namely shungite powder with a particle size of less than 20 microns, was studied. The developed composites were obtained on a laboratory two-rotor batch mixer. The mechanical and rheological properties of the composites (tensile strength and modulus of elasticity, water absorption, density, effective viscosity and modulus of elasticity) have been studied. It has been shown that the adding of shungite powder contributes to increase in the composites mechanical properties, in particular, the tensile strength increases. With an increase in the concentration of shungite, the viscosity of the composition melt decreases. The obtained thermoplastic materials can be used in construction and furniture production, as well as in the automotive industry.