Hybrid Eco-Friendly Biodegradable Construction Composites Modified With Humic Substances

Abstract

Obtaining hybrid eco-friendly biodegradable structural composites was considered. The aim of this work was to determining the properties of hybrid eco-friendly biodegradable construction composites modified with humic substances. Hybrid eco-friendly construction composites were obtained on the basis of bioplastic polylactides with the addition as a filler of coffee grounds with a polyfractional composition within a particle size of 0.5 mm to 1 mm and a hybrid modifier – humic substances from brown coal. Hybrid ecofriendly construction composites were obtained by extrusion of pre-prepared raw materials in a single-screw laboratory extruder at a temperature of 170–200 °С and an auger rotation speed of 30–100 rpm. Investigated impact strength, breaking stress during bending, melt flow index (MFI) and melting temperature of hybrid ecofriendly biodegradable structural composites modified with humic substances. Optimization studies have been carried out to determine the most effective composition of new ecofriendly structural composites based on bioplastics of polylactides, coffee grounds waste and humic substances of three different types. Researching data together with the data of impact strength, allows us to make assumptions about the possibility of forming a variety of products from structurally composite material, herewith a composition with a coffee content of 50 % by mass. deserves a special attention. The data show an increase the impact strength and the breaking stress during bending a hybrid modification of ecofriendly biodegradable construction composites based on polylactide, coffee grounds waste and humic substances in 2.5 times, with optimal in terms of strength characteristics is the content of coffee grounds at 50 % wt. and 0.5 % by mass humic substances with the highest content of volatile substances and the lowest content of carbon. For such hybrid ecofriendly biodegradable construction composites based on polylactide, coffee grounds waste and humic substances, the MFI is characterized by 3.1 g/10 min. and the processing temperature range is 182–188 °C. It is shown, that the designed hybrid eco-friendly biodegradable structural composites modified with humic substances can be used in the production of high-strength structures and elements for engineering purposes.