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Nanofillers (NF) in microfibrillar composites support melt‐drawing and may lead to improved performance. However, antagonistic effects have also been found. The deterioration of mechanical properties by drawing in the presence of NF, as found by other authors in analogous undrawn systems, has not yet been explained. Experiments indicating the importance of NF migration between the HDPE matrix and the PA6 fibrils in the course of drawing have led to a tentative conclusion of changed crystallinity in the interfacial area resulting in a layer with reduced modulus. This was confirmed by the finite element analysis considering the formation of a “soft” interface as a result of reduced content of HDPE spherulites at the fiber surfaces. The results show a marked impact of this phenomenon on modulus. This original concept presents a basis for explaining some antagonistic effects in multicomponent polymer systems and a tool for the more rational design of composite materials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44712.

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The paper describes analytical and numerical solutions for five selected domes (a spherical shell, a geodesicisotensoid shell, a shell with zero transversal strain, a shell with zero transversal stress, and a shell with identical strain) for composite pressure vessels manufactured by means of filament (helical) winding. The stresses and strains in the domes were evaluated analytically from known equations with the use of MATLAB script for numerical evaluation and via finite element analysis (FEA) with Abaqus software and results were compared with each other. Two failure criteria, interactive and non-interactive, were chosen for the evaluation of critical areas of the shells. Moreover, the best dome shape for a given material and polar hole/equator ratio was selected for various types of failure, i.e., a loss of tightness/leakage or the failure of the fibers.