MACHINERY | ALTERNATIVE COMPOUNDERS
Right: Researchers at Aimplas see increasing opportunity in compounding of shear
sensitive and very highly filled formula- tions
incorpotate higher amounts of fillers and fibres. Work is also underway to lift devolatilisation capacity for decontamination processes and to increasing residence times for more complex REX systems. According to Hans-Ulrich Siegenthaler, Technol- ogy Expert at Kneading Experts and Researcher/ Professor within Institut iRAP at the Institute for Applied Plastics Research at Fribourg in Switzer- land, the main reason alternative compounders still exist on the market and can maintain their niches, even expanding them in some cases, is that they have highly specific property profiles. “They simply match the requirements in their applications better than the standard solution of co-rotating twin-screw extruders,” he says. “We also notice this in the development of new
processes at iRAP. For certain applications, qualita- tively better results can be achieved with alterna- tive systems. For us, this means that we use the pilot plants of suppliers or appropriately equipped compounding companies for our work, because standard systems have been in place at the institute up to now,” he says. “In one of the last technology reviews on this
Below: Institut iRAP professor Hans-Ulrich Siegenthaler says com- pounding extruders such as the Buss kneader can “simply match the require- ments in their applications better”
topic, we introduced the ‘Compounding Analytics’ toolbox, which we continue to use intensively and successfully. We also intend to use AI and machine learning methods as further resources to enhance it,” he says.
Siegenthaler highlights some examples of
projects where the benefits of alternative com- pounders have been key. One included work with an industrial partner on natural fibre-reinforced compounds derived from the edge sections of thermoforming processes, so tapping into an otherwise lost source of raw materials. The compo- nents made from them are used in the same assembly process in the automotive industry, fulfilling a single-polymer strategy. In the second project, blended fabrics (polyes- ter/cotton) derived from waste collected from the
fashion industry are being investigated as a resource for reinforcing polyester-based technical components.
Siegenthaler says another project explores the
use of bio-based raw materials to achieve a reduced carbon footprint and novel property combinations. “By-products from the food, feed and wood industries are used. The gentle and specifically adjustable shear rates of alternative systems are the key to success here,” he says. “Other projects with expanded recycling ap-
proaches are currently in development. For example, in material recycling, compounds made from PET flakes from recycled bottles and short glass fibres are being evaluated for their use as extrusion materials for applications in the construction industry. Also, in a pilot project for raw material recycling, the basic principles were developed to return thermoset compounds to their starting material through a solvolysis approach. The conversion of the batch to the continuous process is currently underway. The large free volumes of alternative systems are being utilised in this process,” he says. Siegenthaler also sees AI technology and its
improved insight into the compounding process benefiting the application of alternative extrusion technologies. “AI is already being used successfully in the design of new pharmaceutical compounds. These approaches and the use of data sets from the development and production of plastics are to be used for faster and more efficient recognition and selection of, for example, formulation candi- dates for targeted application fields,” he says. “In the production of battery masses, many players are exploring the possibilities for the DBE (dry battery electrode). In contrast to the slurry process, much higher viscosities have to be handled with gentle mixing processes,” he explains. “Low shear rate levels combined with excellent mixing effects — dispersive and distributive — are
60 COMPOUNDING WORLD | October 2023
www.compoundingworld.com
IMAGE: BUSS CORP
IMAGE: AIMPLAS
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