Thermal stability and flame retardance of EVA containing DNA-modified clays

In this paper, two natural clays (namely, Sodium Cloisite and Sepiolite) were modified with low MW DNA from herring sperm and compounded in EVA copolymer (19 % of vinyl acetate) at 10 wt.% loading, using an internal mixer. The effect of the presence of the biomacromolecule-modified fillers on the thermal properties and on the flame retardance of the resulting composites was thoroughly investigated. In particular, thermogravimetric analyses showed that the presence of the DNA-modified filler enhanced the thermal and thermo-oxidative stability of the polymer matrix. Despite a very limited effect on flammability, cone calorimetry tests revealed that the DNA-modified nanofillers were able to significantly decrease the heat release rate, the peak of heat release rate, the total smoke production, and the specific extinction area. Finally, the presence of the modified nanofillers was responsible for the increase of stiffness, as well as for a certain decrease of ductility of the polymer matrix, as assessed by tensile tests.