recycling | Compatibilisers
solutions already on the market that have interesting effects on mixed polymer blends. DuPont, for example, says its new series of Entira EP compatibilisers based on ethylene copolymers can boost the performance of recycled polyolefins to a similar level as virgin resins. Adding 3-7% of Entira EP bridges the contaminant to the matrix and creates a homogeneous material, DuPont claims, leading to increased performance and surface properties for manufactured items. “In addition to its use for production of bulky items (flower pots, outdoor furniture), such recycled resins will be suitable for use in higher value applications, as in thin films and membranes for the construction industry,” says a company spokesperson. The Entira EP technology is already being used by
Condensation polymers such as PET can present a challenge in terms of compatibiliza- tion, claims Kenrich
tetrablock co- polymer. The researchers report in their paper: “Individually,
pure iPP (isotactic PP) and PE display ductility and strain hardening when pulled in tension at room temperature. Blending the two components leads to a phase-separated material and a marked reduction in strain at the break point (12% versus 300 and 800% for iPP and PE, respectively). The addition of 5 wt% PP60
PE80 PP75 PE90 raises elongation at break to 600%,
owing to the combined effects of interfacial adhesion, reduced particle size, and efficient stress transfer between phases. With just 1% of this tetrablock copolymer, eb=450%, whereas the addition of 1 wt% of the corresponding diblock copolymer (PP60
PE80
a modest improvement (eb=90%).” Another tetrablock polymer with lower molecular ) exhibited similar properties,
weight (PP36 PE20 PP34 PE24
as did other blends with different PE: iPP ratios. The researchers say the new polymer could be on the market quite quickly. “We are looking for industrial partners to assist with scale-up; we hope there could be commercial production soon,” Coates says. Meanwhile, there are other compatibilisation
recycling companies. Besides recycling of PP-PE blends, it is also being used for compatibilisation of PP with polyvinylbutyral (PVB) in commercial applications. Hainaut-Plast, a French company specialising in recycling of PVB recovered from laminated glass, is reported to be using the additive in diverse end-use applications such as sound deadening parts for automotive applications. “PVB is a very interesting polymer modifier, and
) leads to
recycled PVB is offered at a much lower price than virgin PVB, but it is not miscible with other polymers so its use in other polymer matrixes requires use of compatibilisers,” says Lucie Charbonnel, Marketing Leader – Recycling and Industrial Segments at DuPont Performance Materials.
Mixed-metal catalysts Salvatore Monti, President at Kenrich Chemicals, points to the advantages of the company’s Ken-React KPR mixed metal catalysts over more mainstream products for compatibilising diverse polymers in post-consumer waste recycling streams. He explains that the widely used maleic anhydride coupling agent cannot be applied with condensation polymers such as PET, PC and polyamides,
Tracing a future for effective recycling
The need for additives to compatibilise different polymers could be reduced if Tracer Based Sorting (TBS) technology to help recyclers create purer waste streams catches on. PolySecure, which originally developed
fluorescent marker (tracer) additives to help brand owners combat counterfeits, says its products are increasingly being used to facilitate recycling (read more in
40 COMPOUNDING WORLD | April 2017
Compounding World December 2016). PolySecure CTO Martin Fahr cites the EU-sponsored Life Petcycle project, the main objective of which is to create novel upcycling routes for PET bottles. Fluorescent particles incorporated into the polymer could allow optical laser- based detection of the bottles in an automated high-speed sorting process, he claims.
Polysecure is also involved in the
Rewindo project in Germany for recycling PVC windows, which often combine parts made of unreinforced PVC (for aesthetics) and reinforced PVC (for strength). The company recently finished building what is claimed to be the only industrial machine for tracer-based sorting for PVC windows. ❙
www.polysecure.eu
www.compoundingworld.com
PHOTO: SHUTTERSTOCK
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