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Polyamides and Intermediates

Mechanical recycling of polyamides in multilayer film structures

Polyamides in multilayer film structures are currently classified as non-recyclable materials.

We cannot confirm this as it has been known for a long time that:

  1. Limited concentrations ( < 10%) of polyamides are miscible with polyolefines.
  2. Higher concentrations ( > 10%) of polyamides can be compatibilized with polyolefines by using sufficient modifiers and processing conditions.
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“Film-to-film” approach for PE/PA waste blends is a real recycling option including manufacturing of  “new” monolayer films:

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Our series of tests show:

  • PE/PA blend systems without any compatibilizers are recyclable (miscible) with PA contents < 10%, excellent distribution has been analyzed in an area of 5 – 7.5%
  • Implementation of suitable compatibilizers is an efficient way to generate homogeneous PE/PA mixtures containing PA concentrations of > 10%. During our investigations PE/PA blends with up to 30% PA6 have been compatibilized efficiently by using 3-5% of modifiers
  • Copolyamides with lower melt points (</= 200°C) and lower crystallinity levels are recyclable with higher PA con-centrations in final blends compared to standard PA 6.
  • Amount of compatibilizers might be incorporated 
    • already in original multilayer film structures,
    • during reganulation by using standard single screw machinery,
    • by adding as individual component during final processing step (here film manufacturing). 
  • PE/PA mixtures containing PA 6 only need a regranulation temperature of 240°C for proper downstream processing. Nevertheless, real packaging waste streams also contain significant amounts of copolyamides with lower melting temperatures, processing of such PA mixtures is already possible at 210 °C.
  • It is possible to manufacture monolayer films made from 100% PE/PA regranulate blends as well as using highly concentrated PE/PA regranulate core layers in multilayer structures with sufficient mechanical and optical properties without using a dedicated twin screw extrusion processing step.
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Please contact us if you are interested in further information or in case of questions: