An extensive testing programme characterizing materials recovered by the MultiCycle process and evaluating a range of downstream treatments and modifications for property tuning designed to optimize their use in a range of target applications is currently underway. This will ultimately pave the way for their reincoporation back in the value chains from which they arose: a demonstration of the circular economy in action. Thorough characterization of the polymers recovered has indicated that their melt flow rates are suitable for processing either via film extrusion, melt spinning or injection moulding. Moreover, most properties, including density, gas content, and thermal properties, are in line with those of comparative virgin grade reference materials.

In order to evaluate the processability of polyamide-6 (PA6) recovered via the MultiCycle process from multilayer films (rPA6), a 30/70 rPA6/virgin PA6 (melt spinning grade) blend was processed at Centexbel on a lab-scale extrusion line equipped with a multifilament die. The material processed smoothly, exiting the die as well separated filaments (shown below). Homogeneous flow was observed with no melt fracture or filament fusion evident, and the multifilaments could easily be placed onto the take-up and drawing godets downstream in the process.

Multifilament lab-scale extrusion trial with 30/70 recycled/virgin PA6 blend at Centexbel

The 30/70 rPA6/vPA6 blend was subsequently processed on a Spinmaster pilot multifilament extrusion line at Centexbel (below, top left). Although the processing parameters used for vPA6 were not directly transferrable, resulting in some filament fracture during the main drawing step, adjusting the spin temperature and reducing the rPA6 content to 15% resulted in some improvement, and a continuous process, albeit at a slightly reduced draw (down from 3x to 2.75x). The results of tensile tests, shown below, indicate that more brittle (higher modulus and lower elongation) filaments were obtained compared to vPA6 filaments, but tenacity was similar to virgin filaments. Further optimization of the extrusion parameters (such as the cooling settings) is currently ongoing.

Top left: Spinmaster pilot multifilament extrusion line at Centexbel. Top right: Resultant multifilament yarns, from left to right: virgin PA6 multifil, 30% r-PA6 multifil and 15% r-PA6 multifil. Bottom: Tenacity, elongation and modulus of the multifilaments produced from 100% virgin PA6 (vPA6), 30% and 15% recycyled PA6 (rPA6) with draw ratio (DR) 3 or 2.75.

To assess the processability of polyethylene recovered from multilayer films (rPE) several blends of thermoplastic compounds incorporating different percentages of recycled material have been processed at AIMPLAS on a pilot plant blown film extrusion line (pictured below). Extrusion of thermoplastic compounds incorporating rPE at 40% to 100% content has proven feasible, with a smooth process attained using similar operating parameters to those for virgin raw material.

Extrusion blown film pilot line at AIMPLAS.

Samples of extruded blown films have been thoroughly characterized by a range of suitable standard laboratory methods. Films incorporating high percentages of rPE show good transparency and fair optical aesthetics. Processing recovered PE containing materials tends to produce films that are somewhat more yellow in colour than virgin grades, and more matt in appearance, though this is more noticeable in entirely recyclate based films. Films incorporating rPE show mechanical performance in the same range as virgin PE grade film. These promising results obtained at pilot plant level will lead to further optimisation and scale-up in the production of rPE films to be used in packaging applications.