The carbon black dispersion tester is a key tool for evaluating the dispersion degree of carbon black in materials such as rubber, plastics, and coatings. Its testing methods mainly include optical microscopy and image analysis, combined with automated software to achieve precise quantitative analysis. The following is a detailed analysis of the testing process and methods:
1、 Testing principle
Principles of Optical Scattering
When carbon black particles are suspended in the medium, the light beam scatters after entering the sample, and the changes in scattering angle and intensity reflect the particle size and dispersion state of the particles. The dynamic light scattering method calculates the particle size distribution by measuring the scattered light signal; The laser confocal method utilizes the laser beam to focus and extract particle scattering information, achieving high-precision size measurement.
Principles of Image Analysis
Capture surface images of samples through high-resolution cameras, use image processing software to identify the contours of carbon black aggregates, calculate their area, shape, and distribution parameters, and evaluate dispersion. This method combines microscopic magnification and digital analysis to quantify the dispersion state.
2、 Test steps
1. Sample preparation
Sampling: Cut small pieces from the material to be tested (such as rubber, plastic) to ensure that the sample is representative.
Preprocessing:
Rubber sample: Cut into thin sheets to expose the plane where the carbon black particles are located.
Plastic samples: pressed into thin films or sheets to ensure a smooth surface.
Liquid medium: To test the dispersion of carbon black in a solvent, dissolve the carbon black in water, acetone, or isopropanol, stir thoroughly until evenly dispersed, and eliminate bubbles.
2. Instrument settings
Connection and calibration:
Connect a microscope, camera, or industrial camera to a computer, install drivers and image analysis software.
Use standard length rulers and area standard plates to calibrate the measurement system and verify accuracy.
Parameter adjustment:
Set the microscope magnification (such as 100x, 400x), light intensity, and contrast.
Select the testing mode based on the characteristics of the sample (such as polyolefin pipe, wire and cable specific mode).
3. Image acquisition
Place the sample: Place the preprocessed sample on the stage and adjust its position to the center of the field of view.
Focusing and shooting: Use the microscope's coarse and fine focus knobs to make the image clear; Capture the distribution image of carbon black particles using a camera and save it as a digital file.
4. Image analysis
Software processing:
Run image analysis software to automatically identify the contour of carbon black aggregates and calculate parameters such as particle size, area, and distribution uniformity.
Support manual correction of particle size with blurred boundaries or revocation of erroneous measurements.
Data output:
Generate dispersion reports, including aggregate size distribution maps, standard sample comparison maps, etc.
The report format can be customized to meet different standards (such as GB/T18251, ISO18553) requirements.
5. Result evaluation
Quantitative rating: Based on the analysis results, evaluate whether the dispersion degree of carbon black meets the standards (such as dispersion levels 1-5, with level 1 being the best).
Process optimization: Combining dispersion data, adjusting mixing process parameters (such as temperature, time, shear force) to improve product quality.
3、 Comparison of testing methods
methodprincipleadvantage局限性
Optical microscope methodDirectly observe the distribution of carbon black particlesEasy to operate, low cost, suitable for rapid screeningRelying on manual experience, with strong subjectivity
Image analysis methodCombining microscope and digital image processingStrong objectivity, accurate results, and quantifiable ratingProfessional software is required, with high requirements for sample flatness
Dynamic light scattering methodMeasure changes in scattered light signalsSuitable for liquid media, no need for sample preparationUnable to directly observe particle morphology
Laser confocal methodExtracting scattering information using laser beam focusingHigh resolution, observable nanoscale particlesExpensive equipment and complex operation
4、 Application scenarios
Rubber industry: In the production of tires and seals, the dispersion of carbon black affects mechanical properties and durability.
Plastic industry: Optimization formula design for carbon black dispersion in pipes and sheets to improve mechanical properties and weather resistance.
Coatings and inks: Ensure even dispersion of carbon black, improve coating coverage, glossiness, and stability.
Research field: Provide experimental data support for the development of new materials and processes.
5、 Precautions
Sample representativeness: Ensure uniform sampling and avoid local concentration deviations.
Instrument calibration: Regularly use standard samples to verify the accuracy of the measurement system.
Environmental control: Avoid light interference and temperature and humidity fluctuations that may affect test results.
Software operation: Familiar with image analysis software functions, set parameters reasonably to reduce errors.