ADDITIVES | COMPATIBILISERS
Above: Lotader 4210, from SK Functional Polymer, can be used to upcycle a variety of mixed plastics waste,
including EVOH and PA barrier film constructions
to convert mixed plastic waste streams into high value materials (the company was created through SK Geo Centric’s acquisition of Arkema’s functional polyolefins business in 2020). “SKFP has focused significant research efforts on developing reactive polyolefins to compatibilise plastic blends by mechanical recycling. Lotader reactive terpolymers and Orevac grafted resins are widely used as compatibilisers of a wide range of blends. SKFP has solutions for recycled blends such as rPET/rPE, rPET/rPP, rPA/rPE, rPA/rPP, rPA/ rPET... but also PE/EVOH blends,” says Lolita Hauguel, Business Development Manager at the company’s French operation. The Lotader 4210 maleated grade has been
commercialised to upcycle PE and EVOH multilayer waste (the final compound is limited to non-food applications). SKFP says another successful example is the use of Lotader AX for recycled PET contaminated with polyolefins not eliminated by the sorting process.
SKFP says it has also demonstrated that its new
range of highly heterogeneous Lotryl T acrylate copolymers are highly efficient booster solutions for recycled styrenic resins enabling a significant increase in impact performance. The company also provides solutions to improve the impact resistance and adjust the viscosity of rABS compounds by com- bining non-reactive Lotryl highly polar copolymers and reactive Lotader AX. “The combination of polarity and reactivity of these resins is key to successfully upcycle plastics wastes,” says Hauguel. Orevac grafted polyolefins are said to be widely used as coupling agents for filled PP and PE com- pounds. The product range includes grafted PP, grafted HDPE/LLDPE and grafted EVA. They are available with a wide range of reactive maleic anhydride levels, but the grades with higher contents of reactive group are the more efficient coupling agents. They are suitable for use with ATH, MDH,
48 COMPOUNDING WORLD | May 2022
other mineral fillers, and glass and natural fibres. Compatibilisation of dissimilar polymers can be achieved using reactive grafted polymers such as maleated PP; bi-polar copolymers (such as SEBS); free radical grafting initiators such as dicumyl peroxide; and organometallic coupling agents (titanates, for example), according to Salvatore Monte, President of Kenrich Petrochemicals. “Most compounders only think of heteroatom titanate coupling agents when there are issues with fillers or adhesion to various substrates. But, in fact, they are thermally stable catalysts that repolymerise dissimi- lar polymers in the extruder melt much like titano- cenes and Z-N catalysts are used in monomer polymerisation,” he says. “One of the benefits of heteroatom titanate
catalysts is that the resultant polymer flows faster at lower temperatures with slightly increased tensile strength and significantly higher elongation. Using 0.2 wt% of an additive catalyst to lower process temperatures is a novel way to open the process window for dissimilar polymers, such as PC usually requiring high processing temperatures — greater than 300°C — and heat-sensitive rigid PVC,” he says. Providing examples, Monte says that at this addition rate the additive has doubled the extrusion output at a 47°C lower processing temperature for a clear uPVC computer chip housing profile. It has also improved the injection mould flow of a 40% glass fibre reinforced PC compound (which the customer had been using for many years to mould onto steel sheet to produce whetstone bases) at a temperature more than 100°C lower. Modifiers and compatibilisers will play a key role in the move from a linear to circular economy, according to Dow, which is developing an expand- ing range of products to support recycling of non-compatible material combinations. Its Retain 3000 polymer modifier is intended for use in recycling of post-industrial films containing EVOH where it is claimed to minimise gels while Fusabond grades function as impact modifiers and compatibi- lisers in post-consumer polyolefin recyclates.
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.intermixperformancematerials.com �
www.nexamchemical.com �
https://ngc-nordic.com/ (Nordic Grafting) �
www.thecompoundcompany.com �
www.sacoaei.com �
https://polyscope.eu/ �
https://www.tisan.com.tr/ �
https://sk-fp.com/ (SK Functional Polymer) �
https://4kenrich.com/ �
www.dow.com
www.compoundingworld.com
IMAGE: SHUTTERSTOCK
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