Development of conductive cnts-filled polymeric nanocomposites produced via selective laser sintering

• Main Author: Ng, Yao Guang
• Other Authors: Zhou Kun
• Format: Final Year Project
• Language: English
• Published: 2017
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/72294
• Institution: Nanyang Technological University

Through the years, researchers have come to a realization of the importance of the fabrication of electrical conductive polymer composites. These conductive polymer composites have vast capabilities in the manufacturing industry, giving rise to potential electronic applications as well as developments in various fields that is of interest to many different industries. The most widely used processing method to produce electrical conductive polymer composites is also known as Selective Laser Sintering (SLS), which is one of the few established powdered-based 3D printing process. SLS falls into the solid free-form category, commonly known as layered manufacturing and fuses polymer nanocomposite through laser sintering, forming the desired 3D parts. Despite SLS process offering advantages such as abundant flexibilities in producing complex geometries, it also brought along constraints like the limited polymers that fit the bill for laser sintering. Research conducted on the different type of fillers involved in SLS process was discussed from many different studies, however the focus in this study lies with the filler – carbon nanotubes (CNTs). It is important to understand the functionalization and the consequences of sintering CNTs. High aspect ratio of CNT poses serious restrictions on exploring the potential applications due to the problem of entanglement. This entanglement problem often lead to the common dispersion problem, which eventually affect the polymer nanocomposites (PNCs) performance as well as the adhesion between the polymer and the CNTs. Investigation was conducted on the polymeric nanocomposite (PNCs) to further understand the importance of synthesis methods as well as the powder morphology. This phase helps to ensure that the produced laser sintered parts will be able to satisfy the desired property requirements. Also, an ameliorate technique is implanted to acquire separation of individual CNTs from agglomerations and adhering them to the polymer surface to avoid the occurrence of secondary agglomerations. In this study, the effects of the SLS process on the electrical conductivity properties from the incorporation of CNTs into polymeric powders PA12 and PU was examined. Agglomeration of the PNCs is discussed as well as the various laser power applied to produce the sample. In order to achieve the ideal electrical property, it is important to understand the critical filler content. Therefore, different weight percentage of the filler is also investigated to identify the percolation threshold for both polymer nanocomposite. The different planes of the sample is assessed to understand the conductivity between the distinct building planes. The presence of interconnected open channels within the polymer matrix have proven beneficial for the enhancement of electrical conductivity. The high inter porosity encapsulated by the conductive network structure formed by CNT within the polymer matrix is able to effectively transport electrons from the surface CNT layer which significantly increase conductivity.