Carbon Black Content and Distribution

Homogeneously distributed, fine-grained carbon black proved an effective and cost-efficient stabiliser against UV radiation. It is either added to the polyethylene by the raw material manufacturer or during geomembrane production. Properties, content and homogeneity of the distribution of carbon black determine the quality of UV stabilisation. 

The carbon black content is determined in accordance with the standard evaluation method of the actual device from the step in the specimen mass via temperature curve due to the burning of the carbon black. At least three individual measurements are carried out. A prerequisite for a reliable TG measurement is the calibration of the temperature measurement and a buoyancy correction. In so doing the equipment manufacturer s instructions have to be followed. 

After the sharp drop in the mass via temperature curve due to polyethylene pyrolysis, the remaining mass does not usually remain constant with temperature. Rather, the curve continues to gradually decrease. The point of time or temperature for switching over to synthetic air gas flow can therefore affect the measurement result of the carbon black content. Such measurement conditions must be observed to achieve comparable results. Comparing the measurement results with measurements obtained by con- 

During the development of the meanwhile outdated draft DIN 16739 1994 Geomembranes from Polyethylene (PE) for Landfill Liners Requirements, Tests an interlaboratory comparison was organised with the TG test method described (Suddeutsches Kunststoffzentrum (SKZ), the 

The test of homogeneity of carbon black distribution within the framework of the BAM certification is performed in accordance with ASTM D5 5 96-94. Approx. 10 im thick microtome sections are taken from the geomembrane cross-section of 10 test samples which were cut from randomly chosen places in the geomembrane. The microtome sections are tested for the homogeneity of carbon black distribution and any faults with a 100-fold magnification in a microscope. A minimum of a 10 mm surface is investigated. 

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