Contents 2 With Halogens

For a given level of fuel at a given thickness with the same halogen content, most halogenated compounds show more or less the same flame retardancy. The key differences among these FR additives are effects on flow, melt stability, mechanical properties and long-term ageing of the FR-PBT blend. Different end-use requirements may call for the addition of different FR additives. 

Halogen content If halogens in the anion are not crucial for specific reactions performed in the ionic liquid, they should be avoided. Moisture sensitivity, halogenide transfers, alcoholysis and toxic effects are often connected with halogen atoms in the molecule [27]. In addition, the hydrolysis products HCl or HF act corrosively. Within the project reported by Wasserscheid and coworkers they successfully developed ionic liquids with alkylsulfate groups as anions to overcome the halogen content. These new solvents show very favorable properties. 

Efficiency of the procedure used for the preparation of samples containing carbon-14 and sulfur-35 was tested e.g., by cembustion of sampjgs obtained by ighing together standardized benzoic acid- X, methionine- and inactive substances with halogen, sulfur or phosphorus content. Results of duplicate analyses of seme of these sanples is shown in Table... 

It is known that with halogenated systems the higher the laminate glass transition temperature (Tg) the lower the halogen content required to achieve V-0 performance. So to achieve FR properties the resin Tg is increased, making the laminate more difficult to drill and rout. The cost also rises. 

Elastogran has developed pentane blown pol5dsocyanurate formulations with a much-reduced content of halogen-free flame retardants. The company has developed new polyester polyols for the package that contain isocyanurate. The new PIR systems also offer far better dimensional stability for the resultant insulation panels. 

The effects of mill sticking are often most serious with halogenated polymers, where mild corrosion of process equipment may provide a clean steel surface, thus promoting high bond strengths. Heat build-up exacerbates the problem severely. Within the clay minerals it is known that the total surface hydroxyl content (which is the product of surface area and hydroxyl concentration) influences mill sticking and other properties markedly [36]. Other aspects of processability are also known to be influenced by this (Table 7.5). 

Now the world elastomeric market consists of the natural rubber (NR) -40% and S5mthetic rubbers - 60%. According to forecasts of experts the tendency of increase in a share of NR is observed. It is supposed that by 2015-2020 its share will make 50%. For the purpose of expansion of a scope of natural mbber manufacturing of NR with the content of chlorine from 0.5 to 15% is of interest since it is known that such content of halogen doesn t worsen flexural properties of rubber. 

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