September 19-22, 2023 • Boulder, Colorado
Session Chair:
RadTech International North America | The Association for Ultraviolet and Electron Beam Technologies
6935 Wisconsin Ave, Suite 207, Chevy Chase, MD 20815 | (240) 497-1242 | uveb@radtech.org
Kristi Anseth, University of Colorado
Coming Soon.
Celine Croutxe-Barghorn, University de Haute Alsace
Digital light processing (DLP) is one of the most popular 3D printing techniques utilizing a light source for solidifying a liquid resin. High reactivity, limited resolution and thermomechanical properties are still the main obstacles to overcome. Acrylate resins are widely implemented in 3D printing. Despite their important reactivity and commercial availability, they suffer from yielding inhomogeneous and uncontrolled polymer structure and high crosslink density or limited mechanical properties. Different routes have been reported in the literature to tackle these drawbacks. This paper will highlight the potential of the aza-Michael addition or the incorporation of a reversible addition-fragmentation chain transfer (RAFT) agents or to control the polymer network structure and enhance the thermomechanical properties as elongation at break, toughness or SMP properties. In addition, the in situ generation of an inorganic silicate phase will be discussed as an attractive route for hybrid organic-inorganic materials avoiding multi-step procedure and possible phase separation.
Marco Sangermano, Politecnico di Torino
Biobased monomers are becoming essential to develop green products to substitute petroleum-based materials. In this study furfuryl-biobased epoxy monomers have been synthesized and exploited in cationic UV-Curing [1]. An easy tailoring of the properties of the final UV-cured coatings is demonstrated by varying the ratio of the monofunctional-difunctional epoxy monomer or by in-situ generation of hybrid organic-inorganic networks. The same formulations were processed in 3D-printing through Hot Lithography process [2]. UV-Cured composites were achieved by exploiting the frontal induced photopolymerization.
References
1. L. Pezzana, G. Melilli, G. Nathanaël, N. Sbirrazzuoli, M. Sangermano, “Cationic UV-Curing of bioderived epoxy furan-based coatings”, ACS Sustainable Chemistry & Engineering, 9, 17403, 2021.
2. L. Pezzana, R Wolff, G. Melilli, N Guigo, N. Sbirrazzuoli, J. Stampfl, R. Liska, M. Sangermano, “Hot lithography 3D-printing of biobased epoxy resins”, Polymer, 254, 125097, 2022.
Jeffrey Stansbury, University of Colorado Denver
Urethane (meth)acrylate monomers and oligomers are very commonly used components of photocurable formulations due to the non-covalent urethane-urethane interactions that effectively add strength and toughness to the resulting polymer networks. While urethane-based homopolymers can maximize these favorable hydrogen bonding effects, di-/multi-urethane monomers in the pre-cure state are typically too viscous for use in undiluted, ambient temperature photocuring applications. Diluent comonomers are routinely added to control viscosity but this also serves to diminish the positive reinforcement associated with engagement between the urethane functional groups. We have used acid functional diluent comonomers that efficiently compete in donor/acceptor interactions with urethane monomers resulting in low viscosity resins that yield photopolymers with enhanced mechanical properties relative to either conventionally diluted urethane formulations or even fully cured urethane homopolymers. This approach allows control over the covalent network density in photopolymers without compromise to modulus or strength and it leads to high toughness polymers. Additional work to design novel urethane monomer structures has produced acid-urethane copolymers with exceptionally high strength and stiffness that is uniquely coupled with excellent toughness and resilience. Examples for vat and jetted 3D printing that highlight these attractive properties in comparison with relevant controls will be presented.
Jeff Klang, Arkema
UV/EB curing technology is generally recognized to be environmentally sustainable or “green” technology mainly due to the low levels of emissions and low energy usage of the processes compared to solvent or waterborne technologies. At the same time, more and more questions are being raised, and regulations put in place, relating to the (meth)acrylate monomers/oligomers and photoinitiators used as raw materials for photocuring processes. Recent movements on two workhorse materials – TMPTA and TPO – are high-profile examples of toxicity concerns driving new regulations. Increasing focus on climate change is also raising questions about the carbon footprint of UV/EB raw materials. To maintain the position of UV/EB technology as a vibrant area of scientific research and a growing profitable industry, innovations are needed in all raw material categories to address the new realities of the regulatory environment. Innovations in raw materials to address these important topics while continuing to meet the performance demands of end-users will be discussed.
Kimihiro Matsukawa, Kyoto Institute of Technology
Glycerin is one of bio-based materials produced from palm oil, and it is a possible candidate for industrial uses on the target of SDGs. Polyglycerin, which is derived from glycerin, has some hydroxyl groups by the number of repeating units of glycerin. Furthermore, it seems that polyglycerin with longer side chains could be expected to provide a lot of unique functions. In this work, it has been examined the side chain extension of polyglycerin with ethylene oxide (EO) and the application to novel network polymers. In the case of glycerin tetramer as a starting material, six terminated hydroxyl groups were reacted by some EOs for the side chain extension. And these six terminal hydroxy groups were successfully modified to acrylate groups as shown in Figure. Polyglycerin acrylates are expected to be multi-functional monomers for the preparation of new network polymers. These photo-cured materials have many interesting properties such as high reactivity, high flexibility, anti-fogging, etc. In particular, anti-fogging is an interesting property. Polyglycerin acrylates photo-cured with usual multi-functional monomers, DPHA and TMPTA, provided outstanding properties such as low curling, low shrinkage, flexible, and so on. These materials are expected to become practical use in a wide range of industrial fields.