additives | Recycling
Above left: Recycled plastics can be produced from a wide variety of sources
Above right: Blown fi lm produced from a contaminated polyethylene feed stream containing 10% polyamide. The sample left contains no additive; the sample on the right contains 1.5% of PolyAd Recycloblend 720 added at the feed throat
increase thermal and chemical resistance. Another area of development is the compatibilisation of polymers with fi llers. For example, with Nexamite A89 we can address the poor impact properties of some highly fi lled polyolefi n systems. We have also been able to demon- strate that Nexamite A75 can be used to upgrade a recycled thermoplastic polyurethane to a performance equal to virgin grade for an extruded tube,” he says.
Unique problems PolyAd Services has also developed new additive systems for upgrading recycled plastics. “Using post-consumer recycled plastic poses many unique problems that are often not seen in other areas of the polymer industry, where virgin plastic is typically used,” says Jamie Ginn, Marketing and Business Development Manager. “Every recycled plastic feed stream has different properties, contaminants and oxidative history. This makes using recycled plastic resin for high performance applications extremely challenging.” One area where PolyAd Services has been focusing efforts is in developing new solutions for mixed resin barrier fi lm streams. “We offer high performance, low-dose, fully-formulated compatibilisation systems for mixed resin barrier fi lm streams; where polyethyl- ene is contaminated with up to 25% polyester, polyam- ide or EVOH. At a dose of 1.5% of PolyAd’s Recycloblend 720, multilayer fi lm scrap can be converted back into a fi lm quality alloy which can be used as either a partial or a full virgin polyethylene resin replacement. Without proper compatibilisation this mixed resin stream is of very low quality, even for thick section injection
moulded articles, and is often either landfi lled or burned,” says Ginn. “Compounding recycled polyolefi n feed streams, such as bottle fl ake regrind, can dramatically reduce the quality of the fi nished resin,” she continues. “Even thoroughly washed and well separated feed stocks will have acidic residues and oxidation sites that, when heated during compounding, will create gels and make dramatic changes in melt performance of the resin. In order to maintain virgin-like properties and good market value of the resin, it is necessary to both fi lter and stabilise the resin.” PolyAd Services claims to have developed fully
formulated systems to meet these requirements. At dosage levels as low as 0.2%, these systems can help maintain melt viscosity (Figure 1), reduce gel count, decrease resin friction, and minimise screen pack and die build-up. This allows the densifi ed resin to be sold into higher value applications such as fi lm and packag- ing where resin quality is paramount, according to Ginn. PolyAd’s aim is to offer customised solutions for the
sustainable reuse of plastics. The company says that typical applications for the additive systems currently include outdoor decking materials, battery cases and automotive bumpers.
Dissimilar polymers
Kenrich Petrochemicals has introduced a new single site titanium/mixed metal catalyst masterbatch designed to regenerate PCR (Post-Consumer Recycle) plastic mixtures in the extruder melt to virgin-like properties, as well as acting as a compatibiliser between dissimilar polymers. The company says it recommends the use of 1.0-1.5% Ken-React CAPS KPR 12/LV pellets by total weight of polymer processed at lower temperatures for compatibilising polyolefi ns (PE or PP), along with polyamide and/or EVOH. Ken-React CAPOW KPR 12/HV powder with twice the activity and designed for compounders has also been introduced recently.
Figure 1: PolyAd Recyclostab 411 dosed at 0.2% during densifi cation of recycled HDPE maintains melt fl ow performance
42 COMPOUNDING WORLD | April 2016
The company says that, for example, 50% of recycled PP can be added to HDPE to make injection moulded parts that do not delaminate. “Although PP and HDPE are both considered olefi ns, normally HDPE cannot accept more than 5% PP without creating incompatibil- ity issues,” says Salvatore Monte, president of Kenrich
www.compoundingworld.com
PHOTO: POLYAD SERVICES
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