In halogen-containing polymers

In halogen-containing polymers, the multifunctional zinc borate can function as a flame retardant, smoke suppressant, and afterglow suppressant. 

In halogen-containing polymers, the zinc borate can either partially or completely replace antimony oxide as a fire retardant synergist of halogen sources. The combination of antimony oxide and zinc borate can provide not only cost savings but also synergism in fire test performances (Figure 2). In addition, in contrast to antimony oxide, the zinc borate also... 

Further insight into the mode of action of inorganic synergists in halogen-containing polymer formulations has been provided by quantification and analysis of the char residues remaining after combustion of the polymer in air. Data for such experiments on brominated polyester resins are presented in Table 7. 

The tin additives exert their fire-retardant action in both the condensed and vapour phases, by promoting the formation of a thermally stable carbonaceous char and (in halogen-containing polymer formulations) by generating volatile metal halide species which assist in free radical scavenging reactions in the flame. 

In general, tin compounds do not exhibit flame-retardant properties in halogen-free polymer systems, unless the composition contains a high inorganic filler loading. However, tin additives often act as smoke suppressants in non-halogenated polymers. 

RAFT has also been used to produce graft polymers. The grafting from method is achieved by reacting a halogen-containing polymer such as styrene p-chloromethy I styrene copolymer with sodium dithiohenzoate to obtain a polymeric dithioester, which is an initiator in RAFT polymerization (Sec. 3-15d) [Quinn et al., 2002]. 

In addition, the active species of plasma give intensive dehydrogenation and dehydrochlorination reactions of the phosphorus and halogen containing polymers with the generation of macroradicals (8). 

At the oxidation of halogen-containing polymers, the release of halogen atoms which are in P-position to a radical site of chloroalkyl radicals should be considered as well. Worth of noting here is the fact that abstraction of a halogen atom may occur also in a-position [90],... 

Burning may be considered another means of oxidation. Non-burning plastics are a must in commercial constructions according to building codes and are often required for automotive, electronic, and electrical applications. From the numerous thermoplastics, only the halogen-containing polymers, polyamides, polycarbonate, poly(phenylene oxide), polysulfone, and polyimides are self-extinguishing. Even these, such as poly (vinyl chloride), may become flammable when plasticized with a flammable plasticizer. Fire control can be the key to volume use of plastics. Polyester panels, urethane foam, and PVC tarpaulins account for nearly 90% of all fire retardants consumed. Consumption in 1967... 

For aluminum pigments the temperature is less restrictive. In this case their chemical reactivity needs to be considered, particularly with halogen-containing polymers. In extreme cases, if halogen is released, a strong reaction can be anticipated (Wuerz synthesis [15]). 

In general, halogen-containing polymers (e.g. those containing Br and Cl) are not acceptable feedstock for pyrolysis because they would necessitate the use of special alloys to prevent corrosion and pinholing of the plant components (e.g. condenser coils). 

Coated fillers have been evaluated in a range of halogen-containing polymer systems, including rigid and flexible polychloroprene (Neoprene), and in thermoplastic and thermosetting materials... 

Electronic structure of carbonaceous materials produced by chemical dehydrohalogenation of some halogen-containing polymers was studied by various methods of electron spectroscopy, including Auger electron spectroscopy (AES) [7,8,12,27,28], electron energy loss spectroscopy (EELS) [7,8,27,28], x-ray photoelectron spectroscopy (XPS) [12,13,29], and x-ray emission (C spectroscopy [29] in order to corroborate the one-dimensional... 

Yet another serious problem that makes the preparation of perfect carbyne structures (long-chain polyynes or cumulenes) an almost hopeless endeavor is the presence of intrinsic defects in the original halogen-containing polymers. The polymers produced by common polymerization technologies always contain some defect structures such as head-to-head and "tail-to-tail links [32-34] as well as branching sites [35,36]. For instance, poly(vinylidene fluoride) was shown to contain up to 6 mol.% [32,33] and poly(vinylidene chloride) even 12.5% of abnormal links [34], which hamper exhaustive dehydrohalogenation (Scheme 12.9). 

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