(539f) Controlled Mechanical Anisotropy in 3D Printed Core-Shell Soft Material Polymer Composites

The growing applications of soft robotics and printed electronics is leading to an emerging interest in soft material FFF 3D printing techniques. A key missing element in this emerging field of soft robotics is the ability to develop highly selective directional mechanical response. The present study addresses the issue by using ABS+TPE core shell 3D printing filaments. We have previously demonstrated the ability of ABS+TPE filaments to exhibit a wide range of mechanical response based on the ratio of ABS and TPE in the filaments. The core layer consists of Acrylonitrile-Butadiene-styrene (ABS) material, providing the required stiffness to the print structures. Whereas the shell layer is made up of vulcanized silicon based thermoplastic elastomer (TPSiV 75A), providing the enhanced interlayer binding and flexibility to print structures. It results in formation of localized hard and soft segment within print structures, resulting in the formation of a polymer composite structure. In this study we demonstrate the mechanically anisotropic performance of ABS+TPE filament by varying the raster orientation (0°, 90°, and 45°) among print structures. Using 50%ABS+50% TPE print structures, we observed drastically different mechanical response for 0° and 90° raster orientation. The tensile modulus was recorded to be 976 MPa and 108 MPa respectively. In addition to that, 3-point bending study verifies the mechanically anisotropic bending behavior of print structures based on various raster layer orientations. The 3-point bending analysis of [(0)₈ -(90)₈] polymer composite depicts the drastic difference in flexural strength and flexural modulus response when the normal load is subjected to 0°- and 90°-layer orientation respectively. Using 75% ABS+25% TPE structures, we observed an increment in flexural strength from 15.23 MPa to 31.27 MPa, when subjected to raster orientation of 90° and 0° respectively. Further, the mechanical response can be tuned to achieve higher mechanical anisotropy based on the oriented layer composition in polymer composites. Hence, the localized soft and stiff segment using ABS+TPE segment can be used to develop structures for soft robotics applications using conventional FFF technique.