Three-dimensional (3D) printing of biomaterials has the potential to become an ecologically advantageous alternative compared with conventional manufacturing based on oil-derived polymer materials. In this study, a novel 3D printing technology is applied that combines ultraviolet (UV) curing with paste extrusion. This hybrid manufacturing technique enables the fabrication of complex geometries from high filler-ratio pastes. The developed biocomposite aims for suitable mechanical properties in terms of tensile and compressive strength. It is composed of acrylic acid, cellulose acetate, α-cellulose, and fumed silica with a cellulose ratio of more than 25 vol-%. The material is extruded with an in-house-developed 3D printer equipped with a 12 W UV light curing source, which enables concurrent curing and extrusion. Two different UV-curing strategies were tested: postcuring without concurrent curing and postcuring with concurrent curing. The total UV-curing duration was kept constant with all samples. Tensile testing in accordance with ASTM standard D638-14 Type 4, compression testing according to ASTM D695-15, and overhang tests were conducted. As a result, samples without notable shrinkage, suitable tensile strength (up to 17.72 MPa), competitive compression testing parameters (up to 19.73 MPa), and an enhanced overhang angle (increase of more than 25°) were produced, leading to new applications and more freedom in design due to higher possible unsupported overhangs when using UV-curing during the print. Overall, constant UV light radiation during the print leads to improved mechanical properties due to the possibility of bypassing the UV-penetration depth constraint. It should be considered when extruding photopolymer-based composites, especially for large and complex components with a low degree of translucency.
|Julkaisu||3D Printing and Additive Manufacturing|
|Varhainen verkossa julkaisun päivämäärä||13 toukokuuta 2019|
|DOI - pysyväislinkit|
|Tila||Julkaistu - 1 kesäkuuta 2019|
|OKM-julkaisutyyppi||A1 Julkaistu artikkeli, soviteltu|
Kretzschmar, N., Lipponen, S., Klar, V., Pearce, J. M., Ranger, T. L., Seppälä, J., & Partanen, J. (2019). Mechanical properties of ultraviolet-assisted paste extrusion and postextrusion ultraviolet-curing of three-dimensional printed biocomposites. 3D Printing and Additive Manufacturing, 6(3), 127-137. https://doi.org/10.1089/3dp.2018.0148