Packages are often squeezed by external forces or impacted by hard objects during transportation and storage, as well as the impact of the contents. At this time, it is obviously inappropriate to use tensile strength or other strength indicators to evaluate the impact resistance of paper or cardboard. , it is necessary to introduce burst resistance. Bursting strength is the maximum pressure when the sample is evenly applied to the sample and the sample is burst, which belongs to the static strength of paper or cardboard. When the cardboard bears the pressure perpendicular to the cardboard surface, the cardboard begins to deform, and as the pressure increases, the deformation increases accordingly until the cardboard breaks.
Bursting strength refers to the uniformly increased maximum pressure that cardboard can bear on a unit area. The unit is expressed in Pa, and the unit used to be kgf/cm2 (1kgf/cm2 =98kPa). Bursting strength is an important property of paper bag paper, packaging paper and cardboard. It is affected by the bonding force between fibers and the average length of fibers. It is a composite function of tensile strength and elongation. Most of the stress is caused by the rupture of the paper A tension created by the pressure difference across the web. Since the deformation is substantially equal in all directions, a balanced stress is created in the paper. Since the longitudinal elongation of the paper is small, it becomes the longitudinal tension after being compressed, so the crack of the sample is generally perpendicular to the longitudinal direction of the paper.
① Absolute burst strength (Bur) refers to the absolute value indicated by the pressure gauge when the sample ruptures.
② Relative bursting strength refers to the bursting strength measured by different quantitative samples converted into a quantitative bursting strength of 100g/m3, that is, 100Bur/G
③The burst index refers to the ratio of the absolute burst strength of the sample to the basis weight of the paper, and the unit is kPa·m2/g.
④Relationship between absolute bursting strength and tensile strength
