additives feature | Coupling agents & dispersants Recyclate is a
growing market for compatibi- lizers, as
recyclers seek to upgrade reclaimed polymers
copolymers formulated for efficient compounding of incompatible polymers that are also difficult to separate in a commingled stream. Of these materials, Entira EP is the most recent, although Jose Torradas, senior technical consultant for DuPont Packaging and Industrial Polymers, says the company continually enhances Elvaloy and Fusabond grades to fine-tune their properties, extend applications and meet the needs of new olefin chemistries. The initial Entira EP copolymers are formulated for
mixed streams of PP and PE. Likely applications include packaging scrap comprised of PP closures with foamed PE sealing inserts. Adhesion between these materials is poor, and efforts to recycle them without a compatibi- lizer would generate cracks along the interface of the continuous phase or matrix of the higher-fraction mate- rial and the other, dispersed component, with the result being poor mechanical properties. As an ethylene copolymer, Entira EP is compatible with PP and PE, and thus adheres to one or both. A 4% loading of the copolymer promotes a solid bond between the matrix and the dispersed material, substantially improving mechanical properties, expanding end-use applications, and thereby increasing the value of the recyclate. Additional versions of Entira EP will reportedly
include grades that compatibilize PE and PA, or PE and ethylene vinyl alcohol, or EVOH, a common barrier resin in polyolefin-based packaging films, rigid containers and bottles. DuPont is also looking at tailoring the copolymer for commingled streams of PE and polyethylene terephthalate (PET), which would mostly come from PET bottles and PE closures used in the beverage industry. Another producer of additives that are effective in
upgrading recycled plastics is Kenrich Petrochemicals. The company supplies titanates and zirconates, both
40 COMPOUNDING WORLD | August 2014
organometallics and both liquids, for this and other applications. Kenrich president Salvatore Monte says that the materials have advantages over conventional silanes, notably in their ability to react with all organic and inorganic materials and to compatibilize polar and non-polar polymers. The materials also function as thermally stable
catalysts, which means they can repolymerize macro- molecules in polymer melt to rebuild molecular weight. In recycling applications, titanates act as in situ catalysts in extrusion melt, Monte says, which allows them to regenerate molecular chains and rebuild mechanical properties. In a previous article on developments in coupling
agents (Compounding World, January 2013), Monte said that titanates and zirconates would also copolymerize a blend to create what is essentially a new polymer from high concentrations of materials, such as a 50/50 PP/ high-density PE mix. Monte sees considerable potential for the materials
in recycling. In a recent interview, he remarked that most exhibitors at recycling shows are “equipment guys – only a handful understand materials.” The industry has largely been about “collecting, sorting and baling,” at least at the operational level. With the right data about coupling agents, compatibilizers and other relevant additives, he suggests that compounders could make significant gains in the supply of recycled materials and create additional value for their companies.
Click on the links for more information: ❙
www.evonik.com ❙
www.dowcorning.com ❙
www.crayvalley.com ❙
www.dupont.com ❙
www.4kenrich.com
www.compoundingworld.com
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