FIELD: polymer materials. SUBSTANCE: invention relates to methods for preparing compositions based on starch and uniformly distributed fibers that can be used for manufacturing packaging articles. Articles with elevated strength, characterized by sufficient flexibility and impact resistance and having cellular structural matrix with starch binder and reinforced by practically uniformly dispersed fibers are prepared from aforesaid compositions having high yield stress due to liquid fraction presented. In a double-stage mixing process, preliminarily mixed formulation is prepared by gelatinization of a part of starch binder or another thickener in water. Fibers should preferably have average length exceeding about 2 mm and length/diameter ratio exceeding ca. 25:1. Preliminary formulation is supplemented by the rest of starch binder, water, and other desired additives such as process form lubrication agent, mineral fillers, plasticizers, internal coating or sealing materials, and dispersants for manufacturing dimensionally stable products having selectively controlled foamed structural matrix. Resulting articles can replace those manufactured at present time from conventional materials such as paper, cardboard, polystyrene, plastics, and other organic-based materials. EFFECT: improved quality of packaging articles. 90 cl, 36 dwg, 33 tbl, 273 ex
