Effect of clay dispersion on the synergism between clay and intumescent flame retardants in polystyrene

Abstract

Different formulations were designed to evaluate the effect of organically modified clay (DK4) on the combustion behavior of polystyrene (PS) containing an intumescent flame retardant, poly(4,4-diaminodiphenyl methane spirocyclic pentaerythritol bisphosphonate) (PDSPB). The results of transmission electron microscopy reveal that DK4 selectively dispersed in the PDSPB phase. An investigation of thermogravimetric analysis revealed that the thermal stability of PS resin showed no obvious change with the addition of PDSPB and DK4, but the residue increased. From the results of cone calorimetry, we observed that there were two steps during combustion. The dispersion of DK4 played an important role in improving the thermal stability and the flammability of the PS/PDSPB/DK4 nanocomposites. In the first step, DK4 was restricted in the PDSPB phase; there was no synergistic effect. A synergistic effect occurred in the second step when clay had a homogeneous distribution, in which the peak heat release rates were reduced by about 40 and 61% compared to the pure PS. A model of combustion behavior was developed according to these results. The synergistic mechanism was caused by the formation of the silicoaluminophosphate (SAPO) structure formed by reactions between PDSPB and DK4. Field emission scanning electron microscopy characterization showed that such an SAPO structure led to a ceramic-like residue after burning.

Study on intumescent flame retarded polystyrene composites with improved flame retardancy

“…The nanoplatelet of ZrP cannot efficiently insulate the underlying material and slow the escape of the volatile products [30]. Meanwhile, inter-chain bridges would be induced by the presence of Zr 4+ and accelerate the cure reaction of the IFR compositions, which means that the solidification processes cannot be synchronous with the elimination of gaseous products to give the intumescence and form the multicellular structure [31].…”

Combination of montmorillonite and a Schiff-base polyphosphate ester to improve the flame retardancy of ethylene-vinyl acetate copolymer

“…The nanoscale dispersion of the montmorillonite in the polymer is of utmost importance, as the type of dispersion determines the mechanical and thermal properties of the nanocomposites [21]. Previous work on vinyl ester resins by Gilman et al showed that vinyl ester nanocomposites mixed for 10 min results in the formation of intercalated structures [23,24].…”

“…Previous study showed that the addition of organically modified clay into HDPE/EVA with ammonium polyphosphate (APP) and other charring agents could improve thermal stability, as well as reduction in peak heat release rate [20]. However, unlike the synergism between montmorillonite and low molecular weight IFRs, the synergism between polymeric IFRs and montmorillonite is largely affected by the distribution of montmorillonite due to the multiphase structure of such a system [21].…”

Flame retarded polymer nanocomposites: Development, trend and future perspective

“…The combustion behavior and flame retarded mechanism are especially focused on [93][94][95][96][97][98]. In the study of multiphase and multicomponent copolymer ABS/clay nanocomposite, clay can intercalate uniformly into multiphase of ABS by balancing the polarity of butadiene (by grafting maleic anhydride) and acrylonitrile-styrene phase, as shown in Figure 2.…”