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3D printing, also known as additive manufacturing, is becoming increasingly popular for prototype processing in industrial practice. Laser sintering, which is a laser powder bed fusion technique, is a versatile and common 3D printing technology, which enables compact and high-quality products. Polyamide 12, a popular 3D printing material, provides reliable mechanical and thermal properties. Weaknesses in applying this technology for polyamide 12 include incomplete information regarding the application of various types of additives and different printing orientations with respect to the properties. This study aimed to investigate the influence of various additives (including carbon fiber, glass fiber, flame retardant, and aluminum powder) combined with polyamide 12, using processing of predefined powder refreshing mixture on the properties of a finished product. The thermal, surface, and mechanical properties of samples printed with five different polyamides 12-based powders at three different print orientations were investigated. It was found that the inclusion of additives decreases the tensile strength and increases the surface roughness of printed components—however, the toughness increases. The results can assist designers in selecting an appropriate material that will produce a finished part with the required properties for a given application. [ABSTRACT FROM AUTHOR]

Nowadays, additive manufacturing—also called 3D printing—represents a well-established technology in the field of the processing of various types of materials manufacturing products used in many industrial sectors. The most common type of 3D printing uses the fused filament fabrication (FFF) method, in which materials based on thermoplastics or elastomers are processed into filaments. Much effort was dedicated to improving the properties and processing of such printed filaments, and various types of inorganic and organic additives have been found to play a beneficial role. One of them, calcium carbonate (CaCO3), is standardly used as filler for the processing of polymeric materials. However, it is well-known from its different applications that CaCO3 crystals may represent particles of different morphologies and shapes that may have a crucial impact on the final properties of the resulting products. For this reason, three different synthetic polymorphs of CaCO3 (aragonite, calcite, and vaterite) and commercially available calcite powders were applied as fillers for the fabrication of polymeric filaments. Analysis of obtained data from different testing techniques has shown significant influence of filament properties depending on the type of applied CaCO3 polymorph. Aragonite particles showed a beneficial impact on the mechanical properties of produced filaments. The obtained results may help to fabricate products with enhanced properties using 3D printing FFF technology. [ABSTRACT FROM AUTHOR]

• Environmentally friendly hygienic coatings based on acrylic latex were prepared. • Nanostructured ZnO and MgO, respectively, were used as antibacterial additives. • Nano-oxides were incorporated into latexes during emulsion polymerization. • Nanostructured MgO represents a promising replacement for nanosized ZnO. This paper deals with a facile fabrication of environmentally friendly hygienic coatings based on acrylic latex comprising embedded inorganic nanoparticles originating from nanostructured ZnO and MgO, respectively, in the role of antibacterial agents. The incorporation of surface-untreated powdered nanostructured oxides into the latex was performed during the latex synthesis carried out by a two-step emulsion polymerization technique. With this technological approach, latexes comprising dispersed inorganic nanoparticles in the content of ca 0.5 – 1.1 wt. % (based on solids) were successfully prepared. For obtaining high-performance coating films, keto-hydrazide self-crosslinking chemistry was introduced into latexes. The antibacterial efficiency of the coatings was evaluated with respect to the type and concentration of incorporated nanoparticles. It was determined that all the latex coating compositions containing inorganic nanoparticles exhibited a long-term storage stability and provided smooth transparent coating films of enhanced solvent and water resistance due to the combination of covalent and ionic interfacial crosslinking. The latex films displayed significant antibacterial activity, which was more pronounced with the increased content of nanoparticles. It was also found that the addition of nanostructured MgO enabled significant savings of a commercial biocidal additive while maintaining a high antibacterial efficiency. [ABSTRACT FROM AUTHOR]