Heat release rate polystyrene nanocomposites

One invariably finds that nanocomposites have a much lower peak heat release rate (PHRR) than the virgin polymer. The peak heat release rate for polystyrene and the three nanocomposites are also shown graphically in Fig. 5.16. P16-3 means that the nanocompoite was formed using 3% of P16 clay with polystyrene. The peak heat release rate falls as the amount of clay was increased. The suggested mechanism by which clay nanocomposites function involves the formation of a char that serves as a barrier to both mass and energy transport. It is reasonable that as the fraction of clay increases, the amount of char that can be formed increases and the rate at which heat is released is decreased. There has... 

Peak heat release rates for polystyrene and the three nanocomposites. ... 

Another mechanism proposed by Zhu et al. is radical trapping by paramagnetic iron within the clay. They observed that even when the clay was as low as 0.1% by mass fraction, the peak heat release rate of the clay/ polystyrene nanocomposite was lowered by 40%, a value not much different from that observed with higher amounts of clay. 

Cone calorimetry is used to evaluate the flammability imder flre-like conditions. Relevant parameters such as the rate of heat release (HRR) and its peak value, heat of combustion (He), smoke yield (specific extension area, SEA), and carbon monoxide 5ueld are obtained. Table 2 shows some t5q)ical data for layered silicate nanocomposites based on organically treated montmorillonite, with polyamide 6, poly(propylene-gra -maleic anhydride), and polystyrene as the host matrix. Nanocomposites imder investigation have either delaminated (PAG) or intercalated-delaminated structures. In all cases there is a substantial reduction in peak HRR value (50-75%), whereas He and CO formation show little variation. 

The data for nanocomposites polymer/organoclay on the basis of polyamide-6 (PA-6), polyamide-12 (PA-12), polystyrene (PS) and polypropylene (PP), which are listed in table 11.1, were used for the relationships structure-flame-resistance characteristics. The maximum rate of heat release measured with the use of a cone calorimeter according to the standards ASTM 1354-92 and ISO/DIS 13927 [2], the values of which are also listed in Table 11.1, was used as flame-resistance characteristic of the indicated nanomaterials. 

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