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This paper presents results of a study on the effect of filler size in the form of 15 wt% corn stalk (CS) fibers on the mechanical and thermomechanical properties of polylactide (PLA) matrix composites. In the test, polylactidic acid (PLA) is filled with four types of length of corn stalk fibers with a diameter of 1 mm, 1.6 mm, 2 mm and 4 mm. The composites were composed by single screw extrusion and then samples were prepared by injection molding. The mechanical properties of the composites were determined by static tensile test, static bending test and Charpy impact test while the thermo-mechanical properties were determined by dynamic mechanical thermal analysis (DMTA). The composite structures were also observed using X-ray microcomputed tomography and scanning electron microscopy. In the PLA/CS composites, as the filler fiber diameter increased, the degradation of mechanical properties relative to the matrix was observed including tensile strength (decrease 22.9–51.1%), bending strength (decrease 18.9–36.6%) and impact energy absorption (decrease 58.8–69.8%). On the basis of 3D images of the composite structures for the filler particles larger than 2 mm a weak dispersion with the filler was observed, which is reflected in a significant deterioration of the mechanical and thermomechanical properties of the composite. The best mechanical and thermomechanical properties were found in the composite with filler fiber of 1 mm diameter. Processing resulted in a more than 6-fold decrease in filler fiber length from 719 ± 190 µm, 893 ± 291 µm, 1073 ± 219 µm, and 1698 ± 636 µm for CS1, CS1.6, CS2, and CS4 fractions, respectively, to 104 ± 43 µm, 123 ± 60 µm, 173 ± 60 µm, and 227 ± 89 µm. The fabricated green composites with 1 to 2 mm corn stalk fiber filler are an alternative to traditional plastic based materials in some applications.

Comminution processes are one of the most common processes for processing energy materials, e.g. coal, biomass, and post-recycling elements. The hitherto unsolved problem is the high energy consumption of machines and the lack of precise descriptions of the phenomenon of comminution in terms of the relationship between the design features of mills and the properties of comminuted materials. The dynamic development of simulation techniques based on advanced models and the method of discrete elements allows for a certain mapping of occurring phenomena. The purpose of the work is to illustrate the possibility of using simulation software based on the discrete element method to model the grinding processes in the shredders grinding assemblies. The paper presents aspects of modeling the shape and size of particles, their interactions and contacts with mills structural elements, as well as aspects of crushing modeling in RockyDem software.

The paper presents a comparative analysis of the effect of selected design features of blade and disc units on the functional characteristics of the process of grinding corn stalks in specific ranges of input variables. The effect of changes in the geometric features of the working units and rotational speeds on the energy demand during the grinding process was estimated. On this basis, an assessment of the quality of the shredding product in terms of shape and size was also made.

The paper presents issues concerning the implementation of particle size analyzers in the evaluation of the grinding product. A review of the current solutions of the analyzers used in practice was made. The usefulness of the original size analysis system according to its own design has been verified and exemplary results of the size assessment of grinding products - polymeric materials and biological materials have been presented.