Synergic Effect of a combined use of two Chemical Blowing Agents on the Foaming Efficiency of an Extruded Rigid PVC Compound

Abstract-- This work deals with the effect of the addition of a combination of two chemical Blowing Agents (BA); AzoBisFormAmide (ABFA) and/or Sodium BiCarbonate (SBC), on the foaming efficiency and cell structure of a rigid Poly(Vinyl Chloride) (PVC), using a laboratory scale extruder and optical microscope. It was found that the foaming efficiency increased with BA loading to an optimum value, which is characterized by a Critical Concentration (CC) of BA. This CC was noticed to be higher in the case of SBC. On the other hand, the foaming efficiency (expressed in term of diameter of foamed extrudates) showed a synergistic effect according to some mixing ratio of the two BA, which were based on their CC. Index Term-- Poly(vinyl chloride), azobisformamide, sodium bicarbonate, cell structure, expansion, extrusion, decomposition