TECHNOLOGY | ODOUR AND EMISSIONS
Right: Preparing a piece of waste plastic for DSC analysis after the deodorising process at the Luxus laboratory
provided the ‘test house’ that has identified and quantified the likely VOCs responsible for odours. Fellow partners in the project include Matrix Moulding Systems, which has developed the novel processing technology used. Processor IPL Plastics has performed injection moulding trials on the experimental materials. “We have been able to identify and quantify a significant amount of the VOCs that are respon- sible for the odours in various recycling waste streams,” says Atterby. “We may in future be able to be more precise about how odour is measured and make it less subjective.” James Vincent, Technical Lead for Project Odour
Control at Luxus, says: “Gas chromatography can yield hundreds of volatiles from a single piece of plastic. For any source of material, we are identify- ing up to around five different VOCs that seem to be working in combination with each other to produce the odour. We are using this information to be able to remove the VOCs in question.” The intention is for the Project Odour Control technology to be made available for adoption as a retrofit option for Luxus and for other UK plastics compounders as licensees.
Additive approach The Tego Sorb series odour absorbing additives from Evonik are designed to address odours from degradation and contaminants in recycled plastics. Tego Sorb PY 88 was the first in the series and was designed for incorporation via compounding and/or masterbatch processing. It is especially suitable for polyolefins, as well as rubber compounds. More recently, the company has introduced masterbatches based on Tego Sorb PY 88 with PE and PP carriers. The additives are based on zinc ricinoleate chemistry. Evonik says this chemistry reduces and eliminates odours evolving from products, such as
hydrogen sulphide, mercaptan, thioether, isovaleric acid, amines, and ammonia. “Differently from other odour control additives in the market, the Tego Sorb series work in accordance with the ‘lock and key’ principle by irreversibly binding odour-causing molecules rather than covering up or masking odours with a scent,” says Ido Offenbach, Americas Segments Manager, Specialty Additives. “There- fore, the Tego Sorb series enables increasing the percentage of recycled materials in different applications such as film packaging, automotive, and others.” Offenbach says two new masterbatches will soon be introduced — Tego Sorb PY 30 PE and Tego Sorb PY 30 PP. Unlike other Tego Sorb additives, these supress and eliminate odour via two mechanisms: the zinc ricinoleate chemistry and evaporation promotion of low molecular weight odour substances during processing using open vents in the twin screw extruder. Another company offering an odour-absorbing masterbatch is Ampacet. It says its Ampacet Odor Scavenger is a powerful wide spectrum odour- absorbing masterbatch intended for use with recycled polyolefins. It is said to neutralise odours and keep them enclosed inside the polymer and is specially formulated for injection and blow mould- ing, film and some extruded applications. The company foresee end product use in bottles, trash bags and geomembrane liners. German research organisation for applied
Sensory panel test result of malodour reduction in recycled PE film Source: Evonik
20 PLASTICS RECYCLING WORLD | October 2021
research, Fraunhofer, has established a consortium of six of its institutes — the Cluster Circular Plastics
www.plasticsrecyclingworld.com
IMAGE: LUXUS
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