Overview
EN ISO 11897:2001 (identical to ISO 11897:1999) specifies a laboratory method to determine the resistance to tear propagation on edge folds of sacks made from thermoplastic flexible film. The standard defines specimen preparation, conditioning, test apparatus and procedure to measure tear force on folded and unfolded film, and prescribes calculation of the residual resistance of an edge fold as a percentage of the unfolded film strength.
Key Topics
- Scope: Method for determining tear propagation resistance on edge folds of film sacks; comparison between folded and unfolded film to obtain residual resistance.
- Specimens: Trapezoidal specimens with an incision and perforation positioned at the edge fold (see Figure 1). Smooth, notch-free edges; recommended template provided (Annex A).
- Conditioning: Standard laboratory atmosphere G per ISO 2233 - temperature 23 ± 2 °C and relative humidity 50 ± 5 %; specimens conditioned 24 h.
- Test apparatus: Tensile-testing machine conforming to ISO 527-3; clamps aligned with specimen marks and spanning 100 mm. Thickness measured per ISO 4593.
- Test parameters: Test speed 100 mm/min (±10 %). Record maximum force for each specimen.
- Evaluation: Calculate arithmetic mean force for folded and unfolded specimens. Residual resistance = (F_fold / F_film) × 100 %, where F_fold and F_film are mean tear propagation forces (N).
- Reporting: Test reports must reference the standard and include film identification, specimen count, conditioning, thickness, tear forces (folded and unfolded), residual resistance, observations of tear behaviour, deviations and test date.
Applications
- Quality control and specification verification for manufacturers of sacks, bags and tubular films made from polyethylene, polypropylene and other thermoplastic flexible films.
- Design and materials selection for packaging used in transport and storage where edge-fold tear propagation is a failure mode.
- Comparative testing for formulation development (film thickness, additives, seal designs) and for supplier qualification.
- Use by packaging engineers, materials scientists, quality assurance laboratories, test houses and standards bodies that evaluate mechanical tear performance.
Related Standards
- ISO 527-3 - Plastics: tensile testing for films and sheets (test machine requirements)
- ISO 4593 - Film thickness measurement
- ISO 2233 - Conditioning of complete filled transport packages (standard atmosphere)
Keywords: EN ISO 11897:2001, ISO 11897, tear propagation test, edge folds, thermoplastic flexible film, sack tear resistance, residual resistance, packaging standards.