| Summary: | Chemical additives are important materials in the plastics and polymers industries, utilised widely to manipulate the chemistry and resultant physical properties of polymeric products. One group of such additives are chemical blowing agents. Blowing agents are materials commonly used to produce a low density, cellular structure within a polymeric matrix through the generation of gas via thermal decomposition. No chemical blowing agents does this more efficiently than azodicarbonamide. Azodicarbonamide is used across a multitude of applications, and is a high gas yielding, cost-effective, adjustable blowing agent. All commercially used chemical additives are subject to strict, stringent regulatory protocols and azodicarbonamide is no exception. In 2012 the European Chemicals Agency, registered azodicarbonamide as a Substance of Very High Concern due to evidence of respiratory sensitisation. This classification has resulted in a commercial need for suitable replacements for azodicarbonamide for a number of applications. One of these applications is the decorative coatings industry. This study outlines the potential of many materials within an existing decorative coating formulation under standard manufacturing conditions and compares the results to those of the currently used azodicarbonamide. Recommended known alternatives have been studied both independently and in a co-blowing agent system with azodicarbonamide, showing mixed results. Furthermore, a range of bio-based and naturally arrived fragments such as citric acid and urea, have been utilised to synthesise a library of sustainable chemical additives as potential alternatives to azodicarbonamide. The additives were implemented into formulation and analysed for properties such as colour, gloss, expansion, surface structure and internal cellular structure, in comparison with the control azodicarbonamide formulation. Furthermore, the classification of azodicarbonamide as a Substance of Very High Concern, limits its use to a restriction of 0.1% w/w in products. A quantitative analytical technique has been investigated in attempt to accurately identify residual amounts of azodicarbonamide within decorative coating products.
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