In the recently published, ‘Effect of Porosity and Crystallinity on 3D Printed PLA Properties,’ international researchers look further into FDM (FFF) 3D printing with PLA, examining physical changes during fabrication. Mainly, the researchers were concerned with the connection between not only porosity and mechanical properties but also crystallinity.
Reminding us that it can be difficult to find ‘optimal printing conditions’ in FFF 3D printing, the researchers prepared for creating several iterations—being especially aware that this is necessary when the polymer is semi-crystalline—as is the case with PLA. Biodegradability is one of the biggest selling points with PLA, along with its accessibility and availability too. Many choices are also offered in color and texture. PLA still offers challenge, however, and is prone to disordered conformation of crystals.
“These crystals are metastable both at the temperature of their formation and below. From the melt, the polymer tends to crystallize in the α form but also partially crystallizes in the α’ form at lower temperatures,” stated the researchers. “In this case, the PLA has higher internal stresses and presents a lower thermal and mechanical stability. Moreover, the printing process forces semi-molten PLA to flow through a narrow nozzle, and this process induces an orientation of the polymer chains as investigated in a previous study.”
PLA 4043D (NatureWorks, Minnetonka, MN, USA) was used in the study, with filaments manufactured with a single-screw extruder. An Ultimaker 3 was used in final testing of samples. A cross-section was then examined so that researchers could find out more about the effects of porosity. During the study, PLA was found to be defective due to nozzle contact with the polymer. Four-layer thin samples were created too as the researchers continued to expand their studying.
3D printing with PLA is attractive to many users around the world due to the ease in use, affordability, and other applications. The team discovered that a trial-and-error approach is usually necessary.
“Morphological investigations of specimens’ cross-sections revealed the formation of numerous pores in the specimens’ cross-sections, particularly in the middle and top layers,” concluded the researchers. “Moreover, thinner samples and lower build-platform temperatures led to higher mechanical properties thanks to a higher degree of orientation (as determined by 2D-XRD patterns).
“In addition, lower mechanical properties were found when the instable δ crystalline form was present. However, the elastic moduli of almost all the samples are comparable to that of the injection-molded sample (i.e., the isotropic one). A thermal treatment (annealing at 120 °C for 10 min) was investigated in order to remove internal stresses and change the crystallinity of the printed samples.”
Porosity continues to be an ongoing point of concern in 3D printing, and is the center of a plentiful number of research studies from controlling porosity with activated carbon to eliminating it with capillary force, and examining the effects on lattice structures. What do you think of this news? Let us know your thoughts! Join the discussion of this and other 3D printing topics at 3DPrintBoard.com.[Source / Images: ‘Effect of Porosity and Crystallinity on 3D Printed PLA Properties’]
You May Also Like
Mobile Smart Factories Seek to 3D Print Wherever, Whenever
Bionic Production GmBH has developed a very interesting initiative dubbed the Mobile Smart Factory, a modular shipping container-based production site, equipped with 3D printing devices to provide real-time and onsite ...
3D Printing for Preoperative Simulation of Complex Cardiovascular Surgery
Last month, doctors in east China’s Nanchang city used 3D printing technology for the first time to assist a complex cardiovascular surgery. Before outlining their final plan, a pre-operative evaluation...
Greater Potential for Artificial Intelligence in Additive Manufacturing
Researchers from China continue in the quest to continually top 3D printing capabilities, adding complex layers with other technologies into the fold, as detailed in the recently published ‘Smart additive...
Using Symmetry and 3D Printed Medical Models to Repair Bone Fractures
In a new study, a team of researchers from China compared the clinical outcomes of treating isolated acetabular (concave surface of the pelvis) fractures with traditional 3D-printed planning models and...
View our broad assortment of in house and third party products.