Testing the Tensile Strength of Paper

Tensile testing paper can reveal a wealth of information essential for the manufacturer of everything from tissue paper to corrugated cardboard or paperboard. It can help you determine characteristics such as paper stiffness, modulus and tensile strength, as well as tear length and energy absorption. 

Why is testing the tensile strength of paper important?

Knowing the tensile strength of paper is essential for a wide number of industries. Whether you need to ensure that instruction leaflets are sufficiently tear resistant to be included with products or you’re developing tissues that need to withstand a runny nose, tensile strength testing can help you find out when your paper might be susceptible to a web break. 

It is also particularly important for the packaging industry, where tensile testing is critical for measuring the elongation of paper and board. It can also be key in determining the maximum load those materials can take before failure. 

Determining paper tensile strength

To determine the tensile strength of paper, a sample is typically cut to a predetermined size and then placed in a testing machine which applies force until the paper tears. Tensile strength is also measured in two directions, the machine and the cross direction, because of the ways that the fibers bond when paper is made on a machine.   

Testing the tensile strength of paper is similar to the tensile testing methods applied to other materials, but the way of expressing it is different. For most materials, tensile strength is referred to as the load per unit cross-sectional area. In paper industry, it’s more common for the tensile strength to be given as the load per unit of the sample.  

It’s also expressed in relation to paper weighting and grammage. So, the tensile index is recorded as the tensile strength divided by basis weight, this is recorded as Nm/g. The lower the paper is on the tensile index, the lower the strength of the paper.  

Discover the Power of TMI Büchel Horizontal Tensile Tester

International standards for tensile paper testing

When you want to ensure that your paper tensile testing is meeting internationally recognized standards, then following the ASTM D828 method is an excellent idea.  

ASTM D828 is the standard method for determining the tensile properties of paper and paperboard by using constant-rate-of-elongation apparatus. It can be used to test tensile stiffness, breaking length, tensile energy absorption, and tensile index, as well as tensile strength and stretch. 

Also worth noting is Tappi T494, which tests the maximum tensile force a test specimen can bear before rupture and is used for paper and board. Check out our recommended PROFILE/Plus® machines for testing to Tappi T494 standards.   

Complete paper testing system

Whether you’re looking for a single testing solution to address a particular issue or you’re looking to refit an entire paper mill, Industrial Physics can help. our specialist brand Technidyne has developed an innovative building block system called PROFILE/Plus®, which lets you build an automated testing system one instrument at a time. 

Find everything you need for testing the physical and optical properties of paper in our full PROFILE/Plus® range.