Title: 3D Printing of Dual-Cure Benzoxazine Networks

Authors: Jeremy J. Weigand, Christopher I. Miller, Jared C. Bates, and Jeffrey S. Wiggins

DOI: 10.33599/nasampe/c.19.0705

Abstract: 3D printing has emerged as a powerful manufacturing technique for the rapid production of highly complex parts. Stereolithography (SLA) is a 3D printing method that selectively exposes liquid photocurable monomers to a rastering UV laser, building parts in a layer-by-layer approach. While SLA offers manufacturing advantages, the continued use of SLA in a variety of applications necessitates the development of new materials for this innovative process. Here we report a novel dual-cure 3D printing formulation for SLA using a methacrylate functional benzoxazine monomer. Methacrylate groups were first photocured during SLA 3D printing, stabilizing the 3D printed geometry, followed by thermal cure of the benzoxazine resulting in a dual-cured thermoset network. Rheological experiments were conducted to determine the viscosity of 3D printing formulations as a function of reactive diluent concentration before SLA 3D printing. UV cure kinetics were determined using photorheology and real time Fourier transform-infrared spectroscopy (RT-FTIR), where rapid UV curing kinetics at low photo initiator concentrations were observed. FTIR and differential scanning calorimetry (DSC) showed that the thermal cure of 3D printed benzoxazine networks proceeded to high conversion. Thermomechanical properties of 3D printed parts including rubbery storage modulus and glass transition temperature (Tg) were investigated using dynamic mechanical analysis (DMA). 3D printed parts exhibited a single Tg that increased by 118 °C after thermal curing of the 3D printed benzoxazine. The overarching goal of this work was to demonstrate a new class of dual-cure SLA 3D printing materials, expanding the material base for SLA 3D printing and enabling the manufacture of complex thermoset geometries utilizing benzoxazine chemistries.

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Conference: CAMX 2019

Publication Date: 2019/09/23

SKU: TP19-0705

Pages: 14

Price: $28.00