Diffusion Foundations and Materials Applications Vol. 31

Abstract: The advancement of 3D printing in the past few decades propelled many ground-breaking developments in the water treatment industry. More specifically, 3D printing has the unique advantage of prototyping parts of high complexity with acute precision within a short period of time. Innovative feed spacers and membranes, which could not be fabricated using conventional methods, can now be 3D printed and evaluated in actual filtration experiments. However, there are still limitations to 3D printing such as the printing resolution, build volume and printing speed which poses some problems, especially in the fabrication of membranes. This paper presents a comprehensive and critical discussion on the 3D printed feed spacer and membrane prototypes from a 3D printing perspective.

Abstract: Chromium ions and other heavy metals discarded from major industries, if left unchecked, will make their way into waterways and may contaminate food crops, which can cause various chronic and acute health problems. As such, the Department of Science and Technology - Philippine Nuclear Research Institute (DOST-PNRI) developed radiation-grafted wastewater filters that selectively collect trivalent chromium ions from wastewater. To house these filters with the appropriate flow characteristics, column enclosures suitable for rapid prototyping via additive manufacturing, were designed and simulated. The column has two main components: the main chamber, which houses the filter; and an inner core, where the filter fabric is wound, and which evenly distributes the water flow along its length. Different core slit configurations were presented, giving emphasis on the flow uniformity, with the aim of maximizing the filter life.

Abstract: One of the most common orthopedic injuries is fracture found on the metacarpal bones of the hand. It is composed of 14-28 % emergency room cases in hospitals. Despite its frequent occurrence, they are often neglected which may lead to major disability or deformity that limits movement. This is merely due to the high cost of treatment which includes the usage of an external metacarpal fixator. In this paper, an external metacarpal fixator clamp with additive manufacturing polymer material is evaluated based on scenarios of flexural and compressive load on the metacarpal bone with simulated fracture. The material is selected using Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) multi-attribute decision making. Finite Element Analysis (FEA) is also done with increasing load per scenario. The result shows nylon as a suitable polymer additive manufacturing material for external metacarpal fixator. The equivalent stress on the fixator clamp and the deformation at a maximum load of 120 N is less than 1 Mpa and 0.5 mm, respectively. This comprises the suitability of 3D printed polymer material for an external metacarpal application. Future studies of comparison of FEA simulation and actual 3D printed part is recommended.

Abstract: This study utilized the Philippine burley and native tobacco as reinforcing materials to Polylactic Acid (PLA) in creating novel natural fiber-thermoplastic 3D printing filaments. As a new material for 3D printing, the effects of fiber loading, fiber species, and printing pattern on the mechanical properties of the tobacco fiber-PLA composites were investigated. Regardless of tobacco species and fiber loading, the honeycomb pattern showed superior tensile strength than its rectilinear counterpart. The same trend was also observed in the impact strength of some tobacco-PLA samples. Increase in fiber loading on the other hand, decreased the flexural strength and flexural modulus of the tobacco fiber-PLA composites. The trends in the mechanical properties were then analyzed using 3D X-Ray Computed Tomography, which allowed analysis and visualization of voids and layer patterns.

Abstract: Additive Manufacturing (AM) is revolutionizing the manufacturing industry as various AM technologies continue to mature and more AM-compatible materials are being developed. Polyether ether ketone (PEEK) is one of the promising materials at the forefront of this technological revolution as efforts to enhance its application as a 3D-printing material are continuously being pursued. In this study, the effect of printing parameters on the void content of 3D-printed PEEK was examined using a non-destructive method, X-ray micro computed tomography (X-ray micro-CT). Of the fused filament fabrication (FFF) parameters considered, higher nozzle temperature and printing speed were seen to promote an increase in void content while higher build plate temperature reduces it. Void content has a direct effect on the mechanical and other properties of the manufactured material and therefore provides a link between the printing parameters and the expected mechanical performance of these materials. This study also highlights the importance of choosing the right printing parameters to ensure the quality of the manufactured PEEK.