additives | Compatibilisers
recycling operations.” A recycled compound containing Steagreen demon-
strates a significant improvement in dimensional stability compared to recycled PP without talc (Figure 6). Stea- green can also help meet dimensional stability specifica- tions for zero- gap automotive applications, Imerys claims. Talcs also enhance heat resistance. An improve- ment in deflection temperature under load of nearly 7°C can be achieved in PP with a 20% loading of Steagreen. Steagreen is a little greyer than other Imerys talcs.
This rules it out for use in numerous compounds based on virgin polymer, but is more acceptable in recyclates. It is available in one-pack versions containing other additives that cut odour and thermal ageing. Imerys is also stepping up support for plastics
Figure 6: Talc in recycled PP significantly improves dimensional stability Source: Imerys
Finding the right fineness of talc Another way of improving mechanical performance in recycled plastics is through the addition of talc. One major supplier, Imerys, points out that as talc is chemically inert, thermally stable and is not affected by multi-pass extrusion, it can be recycled indefinitely with- out losing its initial properties (Figure 5). The company recently introduced Steagreen, a fine, lamellar, engineered talc grade, which it says is “designed specifically to impart excellent reinforcing properties to recycled plastics for highly exacting applications.” It is aimed more at post-industrial scrap than post-consum- er, owing to its price point. Adding talc to recycled polypropylene
Right: Waste bags produced from post-con- sumer PE using Granic 321 talc masterbatch
from GCR Group show better mechanical performance
increases stiffness and the finer the talc, the greater the effect on flexural modulus. Steagreen has a top-cut of 20 microns, which sits between a coarse talc with a typical top-cut of 40 microns and a very fine talc like Imerys’s own Steamic, which has a top-cut of 7 microns. Caroline Abler, Development Engineer – Polymers in Performance Additives EMEA at Imerys, describes Steagreen as “a fine product, but not too fine, so the costs are quite interesting for
50 PLASTICS RECYCLING WORLD | June 2017
recyclers with the introduction of a new formulation service to support its ImerLink mineral additive, which allows blends of PE and PP to be compatibilised. The new service allows recyclers to make use of the company’s in-house compounding and materials testing equipment to develop formulations that meet market needs and includes analysis of input streams and final product quality testing. Aside from recipe development, the company says it can also offer customers support in ramping up production as projects move towards commercialisation. Spanish compounder GCR Group is also exploiting mineral fillers in recycling applications, last year
introducing a CaCO3-based masterbatch designed to improve the performance and reduce the cost of produc- tion of waste bags from post-consumer recycled PE. Granic 321 is based on post-industrial PE resin
compounded with CaCO3 and a special additive package. Used at an addition rate of 30% in 30 micron
post-consumer PE waste sacks, it has been shown to improve impact resistance by more than 400% and to enhance tensile and tear performance. The master- batch also helps to cut production cost by eliminating the need for the addition of desiccants to absorb moisture from the recycled materials.
Click on the links for more information: ❙
www.cornell.edu ❙
www.dupont.com ❙
www.4kenrich.com ❙
www.vertellus.com ❙
www.dow.com ❙
www.velox.com ❙
www.lbf.fraunhofer.de ❙
www.polyadservices.com ❙
www.greenmantra.ca
❙
www.imerys-perfmins.com ❙
www.gcrgroup.es www.plasticsrecyclingworld.com
PHOTO: GCR GROUP
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