Experimental verification of theoretical model of curing curve according to CNTs concentration and dispersion in CNT/resin nanocomposites for DLP 3D printing

Abstract

As one of VAT photopolymerization, Digital light process (DLP) 3D printing has the advantage of high resolution and fast printing speed, and also has easy material development due to using liquid resin for printing. In addition, since carbon nanotubes (CNTs) has excellent physical properties, various application researches are being conducted as additives for resin. Therefore, as a basic study combining DLP, an innovative process, and CNT, a smart material, the curing characteristics of CNT/resin composites were identified. Dispersion is essential because CNTs have a strong tendency to agglomerate. As the degree of CNT dispersion increases, the area where the CNTs block light increases, hindering the curing of the resin. Therefore, in this study, the curing characteristics of the CNT/resin composites according to the CNT concentration and dispersion were theoretically modeled and verified through experiments. The absorbance of the CNT/resin was measured using UV-Vis spectroscopic analysis, and the relationship with the absorbance and curing thickness was identified. It was found that the absorbance of the CNT/resin is a function of dispersion and concentration of CNTs. Moreover, it was found that the curing thickness is the logarithm of the exposure time and is inversely proportional to the absorbance.