Flame Retardant Mechanism of Polyamid 6-Clay Nanocompsoites.
Flame Retardant Mechanism of Polyamid 6-Clay
Kashiwagi, T.; Harris, R. H., Jr.; Zhang, X.; Briber, R.
M.; Cipriano, B. H.; Raghavan, S. R.; Awad, W. H.;
Shields, J. R.
Polymer, Vol. 45, No. 3, 881-891, February 2004.
flammability; nanocomposites; polyamid 6; flame
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.