TY - JOUR AB - Polylactic acid (PLA) belongs to the few thermoplastic polymers that are derived from renewable resources such as corn starch or sugar cane. PLA is often used in 3D printing by fused deposition modeling (FDM) as it is relatively easy to print, does not show warping and can be printed without a closed building chamber. On the other hand, PLA has interesting mechanical properties which are influenced by the printing parameters and geometries. Here we present shape-memory properties of PLA cubes with different infill patterns and percentages, extending the research reported before in a conference paper. We investigate the material response under defined quasi-static load as well as the possibility to restore the original 3D printed shape. The quasi-static flexural properties are linked to the porosity and the infill structure of the samples under investigation as well as to the numbers of closed top layers, examined optically and by simulations. Our results underline the importance of designing the infill patterns carefully to develop samples with desired mechanical properties. AU - Ehrmann, Guido AU - Ehrmann, Andrea ID - 1633 IS - 1 JF - Polymers KW - polylactic acid (PLA) KW - fused deposition modeling KW - 3-point bending test KW - infill parameters KW - infill density KW - shape-memory properties TI - Investigation of the Shape-Memory Properties of 3D Printed PLA Structures with Different Infills VL - 13 ER - TY - JOUR AB - Poly(lactic acid) is not only one of the most often used materials for 3D printing via fused deposition modeling (FDM), but also a shape-memory polymer. This means that objects printed from PLA can, to a certain extent, be deformed and regenerate their original shape automatically when they are heated to a moderate temperature of about 60–100 °C. It is important to note that pure PLA cannot restore broken bonds, so that it is necessary to find structures which can take up large forces by deformation without full breaks. Here we report on the continuation of previous tests on 3D-printed cubes with different infill patterns and degrees, now investigating the influence of the orientation of the applied pressure on the recovery properties. We find that for the applied gyroid pattern, indentation on the front parallel to the layers gives the worst recovery due to nearly full layer separation, while indentation on the front perpendicular to the layers or diagonal gives significantly better results. Pressing from the top, either diagonal or parallel to an edge, interestingly leads to a different residual strain than pressing from front, with indentation on top always firstly leading to an expansion towards the indenter after the first few quasi-static load tests. To quantitatively evaluate these results, new measures are suggested which could be adopted by other groups working on shape-memory polymers. AU - Ehrmann, Guido AU - Ehrmann, Andrea ID - 1610 IS - 8 JF - Polymers KW - polylactic acid (PLA) KW - fused deposition modeling (FDM) KW - three-point bending test KW - infill parameters KW - infill density KW - shape-memory properties TI - Pressure Orientation-Dependent Recovery of 3D-Printed PLA Objects with Varying Infill Degree VL - 13 ER - TY - CONF AB - Polylactic acid (PLA) belongs to the few thermoplastic polymers that are derived from renewable resources such as corn starch or sugar cane. PLA is often used in 3D printing by fused deposition modelling (FDM) since it is relatively easy to print, does not show warping and can be printed without a closed building chamber. On the other hand, PLA has interesting mechanical properties which are influenced by the printing parameters and geometries. Here we present shape-memory properties of PLA cubes with different infill patterns and percentages. We investigate the material response under defined quasi-static load as well as the possibility to restore the original 3D printed shape. The quasi-static flexural properties are linked to the porosity and the infill structure of the samples under investigation, examined optically and by simulations. Our results underline the importance of designing the infill patterns carefully to develop samples with desired mechanical properties. AU - Ehrmann, Guido AU - Ehrmann, Andrea ID - 682 KW - polylactic acid KW - fused deposition modelling KW - 3 point bending test KW - infill parameters KW - infill density KW - shape-memory properties T2 - The First International Conference on “Green” Polymer Materials TI - Shape-memory properties of 3D printed PLA structures ER - TY - CONF AB - Polylactic acid (PLA) belongs to the few thermoplastic polymers that are derived from renewable resources such as corn starch or sugar cane. PLA is often used in 3D printing by fused deposition modeling (FDM) since it is relatively easy to print, does not show warping, and can be printed without a closed building chamber. On the other hand, PLA has interesting mechanical properties which are influenced by the printing parameters and geometries. Here we present shape-memory properties of PLA cubes with different infill patterns and percentages. We investigate the material response under defined quasi-static load as well as the possibility to restore the original 3D printed shape. The quasi-static flexural properties are linked to the porosity and the infill structure of the samples under investigation, examined optically and by simulations. Our results underline the importance of designing the infill patterns carefully to develop samples with desired mechanical properties. AU - Ehrmann, Guido AU - Ehrmann, Andrea ID - 1626 KW - polylactic acid KW - fused deposition modelling KW - 3-point bending test KW - infill parameters KW - infill density KW - shape-memory properties T2 - Proceedings of The First International Conference on “Green” Polymer Materials 2020 TI - Shape-Memory Properties of 3D Printed PLA Structures ER -