PETpla.net Insider 09 / 2019

MATERIALS / RECYCLING PET planet Insider Vol. 19 No. 09/19 www.petpla.net 40 PEF and PET, side by side Polyethylene 2,5-furandicarboxylate (PEF) is a novel polymer with a chemical structure that highly resembles PET. It is produced by polycondensation of FDCA (2,5-furandicarboxylic acid) and MEG (mono-ethylene glycol) monomers, analogous to the polycondensation of raw materials used to produce PET. The PEF polymer itself has been known for a long time but has never been produced at large scale or applied commercially, as there were no economically viable production routes to manufacture FDCA. Avantium (and other companies) are working on new methods of producing FDCA that will enable PEF to become a widely used polymer in the future. Basic properties The Furan ring in this polymer introduces a ‘kink’ into the polymer chains that makes them less mobile than the straighter chains of PET, affecting its properties significantly. The dipole in the ring introduces attraction forces between the mole- cules, further reducing mobility. Some of the resulting effects are a higher glass transition temperature and higher modulus, relative to PET, and a higher barrier against gases, which makes PEF very interesting for pack- aging applications. Property 1 2 3 PET (amorphous ) PEF (amorphous) Molecule Density 1.36 g/cm 3 1.43 g/cm 3 Tm 250-270 °C 210-230 °C Tg ~76 °C ~88 °C E-modulus 2.1-2.2GPa 3.1-3.3GPa Yield strength 50-60MPa 90-100MPa O 2 permeability 4.7–7.4 cc*mm/(m 2 *24h*bar) 0.4–0.7 cc*mm/(m 2 *24h*bar) CO 2 permeability 20–30 cc*mm/(m 2 *24h*bar) 1–3 cc*mm/(m 2 *24h*bar) Many, if not all, the relevant manufacturing processes under development aim at using plant-based resources (e.g. fructose) as a feed- stock. When plant-based MEG is used with FDCA, PEF is a fully bio-based polymer and thus a good candidate for the bio-based economy. In many regions around the globe, recyclability of everyday materials is of prime interest and industry and government organisations are setting high recycling targets. By 2030 the EU requires all beverage bottles to con- tain at least 30% recycled material. High quality PET waste is essential to achieve those recycling targets but is notoriously difficult to obtain. One of the main challenges is that most polymers used in combination with PET hamper its recyclability. In a mul- tilayer bottle that uses polyamide (PA) as a barrier layer, the PA disturbs the output of a mechanical recycling pro- cess and induces haze in the rPET. Less than 2% of PA in a PET waste stream can cause enough haze to render rPET unusable; a higher per- centage of bottles with a 5% PA bar- rier layer is considered unrecyclable in mechanical bottle to bottle recycling processes. PEF is chemically so similar to PET that it blends well during the recycling process, forming a co- polymer and thus causing very little disturbance in the resulting rPET; a PET/PEF mixture will stay almost completely transparent with up to 5% PEF. This makes it highly suitable for combinations with PET and, as a poly- ester, it can itself be recycled by the same technology used for PET. MATERIALS