Soliflex PRO Recycling trial

Soliflex PRO Recycling trial

Vanderlande and the Blueveyor Vanderlande is working on a sustainable conveyor concept called the Blueveyor. In addition to a very low energy usage, the Blueveyor is designed with recyclability in mind. The belt on these conveyors is the positive driven Soliflex PRO belting system manufactured by Ammeraal Beltech. These belts are made from a thermoplastic polyester elastomer (TPE), specially chosen for its durability and ease of recycling.

Belt replacement At Schiphol some 14 Blueveyor s were in use for luggage transport. After 18 months in service, the belts were replaced on three conveyors. The old end-of-life belts were sent back to Ammeraal Beltech for recycling. This resulted in 60m 2 of used belt, which amounted to some 150kg. The belts showed some slight wear and the top surface was dull and dirty. Mechanical tests showed that the material still had its original properties. The dirt on the top was believed to be a mixture of glue (from stickers and labels) and dust. Lab scale cleaning with a mild detergent went well.

Cleaning In standard recycling operations, the end-of-life plastics are ground before washing and separation. That wasn t feasible with the small amounts available. Industrial installations for the recycling of plastics use tons rather than kilos! For this trial the same mild detergent as in the lab was used. It is a Cradle2Cradle cleaning agent based on limonene (Ecover Power Cleaner). After washing, the soap was removed with clean cold water.

Grinding After cleaning the belts were ground and dried.

Recycling For the recycling trial Ammeraal Beltech started production of a sheet with an unused batch of Arnitel EM550. No colorants were used. When production was stable, they started with ground material. The extruder has a gravimetric dosing system which allows for accurate measurement of the amount of recycled material. The trials were done with 25%, 50%, 75% and 100% recycled material. For each step it was necessary to adjust the process to accommodate the ground material. The ground material has a different shape than virgin granules and, as a consequence, the filling of the extruder is slightly different. It was noticed that the ground material has a slightly lower apparent viscosity than the virgin material. With 100% regrind the extruder could run at 210 C where 230 C was used for the virgin material. This viscosity drop may be caused by degradation of the polymer, but it could also be caused by contamination left after the cleaning. Mechanical testing is the next step to check the performance of the recycled belt material.

Mechanical testing Five different sample materials were derived from this trial ranging from 100% virgin material to 100% recycled material. These sample materials were evaluated with the following (standard) tests: Force Elongation behavior : The belt force needed for 1% - 4% elongation Relaxed Modulus : Measures the reduction of the stiffness during cycled loading Strength and elongation at break of the sample materials

F/E [N/mm] K1 [N/mm] Results From each sheet, several samples were taken for mechanical testing: 14,0 12,0 Force Elongation behaviour 3,00 2,50 k1% 24h Relaxed Modulus 10,0 8,0 6,0 4,0 2,0 F/E @ 1% F/E @ 2% F/E @ 3% F/E @ 4% 2,00 1,50 1,00 0,50 0,0 0% 25% 50% 75% 100% 0,00 0% 25% 50% 75% 100% The results show that adding recycled material improves both the stiffness (Force/elongation) and the relaxed modulus of the material, albeit only marginally. The stiffness seems to peak around 50%, exactly where the elongation at break is found to be at its minimum. Elongation @ break

Conclusions For this experiment three conveyor belts were replaced at Schiphol Airport after 18 months of service. This is well before their expected end-of-life. Nonetheless, the belts are considered to be representative of used Soliflex PRO luggage belts. The extrusion trials were done on a small, but industrial, sheet production line. However, even for this relatively small line, the amounts of material were too little to optimize the settings in all cases. Therefore, only some running lengths of belt with a limited width were produced. The surface quality of the recycled belt was below the commercial standards normally produced by Ammeraal Beltech. Therefore, the belt is evaluated only mechanically. The extrusion part can be scaled up relatively simply provided enough clean regrind is available. However, the industrial infrastructure for gathering, storing and cleaning used belts does not yet exist. The trials clearly show that Soliflex PRO belts can be recycled after their end-of-life. Even belts made from 100% old, used belts, fulfill all the mechanical requirements for sheets made from virgin material. Technically, we have closed the loop.