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issue 05/2021

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Highlights: Fibres, Textiles, Nonwovens Biocomposites Basics: CO2-based plastics

Biocomposites Biobased

Biocomposites Biobased semi-finished SMC products The ecological footprint of plastics and their energyintensive production has long been subject of public criticism. An increasing amount of research has been ongoing, focussed on the development of environmentallyfriendly alternatives - organic plastics – to improve their CO 2 balance. Among these efforts were those of Lorenz Kunststofftechnik (Wallenhorst-Hollage, Germany) and the Institute for Composite Materials (IVW) (Kaiserslautern, Germany), who, from 2018 to 2020, worked to find ways to make a thermoset composite with a lower CO 2 footprint. The result is a weight-reduced semi-finished product based on renewable raw materials of organic origin. The reduction in density gives this new semi-finished product possibilities for use as a lightweight material in fields like automotive manufacture, e-mobility, and infrastructure construction. To improve the ecological balance, the company decided to source raw materials regionally within 500 km in the pending commercialization of the project results. This sustainable plastic is flame-proof to UL 94 V0 4 mm HB and mouldresistant. The research project received financial support from the Federal Ministry of Economics and Technology (BMWi) as a ZIM subsidy (Central Innovation Program for SMEs). The first ideas for environment-friendly polymers started making the rounds at Lorenz Kunststofftechnik after the UN Climate Conference in Paris in 2015. The company, which specializes in thermosets, looked for a suitable research partner and in 2018 found one in IVW. “In earlier projects we had already provided IVW with semi-finished products, so we could build on a good and effective relationship,” said Peter Ooms, director of Sales and Business Development at Lorenz Kunststofftechnik. “In the current research project, we assisted the IVW with our expertise and SMC materials, as well as in the subsequent testing for industrial production. The Kaiserslautern institute did the lab-scale preliminary testing, general research, and the development of the formulations for the new organic SMC.” Analysis of the required parameters As the first step, Lorenz and the IVW jointly drew up a material specification sheet. To do so, they asked some 30 companies in various industries who might be interested in such a thermoset, including specialists in electrical, automotive, and industrial manufacture. “Our survey showed that different industries have different requirements for the material. However, almost all wanted it to have a life-cycle assessment (LCA) to document environmental aspects and CO 2 reduction in production, as well as recyclability. One approach to this is the research into sustainable fillers, fibres, and resins for the manufacture of semi-finished BMCs and SMCs,” adds Ooms. “We chose the possible organic materials for SMC production based on these requirements.” A number of organic-based lightweight fillers and fibres were shortlisted, for example ground sunflower seed shells and reeds. In the next phase of the project the IVW prepared the characterization and lab-scale production of the organicbased SMC. “First we did initial tests with various lightweight fillers and fibres,” explains Florian Gortner, a scientist at the IVW who works on processing techniques. “Based on the results we analysed all the necessary parameters and examined which materials would be especially suitable.” The data obtained included impregnability, density, viscosity, and the availability of the respective raw material. Characterization and manufacture of a partially organic semi-finished product Once a basic understanding of the formulation and the interactions among its components had been worked out, in the next work step a demonstrator was defined. “This demonstrator, in the form of a component with obstacles, helped us examine the flow and mould filling behaviour of the material, and compare it with conventional SMC semi-finished products. Building on these results and on press rheometry testing, we built a simulation model to demonstrate the flow behaviour and enable predictions about other mould geometries,” explains Gortner. “That made the support from the SMC experts at Lorenz so invaluable, and without it our progress in development would not have been possible.” The subsequent primary goal was the comparability of the available SMC semifinished products, and the creation of a solid basis for further test series. This comparability was demonstrated in producibility and workability with conventional equipment and processes, and in selected mechanical properties. After all the specifications were clarified in cooperation with materials suppliers, SMC experts and vendors, and through extensive research of the literature, the initial development of an SMC resin paste based on conventional fillers began. “As a starting point for the research project, we chose a UP resin and the appropriate anti-shrinkage additive to understand the basis of SMC formulation development,” says Gortner. “Magnesium oxide and an internal release agent were used to thicken the resin, and a colour paste was added to colour the semi-finished products. Working from the survey results, we added further additives and adapted the resin paste to the application.” The challenge at this stage of the project was to get a basic understanding of the interactions of the individual components of an SMC formulation. After iterative test series for different resin systems, largely organic-based formulations were developed that showed the desired viscosity, flow, and impregnation behaviour. These formulations were comparable to formulations on the market, given similar fibre mass content. 44 bioplastics MAGAZINE [05/21] Vol. 16

Industrial-scale use In this way, a semi-finished product was developed that has lower density than conventional SMC. This makes it especially suitable as a lightweight material for electric vehicles, and so Lorenz intends to produce it for industrial manufacture. “Now that together with IVW we have succeeded in making this new thermoset, we’re planning further improvements for practical applications,” says Ooms in conclusion. “As it goes into regular use, we will doubtless get further useful feedback for changing certain elements in the formulation or for tuning individual parameters for specific applications.” One such improvement might consist of varying the amount of resin paste with the other materials, or the amount of natural fibres. This makes it possible to create a semi-finished product with the ideal density and mechanical properties for each application. Unsaturated polyester resins could also be replaced, to reduce environmental impact as well as to reduce or even eliminate the health risks of daily work with polymers. “The objective of our research project was to show that the use of organic-based components in semi-finished thermoset products is possible,” summarizes Gortner. Lorenz Kunststofftechnik GmbH “Thanks to the active support of Lorenz, we were able to do this successfully, and will continue to incorporate feedback from industrial production into our results.” Lorenz and the IVW expect that this will lead to further development and improvement of semi-finished products with organic-based components. AT | Biocomposites Stay in the loop! Subscribe for free! @ Subscribe for free! @ Subscribe for free! @ bioplastics MAGAZINE [05/21] Vol. 16 45

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