Thermoplastic Cellulose-Based Compound for Additive Manufacturing

Abstract

The increasing environmental awareness is driving towards novel sustainable high-performance materials applicable for future manufacturing technologies like additive manufacturing (AM). Cellulose is abundantly available renewable and sustainable raw material. This work focused on studying the properties of thermoplastic cellulose-based composites and their properties using injection molding and 3D printing of granules. The aim was to maximize the cellulose content in composites. Different compounds were prepared using cellulose acetate propionate (CAP) and commercial cellulose acetate propionate with plasticizer (CP) as polymer matrices, microcellulose (mc) and novel cellulose-ester additives; cellulose octanoate (C8) and cellulose palmitate (C16). The performance of compounds was compared to a commercial poly(lactic acid)-based cellulose fiber containing composite. As a result, CP-based compounds had tensile and Charpy impact strength properties comparable to commercial reference, but lower modulus. CP-compounds showed glass transition temperature (Tg) over 58% and heat distortion temperature (HDT) 12% higher compared to reference. CAP with C16 had HDT 82.1 °C. All the compounds were 3D printable using granular printing, but CAP compounds had challenges with printed layer adhesion. This study shows the potential to tailor thermoplastic cellulose-based composite materials, although more research is needed before obtaining all-cellulose 3D printable composite material with high-performance.

3D Printed Cellulose-Based Filaments—Processing and Mechanical Properties

“…Above 240 °C, the material showed some signs of degradation such as color variations and the release of white color smoke during extrusion. Earlier work showed that critical temperatures regarding degradation occur in a range of 265–280 °C for different cellulose-based materials [ 20 ]. Therefore, it can be assumed that a short-term temperature influence of 240 °C will not damage the material.…”

“…In comparison with previous work, where direct granule printing and a nozzle with 0.8 mm were used, the FFF process with a nozzle size of 0.4 mm led to better geometrical accuracy. The single strands and layers were less visible than in a direct granule printing [ 20 , 21 ].…”

“…Compared with other cellulose-based materials, it has a high cellulose-based carbon content of 50–60 wt%. VTT developed the material in the European research project “Novum project.” This particular material was chosen based on previous research on different cellulose materials [ 20 ]. Compounding for granules was made using a corotating twin-screw extruder (Berstorff ZE 25x33 D, Berstorff GmbH, Hannover, Germany).…”

“…In a previous study, different variations of cellulose-based thermoplastic materials were used as printing materials to evaluate processing and mechanical properties to identify suitable materials for the printing process. It was shown that cellulose esters with longer aliphatic carbon chains (≥8 C) could be used as plasticizers for cellulose acetate propionate (CAP) based compounds, and there is potential for improved material properties in printed materials [ 20 ]. A following study showed the recyclability of these materials up to seven processing cycles and improved performance in up to five times recycled materials [ 21 ].…”

The Synergistic Effect of Micro to Nano-Cellulose-Clay on the Mechanical Properties of Biodegradable Polypropylene Nanocomposites

“…At optimal processing conditions, cellulose materials derived from agriculture have been widely reported by many researchers to be effective replacements for inorganic/mineral-based fillers, such as Talc, TiO2, CaCO3, MgO, and Mg2(OH)3, in thermoplastics [14][15][16]. Incorporating long natural fibers, such as jute, as reinforcements in thermoplastics has environmental advantages, improved mechanical properties, lower weight, and higher cost effectiveness.…”