Abstract
Three-dimensional (3D) printing, or additive manufacturing, is a group of innovative technologies that are increasingly employed for the production of 3D objects in different fields, including pharmaceutics, engineering, agri-food and medicines. The most processed materials by 3D printing techniques (e.g., fused deposition modelling, FDM; selective laser sintering, SLS; stereolithography, SLA) are polymeric materials since they offer chemical resistance, are low cost and have easy processability. However, one main drawback of using these materials alone (e.g., polylactic acid, PLA) in the manufacturing process is related to the poor mechanical and tensile properties of the final product. To overcome these limitations, fillers can be added to the polymeric matrix during the manufacturing to act as reinforcing agents. These include inorganic or organic materials such as glass, carbon fibers, silicon, ceramic or metals. One emerging approach is the employment of natural polymers (polysaccharides and proteins) as reinforcing agents, which are extracted from plants or obtained from biomasses or agricultural/industrial wastes. The advantages of using these natural materials as fillers for 3D printing are related to their availability together with the possibility of producing printed specimens with a smaller environmental impact and higher biodegradability. Therefore, they represent a “green option” for 3D printing processing, and many studies have been published in the last year to evaluate their ability to improve the mechanical properties of 3D printed objects. The present review provides an overview of the recent literature regarding natural polymers as reinforcing agents for 3D printing.
Highlights
Three-dimensional (3D) printing, or additive manufacturing, is an innovative method to produce a three-dimensional object using different processes and raw materials, such as resins and powder grains, generally building a product layer by layer [1]
The aim of this review is to provide a general overview about natural polymers recently employed for 3D printing processes
An element of novelty is brought by the work conducted by Shariatnia et al [23], where a solution of water and cellulose nanocrystals (CNCs) was sprayed between polymer layers during 3D printing with the fused deposition modelling (FDM) method
Summary
Three-dimensional (3D) printing, or additive manufacturing, is an innovative method to produce a three-dimensional object using different processes and raw materials, such as resins and powder grains, generally building a product layer by layer [1]. Among the different 3D printing techniques, FDM is the most common and widespread, and its success depends on the availability of materials that can be processed with it. These materials are represented by thermoplastic polymers characterized by a glass transition temperature in the range of 50 ◦ C up to around 230 ◦ C. The reinforcement is obtained by mixing the polymeric matrix with fillers, characterized by an extraordinary mechanical performance and an excellent functionality [14] In this way, composite materials, commonly used to perform 3D printing, are obtained.
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