Formation of Cellular Plastics

TABLE 17.1 Characteristics of Some Commercially Available CFAs [20] 

Names lypes Decomposition Temperature (°C) Gas Evolution (cm /g) Main Gas Evolved Additional Gases 

About 88% of global CFA volume is ADC, with 5% in endothermic foaming agents and 7% of the volume in various other types [21]. However, endothermic CFAs are expected to grow slightly faster than exothermic CFAs due to both technical and regulatory concerns about exothermic CFA use. The desire by processors for finer cell strucmre and the prohibition by the European Food Safety Authority of the use of ADC in food contact materials due to its decomposition into toxic by-products are the driving forces for the future increased use of endothermic CFAs in many applications [21]. 

Over the past years, blends of exothermic and endothermic CFAs are increasingly used to exploit the exothermic CFA s high gas yield and expanding ability, as well as the small cell structure induced by endothermic agents. 

The fundamentals of foam formation have been reviewed in detail by a number of authors [17-19]. Therefore, only the main concepts will be reviewed in this chapter. Cellular plastics are produced through several methods, irrespective of cell structure (open or closed). However, the most commonly used methods for cellular PLA are the following  

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