How to Measure Extensibility/Elongation

EXTENSIBILITY/ELONGATION is the degree (distance) to which a product can be extended/stretched before breaking. It is related to the 'elasticity' of a product. It is commonly the textural property possessed by raw baked goods (e.g. dough, pastry), cooked baked goods and pasta (e.g. pancakes, tortillas, noodles) but can be a novel property of confectionery products (e.g. liquorice, chewing gum).

ELONGATION measures the percentage change in length before fracture. Elongation to failure is a measure of ductility of a material, in other words, it is the amount of strain it can experience before failure in a tensile situation. A ductile material will produce a high elongation measurement. Brittle materials like ceramics tend to show very low elongation because they do not plastically deform whereas rubber extends by a large amount before failure, but this extension is mostly elastic and is recovered.

Metals have moderate elongation to failure (1-50%) with deformation occurring by plastic flow. Thermoplastics have large elongations (>100%) because the molecules can stretch out and slide over one another.

Elongation is important in manufacturing – it measures how much bending and shaping a material can withstand without breaking and is an important characteristic in components which absorb energy by deforming plastically (e.g. crash barriers, car bumpers) and for items such as plastic hinges.

Typical properties that can be obtained from a texture analyser graph:

Tensile Strength, Burst Strength, Distance to Burst, Resistance to Extension/Toughness, Extensibility, Stretch Quality, Elasticity, Tug Force, Tear Strength, Elongation, Breaking Strain, Energy to Failure, Yield Stress/Strain, Resilience, 0.2% proof stress, Young’s Modulus, Resilience

Typical Texture Analyser graph with annotated properties of material tension to failure

Typical Probe/Fixture used for Measurement:

Tensile Grips and all fixtures that allow successful holding of a product in order to test in a tensile manner >>

The above are only typical examples of extensibility measurement. We can, of course, design and manufacture probes or fixtures that are bespoke to your sample and its specific measurement.

Once your measurement is performed, our expertise in its graphical interpretation is unparalleled – no-one understands texture analysis like we do. Not only can we develop the most suitable and accurate method for the testing of your sample, but we can prepare analysis procedures that obtain the desired parameters from your curve and drop them into a spreadsheet or report designed around your requirements.

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