Research

Zinc Oxide Nano-Additives for Improving Dimensional Accuracy for Vat Photopolymerization

To improve the dimensional accuracy of 3D printed parts in digital light processing (DLP), a controlled UV penetration through the photopolymer resin is necessary to avoid excessive unwanted curing caused by overexposure. 

The research scope includes that photocatalytic zinc oxide nanoparticles (ZnONP) is used as resin additives substituting photoabsorbers to control overexposure caused loss in dimensional accuracy. 

• Ng, Chin Siang, Alamelu Suriya Subramanian, and Pei-Chen Su. "Zinc oxide nanoparticles as additives for improved dimensional accuracy in vat photopolymerization." Additive Manufacturing 59 (2022): 103118. LINK

Curing Properties Dependence on CNT Dispersion for Vat Photopolymerization

Carbon nanotubes (CNTs) have been often implemented as an additive in photopolymer resins for photo-reactive manufacturing processes such as vat photopolymerization 3D printing to endow various functionalities and improve properties of components. 

However, CNTs are known for their effective UV absorption and strong agglomeration tendency, which reduce the 3D-printability of the resin composites. Moreover, since varying dispersion qualities and concentrations of CNTs significantly influence curing depth photo-curing characteristics, it remains a challenge to determine the appropriate curing parameters. Consequently, many time-consuming and tedious experiments are required to find the proper curing parameters for adequate manufacturing. 

The research scope includes a theoretical model that considers both the dispersion and concentration of CNTs needs to be established to provide appropriate curing parameters to overcome the need for extensive experimentation.

• Lee, Taehyub, Jeong-Hwan Kim, Chin Siang Ng, Alberto Andreu, Insup Kim, Wonhee Lee, Hyoungsoo Kim, Pei-Chen Su, and Yong-Jin Yoon. "Prediction of curing depth dependence on CNT nanofiller dispersion for vat photopolymerization 3D printing." Chemical Engineering Journal 482 (2024): 149110. LINK

Magnetically Responsive 3D-Printed Microstructures

Digital Light Processing® (DLP) 3D printing is a powerful additive manufacturing technology based on layer-by-layer photopolymerisation. Functional materials are commonly produced with this fabrication method by applying stimuli-responsive fillers in the polymer.

The scope of this research project is to 3D print magnetically responsive soft materials with characteristic feature sizes of less than 500 µm. The high aspect ratio 3D-printed magnetic materials may find applications as actuators or sensors at the intersection of robotics and healthcare.

Ferric Oxide Additives for Magnetic Polymer

Iron oxide has strong magnetic properties that can induce physical changes through stimulation for the shape memory polymer (SMP) in response to external magnetic fields. The feasibility of printing iron oxide-filler SMP was evaluated using a 3D printing technology called Digital Light Processing (DLP) that utilizes a vat polymerization process. The effects of increasing iron oxide particle loading on the material properties and the viability of heat generation were examined. Various experimental methods were used to obtain quantitative results for analysis. The sedimentation test evaluated the effect of ultrasonication on the dispersion of iron oxide particles in liquid resin. The cure depth test and printability test examined the printing properties, and the tensile test determined the mechanical properties.