A Dyciandiamine-Based Methacrylate-Epoxy Dual-Cure Blend-System for Stereolithography

Abstract

In this research, an epoxy-based dual-cure system is developed and characterized for SLA additive manufacturing. Dual-cure systems consist of UV-curable acrylates and thermal active components. The second curing step offers an additional degree of freedom to design specific material properties. In this study, a blend of varying concentrations of an epoxy/curing agent mix, respectively, DGEBA, DICY and photocurable methacrylate, was used to create a material that is printable in the SLA process into a UV-cured or green part and subsequently thermally cured to achieve superior thermal and mechanical properties. Calorimetric measurements were performed to determine the reactivity of the thermal reaction at different concentrations of epoxy. The fully cured specimens were tested in mechanical and dynamic mechanical measurements, and the results showed a significant improvement in tensile stress and glass transition temperature with rising epoxy concentrations. Fractured surfaces from tensile testing were investigated to further characterize the failure of tested samples, and thermal degradation was determined in TGA measurements, which showed no significant changes with an increasing epoxy concentration.

3D Printing Thermally Stable High‐Performance Polymers Based on a Dual Curing Mechanism

“…Comparing these results to those previously reported for blending acrylates and epoxides (Table S1, Supporting Information) indicates that in some cases, a higher Young's modulus and tensile strength can be achieved, [15,19,21,25] however, their Tg values are below 150 °C. Moreover, the flexural modulus evaluated by three-point bending measurements was 3.3 GPa which is in the same order of magnitude as other reported materials (Figure S11, Supporting Information).…”

“…[13] Epoxy-acrylate hybrid systems have been previously molded, [14,15] and printed by Digital Light Processing (DLP). [16][17][18][19][20][21][22][23][24][25] In both methods, the resulting hybrid polymers usually have inferior mechanical properties compared to the epoxy resin without the acrylate component. The reported Young's modulus of the hybrid polymers is 0.036-2.59 GPa, with a maximum Tg of only 150 °C (Table S1, Supporting Information).…”

Green Monomers for 3D Printing: Epoxy-Methacrylate Interpenetrating Polymer Networks as a Versatile Alternative for Toughness Enhancement in Additive Manufacturing

“…By contrast, Kuang et al used anhydride chemistry to cure the epoxides thermally after 3D printing of a (meth)­acrylate resin . Furthermore, Drummer et al proposed a dicyandiamine-based methacrylate epoxy blend system for SLA …”

“…However, the majority of photopolymerizable IPNs contain diglycidyl ether of bisphenol A (BADGE od DGEBA) as an epoxy monomer or the (meth)­acrylate modification (bis-GMA), as they impart good thermal resistance and (thermo)­mechanical properties to the photopolymer networks. ,− But, bisphenol A is known to act as a reprotoxic R2 substance and was originally used as an artificial estrogen. Hence, this endocrine disruptor may lead to alterations in both the immune and reproductive systems .…”

Influence of Postprinting Conditions on Morphologies in a Three-Dimensional Printable Dual-Cure Interpenetrating Dimethacrylate/Epoxy Polymer Network

“…While a mixed system approach offers more flexibility in controlling viscosity, cross-linking density, and backbone properties, miscibility is a concern both prior to printing and during polymerization, which can impact the morphology and final properties, and is strongly dependent on the polymerization kinetics and thermodynamic miscibility of the polymer blend . Both curing kinetics and miscibility are dependent on factors such as curing and postcuring times, cure temperatures, and cure sequence. − Previous studies of dual-cure resins have investigated the effects of different UV postcure times, postcure temperatures, curing sequences, postcure processes, and resin formulations , on thermo-mechanical properties. For example, Obst et al investigated the influence of UV exposure time on a dual-curing system and found that longer exposure time reduced the effect of the second-stage thermal curing, while Kuang et al , photocured and thermally cured epoxy/acrylate mixtures at 100 °C for 2 h followed by 160 °C for 1 h and observed a single T g and concluded that they had formed an interpenetrating polymer network (IPN) with no macroscale phase separation.…”