@article{1578, abstract = { While shape memory alloys (SMAs) and shape memory polymers (SMPs) can already be found in diverse applications, shape memory textiles are less often used. Nevertheless, they are regularly investigated. Typical ways to produce shape memory textiles (SMTs) are introducing shape memory wires, printing shape memory polymers on them (“4D printing”), or using textile materials such as poly(lactic acid) (PLA) which show shape memory properties on their own. This review gives a brief overview of these technological possibilities and possible applications of shape memory textiles. }, author = {Ehrmann, Guido and Ehrmann, Andrea}, issn = {2701-939X}, journal = {Communications in Development and Assembling of Textile Products}, keywords = {shape memory properties, 3D printing, 4D printing, polyurethane, wrinkle-free, design, stimulus, smart textile, recovery}, number = {2}, pages = {162--172}, publisher = {Sachsische Landesbibliothek, Staats- und Universitatsbibliothek Dresden}, title = {{Shape memory textiles – technological background and possible applications}}, doi = {10.25367/cdatp.2021.2.p162-172}, volume = {2}, year = {2021}, } @article{1590, abstract = { Poly(lactic acid) (PLA) belongs to the 3D printable materials which show shape-memory properties, i.e., which can recover their original shape after a deformation if they are heated above the glass transition temperature. This makes PLA quite an interesting material for diverse applications, such as bumpers, safety equipment for sports, etc. After investigating the influence of the infill design and degree, as well as the pressure orientation on the recovery properties of 3D printed PLA cubes in previous studies, here we report on differences between different PLA materials as well as on the impact of post-treatments after 3D printing by solvents or by heat. Our results show not only large differences between materials from different producers, but also a material-dependent impact of the post treatments. Generally, it is possible to tailor the mechanical and recovery properties of 3D printed PLA parts by choosing the proper material in combination with a chemical or temperature post-treatment. }, author = {Ehrmann, Guido and Brockhagen, Bennet and Ehrmann, Andrea}, issn = {2227-7080}, journal = {Technologies}, keywords = {polylactic acid (PLA), shape-memory properties, fused deposition modeling (FDM), three-point bending test, post-treatment, solvent, heat}, number = {4}, publisher = {MDPI AG}, title = {{Shape-Memory Properties of 3D Printed Cubes from Diverse PLA Materials with Different Post-Treatments}}, doi = {10.3390/technologies9040071}, volume = {9}, year = {2021}, } @article{1633, abstract = { 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. }, author = {Ehrmann, Guido and Ehrmann, Andrea}, issn = {2073-4360}, journal = {Polymers}, keywords = {polylactic acid (PLA), fused deposition modeling, 3-point bending test, infill parameters, infill density, shape-memory properties}, number = {1}, publisher = {MDPI AG}, title = {{Investigation of the Shape-Memory Properties of 3D Printed PLA Structures with Different Infills}}, doi = {10.3390/polym13010164}, volume = {13}, year = {2021}, } @article{1610, abstract = { 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. }, author = {Ehrmann, Guido and Ehrmann, Andrea}, issn = {2073-4360}, journal = {Polymers}, keywords = {polylactic acid (PLA), fused deposition modeling (FDM), three-point bending test, infill parameters, infill density, shape-memory properties}, number = {8}, publisher = {MDPI AG}, title = {{Pressure Orientation-Dependent Recovery of 3D-Printed PLA Objects with Varying Infill Degree}}, doi = {10.3390/polym13081275}, volume = {13}, year = {2021}, } @inproceedings{682, abstract = {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.}, author = {Ehrmann, Guido and Ehrmann, Andrea}, booktitle = {The First International Conference on “Green” Polymer Materials}, keywords = {polylactic acid, fused deposition modelling, 3 point bending test, infill parameters, infill density, shape-memory properties}, publisher = {MDPI}, title = {{ Shape-memory properties of 3D printed PLA structures}}, year = {2020}, } @inproceedings{1626, abstract = { 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. }, author = {Ehrmann, Guido and Ehrmann, Andrea}, booktitle = {Proceedings of The First International Conference on “Green” Polymer Materials 2020}, keywords = {polylactic acid, fused deposition modelling, 3-point bending test, infill parameters, infill density, shape-memory properties}, location = {Sciforum.net}, pages = {7198}, publisher = {MDPI}, title = {{Shape-Memory Properties of 3D Printed PLA Structures}}, doi = {10.3390/CGPM2020-07198}, year = {2020}, }