SUSTAINABILITY | ADDITIVES FOR RECYCLING
Riverdale’s +ReStore additive can improve flexural modulus and impact resistance of recycled PP to near virgin standards Source: Riverdale Global
while reducing cell size and improving process stability, he reports. The NC203C additive also increases the strength and tensile properties of foamed or unfoamed extruded parts. Addisperse is currently developing custom blowing agent concentrates containing NC203. A new nucleating agent concentrate is also in development based on a halloysite mineral filler. It is intended to allow shorter cycle times for injection moulding of recycled HDPE compounds and recycled polypropylene (PP). Riverdale Global’s +Restore Additive is being used to improve properties of PP and HDPE PCR. Tests using regrind have shown that virgin-like properties can be obtained with 100% recycled PP or HDPE and a low level of the liquid additive (typically 0.1 to 0.5%). “Because the additive has an affinity for the base polymer, it acts as a lubricant, enhancing melt flow. In addition, the +Restore molecule has a functional group that readily reacts with pigments, fibres, or fillers in the resin, while a different segment of the same molecule is designed to couple with the polymer; as a result, it forms a strong bond between resin and filler without compromising flexibility,” said Jared Arbeter, Technical Sales Manager at Riverdale Global. Britec Solutions has developed BTec REA360
Regrind Enhancing Additive, which the US additives company says improves physical properties, reduces odour and enhances processing perfor- mance of regrind and recycled resins. The additive (available in liquid and pellet forms) can be used by processors such as injection moulders and blow moulders with process scrap, and by recyclers that process mixed-melt grades and industrial feed- stocks. “Data supports that physical properties of regrinds and recycled resins are replaced to levels similar to that of virgin grades in both polypropyl- ene and polyethylene at very low use rates of 0.1 to 0.5%,” says the company.
38 COMPOUNDING WORLD | October 2020 Britec illustrates the benefits of the additive with
the example of an unnamed recycler in Texas reprocessing HDPE PCR waste, which consisted of mixed colours and mixed MFIs along with 2% carbon black. It says: “Testing concluded that with addition of 0.03% BTec REA360 to their regrind feedstock, critical physical properties were im- proved dramatically. The Izod impact strength showed a vast improvement of 37% and the flexural modulus was improved by more than 30%. Melt flow was enhanced and stabilised, contributing to more than 18% increase in production output.” Völpker Spezialprodukte bases its plastics additives on montan waxes and develops grades to deliver specific solutions for producers of virgin and recycled plastic compounds. The company’s Cevo range of additives has been developed to solve processing and application-related issues in many processing areas, with Cevo-process B-3680 and Cevo-process B-3690 said to be particularly effective dispersion additives for recycling of PCR HDPE/LDPE. “Post-consumer HDPE/LDPE waste in most cases contains unwanted polymer particles and mineral — or other — contaminations that prove to be disruptive in the production of recyclates and that reduce the quality,” the company says. “Their proper dispersion as well as the dispersion of fillers — for example, carbon black — is mandatory in order to produce adequate recycling qualities, for example for injection moulding.” The company says that tests have shown that carbon black can be “excellently dispersed” when Cevo-process B-3680 or Cevo-process B-3690 is added at 0.5% loading in virgin HDPE and at 2.0% in recycled HDPEs. “This was proven by a classical filter pressure test: the results show that the increase in pressure is significantly reduced. This proves the dispersing effect of these additives in the post-con- sumer compound,” says the company.
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