Title: Direct Ink Writing of Benzoxazine Nanocomposites
Authors: Cecile A. Grubb, Carter F. Dojan, Kevin A. Hjelstrom, Nicole Vijgen, Lina N. Ghanbari, John M. Misasi
Abstract: Thermoset nanocomposites are of great interest to the composites industry due to their excellent thermal and mechanical properties. However, they remain challenging to process using traditional composites manufacturing techniques due to the high minimum viscosities required to maintain nanomaterial dispersion and dimensions during cure. Direct ink writing (DIW) is an additive manufacturing technique in which a high viscosity feedstock is extruded through a micro-nozzle in a layer-by-layer fashion to form a three-dimensional part. This work investigated the viability of manufacturing benzoxazine-based nanocomposites using DIW. Benzoxazine was blended with carbon nanostructures and polycarbonate to produce a high viscosity DIW capable feedstock. Processing properties such as temperature and shear rate dependent viscosity were studied of the uncured resin using parallel-plate rheology. A procedure was developed by manipulating print parameters and the cure profile to successfully create parts that retain design intent during printing and throughout the cure. Parts were then fabricated using DIW and were also compression molded as a baseline. Cured mechanical properties were characterized via three point bend testing using ASTM D790. Dynamic mechanical analysis was done to inspect how the glass transition temperature as well as storage and loss modulus were affected during the printing process. Printed part geometries were measured to analyze dimensional stability during DIW and after cure. Finally, printed specimens were characterized using optical microscopy to observe differences in void content associated with both thermoplastic concentration and manufacturing process.
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Conference: SAMPE NEXUS 2021
Publication Date: 2021/06/29
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