Synergy between conventional phosphorus fire retardants and organically-modified clays can lead to fire retardancy of styrenics

Polystyrene–clay nanocomposites combined with phosphorous-containing fire retardants have been prepared and used to explore the thermal stability and mechanical properties of the polymer formed. The amounts of fire retardants and clay used were varied to study the effect of each on thermal stability and mechanical properties of the polymer. The samples were prepared by bulk polymerization and analyzed by X-ray diffraction, thermogravimetric analysis, cone calorimetry, Fourier Transform infrared spectroscopy and the evaluation of mechanical properties. The thermal stability of the polymers is enhanced by the presence of the phosphorus-containing fire retardants

Enhanced Fire Retardancy of Vinyl Ester Resins by Combination of Additives

In pursuit of fire-retardant materials, vinyl ester resins were combined with commercially available fire retardants at lower loadings than that at which they are usually effective when used alone. The thermal stability and flammability of the various combinations of fire retardants were evaluated by thermogravimetric analysis and cone calorimetric analysis. With some combinations, the 50% degradation temperature was improved by about 5-10ºC Different additives affected the flammability to varying extents and some combinations resulted in an enhanced fire retardancy compared to the additives used alone. The combinations that showed the best reductions in the peak heat release rate (PHRR) were further used to prepare glass reinforced resins and the flammability of those systems was also evaluated using cone calorimetry

History of the Study of Theology

Traces the study of theology from its beginning until the beginning of the 20th centur

Synergy Between Nanocomposite Formation and Low Levels of Bromine on Fire Retardancy in Polystyrenes

An organically-modified clay has been prepared using ammonium salts which contain an oligomeric material consisting of vinylbenzyl chloride, styrene and dibromostyrene. The presence of dibromostyrene enhances the flame retardancy of polystyrene nanocomposites compared to both the virgin polymer and polystyrene nanocomposites prepared from non-halogen-containing organically-modified clays. The nanocomposites were prepared both by bulk polymerization and melt blending and they were evaluated by X-ray diffraction, transmission electron microscopy, thermogravimetric analysis and cone calorimetry measurements. Bulk polymerization produced nanocomposites with reduced peak heat release rate, reduced total heat release and improved thermal stability. It is noteworthy that all these improvements were obtained with clay loading as low as 3% and bromine content less than 4%

Styrenic Nanocomposites Prepared using a Novel Biphenyl-Containing Clay

Montmorillonite was organically modified using an ammonium salt containing 4-acetylbiphenyl. This clay (BPNC16 clay) was used to prepare polystyrene (PS), acrylonitrile butadiene styrene (ABS) and high impact polystyrene (HIPS) nanocomposites. Polystyrene nanocomposites were prepared both by in situ bulk polymerisation and melt blending processes, while the ABS and HIPS nanocomposites were prepared only by melt blending. X-ray diffraction and transmission electron microscopy were used to confirm nanocomposite formation. Thermogravimetric analysis was used to evaluate thermal stability and the flammability properties were evaluated using cone calorimetry. By thermogravimetry, BPNC16 clay was found to show high thermal stability, and by cone calorimetry, a decrease in both the peak heat release rate and the mass loss rate was observed for the nanocomposites

Fire Retardancy of Vinyl Ester Nanocomposites: Synergy with Phosphorus-Based Fire Retardants

Vinyl ester (PVE) nanocomposites were prepared using both clay and polyhedral oligosilsesquioxanes (POSS) as the nano-dimensional material. From cone calorimetric data, it was shown that both POSS and clay affect the flammability of the nanocomposites to the same extent. To improve on the flame retardancy, the nanocomposites were combined with phosphorous-containing fire retardants (FRs) and the result compared to the benchmark halogen-containing system. The use of the cone calorimeter to investigate the fire properties of these nanocomposites showed a great reduction in peak heat release rate (PHRR) in the presence of phosphate and slight improvements in average mass loss rate (AMLR) while thermogravimetric analysis showed improvement in char yield in the presence of phosphate. Several different organically modified clays were used and they affected the flammability to different extents. The time that the resin and clay were mixed and the atmosphere in which the reaction was carried out do not have an effect on the flammability and thermal stability of the nanocomposites. The effect of curing temperature on the clay dispersion and flammability was also investigated

Nanostructured Layered Copper Hydroxy Dodecyl Sulfate: A Potential Fire Retardant for Poly(vinyl Ester) (PVE)

Composites of poly(vinyl ester) (PVE) with copper hydroxy dodecyl sulfate (CHDS) were prepared by thermal curing. The efficiency of the additive, CHDS, in reducing flammability is demonstrated via cone calorimetry and thermogravimetric analysis (TGA). The addition of 1-10% by mass of the CHDS additive resulted in significant increments in char formation (~4-11%) from thermogravimetric analysis (TGA). Incorporation of the CHDS into the polymer matrix at these low concentrations leads to substantial reductions in the total heat release (~20-30%) but no significant change in the peak heat release rate. The composite materials generally ignite more quickly, however, the flame extinguishes faster for the composites relative to the virgin polymer. X-ray diffraction (XRD) and infrared spectroscopic analyses of the residues collected at various stages during thermal decomposition of the composities, suggest the participation of copper-containing species in promoting enhanced thermal stability of PVE

Demographic Data for Development Decisionmaking: Case Studies From Ethiopia and Uganda

Analyzes the lack of demographic and socioeconomic data, limited access to and use of existing data, and insufficient demand for their application in policy making and resource allocation. Makes recommendations for greater access, demand, and use of data