ADDITIVES | MATERIALS


Fusabond. These enhance functions such as impact resistance, viscosity control, stress cracking control and compatibilisation. Arroyo showed some of the work the group has been doing with film converters on recycling of PE and PP with barrier layers such as EVOH and PET. One case study looked at LDPE film with EVOH layer for packaging of cheese and other food. Without modification, this recyclate used at 30% inclusion to make new barrier film creates gels at an unacceptably high level. The addition of Retain on a 1:1 basis reduces the gel count to 23 gel/m² for 300 micron film and zero for 800 micron film. In an automotive application, Arroyo showed how the addition of Engage elastomer to a compound of PP from used battery cases and also from bumpers can enhance impact resistance and stiffness. This compound can then be used for an application under the hood. Dow worked on another study with Centexbel Institute which explored recycling of PET thermoformed trays containing an inner LDPE layer for sealability of the tray to lidding film. The study demonstrated that the addition of Elvaloy copolymer alloy improves the tenacity of fibres produced from the recyclate. Along with Dow, other major polymer producers have been promoting existing product lines that can be added to recyclate as well as to virgin polymer compounds. ExxonMobil produces a PE-PP copolymer range called Vistamaxx which can be used to compatibilise PP and PE in a mixed recyclate. Among the Vistamaxx benefits are enhancement to impact performance and modifi- cation of melt flow, says ExxonMobil (see feature on compatibiliers in Plastics Recycling World March- April 2019 issue). Arkema is another polymer major that is highlighting use of its products with recyclates. The group spoke of the need for improving the performance of recyclate from post-consumer mixed waste streams: “Pressure from legislation as well as consumer more and more drive the industry to increase recycling rates and green initiatives. That is why Arkema has designed a full range of compatibilisers and impact modifiers that allows mixed waste streams, targeting higher added-value applications. Lotader reactive terpolymer, Lotryl copolymer and Orevac grafted polyolefins have been widely used for example as compatibilisers for multilayer structures based on polyolefins (LDPE, PP and HDPE) and engineering plastics (EVOH, PA and PET). Mechanical properties, and in particular impact strength and elongation at break, are significantly improved, opening up recycling opportunities in various extrusion and injection


www.plasticsrecyclingworld.com


Riverdale Global’s new +Restore liquid additive improves impact strength Source: Riverdale Global


moulding applications.” Taking a novel approach to recyclate enhance-


ment is Riverdale Global, which has built expertise around liquid additives and colours for virgin polymers. It has developed +Restore additive which reduces the polymer degradation that takes place during melt processing and increases physical property retention in regrind as compared with unmodified material. “+Restore enables recyclers to obtain physical


properties much closer to those of virgin polymer than with unmodified regrind,” said Jared Arbeter, Technical Sales Manager. “This innovation expands end-use possibilities for recycled material, opening new applications in moulded or extruded products, including fibres.” Riverdale said that in tests, reground homopoly- mer PP containing +Restore additive exhibited 65% greater Izod impact strength than unmodified regrind. Improvements have also been achieved with PP copolymer and HDPE, it said. The new additive can be used alone or in a blend with Riverdale Global’s liquid colours. Typical usage rates are in the 0.1 to 0.5% range.


CLICK ON THE LINKS FOR MORE INFORMATION: � www.byk.com � www.milliken.com � www.aaroninc.com � www.struktol.com � www.greenmantra.com � www.dow.com � www.exxonmobilchemical.com � www.arkema.com � www.riverdaleglobal.com


July/August 2019 | PLASTICS RECYCLING WORLD 19


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