Comparison of Thermal Decomposition of Polystyrene Products vs. Bio-Based Polymer Aerogels

Samples of polystyrene (PS), extended polystyrene foam (EPS foam), and 3 bio-based foam-like polymer/clay aerogels were produced, and examined under pyrolysis conditions. The polystyrene products produced pyrolysis products including toluene, styrene, benzaldehyde, and 4-phenyl-1-butyne; all consistent with previous reports. These highly flammable volatiles would be further expected to combust under flame conditions, producing carbon monoxide and carbon dioxide; prior work suggests that carbon monoxide poses the greatest health risk from the burning of both polystyrene and EPS. Pectin and alginate carbohydrate polymer aerogels, subjected to the same pyrolysis conditions as the polystyrene materials, produced products which were generally consistent with prior literature, and presented only moderate known health risks (similar to those of the EPS pyrolysis). As with PS and EPS foams, the alginate and pectin aerogel by-products are flammable, and are expected to be converted to carbon oxides. Casein, a milk-derived protein, generated organic nitriles and aromatic compounds under pyrolysis conditions, again consistent with literature for proteins in general. While none of the bio-based pyrolysis products of this study pose known significant health risks, it is possible that some of nitriles could be converted to hydrogen cyanide, leading to the recommendation that such protein-based products be further investigated prior to implementation in consumer/civil engineering applications.