Cone calorimeter blends

The resulting blends were shown to possess enhanced flammability and mechanical properties. The cone calorimeter data shown in Table 8.1 indicate that the highest reduction in the PHRR was obtained for the Pebax system where a reduction of 65%-70% in PHRR was reported. The reduction in heat release was obtained by enhanced char formation. The char reduces the escape of small volatile molecules to the gas phase, which in turn reduces the amount of heat release feedback to the polymer surface. 

Cone Calorimeter Data for Polymers and Pre-Ceramic Polymer-Polymer Blends... 

In the work of Wilkie et al.,55,56 oligomers of styrene, vinylbenzyl chloride, and diphenyl vinyl-benzylphosphate and diphenyl vinylphenylphosphate (DPVPP) have been prepared and reacted with an amine and then ion-exchanged onto clay. The resulting modified DPVPP clays have been melted blended with polystyrene and the flammability was evaluated. XRD and TEM observations proved the existence of intercalated nanocomposite structures. Cone calorimeter tests have shown a substantial reduction in the PHRR of about 70% in comparison with pure PS. According to the authors, this reduction was higher than the maximum reduction usually obtained with PS nanocomposites. Other vinylphosphate modified clay nanocomposites were also elaborated. The reduction in PHRR was greater with higher phosphorus content than for DPVPP. Consequently, the reduction in PHRR seemed attributed to both the presence of the clay and to the presence of phosphorus. 

The effects of an organoclay and alumina trihydrate (ATH) and/or magnesium dihydroxide (MDH) on the fire retardancy of a ethylene-vinyl acetate (EVA) and low-density polyethylene (LDPE) blend were assessed by TGA and the cone calorimeter (Zhang et al. 2009). 

This chapter is organized in the following way. First, we present some common techniques for characterizing the dispersion of nanoclays in polymer blends. The dispersion level has been shown to have a fundamental effect on the fire performance of polymer-clay nanocomposites (PCNs), as an exfoliated or intercalated polymer-clay system seems to enjoy reduced flammability. Second, the effects of nanoclays on the viscosity of polymer blends are discussed. With increased temperature in the condensed phase during combustion, most polymers (and hence polymer blends) have sufficiently low viscosity to flow under their own weight. This is highly undesirable, especially when the final products will be used in vertical orientation, because the melt can drip, having the potential to form a pool fire, which can increase fire spread. The results on thermal stability are presented next, followed by those for the cone calorimeter. The quantitative effects of nanoclays on the... 

Table 8.6 A summary of the cone calorimeter results for EVA/LDPE polymer blend with nanoclay (OMMT) and/or FRs (ATH and MH)...

Compounds of SWCNTs and MWCNTs in LDPE BPD 8063 were melt blended in a Brabender mixing chamber according to the formulations indicated in Tables 7.5 and 7.6. The corresponding cone calorimeter measurements are shown... 

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