3D Printing of Amylopectin‐Based Natural Fiber Composites

Abstract

Many ancient Chinese structures, such as portions of the Great Wall, use a unique mortar that derives from glutinous rice (commonly called “sticky rice”). Unlike other types of rice, sticky rice is rich in amylopectin with negligible amylose. Inspired by the long‐term stability of the amylopectin‐based mortars in ancient structures, sticky rice (SR)‐based materials for 3D printing are developed. Heat causes amylopectin gelatinization, during which molecular branches open to form a large network of gel balls. This causes a merger of the granules and improved interaction between the matrix and fillers. To enhance the mechanical properties, cotton fibers are included, ≈11 µm in diameter. During amylopectin gelatinization, secondary fibers emerge from the primary fibers, creating a complex two‐level fiber network. Both the fibers and matrix constitute a 3D printable fiber composite consisting entirely of natural, inexpensive, and scalable components. The processing steps make no use of any non‐natural materials or hazardous chemicals. A systematic design of experiments is conducted to understand the effect of processing parameters on the mechanical properties. Scalability by printing low‐density cellular materials is demonstrated. Finally, it is shown that SR composites are more resilient than common thermoplastic composites when subjected to flame, heat, or ultraviolet light.

Spirulina‐based composites for 3D‐printing

“…21,22 A recent study shows that entirely biobased, amylopectin/cotton fiber mixtures can be used as standalone 3Dprinting materials, and upon post-processing the produced structures can achieve properties comparable to commonly used plastic filaments. 23 This finding opens up new possibilities for integrating fully biomass-based materials in extrusion-based 3D-printing. Biomass-based materials require the addition of a solvent, most often water, to be able to flow under ambient conditions.…”

“…The ability to tune the achieved mechanical properties would effectively expand the range of applications that these materials can reach. 28,29 Commonly applied post-processing strategies to alter the micro-morphology and mechanical properties of a given polymer, fabricated through extrusion-based printing, include: (a) drying processes at various flow rates, pressures, and temperatures, 26,27,28 (b) heat treatments, either to promote thermal annealing 30 or gelatinization, 23,31 and (c) inducing gelation or cross-linking by exposure to selected ion solutions. 28,32 Among drying processes, freezedrying (lyophilization), which dehydrates materials through ice sublimation, allows shape retention even in complex structures.…”

Amylopectin Regulated Mineralization of Calcium Carbonate and Its Application in Removing of Pb(II)

“…[38] But when it is heated to a certain temperature, new hydrogen bonds formed between the free hydroxyl groups on the glucan chain and the water molecules, which causes the expansion process of the particles and forms a stable colloid in water. [28,39] The mineralization reaction occurred under ambient conditions, CaCl 2 was used to supply Ca 2+ while (NH 4 ) 2 CO 3 was used as the source of CO 3 2− , amylopectin acted as the organic matric, which could assist the growth and crystallization of CaCO 3 as well as its crystalline polymorphic phases. When CaCl 2 is added to the amylopectin colloidal solution, Ca 2+ first coordinates with functional groups ─OH from amylopectin, then, the carbonate ions enter the solution, and bond directly to the amylopectin chain with the Ca 2+ , and stable hexagonal slices of CaCO 3 appear.…”

“…As a major component of the organic matter in the sticky rice, amylopectin is insoluble in water and most organic solvents, which plays an important role in repair and maintenance of cultural relics. [26][27][28] Researchers believe that ancient city wall and some other ancient buildings used amylopectin in sticky rice mortar to induce mineralization of CaCO 3 . After thousands of years of evolution, the ancient ruins can still maintain good mechanical properties, and keep it intact for a long time.…”

A 3D Printed Morphing Nozzle to Control Fiber Orientation during Composite Additive Manufacturing

“…[5] In recent years, researchers have increasingly leveraged this extrusion-enabled material versatility to print composite materials comprising a diversity of embedded fibers. [6][7][8][9][10] Notably, the type, length, and orientation of such fibers can be designed to educe distinct functionalities for printed systems, such as enhancements of mechanical, thermal, and electrical properties. [11][12][13] One critical challenge in printing fiberladen composite materials, however, is that conventional extrusion nozzles yield identical fiber alignment during the deposition process.…”