Diffusion Foundations and Materials Applications Vol. 32

Abstract: This paper presents a concise review on 4D printing of shape memory polymers that focuses on the use of acrylate-based materials using photopolymerization. Stereolithography (SLA), Digital Light Processing (DLP), Inkjet Printing (IJP), and UV assisted Direct ink Writing (UV-DIW) are the photopolymerization printing techniques that uses acrylate-based materials. These acrylate-based feedstocks will be polymerized during printing by the presence of UV light to form shape memory polymers (SMPs). Acrylate-based SMPs will change their shape in response to heat, water, light, and pH. Demonstrated applications of these 4D printed acrylate-bases SMPs are in biomedical, soft robotics, flexible electronics, and structural materials. However, 4D printing is still in the early stage and there are a lot of challenges like enhancing mechanical properties, biocompatibility, limited kind of SMPs, high cost of 4D printing system, and many more that needs to be addressed before a viable product can be produced.

Abstract: PEEK is a polyaromatic semi-crystalline thermoplastic polymer with good mechanical characteristics for biomedical applications. The medical field has been applying its mechanical properties to make bone implants and modeling for surgical planning using 3D printing, more formally called Additive Manufacturing (AM). This paper provides a concise discussion about PEEK and its development for orthopedic applications. Some of the designs used to fix specific issues are shown in this review paper including the mechanical properties development for PEEK to be applicable in the medical field. Challenges and prospects when 3D printing using this material on improving PEEK’s biocompatibility and ease of printing are also discussed.

Abstract: The Additive Manufacturing or 3D printing technology gives an unmatched flexibility and innovative solution to different problems of various industries, including maritime industry. Even though the application of this technology is mainly used in the manufacturing and shipbuilding sector of the industry, it is now also being used by some maritime schools or institutions, like the Maritime Academy of Asia and the Pacific (MAAP). Thus, this paper presents the recent applications of 3D printing in maritime industry, as a whole, and in the academe. The 3D printed projects created by MAAP faculty and students will also be demonstrated and discussed in this paper. Lastly, future perspectives on the application of 3D printing technology in maritime education, like what will be the possible impact if it was included in their curriculum, will be presented as well.

Abstract: Additive manufacturing can be utilized to harness developments in polymer research. This study aims to investigate the effect of Philippine halloysite on poly(lactic acid) (PLA) filament for 3D printing using Fused Deposition Modeling (FDM). PLA-based filaments with halloysite powders were prepared by melt-compounding using a twin-screw extruder. The chemical composition and morphology of the halloysite powder was determined using XRD and SEM, respectively. Composite filament with 3% halloysite (PLA/HSC) was developed and characterized. The thermal properties of pure PLA and PLA/HSC were measured using DSC and TGA. CAD files for XRD analysis and tensile tests were generated using SolidWorks computer software (Dassault Systemes). Printability of pure PLA and the composite filament was observed by using Ultimaker S5 3D printer. The effect on chemical composition and mechanical performance of the 3D printed specimens was evaluated using XRD and UTM, respectively. XRD result confirmed the presence of dehydrated halloysite clay mineral. SEM image revealed the spherical morphology of the halloysite powder with average particle size of 72.472 nm. DSC analysis showed that incorporation of halloysite powder filaments had slightly decreased the glass transition of pure PLA matrix. This could be attributed to the enhanced mobility of polymeric chains by plasticization. Moreover, the melting temperature of PLA/HSC composite has slightly higher value than pure PLA filament owing to increased crystallinity imparted by the halloysite particles. With high stability of halloysite at elevated temperatures, the thermal stability of PLA/HSC filament was also enhanced. Mechanical performance of pure PLA was also improved with addition of halloysite. The tensile strength and elastic modulus of pure PLA matrix increased by 180.32% and 143.96%, respectively which could be due to the formation of hydrogen bonds between PLA matrix and halloysite particles. Digital micrographs of the fractured surface reveal that tensile pieces predominantly ruptured by brittle fracture.

Abstract: This paper reports the temperature and the concentration dependence of anisotropic etching for (100) p-Silicon in an aqueous KOH solution etching rate of wet etching has been experimentally determined with varying concentrations and the temperature of the KOH solution. The texturing process was managed at different etching durations ( 20 min, 40 min, and 60 min). XRD test showed that the lowest value of grain size was 5.0 nm (obtained with the highest porosity percentage of 50% with 4.5% KOH concentration for 60 min). FESEM test showed that the pore diameter increased with increasing etching time. The lowest reflectance value was (2.8 % at 550 nm wavelengths for samples treated with 4.5% KOH concentration for 60 min etching time. The refractive index value was 1.8 for the same black Si sample, also Hall test is introduced.

Abstract: Coumarin dye laser compounds are often used as components in coloring agents and sprays., as well as in the odorization of foods. Therefore, the important of these compounds in many felids leading to growth of several ways aiming to advance the control of pharmaceutical and superficial producing. Solvents play an important role in changing the character of coumarin. The investigated spectral properties, as well as the effect of changing the solvent on this property, have been published. results referred that the molar electronic transition energy increased with decreasing the maximum absorption wavelength, and the highest intensity of the absorption spectrum was in the case of acetone solvent. In addition, many bands appear in Raman shift attributed to the ''C=O'' band, ''O=C–O, C–C'', and ''C–O'' deformation. The characteristic vibrations involving the ''O-H'' group is the stretching and bending modes of the ''O-H'' and ''C-O'' parts.