Dispersion of additives in plastics

Automatic analysis of carbon black dispersion

Using breackthrough technology, our Lab-Robot CB4 is a fast and totally automatic system  to analyze additive dispersion in plastics. The importance of pigments, particles and other additives for quality control in the plastic industry is well known. With this system, particle recognition and  size, shape and color distribution and filtering maybe be reported in few seconds for more than a dozen samples in an easy and fully automated way. Engineered robotics, customized illumination, and a highly featured software with user friendly interface make it a versatile tool for quality control inspection of different types of samples in accordance to ISO standards. Setup for automatic analysis of carbon black dispersion


Unique concept based on ISO methodology  
Fully automatic and semi automatic inspection 
Digital control of all components 
User friendly, powerful and highly adaptive software 
Windows™ based operating system


Thermoplastic products manufactured for pipeline systems are normally coloured. Typically fine carbon black particles or coloured pigments are used are used for that purpose. These are normally incorporated into the raw material prior to either extrusion of pipe or injection moulding of pipe fittings.The purpose of colouring is to allow identification of the pipeline in service and also, in the case of carbon black, to act as protection of the polymer from degradation by ultra-violet light if the product is stored externally or used for external service. 

It is important that the carbon black or pigment particles are correctly dispersed in the polymer, and hence the final product, to ensure that the physical, mechanical and surface protection properties are maintained.

Correct dispersion may also be an indication that anti-oxidants and ultra-violet stabilizers are correctly dispersed, and that the size of agglomerates of particles is not excessive. Micro-Optik has developed a method for the evalutation of the degree of pigment or carbon black dispersion in polyolefin pipes, fittings and compounds. The method is applicable to polyole fin pipes and fittings, as well as raw material in pellet form, with the choice of procedure to be determined by the referring specification. The method is applicable to carbon black pigmented polyolefin pipes, fittings and compounds with a carbon black content of less than 3 %.


Small samples of raw-material pellet or material removed from the pipe or fitting are heated and compressed between microscope slides. Alternatively, a microtome slice can be taken. The specimens produced are examined microscopically and the sizes of particles and agglomerates are measured, recorded and graded by comparison with a tabulated grading system. A particle/agglomerate size grading is determined from an average of the gradings determined for six specimens. System generates rich text format report, with recorded and calculated data. Example of the short report is shown on the next page.

Automatic analysis of carbon black dispersion principle

Microptik Lab-robot CB4 principle

Grading of particle and agglomerate size

Using following table, determine the highest particle/agglomerate size grade for each specimen. Calculate the arithmetic mean of the six grades obtained and express the result to a single decimal point, rounded up to the next higher value.

Automatic analysis of carbon black dispersion grading

Arithmetic mean of the six grades obtained: ( 0+ 0+ 2+ 0.5+ 0.5+ 3)/6= 1