RECYCLING | ADDITIVES
Reactive approach to polymer recycling
Swedish company Nexam Chemical developed its Reactive Recycling technologies to enable modification of the viscosity of PET and polyolefins through chain-extension and/or chain- branching. Its recently-patented heat-activated reactive processes are designed to be used within the standard mechanical recycling process and can be performed on a regular com- pounding line or extruder. An example of the technol-
ogy at work can be seen in recycling of LDPE from beverage cartons. This post-consumer recyclate has undergone several process steps to separate it from the cardboard
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Ampacet is among many companies offering additive solutions to boost the quality of recycled PET
carton. Nexam’s proprietary technol- ogy can be used to reduce MFR and enhance the mechanical properties of the melt so it can be processed in
car industry and are produced using a proprietary delaminating process. They are claimed to improve mechanical properties without impairing the ductility of the moulded part. Tests comparing a HAR talc and a reference talc compounded using a twin-screw co-rotating extruder with talc intro- duced to the PP via a side-feeder showed the HAR version displayed a 20% higher flexural modulus, 20% lower Coefficient of Linear Thermal Expansion (CLTE), and 8% lower shrinkage. Imerys says HAR talc can provide an alternative
G E : S H
to short glass fibre reinforcement in applications where stiffness is not critical. With regard to recycling, the company says they offer the additional benefit that, unlike glass fibres, the talc particles do not suffer degradation during processing or recycling. Traditional mineral fillers alter PP density and this can affect the recyclabil- ity of PP compounds, at least in facilities using sink-float separation and sorting methods. To address this issue, Ampacet has developed Nucleant PP 4000389-E. It is a nucleating additive that improves the mechanical properties of injected or thermoformed PP parts without increasing density or sacrificing transparency. The company says it allows downgauging of PP parts while maintaining the same rigidity and allowing flotation separation.
Ampacet has also extended its OdorClear range of odour-absorbing masterbatches. Originally
32 COMPOUNDING WORLD | October 2023
Left: Nexam Chemical’s Nexamite reactive additives can improve processing of LDPE recycled from beverage cartons
blown film plant. The technology can also reduce the MFR of rPP. “Nexam has developed the
Reactive Recycling Technology to address the unmet needs of our customers, i.e. to have similar processing and final properties when using larger amounts of recycled polymers,” says Christer Svanberg, Chief
Technology Officer at the company. “This contributes to a more circular and sustainable use of plastics.” �
www.nexamchemical.com
introduced under the Odor Scavenger name, the OdorClear masterbatches minimise odour and keeps it enclosed inside the polymer. They can also be used in combination with other Ampacet R3 Sustainable Solutions products cush as ThermPro- tect, a range of rPET stabilising masterbatches designed to reduce yellowing. A challenge for any company using rPET bottles
to package mineral waters is to manage the risk of acetaldehyde (AA) contamination. AA is produced as a by-product of thermal degradation of the PET during extrusion, injection moulding or recycling and can taint the flavour of the packaged bever- age. Ampacet has developed AA Scavenger 0846 to reduce the level of acetaldehyde in PET and rPET bottles and to help preserve the organoleptic properties of water. Acting as a scavenger agent and intended for use at very low addition rates, AA Scavenger 0846 reduces migration of acetalde- hyde by up to 80%. The masterbatch producer has also introduced Gastop-Flex, which is claimed to help reduce gas transmission rates in flexible packaging applica- tions and to allow some multi-material laminate constructions to be replaced with more easily recycled simpler alternatives. Ampacet says Gastop-Flex reduces oxygen and water vapour transmission rates by up to 60%. It enables down- gauging to reduce weight and supports manufac- turing of high barrier packaging with less than 5% EVOH to comply with circular economy design guidelines.
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www.compoundingworld.com
IMAGE: NEXAM
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