Читать книгу 3D Printing of Foods - C. Anandharamakrishnan - Страница 48

Another variant of selective sintering is the use of hot air instead of a laser as a thermal source. The process remains the same as the hot air is used to fuse the powdered material supply. Researchers had successfully printed sugar‐based 3D constructs using hot air as the heating medium for the fusion of printed layers. Powder density and compressibility are the critical factors in SHASAM that significantly affect the flowability and have an impact on the carnation of 3D design patterns (Schmid et al. 2013). In general, free‐flowing powder without any solid clumps is suitable for the sintering process. Further, the powdered material supply must be adhesive enough and possess the tendency to agglomerate to get adhere to the contact points of adjacent molecules. It was reported that the layer thickness was inversely related to the mechanical strength of the 3D constructs (Amorim et al. 2014). As a result, thin layers possess higher mechanical strength with decreased porosity of the fabricated structures. Also, the particle size of the powders greatly influences the finishing quality of 3D printed samples. Diaz et al. (2018) described the method for the fabrication of multi‐material 3D construct using the sintering process with a greater degree of printing precision and resolution. The material supply is comprised of structural elements and binder components. Thus, the structural element remains the base that provides bulk and scaffold function to the 3D construct and is fused by the particle‐particle sintering of the binder component. It was reported that the use of a combination of two or more binders with different glass transition and melting temperatures exhibits better printing performance (Liu and Zhang 2019). In general, the glass transition and melting temperature of the binder component should range between 10 and 200 °C. So, the phase transition of the binder material can occur in less than 5 seconds while the structural element remains unaffected at temperatures below 200 °C (Diaz et al. 2018). Similar approaches have yet to be studied in detail for the optimization and characterization of structural and binder materials for improved printing performance.