COMPATIBILISERS | ADDITIVES
The need to recycle often incompatible polymer resins has given new impetus to developers of polymer compatibilisers and coupling agents. Peter Mapleston learns more
Compatibilisers deliver performance blends
Additive suppliers and academics have a whole raft of solutions available — or in development — to allow incompatible polymers to mix together to form materials that deliver improved and more consistent performance. Many of the develop- ments are geared towards upcycling recycled plastics, often but not exclusively post-consumer recyclate (PCR). Many, but not all, make use of maleic anhydride grafting technology to bridge the interface between polar and non-polar polymers, or between non-polar yet still incompatible polymers such as PE and PP. US-based Intermix Performance Materials is a
start-up that was set up last year to commercialise an ethylene-propylene multi-block compatibiliser additive technology development licensed from Cornell University. It was established by Tisch University Professor in the Department of Chemis- try and Chemical Biology at Cornell Geoff Coates, Business Analyst Andrew Arriz and Principal Investigator Ting-Wei Lin.
“High-density polyethylene and isotactic
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polypropylene (iPP), the world’s most manufac- tured commodity plastics, share similar optical properties, which makes sorting process between these two plastics challenging in large scale,” says Lin. “Despite the resemblance in chemical struc- tures, HDPE and iPP are immiscible with each other and therefore result in brittle and valueless materi- als when melt-blended. This has hampered the recycle efficiency of these plastics. Only less than 7 wt% and 1 wt% of HDPE and iPP, respectively, are reportedly recycled. Working with established plastics recyclers, Intermix obtained a batch of pellets mainly pro- cessed from used ropes and nets that were recov- ered from the ocean. The composition of these ocean plastics was approximately 1:1 weight ratio of HDPE and iPP. The company says blends displayed brittle mechanical properties and failed on stretch- ing without much elongation. By adding 2 wt% of the company’s compatibiliser, toughness was improved to more than 800% elongation at break. Lin says compatibilised HDPE/iPP blends “now
Main image: The need to ‘upcycle’ mixed and difficult to sort plastic waste streams is giving new impetus to compatibiliser development
May 2022 | COMPOUNDING WORLD 41
IMAGE: SHUTTERSTOCK
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