Mullen tear strength refers to the pressure that paper or cardboard can withstand per unit area under experimental conditions, uniformly increasing perpendicular to the surface of the specimen. Mullen tear strength demonstrates the ability of cardboard boxes to bear handling, loading, unloading, impacts, and tearing forces during the flow process, and is one of the evaluation methods for the comprehensive performance of cardboard boxes. Additionally, different regions and cardboard box manufacturers may have varying names for mullen tear strength. Besides mullen tear strength, there are also terms like burst strength and tensile strength. In some places, mullen tear strength is colloquially known as "pound test."

Testing Principle:

The basic principle of bursting strength testing involves placing the sample on a film, securing it, and then applying pressure uniformly until the sample bulges under the top pressure of the film and ultimately bursts. The highest hydraulic value displayed by the instrument at this point is the bursting strength of the sample.

Sample Collection and Preparation:

The test specimen must be larger than the clamping disk of the bursting strength tester, and the specimen must not have any watermarks, creases, or obvious damage. During the test, do not use a specimen that has been previously clamped by the disk.

Sample Pretreatment:

Test specimens must be processed in accordance with GB10739-89 regulations.

Tearing Resistance Test Process:

Place the sample in the middle of the instrument's chuck and secure it with a clamping force of no less than 690Kpa. Activate the testing machine, gradually increasing the pressure at a rate of (170±15) ml/min until the sample ruptures, then read the pressure value indicated on the gauge.

Cautionary Notes for Testing

Pre-test calibration of the equipment ensures that the upper and lower clamping disks are concentric (error not exceeding 0.25mm) and parallel.

2. The upper surface of the film is higher than the top of the lower clamp ring.

Three. During testing, ten samples were taken, with five measurements on each side, front and back.

4. The sample must be larger than the ring area.