Blocking tests

Causes of blocking include residual solvents, plasticizers, and static which can promote adhesion between flexible packaging materials,

ASTM D3354 quantifies the degree of blocking (unwanted adhesion) between layers of plastic film. It is not intended to measure susceptibility to blocking. The blocked sample is adhered between two compression plates and the force to separate the films determined.

ASTM D918 This determines the blocking resistance of flexible types of packaging materials, including paper, and the impregnated, coated or laminated, or coated and laminated, combinations of paper with metallic foils and synthetic films that may be produced from them, but is applicable to papers in general, whenever a tendency to block is important.

The test method provides a range of standard conditions of temperature and relative humidity at constant pressure for a specified time which is designed to simulate varying climatic conditions that may be encountered in the manufacture, storage, transportation, or use of the materials. A simple subjective three-level assessment is made: no block, some block or well blocked.

 

Expert Profile

  • Doug joined Pira in 1989 and has 20 years experience in the physical testing of packaging and packaging materials. He heads a team specialising in packaging and print related technical investigations. In 2004 Doug gained his postgraduate degree with distinction in Packaging Technology from Brunel University.

    Doug Leatherdale
    Doug Leatherdale

    Head of Physical Testing

    Pira International

    +44 1372 80 2108

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