Development of electrically conductive thermoplastic polyurethane nanocomposite powders for 3D printing

• Main Author: Tan, Yong Jing
• Other Authors: Zhou Kun
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2021
• Subjects: Engineering::Materials; Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/150684
• Institution: Nanyang Technological University

With the introduction of Additive Manufacturing (AM) in this rapidly developing world, studies on fully utilizing this technology have been carried out. AM techniques have been constantly evolving and proven to be able to replace common manufacturing technology. Selective Laser Sintering (SLS) technique is most widely used over other techniques and it also refers to as layered manufacturing. One advantage of SLS is its wide range of available powders that is able to be used in SLS printing. SLS fuses the nanocomposite powders through laser sintering, forming the desired 3D parts. Another advantage of SLS printing is that the final product requires little to almost no post processing. However, even though SLS process can offer multiple advantageous, the trade-off is that the product fabricated is often porous and brittle due to the general characteristic of nanocomposite powders after creating the master batch. The focus in this study regards toelectrical conductive nanocomposite powder, mainly Thermoplastic Polyurethane (TPU). To enhance the electrical conductivity, Carbon Nanotubes (CNTs) will be mixed with the TPU powder to form a nanocomposite powder for 3D printing. Therefore it is important to understand the function and limits of sintering CNTs. Adding too much CNT will lead to entanglement and caused dispersion problem, deteriorating the performance of the nanocomposite powder and becoming a liability. In order to prevent this case, it is important to study the ideal CNT filler content. Different weight percentage of the filler will be experimented to find the ideal weight percentage that is able to achieve good electrical conductivity without entanglement. In this study, the properties of the nanocomposite powder will also be evaluated to compare the printing compatibility of using this nanocomposite powder in SLS printing. Therefore, optimization of the parameters for the SLS process such as laser power, laser scan speed, and hatching distance will be evaluated. The result of the optimization will yield better quality print fabrication with ideal mechanical properties.