scholarly journals A Critical Review for Synergic Kinetics and Strategies for Enhanced Photopolymerizations for 3D-Printing and Additive Manufacturing

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2325
Author(s):  
Jui-Teng Lin ◽  
Jacques Lalevee ◽  
Da-Chun Cheng
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Experimental Studies ◽  
Dual Wavelength ◽  
Dual Function ◽  
Combined System ◽  
Uva Light ◽  
Initiator System ◽  
New Applications ◽  
First Time

The synergic features and enhancing strategies for various photopolymerization systems are reviewed by kinetic schemes and the associated measurements. The important topics include (i) photo crosslinking of corneas for the treatment of corneal diseases using UVA-light (365 nm) light and riboflavin as the photosensitizer; (ii) synergic effects by a dual-function enhancer in a three-initiator system; (iii) synergic effects by a three-initiator C/B/A system, with electron-transfer and oxygen-mediated energy-transfer pathways; (iv) copper-complex (G1) photoredox catalyst in G1/Iod/NVK systems for free radical (FRP) and cationic photopolymerization (CP); (v) radical-mediated thiol-ene (TE) photopolymerizations; (vi) superbase photogenerator based-catalyzed thiol−acrylate Michael (TM) addition reaction; and the combined system of TE and TM using dual wavelength; (vii) dual-wavelength (UV and blue) controlled photopolymerization confinement (PC); (viii) dual-wavelength (UV and red) selectively controlled 3D printing; and (ix) three-wavelength selectively controlled in 3D printing and additive manufacturing (AM). With minimum mathematics, we present (for the first time) the synergic features and enhancing strategies for various systems of multi-components, initiators, monomers, and under one-, two-, and three-wavelength light. Therefore, this review provides not only the bridging between modeling and measurements, but also guidance for further experimental studies and new applications in 3D printings and additive manufacturing (AM), based on the innovative concepts (kinetics/schemes).

Fabrication and stress analysis of ankle foot orthosis with additive manufacturing

2018 ◽  
Vol 24 (2) ◽  
pp. 301-312 ◽  
Author(s):  
Harish Kumar Banga ◽  
Rajendra M. Belokar ◽  
Parveen Kalra ◽  
Rajesh Kumar
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Stress Analysis ◽  
Low Cost ◽  
The Body ◽  
Lower Limbs ◽  
Content Type ◽  
Body Of Knowledge ◽  
New Applications ◽  
Foot Orthosis

Purpose Ankle–foot orthoses (AFOs) are assistive devices prescribed for a number of physical and neurological disorders affecting the mobility of the lower limbs. Additive manufacturing has been explored as an alternative process; however, it has proved to be inefficient cost-wise. This work aims to explore the possibilities of generating modular AFO elements, namely, calf, shank and footplate, with the localized composite reinforcement that aids in the optimization of the device in terms of functionality, aesthetics, rigidity and cost. Design/methodology/approach The conventional lower leg–foot orthosis configuration depends on thermoforming a polymer sheet around a mortar cast with a trademark firmness relying upon the trim-line with the inalienable plan restrictions. In manufacturing of AFO the expert, i.e. orthotist's, guidance is used. Polypropylene and polyethylene material is used in fabrication of AFO to complete all-round reported points of interest over the ordinary outlines, yet their mechanical conduct under administration conditions cannot be effectively anticipated. Findings AFOs made of polypropylene and polyethylene material are available in the market, which are used by children of age 3-5 years. With the existing AFO design, patients are facing excessive heating and sweating problems during long-term usage. After feedback from patients and orthotists (who prescribed AFO to patients), an attempt has been made to solve the problem with a new and improved AFO design of AFO by using finite element modelling and stress analysis. Also, the results indicate that the new design is similar to the actual product design. Originality/value This work introduces the low-cost 3D printing with reinforcement approach as an alternative route for the designing and manufacturing of orthotic devices with complex shapes. It is expected that new applications add-up to increase the body of knowledge about the behaviour of such products which will mix both areas, composite theory and additive manufacturing. This study investigated the fields related to 3D scanning, 3D printing and computer-aided designing for the manufacturing of a customized AFO.

scholarly journals Towards Distributed Recycling with Additive Manufacturing of PET Flake Feedstocks

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4273
Author(s):  
Helen A. Little ◽  
Nagendra G. Tanikella ◽  
Matthew J. Reich ◽  
Matthew J. Fiedler ◽  
Samantha L. Snabes ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Thermal Characterization ◽  
3D Print ◽  
Wide Range ◽  
3D Printed ◽  
Sequential Combination ◽  
Future Work ◽  
The Impact ◽  
First Time

This study explores the potential to reach a circular economy for post-consumer Recycled Polyethylene Terephthalate (rPET) packaging and bottles by using it as a Distributed Recycling for Additive Manufacturing (DRAM) feedstock. Specifically, for the first time, rPET water bottle flake is processed using only an open source toolchain with Fused Particle Fabrication (FPF) or Fused Granular Fabrication (FGF) processing rather than first converting it to filament. In this study, first the impact of granulation, sifting, and heating (and their sequential combination) is quantified on the shape and size distribution of the rPET flakes. Then 3D printing tests were performed on the rPET flake with two different feed systems: an external feeder and feed tube augmented with a motorized auger screw, and an extruder-mounted hopper that enables direct 3D printing. Two Gigabot X machines were used, each with the different feed systems, and one without and the latter with extended part cooling. 3D print settings were optimized based on thermal characterization, and both systems were shown to 3D print rPET directly from shredded water bottles. Mechanical testing showed the importance of isolating rPET from moisture and that geometry was important for uniform extrusion. The mechanical strength of 3D-printed parts with FPF and inconsistent flow is lower than optimized fused filament, but adequate for a wide range of applications. Future work is needed to improve consistency and enable water bottles to be used as a widespread DRAM feedstock.

scholarly journals Embedding Carbon Dots in Superabsorbent Polymers for Additive Manufacturing

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 921 ◽  
Author(s):  
Yiqun Zhou ◽  
Keenan Mintz ◽  
Cagri Oztan ◽  
Sajini Hettiarachchi ◽  
Zhili Peng ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Citric Acid ◽  
3D Printing ◽  
Carbon Dots ◽  
High Yield ◽  
Sodium Polyacrylate ◽  
Superabsorbent Polymers ◽  
Low Degree ◽  
3D Printed ◽  
First Time

A type of orange carbon dots (O-CDs) synthesized via an ultrasonication route with citric acid and 1,2-phenylenediamine as precursors was embedded into sodium polyacrylate (SPA) as the ink for 3D printing. Characterizations of these spherical O-CDs revealed an ultra-small size (~2 nm) and excitation-independent, but solvent dependent, emission. The O-CDs were evenly distributed with low degree of aggregation in sodium polyacrylate (SPA), which was achieved due to the property that SPA can absorb water together with O-CDs. The 3D printed photoluminescent objective with the ink revealed a great potential for high yield application of these materials for additive manufacturing. This also represents the first time, bare CDs have been reported as a photoluminescent material in 3D printing, as well as the first time SPA has been reported as a material for 3D printing.

scholarly journals Efficient 3D printing via photooxidation of ketocoumarin based photopolymerization

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xiaoyu Zhao ◽  
Ye Zhao ◽  
Ming-De Li ◽  
Zhong’an Li ◽  
Haiyan Peng ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Visible Light ◽  
Light Exposure ◽  
Three Dimensional ◽  
3D Printer ◽  
Light Penetration ◽  
Viable Solution

AbstractPhotopolymerization-based three-dimensional (3D) printing can enable customized manufacturing that is difficult to achieve through other traditional means. Nevertheless, it remains challenging to achieve efficient 3D printing due to the compromise between print speed and resolution. Herein, we report an efficient 3D printing approach based on the photooxidation of ketocoumarin that functions as the photosensitizer during photopolymerization, which can simultaneously deliver high print speed (5.1 cm h−1) and high print resolution (23 μm) on a common 3D printer. Mechanistically, the initiating radical and deethylated ketocoumarin are both generated upon visible light exposure, with the former giving rise to rapid photopolymerization and high print speed while the latter ensuring high print resolution by confining the light penetration. By comparison, the printed feature is hard to identify when the ketocoumarin encounters photoreduction due to the increased lateral photopolymerization. The proposed approach here provides a viable solution towards efficient additive manufacturing by controlling the photoreaction of photosensitizers during photopolymerization.

Fused Filament Fabrication 3D Printed Polylactic Acid Electroosmotic Pumps

Lab on a Chip ◽  
2021 ◽  
Author(s):  
Liang Wu ◽  
Stephen Beirne ◽  
Joan-Marc Cabot Canyelles ◽  
Brett Paull ◽  
Gordon G. Wallace ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Polylactic Acid ◽  
Fused Filament Fabrication ◽  
Flexible Approach ◽  
Electroosmotic Pump ◽  
3D Printed ◽  
Electroosmotic Pumps

Additive manufacturing (3D printing) offers a flexible approach for the production of bespoke microfluidic structures such as the electroosmotic pump. Here a readily accessible fused filament fabrication (FFF) 3D printing...

3D Printing of Biphasic Inks: Beyond Single-Scale Architectural Control

2021 ◽  
Author(s):  
Gianluca Cidonio ◽  
Marco Costantini ◽  
Filippo Pierini ◽  
Chiara Scognamiglio ◽  
Tarun Agarwal ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Disruptive Technology ◽  
Main Research ◽  
Single Scale

To date, Additive Manufacturing (AM) has come to the fore as a major disruptive technology embodying two main research lines - developing increasingly sophisticated printing technologies and new processable materials....

scholarly journals What voiced obstruents symbolically represent in Japanese: evidence from the Pokémon universe

2021 ◽  
Vol 37 (1) ◽  
pp. 3-24
Author(s):  
Shigeto Kawahara ◽  
Gakuji Kumagai
Keyword(s):  
Experimental Studies ◽  
Sound Symbolism ◽  
Visual Images ◽  
General Issue ◽  
First Time

Abstract Kawahara, Noto, and Kumagai (2018b) found that within the corpus of existing Pokémon names, the number of voiced obstruents in the characters’ names correlates positively with their weight, height, evolution levels and attack values. While later experimental studies to some extent confirmed the productivity of these sound symbolic relationships (e.g. Kawahara and Kumagai 2019a), they are limited, due to the fact that the visual images presented to the participants primarily differed with regard to evolution levels. The current experiments thus for the first time directly explored how each of these semantic dimensions—weight, height, evolution levels, and attack values—correlates with the number of voiced obstruents in nonce names. The results of two judgment experiments show that all of these parameters indeed correlate positively with the number of voiced obstruents in the names. Overall, the results show that a particular class of sounds—in our case, a set of voiced obstruents—can signal different semantic meanings within a single language, supporting the pluripotentiality of sound symbolism (Winter, Pérez-Sobrino, and Brown 2019). We also address another general issue that has been under-explored in the literature on sound symbolism; namely, its cumulative nature. In both of the experiments, we observe that two voiced obstruents evoke stronger images than one voiced obstruent, instantiating what is known as the counting cumulativity effect (Jäger and Rosenbach 2006).

scholarly journals Additive Manufacturing for Effective Smart Structures: The Idea of 6D Printing

2021 ◽  
Vol 5 (5) ◽  
pp. 119
Author(s):  
Stelios K. Georgantzinos ◽  
Georgios I. Giannopoulos ◽  
Panteleimon A. Bakalis
Keyword(s):  
Additive Manufacturing ◽  
Degrees Of Freedom ◽  
Smart Structures ◽  
Interaction Mechanism ◽  
Modeling And Simulations ◽  
Environmental Stimulus ◽  
Material Component ◽  
Design And Manufacturing ◽  
First Time ◽  
Printing Techniques

This paper aims to establish six-dimensional (6D) printing as a new branch of additive manufacturing investigating its benefits, advantages as well as possible limitations concerning the design and manufacturing of effective smart structures. The concept of 6D printing, to the authors’ best knowledge, is introduced for the first time. The new method combines the four-dimensional (4D) and five-dimensional (5D) printing techniques. This means that the printing process is going to use five degrees of freedom for creating the final object while the final produced material component will be a smart/intelligent one (i.e., will be capable of changing its shape or properties due to its interaction with an environmental stimulus). A 6D printed structure can be stronger and more effective than a corresponding 4D printed structure, can be manufactured using less material, can perform movements by being exposed to an external stimulus through an interaction mechanism, and it may learn how to reconfigure itself suitably, based on predictions via mathematical modeling and simulations.

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