ASSESSMENT OF THE DEGREE OF PIGMENT OR CARBON BLACK DISPERSION (TS ISO 18553)

Thermoplastic products, produced for pipeline systems, are usually colored. Typically, fine carbon black particles or colored pigments are used. These materials are normally mixed with raw materials before pipe extrusion or before the pipe inserts are injection molded. The purpose of coloring is to identify the pipeline in use, and also to prevent degradation of the polymer by ultraviolet rays if the product is used or stored in the outdoor environment. Proper dispersion of carbon black or pigment particles in the polymer and thus in the final product is important in order to maintain the physical, mechanical and surface protection properties. The correct distribution is also an indication that antioxidants and ultraviolet stabilizers are not correctly distributed and that the size of the particles does not exceed a certain limit. This method involves the physical measurement of scattered particle sizes and the evaluation of the distribution degree and the classification of the particle size distribution as arithmetic. For the PE pipe and fittings, the distribution dimension should be ≤ 3.