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issue 03/2021

Highlights: Bottles / Blow Moulding Joining Bioplastics Basics: Carbon Capture

Materials PLA for large

Materials PLA for large format 3D printing NatureWorks (Minnetonka, MN, USA) continues to grow its portfolio of Ingeo biopolymers specially designed for additive manufacturing with the introduction of Ingeo 3D700 for use in large-format 3D printing. Monofilaments made with Ingeo biopolymer PLA are broadly used in the desktop 3D printing market having notable performance characteristics such as precise detail, good adhesion to build plates with no heating needed, reduced warping or curling, and low odor while printing. These properties make Ingeo well-suited for 3D printing using many different types of printers and for a broad range of printing applications from consumer-level to industrial applications. In large-format printing, the higher rate and volume of polymer deposition can quickly result in excessive warpage with certain materials, like ABS, or significant shrinkage as with some polyolefins or even some general-purpose PLA grades. This can result in failed prints as warping pulls the part away from the print bed or causes layer separation. With the longer print times and higher-volume material use in industrial applications, failure during production is costly. By controlling the polymer-microstructure, the resulting amorphous PLA grade, Ingeo 3D700, has a low material shrink rate which is critical for reducing warpage, improving gap fill and adhesion, and ensuring successful prints. “As the 3D printing space expands into larger, more complex applications, we are seeing an increased need for printing materials that are tailored for a specific application or process,” says Dan Sawyer, Business Development Leader for NatureWorks. “With significant growth in large-format additive manufacturing for industrial applications, we saw the opportunity to develop a new Ingeo biopolymer grade specifically designed to minimize the loss of time and material due to failures in large format prints.” A common approach for minimizing part warpage in large prints is to use compounded materials with reinforcement such as mineral fillers, glass, carbon, or cellulosic fiber. Because Ingeo 3D700 has been designed for low shrinkage, there is an opportunity to use less reinforcing product and still achieve quality large-format parts, while maintaining the reliable printability of Ingeo PLA. If a specialty print requires additional reinforcement, then cellulose-based additives are easily compounded with Ingeo 3D700 creating a biobased compound alternative to high-cost petrochemical-based compounds such as carbon-fiber ABS. Partner testing results Multiple partners evaluated Ingeo 3D700 for use in largeformat fused filament fabrication (FFF) and direct resin-toprint processes with positive results. “In our testing, we found that Ingeo 3D700 goes one step further towards reducing warpage in large-format prints beyond previous Ingeo PLA grades designed for 3D printing,” said Xiaofan Luo, President at Polymaker (headquartered in Shanghai, China), a leading manufacturer of 3D printing material and filament. In addition to lower shrinkage, Polymaker also measured improved z-layer adhesion when printing with Ingeo 3D700. Dyze Design (LeMoyne, QC, Canada), an extruder designer and supplier of components for large-format printers, ran print tests comparing Ingeo 3D850, a grade already known for its low-shrink characteristics, and Ingeo 3D700. “Our tests showed that a large-format part printed using Ingeo 3D850 demonstrated a shrink rate of 1.25 %. In comparison, the same part printed with Ingeo 3D700 had a shrink rate of less than 0.25 %,” said Philippe Carrier, CTO at Dyze. “Because Ingeo 3D700 also has a higher throughput rate, we were able to successfully print at the lower temperature of 190ºC without seeing shrinkage or warping in the part.” Filament manufacturer, MCPP (Helmond, The Netherlands), conducted printing tests using filament made from Ingeo 3D700 and demonstrated an 11–13 % increase in flow rate due to the optimized melt viscosity, compared to a general-purpose PLA. According to MCPP, “this resulted in improved gap fill and adhesion between perimeter layers. Therefore, it is also expected to be suitable for FGF (fused granular fabrication) 3D printing.” The new Ingeo 3D700 grade is already finding use in metal casting manufacturing. Using a direct resin-to-print process, Shanghai TuoZhuo is printing sand casting molds that can be as tall as 1–2 meters. The 3D printed molds are replacing traditional wood foundry molds because they are faster to produce, more cost efficient, and easier to maintain as wood molds warp over time due to moisture. “There is no warping or deformation when printing with an amorphous PLA grade like Ingeo 3D700,” said Gabino Chen, Project Manager at Shanghai TuoZhuo New Materials Technology. “Using ABS, PETG, or PA in prints of this size is difficult, which is why it’s important to use PLA and useful to have a PLA grade specifically designed for large format printing.” MT www.natureworksllc.com Part (A) in black printed with polypropylene shows notable warpage in the side wall compared with the same part (B) printed with clear Ingeo 3D700 even when print conditions were optimized for each material. Parts courtesy of Dyze Design. 48 bioplastics MAGAZINE [03/21] Vol. 16

Smart wood foam Edible shock- and heat-resistant wood foam could replace plastic packaging By: Mikko Alava, Juha Koivisto, Antti Puisto, and Luisa Jannuzzi Fonseca Aalto University Espoo, Finland Materials Researchers at Aalto University (Espoo, Finland) are developing wood-based foam materials with the help of artificial intelligence (AI) in their Smart Foams research project. The project got funding for research into foams from the Technology Industries of Finland Centennial Foundation and the Jane and Aatos Erkko Foundation, while a grant from Business Finland is helping commercialise the foam innovation. The total budget of the project is just under a million EUR. With more than ten years of experience with foam the research group is looking for ways to replace plastic with wood-based materials, which have cell structures that provide strength and good heat insulation. “The project is based on biomimetics, which replicates natural phenomena. With the help of AI, we are trying to develop a foam with wood-like features, such as strength, flexibility, and heat resistance,“ says Mikko Alava. The researchers are seeking to optimise the features of the foam. For example, a mixture of the compounds lignin, wood fibre, and laponite (a synthetic smectic clay that forms a clear, thixotropic gel when dispersed in water) can produce a foam that resists shock and humidity and can be used to replace plastic. Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants, including wood, and when it is converted into a dried foam it is hard, water-resistant, and even conducts electricity. “Traditional material development is slow and unpredictable, and new materials may even have emerged by accident, as was the case with Teflon. In this project we utilise machine learning, with which we can exclude superfluous combinations of materials and processes and considerably accelerate development work,“ says researcher Juha Koivisto. Foams can also be produced using different technologies. Web formation, or paper manufacture technology, produces material with exactly the right thickness, but the wet foam dries slowly. Extrusion, or 3D printing, produces hard and long bubbles which make the structure stick-like and strong. “AI uses previous data to show us how to add a desired feature with less effort,“ Koivisto says. With funding from Business Finland, the researchers are looking for commercial applications and markets for the new material. “Commercialisation and the replacement of Styrofoam and bubble wrap, for example, in packaging require that the biobased material really is biodegradable, cheap, and can be produced in massive quantities. In some applications, it also needs to resist humidity,“ Alava says. Because of its lightness, its heat insulation properties (the insulation value is about 0.03 W/mK), and its strength, the rigid, closed-cell foam material can be used for insulation in buildings if it is both resistant to humidity and fire safe. Research continues into this. The foam material is remarkably similar to cork, for example, but with a density of about 40 g/dm³, it is ten times lighter. “Fibres can be manufactured from other materials, including carbon. The geometric features of the fibres are significant in the material, enabling the modification of the features of the material that is to be manufactured. Spiky fibres produce better foam than materials with a powderlike texture. The goal of material optimisation is to produce extraordinarily strong and light materials that are also environmentally friendly,“ says researcher Antti Puisto. “The most extraordinary feature of the foam is that it is edible. The method makes it possible to produce foam from carrot, lingonberry, cranberry, or beetroot powder, and make chips out of them similar to potato crisps,“ Koivisto says. The research group has extensive skills and knowledge in forest-based materials, foams, and the use of AI in materials research. Design and planning of packaging are the responsibility of Luisa Jannuzzi, who has studied the use of cellulose-based materials as packaging material. “The packaging material is fully biobased, it biodegrades in natural conditions and it is easily recyclable with cardboard,” says Jannuzzi. The Smart Foams research project involves the Aalto University Complex Systems and Materials (CSM) group, which is part of FinnCERES, a competence centre of Aalto University and VTT Technical Research Centre of Finland on the bioeconomy of materials. The goal of FinnCERES is to develop bioeconomy materials using wood as a raw material to promote a sustainable future to protect the environment. AT www.aalto.fi/en Because of its lightness, its heat insulation properties, and its strength, the foam material can also be used for insulation in buildings if it is both resistant to humidity and fire safe (Picture: Mikko Raskinen) bioplastics MAGAZINE [03/21] Vol. 16 49

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