Migration testing of TPEs

Evaluation of suitable migration test conditions for conformity testing of thermoplastic elastomers

Workgroup: Compliance of packaging material

Scientific Partners and Guidance:

  1. Fraunhofer Institut für Verfahrenstechnik und Verpackung IVV, Dr. Angela Störmer

Financing: IVLV
Duration: 2020

Thermoplastic elastomers (TPE) are plastic materials that show elastic properties similar to rubber at room temperature but can be processed like thermoplasts. From a physical chemical point of view, TPEs have intermediate properties between plastic materials and rubber like elastomers. Typical applications in direct and partially multiple contact to foods are gaskets for reusable food containers, drinking bottles, sealing masses in bottle closures, dosing vents or flexible kitchen articles like folding strainers, infant spoons or drinking cups. From a food regulatory point of view, TPEs fall within the scope of the European Plastics Regulation No. 10/2011 and have to fulfil the migration limits (overall migration and specific migration) given there. The test conditions and requirements for migration testing according to Annex III and V of the Plastics Regulation have to be applied. However, TPEs differ in their physical-chemical properties from the usual bulk plastics because of their elastomeric properties. At migration testing with vegetable oils (e.g. olive oil, food simulant D2), TPE materials get swollen. The same is the case with the alternative fat simulants 95 % ethanol or isooctane and partially with 50 % ethanol. Therefore, migration into real fat containing foods will be overestimated. Compliance with the migration limits cannot be shown this way in many cases.

Within this pre-project a non-targeted screening on migratable components of various TPE types shall be performed and the suitability for comparative investigations with food simulants and foods shall be checked. Furthermore, the degrees of swelling of various TPE types in contact with simulants and real foods shall be compared. Based on that work a concept will be developed in order to work out realistic experimental and theoretical simulations of the transfer of TPE components onto real foods that shall be realised within a future larger research activity.