What are the dangers of using carbon black Masterbatches with natural PE ?

1) By hand mixing of natural PE granules with a carbon black masterbatch (which is a concentrate of typically 40% carbon black in a very high MFI PE resin) and extruding the mixture in a pipe extruder into pipes, the pipes will surely look black, but there is hardly a good distribution and dispersion of Carbon black for proper UV protection. This is because in a single screw pipe extruder the residence time of material is quite low and intensity of mixing is also less. This may lead to agglomerates of Crabon black in pipe wall which work as crack initiation points. 2) In case of any premature failure of pipes, neither the resin manufacturer, nor the masterbatch manufacture will take the responsibility of failure. 3) It has been seen that using the same natural PE, but different Carbon black Masterbatches, the time to failure in pressure test vary considerably. 4) Carbon black is a material which remains in colloidal form even in molten state. It is very difficult to disperse in a ...  more