A number of mechanical properties are very important in paper and cardboard products. For example, tensile strength, tear strength, bending strength, folding strength, burst strength, surface strength, compression strength and internal strength are among these properties.

Such strength properties are mostly dependent on the type of fibers used and the processes applied in production. For example, if long and soft wood fibers are used, higher strength products are obtained than hard wood fibers. Filling materials used in production processes are a factor that decreases the strength. Grinding degree and wet pressing processes increase the strength of the products.

A number of water-soluble and hydrogen-bonding polymers are used as dry strength additives during the production of products such as paper and cardboard. However, the wood fibers contain the dry strength material themselves. Separating the hemicellulose contained in these fibers from the fiber reduces the strength of the product.

Accredited laboratories carry out tests and analyzes in order to determine dry breaking strength of paper products within the scope of specific tests. These studies are based on standards published by domestic and foreign organizations. The standards considered to determine dry tensile strength are:

• TS EN ISO 12625-4 Soft tissue and products - Part 4: Determination of tensile strength, elongation at break and absorption of tensile energy

 

This standard specifies a test method for the determination of tensile strength, elongation at break and tensile energy absorption of soft tissue and similar products. In these tests, tensile tester operating at a constant elongation speed is used. With this standard, tensile index and tensile energy absorption index are also calculated. ISO 15755 standard must be followed to detect impurities and discrepancies in soft tissue and similar products.