Extrusion-based 3D printing is widely used to fabricate precise and accurate 3D structures with nanocellulose suspensions due to its excellent material flow control and system stability. The current issues related to high concentration nanocellulose 3D structures are low printability, layers adhesion, shape fidelity, and mechanical strength. Herein, the issues associated with 3D printed concentrated nanocellulose structures were resolved by mixing different concentrations of tannic acid. The printing parameters of a twin-screw extruder, tannin acid content, and drying conditions were optimized for concentrated nanocellulose paste. The mechanical results showed that tannic acid effectively improved the adhesion between printed layers, as confirmed by a scanning electron microscope.
Piezoelectric ceramics, lead zirconate titanate (PZT), have been widely used for sensors and actuators due to their high electromechanical properties. However, the brittle nature of ceramics limits their applications to only small deformations as the flexibility and durability of these materials are the main essential factors required for practical applications. The flexible piezoelectric materials can be developed by blending PZT with flexible polymeric materials such as nanocellulose fibers. The bio-based nanocellulose fibers (CNF) have been reported as a type of electroactive polymer with a piezoelectric response exhibiting excellent mechanical strength and modulus. In this regard, the present study focuses on enhancing the mechanical strength and load-bearing capability of PZT by blending 20 and 30wt% of PZT powder with 80 and 70wt% CNF to obtain a flexible piezoelectric composite film via 3D printing. The 3D printed films' structural, morphological, and mechanical properties were investigated through XRD, SEM, and tensile tests. The SEM images and XRD analysis demonstrated that the PZT powder was uniformly dispersed in the CNF films and showed the morphotropic phase boundary (MPB) in PZT/CNF films. The addition of CNF in PZT has improved the mechanical strength significantly.
Recently, extrusion-based 3D printing has been widely used to manufacture precise and accurate 3D structures with high nanocellulose concentrations due to excellent materials flow control and system stability. With the extrusion-based 3D printing technique, the main challenges for precision and accuracy in high concentration nanocellulose 3D printed structures are proper printing parameters and appropriate adhesion between printed layers. Therefore, this study aims to improve the adhesion between high content nanocellulose printed layers by blending different lignin concentrations and optimizing the twin-screw extruder printing parameters. The lignin concentrations are optimized in nanocellulose paste by assessing the mechanical properties, shape retention, and shrinkage of 3D printed structures. To ease shape retention, the 3D printed structures are dried at controlled humidity (45%) and temperature (25oC). The surface morphology of the 3D printed structures is observed by scanning electron microscope.
KEYWORDS: 3D printing, 3D modeling, Structural engineering, Scanning electron microscopy, Manufacturing, Humidity, Electron microscopes, Computer simulations, Additive manufacturing
3D printing, commonly referred to as additive manufacturing (AM), is a rapid technique of making three-dimensional structures from a computer-based design model. Various materials have been used to manufacture 3D structures for different engineering applications, including synthetic and natural materials. In the case of natural materials for 3D printing, nanocellulose gain much attention as a feedstock material for AM techniques due to its high strength, lightweight, and biocompatibility. However, the mechanical properties exhibited in high concentration nanocellulose printed 3D structures are unsatisfactory, as demonstrated in their building blocks due to drying issues. Therefore, this research aims to optimize the proper drying conditions for 3D printed high concentration nanocellulose structures. The 3D printed structures are dried at different humidity and temperature conditions and evaluated their mechanical properties. The scanning electron microscope is utilized to observe the morphology of 3D printed high concentration nanocellulose structures. The research results will significantly help nanocellulose-based industries to overcome the drying issues in 3D printed high concentration nanocellulose structures.
Twin-screw extruder (TSE) based additive manufacturing technology can effectively print high viscous materials into precise and complex shapes. The dimensional accuracy and quality of the printed parts depend on the correct selection of the extruder machine's processing parameters to the printing materials. Hence, this paper presents an experimental study on optimizing the processing parameters of TSE for high concentration nanocellulose paste. The optimized parameters include twin-screw speed, feeding rate, printing speed to the nozzle diameter, and nanocellulose paste concentration. The feed rate of 1.2 ml/min, screw speed of 150 rpm, and the printing speed of 9.37 mm/s were the optimum process parameters for high accuracy and high-quality 3D printed structures 25wt% nanocellulose paste. Furthermore, pyramid-shaped and star-shaped structures were printed to verify the optimized parameters.
The development of high-strength nanocellulose long-fiber (CLF) has been required for future composite faced with environmental concerns as well as energy efficiency and biocompatibility towards the high value-added industry. To meet the demand, our research group has studying not only the top-down process, such as the isolation and characterization of nanocellulose from wood pulp, also the bottom-up process which is a continuous fabrication of CLF based on the nanocelluloses. Moreover, high-strength CLF was made via nanocellulose alignment technique by wet spinning and physical stretching. However, the specific modulus and specific strength of currently available CLFs are away behind the technical requirement. Thus, to enhance the mechanical properties, a chemical approach based on increased intermolecular binding through cross-linking induction is attempted with the existing continuous fabrication process. The process parameters and chemical reactions are experimentally investigated, and their effects are evaluated by chemical and mechanical analysis.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.