Overview
The dry pulp zero-distance tensile strength tester is a precision instrument specifically designed to evaluate the intrinsic strength of pulp fibers. Its core principle is to measure the maximum force required for the breakage of pulp fibers clamped by two fixtures at or near zero distance. This test method effectively avoids the influence of inter-fiber bonding force and fiber length, so as to directly reflect the tensile properties of the fiber itself. In industries such as papermaking, nonwovens, and composites, the instrument provides key data support for raw material screening, process optimization, and quality control.
How it works:
The instrument uses zero-pitch clamping technology to ensure that the initial spacing of the fixture is close to zero to eliminate the fiber length factor. During the test, the sample is precisely clamped between the upper and lower clamps, and a uniform and increasing tensile force is applied through the drive system until the fibers break. The force value sensor and the displacement sensor collect data synchronously, and the system software processes it to calculate the zero-distance tensile strength, elongation at break and other parameters. Its technical features include high-precision force measurement (typically up to 0.01 N resolution), macro clamping control (adjustable spacing range of 0-0.5 mm), and real-time data acquisition and analysis to meet the requirements of relevant standards for repeatability and accuracy.
Calculation formula
Z-span tensile strength is the core evaluation index, which can be calculated by the following formula:
T = F / (w × t)
Where T is the zero-pitch tensile strength (unit: kN/m or N/m), F is the maximum force value at fracture (unit: N), w is the width of the sample (unit: m), and t is the thickness of the sample (unit: m). This formula is based on the principles of material mechanics and emphasizes the bearing capacity per unit cross-sectional area. Some instruments can also analyze the elastic modulus of fibers using stress-strain curves, which are calculated based on the linear intervals of Hooke's law:
E = σ / ε
E is the modulus of elasticity (unit: Pa), σ is the stress (unit: Pa), and ε is the strain (dimensionless).
Applications:
This instrument is widely used in the evaluation of papermaking raw materials, nonwoven fiber strength testing, composite reinforced fiber performance analysis and other fields. In the paper industry, test results can be used to predict paper strength potential; In nonwovens production, it helps to optimize the fiber ratio and carding process. Relevant domestic and foreign standards provide a regulatory basis for testing, such as ISO 15754 (paper and paperboard - determination of zero-distance tensile strength) and GB/T 24329 (determination of zero-distance tensile strength of paper fiber raw materials), which specify the requirements for sample preparation, environmental conditions, calibration procedures and result reporting.
| Applications: | Primary test purpose: |
| Paper industry | Evaluate the intrinsic strength of pulp fibers and predict the tensile properties of paper |
| Nonwovens production | Analyze the strength of fiber raw materials and optimize process parameters |
| Composite material research and development | The mechanical properties of reinforced fibers were determined to assist in material design |
| Quality control laboratory | Monitor raw material batch consistency to ensure product stability |
Operation process
The standard operating procedure includes: sample preparation (cutting uniform fiber strips according to the standard), instrument calibration (force and displacement are zeroed), clamping alignment (ensuring that the fixtures are parallel and zero distance), test execution (constant rate stretching), and data logging. During operation, attention should be paid to the control of ambient temperature and humidity (usually 23±1°C, 50±2% RH), avoid vibration interference, and regularly use standard weights for force value verification. Insufficient sample representation or clamping offset can lead to biased results, so standardized operation and equipment maintenance are the basis for data reliability.
The test data can directly reflect the mechanical qualities of the fibers themselves. A higher zero-pitch tensile strength usually indicates that the fiber has good breakage and tensile potential, which can help reduce the amount of fiber used in production or improve the strength of the final product. Combined with other indicators (e.g., fiber length, roughness), the suitability of the raw material can be comprehensively evaluated. In the context of sustainable development, this test provides a quantitative basis for the development of high-strength recycled fiber materials, which helps promote the efficient use of resources.
References
ISO 15754:2009, Paper and board — Determination of zero-span tensile strength.
GB/T 24329-2009, Fibrous raw materials for papermaking — Determination of zero-span tensile strength.
Page, D. H., The mechanism of strength development of dried pulps by beating. Journal of Pulp and Paper Science, 1985.
Batchelor, W. J., The measurement of fibre strength. Appita Journal, 2003.