FINAT FTM 31 Testing of Peeling

We carry out the FINAT FTM 31 test in our test laboratory to determine the splitting propagation force of cavitated or expanded multilayer films under defined 90° peel conditions. The method is used to evaluate the internal resistance of flexible, especially cavitated film structures against progressive delamination or crack propagation under tensile load at low speed. It provides a basis for assessing mechanical stability, interlayer cohesion, and the failure behaviour of multilayer films under realistic stress conditions.

Application of FINAT FTM 31

FINAT FTM 31 is used to characterise the propagation of interlayer splitting or delamination within cavitated or structured multilayer films. It is particularly relevant for BOPP multilayer systems and expanded film structures where controlled internal separation may occur under tensile stress.

The method is suitable for assessing resistance to internal layer failure and provides important information on processability and in-use stability, for example during converting operations, printing, packaging, or mechanical loading in end-use applications.

Test procedure and details

In FINAT FTM31, defined strips are cut from the test material and reinforced on both sides with adhesive tapes to stabilise the specimen. This reinforcement ensures controlled force application and prevents premature failure outside the targeted splitting zone.

The specimens are fitted with pulling tabs and prepared so that a controlled initiation of the split front is created by a short manual tear. The specimen is then mounted in a tensile testing machine and loaded at a constant speed of 300 mm/min under a 90° peel angle.

During testing, the force is continuously recorded. Minimum, maximum, and mean values are determined from a stable region of the force curve. In addition, the location of the failure zone within the film structure is documented, such as within a cavitated layer or at interfaces between layers.

Optionally, the propagation depth of the split front may be determined using geometric or microscopic methods. Material orientation (MD/TD), specimen homogeneity, and failure mode must also be recorded.

Relation to other film and label tests

The values obtained from FINAT FTM 31 are typically used as part of the mechanical characterisation of multilayer films and complement other peel and tensile tests within the FINAT test programme. In combination with adhesion and peel resistance tests, they provide additional insight into the structural integrity and failure behaviour of complex film constructions.

Please feel free to request this test or obtain information about our complete FINAT testing programme.