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        # Azodicarbonamide (ADCL) as a Blowing Agent: The Complete Guide to Foam Cell Structure in PVC and Rubber

        

**Topic:** Explainer

        

In cellular PVC and footwear compounding, achieving a uniform, closed-cell foam structure requires a highly predictable blowing agent. NBT supplies premium azodicarbonamide grades, including [NBT ADCL (Azodicarbonamide)](/products/additives/adcl) for WPC boards and [NBT2 Blowing Agent](/products/additives/nbt2) optimized for footwear injection soles.

        
        
        
        
        
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          ## Frequently Asked Questions

          
### Can I mix NBT2 and NBTN grades to adjust activation temperature?

Yes. Blending the two grades in proportions (e.g., 70% NBT2 + 30% NBTN) will produce an intermediate activation temperature. This is a valid technique for fine-tuning foam activation in processes where temperature profiles vary across the extruder zones.

### What is the correct ADCL loading to achieve a specific foam density?

The relationship is approximately: ADCL loading (PHR) × Gas volume (cm³/g) × Polymer density (g/cm³) = volumetric expansion ratio. For a target density of 0.2 g/cm³ in EVA foam (base density 0.93 g/cm³), a loading of approximately 4-5 PHR NBT2 is the starting point, adjusted based on trial results.

### Does ADCL affect the colour of white foam products?

The solid residue from ADCL decomposition (biurea, cyanuric acid) is off-white to pale yellow. In white EVA shoe sole foam, this residue contributes to yellowing  -  particularly visible after UV exposure. For colour-critical white foam, reduce ADCL loading and compensate with physical blowing agents or optimized nucleation systems.

### Is azodicarbonamide banned in India?

No. ADCL is banned as a food additive (flour bleaching) in the EU and Australia, but it is fully permitted for industrial polymer foam applications in India and globally. There are no current restrictions on industrial ADCL use in India.

        
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By NBT Technical Desk · Updated 2026-07-04

        

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