COMPATIBILISERS | ADDITIVES
Above: SEM images of 80/20 PE/PA6 blend, showing matrices with: no compatibiliser (left); PE-grafted-MAH (centre); Polarfin compatibiliser (right). Interface Polymers says that with the Polarfin additive, the PA particles are highly adhered, the PE/PA interface is stronger than the PE matrix itself, the PA particles reinforce/strengthen the PE
BYK’s SCONA modifiers are grafted polymers
that act as compatibilisers, coupling agents, and viscosity and toughness modifiers. The bio-based SCONA TPPL series additives are composed of grafted PLA, which makes the additives compatible with PLA and other polar, bio-based polymers. The maleic anhydride (MAH) grafted SCONA TPPL 1112 PA acts as a coupling agent to achieve adhesion between fillers and fibres with the polymer matrix and as a compatibiliser in polymer blends. SCONA TPPL 5112 PA, which is also an MAH-grafted polymer, has a lower viscosity and can also be used as a dispersing aid. SCONA TPPL 1214 PA, a glycidylmethacrylate (GMA)-grafted polymer, is a high-molecular-weight melt strength enhancer for PLA. SCONA TPPL 1310 PA, an acrylic acid (AA) grafted polymer, has been found to work synergistically with conventional melt strength enhancers (for example, epoxy oligomers) at low loading levels.
Recycled BYK’s latest product, SCONA TPPET 4214 PA, is based on PET functionalised with GMA. It is best used as a high-molecular-weight viscosity modifier, but it can also act as a compatibliser or coupling agent. The additive helps mitigate the challenge of reduced intrinsic viscosity (IV) in recycled PET (rPET), which is caused by thermomechanical and hydrolytic degradation. A lower IV can result in insufficient melt stability, non-uniform rheological properties, and poor performance in injection moulding, said Inch. In particular, in foam mould- ing, low IV can result in large voids, an uneven bubbled surface, and yellow discoloration. The additive increases the IV value through reactive compounding, which improves melt stability and foam structure. Interface Polymers is preparing to start its first
production plant for its new Polarfin di-block polymer compatibilisers in Visakhapatnam, India. The compatibilisers have been designed to help reduce flow defects and gels in mixed or cross-
www.compoundingworld.com May 2024 | COMPOUNDING WORLD 63
contaminated plastic recycling streams. In film packaging using post-consumer recyclate (PCR), for example, the additive helps to create smooth and printable surfaces. The compatibilisers are used at low levels (often less than 1%) in combina- tions such as polyolefins (PP or PE) with polyamides (PA), PE or PP with EVOH, PE or PP with PET, and PE or PP with cellulose (a bio-based polymer). Package and film producers are working to
create recyclable solutions to replace conventional multi-layer, multi-material structures that were historically optimised for properties and light- weighting but not recycling. One option is to use one material (i.e. monomaterial PP or PE); compa- nies are working to address the limitations of these structures, particularly with barrier properties. Existing, multi-material barrier structures are also being tested for recyclability. For example, PE films with both PA and EVOH barrier layers were tested by the independent institute Cyclos-HTP and found to be compatible with recycling, BASF reported. The studies were conducted on co-extruded PE/ PA6/EVOH high-barrier films and laminated PA6/PE films in household packaging waste. The laminated structures contain a compatibiliser that is added to help distribute the PA component in the PE matrix. In the coextruded structures, the tie layer (used to
Below: A broad portfolio of polyamide- containing packaging can now be certified as recycling compatible
IMAGE: BASF
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