How to Understand Tensile Test Results of Paper

Tensile properties are a fundamental and key quality indicator of paper products. Tensile testing is commonly used to determine the stress-strain relationships of mass-produced paper. Typically, mechanical behavior is measured by utilizing strips of paper cut from the same sheet in perpendicular directions: machine direction (MD--the direction in which the paper moves during manufacture) and cross-machine direction (CD--the direction orthogonal to the machine direction). The resulting stress-strain plot will provide a fundamental engineering description of the mechanical behavior of paper when subjected to tensile stresses as they are pulled to failure. Another fundamental measure of the tensile strength properties of paper is represented by the area under the stress-strain curve. This area represents the work expended to cause rupture of the strip of paper; this work is called the tensile energy absorption (TEA). Even though the breaking strength of paper in the machine direction is greater than in the cross-machine direction, it may require more work to break a tensile strip in the cross-machine direction. because itsThe greater stretch percentage in the cross-machine direction makes the TEA greater in the cross-machine direction than in the machine direction. In certain instances, TEA can prove to be a significant property relating to durability. Tensile energy absorption is a measure of the ability of paper to absorb energy under variable loading conditions and can be used to gauge durability. The initial straight section of the stress-strain curve, which represents the elastic deformation of paper, has a slope that defines the property known as Young's modulus. Young's modulus is a fundamental concept in engineering design because it is critical in determining the stiffness of your paper product. Another essential factor to determine is the tensile breaking strength of paper.

Tensile breaking strength is determined to be the maximum value of stress that occurs when the paper ruptures or tears. Elongation at rupture is the measure of the maximum percentage of stretch, or the maximum strain, that the paper can achieve before failure. Tensile strength can be described by stress-strain graphs and measured by TAPPI tests T-404 and T-494. Stress-strain curves provide a fundamental engineering description of the mechanical behavior of paper when subjected to tensile stress. TAPPI method T-404 measures tensile breaking strength end elongation of paper and paperboard using a pendulum-type tester, and T-494 measures tensile breaking properties of paper and paperboard using constant rate of elongation apparatus. TAPPI tensile strength tests of paper. TAPPI tests T-404 and T-494 are useful in evaluating the tensile properties of paper. TAPPI T-494 enables the simultaneous evaluation of three properties for the same test specimen: tensile breaking strength, stretch or elongation at break, and TEA. Method T-404 allows only the evaluation of tensile breaking strength and elongation at break. TAPPI cautions that the two methods, T-404 and T-494, are not strictly comparable because different instruments are used. These tests give similar results for tensile strength and elongation at break only when similar testing conditions apply. 100 Series Electromechanical universal test machines are configurable to serve paper tension testing applications. The 100 Series test machines are constant rate of extension (CRE) machine, as specified by TAPPI T-404 and TAPPI T-494. A selection of different controllers, actuators and accessories makes them one of our most popular choices. TestResources G149 and G229 Series grips are ideal for gripping paper specimens. Translating raw data from your tests into measurement concepts can be a daunting task. Our application engineers are available for consultation. Contact us or give us a call today.

Applicable Testing Standards

• TAPPI T-404 Tensile Strength Tests of Paper and Paperboard | Testing Equipment

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100 Series Universal Test Machines

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