Abstract
Vat photopolymerization additive manufacturing (Vat AM) technologies have found niche industrial use being able to produce personalized parts in moderate quantity. However, Vat AM lacks in its ability to produce parts of satisfactory thermal and mechanical properties for structural applications. The purpose of this investigation was to develop high-performance resins with glass transition temperatures (Tg) above 200 °C for Vat AM, evaluate the properties of the produced thermosets and establish a structure–property relationship of the thermosets produced. Herein, we have developed SLA-type resins that feature bio-derived monomer hesperetin trimethacrylate (HTM) synthesized from the flavonone hesperetin. Diluents 4-acryloyl morpholine, styrene, 4-methyl styrene and 4-tert butylstyrene (tbutylsty) were photocured with HTM as the monomer and all produced thermosets with Tg values above 200 °C. Investigations of suitable crosslinkers urethane dimethacrylate, the vinyl ester CN 151 and Ebecryl 4859 (Eb4859) showed that each crosslinker displayed different benefits when formulated with HTM as the monomer and tbutylSty as the diluent (HTM:crosslinker:tbutylSty with mass ratio 2:1:2). The crosslinker CN 151 produced the thermoset of greatest onset of thermal decomposition temperature (T0) of 352 °C. Eb4859 produced the thermoset of highest tensile strength, 19 ± 7 MPa, amongst the set of varied crosslinkers. The formulation featuring UDM (HTM:UDM:tbutysty) offered ease of processing and was seemingly the easiest to print. Investigations of reactive diluent showed that styrene produced the thermoset of the highest extent of cure and the overall highest tensile strength, 25 ± 5 MPa, while tbutylSty produced the thermoset with the greatest Tan-δ Tg, 231 °C. HTM was synthesized, formulated with diluents, crosslinkers and initiators. The HTM resins were then 3D printed to produce thermosets of Tg values greater than 200 °C. The polymer properties were evaluated and a structure–reactivity relationship was discussed.
Highlights
Additive manufacturing has been propelled to the forefront of research efforts in the US armed forces due to its ability to produce materials in a timely manner, the ability to produce parts of unique geometry difficult to produce by any other means, and the possibility of on-demand manufacturing at the warfighters’ fingertips [1–3]
The identifiable methacrylate peaks are noticed in the hesperetin trimethacrylate (HTM) Fourier Transform Attenuated Total Reflection (FT-ATR) spectrum such as the ester C=O functionality near 1760 cm−1 as well as the keynote peaks of the methacrylate double bond (C=C) at 943 cm−1
The flavone monomer HTM was synthesized in one simple synthetic step using phase transfer catalysis from hesperetin as the starting material
Summary
Additive manufacturing has been propelled to the forefront of research efforts in the US armed forces due to its ability to produce materials in a timely manner, the ability to produce parts of unique geometry difficult to produce by any other means, and the possibility of on-demand manufacturing at the warfighters’ fingertips [1–3]. Taking advantage of the high resolution attainable for vat photopolymerization, researchers have produced functional parts including microfluidic devices for biological and chemistry applications, optical components and materials containing magnetic properties [14,15]. Other investigators have turned to clever methods to allow for AM of high-performance materials, including dual-cure technologies where the vat photopolymerization is mostly relied upon to set the matrix and allowing for the desired geometric shape, but not pivotal in obtaining the high-temperature properties. Hegde et al used organic solvents to aid in dissolution of their synthesized acrylate functional aromatic polyimide oligomer, followed by 3D printing to slightly crosslink the network, followed by high-temperature post-cure to afford the first ever AM assisted formation of engineering plastic Kapton-type material Their material exhibited Tg values near 400 ◦C. Standard abbreviations indicating multiplicity were utilized as follows: s(singlet), bs (broad singlet), d (doublet), t (triplet), q (quar2te.2t.)2, .aFnTdIRmS(pmeuclttriopslceot)p.y
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
