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This study addresses the mechanical behavior of lattice materials based on flexible thermoplastic polyurethane (TPU) with honeycomb and gyroid architecture fabricated by 3D printing. Tensile, compression, and three-point bending tests were chosen as mechanical testing methods. The honeycomb architecture was found to provide higher values of rigidity (by 30%), strength (by 25%), plasticity (by 18%), and energy absorption (by 42%) of the flexible TPU lattice compared to the gyroid architecture. The strain recovery is better in the case of gyroid architecture (residual strain of 46% vs. 31%). TPUs with honeycomb architecture are characterized by anisotropy of mechanical properties in tensile and three-point bending tests. The obtained results are explained by the peculiarities of the lattice structure at meso- and macroscopic level and by the role of the pore space.

The effect of orientation of the layers of the original structure of polymers produced by fused deposition modeling (FDM) on the reinforcing effect caused by succeeding equal channel multiple angular extrusion (ECMAE) is studied. As test objects, glassy acrylonitrile butadiene styrene copolymer (ABS), glycol-modified poly(ethylene terephthalate) (PET-G) and semicrystalline PET are selected, as well as layered composites ABS/PET and ABS/PET-G. It is demonstrated that ECMAE results in enhancement of microhardness, storage modulus, impact strength. The density, the glass transition temperature, the melting temperature are increased, too. The crystallinity degree of extrudates is enhanced. It is shown that an increment in the mechanical characteristics is better in the case of longitudinal position of the melt layers, as compared to the transversal one. The achieved effects are related to the pore healing, formation of orientation ordering, and enhanced interphase interaction and homogenization of the system in the course of production of layered composites of thermodynamically incompatible polymers. A physical model is suggested that describes the behavior of the layered materials under ECMAE. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45727.