Compatibilisers For Mixed Waste

The recycling of mixed waste presents a fmther market opportunity for compatibilisers. European Directives on the recychng of end-of-life products encourage the recycling of plastics products, although in practice this does not often involve mixed waste. This is because the lack of compatibility between polymers degrades the mechanical properties and drastically reduces the market for the recyclate. 

It has been suggested that a small quantity of the triblock copolymer poly(styrene-b-ethylene-co-butylene-b-styrene) (SEES) will improve the properties of blends of PP, obtained from post-consmner mineral water bottles, with high-impact polystyrene (HIPS) derived from disposable cups. 

Reclaimed LDPE and HIPS have been compatibilised with styrene-butadiene copolymers and ethylene-propylene rubbers at Prague s Institute of Macromolecular Chemistry. 

Attempts have been made to use compatibiUsers in reclaiming three-component plastics waste consisting of PE, PP and PS. The PET (bottles) were first separated, and the remaining three polymers were successfiilly compatibilised with a mixture of EPDM rubber and styrene-butadiene block copolymer. Provided that a substituted diamine stabiliser was also added, the recycled mix achieved impact strength values comparable with those of virgin polyolefins. 

DSM has produced a carbonyl-bis-caprolactam compatibiliser called Allinco that has been used by IKV to compatibilise PET and polyamides so that PET bottles with a polyamide barrier layer can be recycled and made into strong tape. A different approach to compatibilising the same pair of polymers is to use a specially modified PET functionalised with suUb-isophthalic units. 

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