MATERIALS | COMPATIBILISERS
Effect of Nexamite on MFR in recycled PP (*Compounded 90 sec @ 230°C) Source Nexam Chemical
been trickier unless you blend in high amounts of virgin PP with low MFR. We have developed a new technology for building molecular weight in recycled PP.” First product, recently introduced to the market,
is Nexamite R201, part of Nexam’s Reactive Recy- cling portfolio. In addition to building molecular weight, it can compatibilise with other polyolefins like PE. “Nexamite R201 reacts and forms strong connections both in rPP itself and with rPE,” says Öhrn. Typical dosing of Nexamite R201 is 1-5% depending on final target and is compounded with the recycled PP at temperatures over 200°C. Öhrn cites a post-consumer recycled (PCR) PP containing 10% PE, where the need was to increase molecular weight so that it could replace virgin PP. Minerals supplier Imerys has yet another way of
compatibilising PE and PP. Marketing Manager Cyril Coppel says the company’s ImerLink is an innovative engineered mineral designed specifi- cally to compatibilise recycled blends of the two polyolefins.
“Imerlink enables true compatibilisation by
creating a chemical bond with PE and PP,” he says. “It results in improved mechanical properties with an optimum stiffness/toughness and is also cost
SEM images of HDPE/PP blends, one containing no compatibiliser (left) and the other compatibilized with ImerLink, which bonds with both phases to create a more homogeneous structure (right)
Source: Imerys 42 PLASTICS RECYCLING WORLD | May/June 2021
www.plasticsrecyclingworld.com
effective. In addition to improved mechanical properties, Imerlink provides thermal stability and improved aesthetics. Focusing on two applications, one in injection moulding and the other in extru- sion, will better show benefits of this technology.” Coppel points to a shortage of recycled high- density polyethylene (HDPE) with a melt flow index (MFI) above 2.0 g/10min. “To try to solve the problem, some recyclers developed a blend of HDPE and PP for their customers, wheelie bin producers. However, sales are limited due to aesthetic issues. Tiger stripes appear on the injected containers due to unstable melt flow during mould filling. This is caused by insufficient bonding of the molten polymers due to immiscibility.” He continues: “It was clearly demonstrated that the container produced with the ImerLink compati- bilised formulation resulted in homogeneous surface appearance and mechanical properties were aligned with the demanding application’s requirements.” For extrusion, a typical use for recycled HDPE is in twin-wall pipes. The material is readily available from a variety of post-industrial (old pipes) and post-con- sumer sources (bottles). Problems occur when PP contamination rates in the rHDPE are above 3-5%. Using ImerLink as a compatibiliser allows recyclers/ compounders to use post-consumer wastes that have not been highly sorted, Coppel says. ReVive Compatibiliser, a blend of functional additives from masterbatch major Ampacet, was developed to allow post-industrial and post-con- sumer barrier films to be reprocessed back into the polyolefin recycling stream (see also Plastics Recycling World May-June 2020). Doreen Becker, Ampacet Sustainability Director, says ReVive gives film producers the opportunity to meet Association of Plastics Recyclers (APR) test protocols used in the USA, which enable CPG brands to apply for How- 2Recycle designations developed by the Sustain- able Packaging Coalition (SPC), based in Charlottes- ville, Virginia. How2Recycle is a standardised labelling system intended to communicate recycling
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