- Author
- Kashiwagi, T. | Harris, R. H., Jr. | Zhang, X. | Briber, R. M. | Cipriano, B. H. | Raghavan, S. R. | Awad, W. H. | Shields, J. R.
- Title
- Flame Retardant Mechanism of Polyamid 6-Clay Nanocompsoites.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD Maryland Univ., College Park
- Journal
- Polymer, Vol. 45, No. 3, 881-891, February 2004
- Keywords
- flammability | nanocomposites | polyamid 6 | flame retardants | clay
- Abstract
- The thermal and flammability properties of polyamide 6/clay (2% and 5% by mass) nanocomposites were measured to determine their flame retardant performance. The gasification process of the nanocomposite samples at an external radiant flux of 50 kW/m2 in a nitrogen atmosphere was observed, and the residues collected at various sample mass losses were analyzed by TGA, TEM, and XRD to determine the content of the residue and to understand the flame retardant mechanism of the nanocomposites. The analysis of the floccules of blackened residues shows that up to 80% by mass of the residues consists of clay particles and the remainder is thermally stable organic components with possible graphitic structure. Furthermore, clay particles are stacked in the carbonaceous floccule residues and the d-spacing of the clay platelets is in the range of 1.3-1.4 nm as compared to the well exfoliated original sample. The accumulation of clay particles is facilitated by numerous rising bubbles (consisting of degradation products of PA6) pushing and stacking clay particles on to the sample surface through the molten polymer layer. The extent of coverage of the sample surface by the blackened floccules determines the FR performance of the PA6/clay nanocomposite samples. Vigorous bubbling was observed on the sample surface which was not covered by the protective floccules. Neither PA6/clay sample produced sufficient amounts of protective floccules to cover the entire sample surface.