Plastics additives flame retardants

These are the issues with which we are currently involved. In this section. I ve talked about one kind of plastic additive flame retardants in marine organisms. However, plastic additives can also sometimes cause problems directly for humans, as discussed in the next section. 

Cblorina.ted Pa.ra.ffins, The term chlotinated paraffins covers a variety of compositions. The prime variables are molecular weight of the starting paraffin and the chlorine content of the final product. Typical products contain from 12—24 carbons and from 40—70 wt % chlorine. Liquid chlotinated paraffins are used as plasticizers (qv) and flame retardants ia paint (qv) and PVC formulations. The soHd materials are used as additive flame retardants ia a variety of thermoplastics. In this use, they are combiaed with antimony oxide which acts as a synergist. Thermal stabilizers, such as those used ia PVC (see vinyl polymers), must be used to overcome the inherent thermal iastabiUty. 

Most of the phosphate esters are used in the production of hydrauHc fluids (qv), plastic and elastomer additives, flame retardants (qv), oil stabilizers, pesticides (qv), and medicinal intermediates (see Surfactants). Some trialkyl phosphates, OP(OR)2, are outstanding solvents for nitrates, especially (UO2) (N02)2, and therefore are important in uranium processing (see Extraction). 

Organophosphoms compounds, primarily phosphonic acids, are used as sequestrants, scale inhibitors, deflocculants, or ion-control agents in oil wells, cooling-tower waters, and boiler-feed waters. Organophosphates are also used as plasticizers and flame retardants in plastics and elastomers, which accounted for 22% of PCl consumed. Phosphites, in conjunction with Hquid mixed metals, such as calcium—zinc and barium—cadmium heat stabilizers, function as antioxidants and stabilizer adjutants. In 1992, such phosphoms-based chemicals amounted to slightly more than 6% of all such plastic additives and represented 8500 t of phosphoms. Because PVC production is expected to increase, the use of phosphoms additive should increase 3% aimually through 1999. 

A multidimensional system using capillary SEC-GC-MS was used for the rapid identification of various polymer additives, including antioxidants, plasticizers, lubricants, flame retardants, waxes and UV stabilizers (12). This technique could be used for additives having broad functionalities and wide volatility ranges. The determination of the additives in polymers was carried out without performing any extensive manual sample pretreatment. In the first step, microcolumn SEC excludes the polymer matrix from the smaller-molecular-size additives. There is a minimal introduction of the polymer into the capillary GC column. Optimization of the pore sizes of the SEC packings was used to enhance the resolution between the polymer and its additives, and smaller pore sizes could be used to exclude more of the polymer... 

There are methods to manipulate the backbones of polymers in several areas that include control of microstructures such as crystallinity, precise control of molecular weight, copolymerization of additives (flame retardants), antioxidants, stabilizers, etc.), and direct attachment of pigments. A major development with all this type action has been to provide significant reduction in the variability of plastic performances, more processes can run at room temperature and atmospheric pressure, and 80% energy cost reductions. 

The list of new chemicals whose presence in the environment represents an ascertained or potential risk is sizeable and broadly contains resins, plastics, and plastic additives (e.g., plasticizers and flame retardants) pharmaceuticals and personal care products (e.g., disinfectants, fragrances, sunscreens, antibiotics, drugs of abuse, and natural and synthetic hormones) detergents and other cleaning... 

Bromide analysis, of water, 26 41 Bromide ions, in development solution, 79 205-206 Bromides, 4 319-330 thorium, 24 763 titanium, 25 54 tungsten, 25 379 uranium, 25 439 Bromimide, 4 299, 319 Brominated additive flame retardants, 77 461-468, 471-473t Brominated Anthanthrone Orange, pigment for plastics, 7 367t Brominated aromatic compounds, 7 7 459 Brominated bisphenol A-based epoxy resins, 70 366... 

Sometimes, addition of plasticizer imparts flame retardant characteristics in addition to other properties. Phosphate esters such as tris(2-ethyl hexyl) phosphate (TOP), tricresyl phosphate (TCP), chlorinated paraffin hydrocarbons etc. impart excellent flame retardant characteristics to many polymers. 

A special class of non-reactive additives in polymer materials are CPs, which have plasticizing and flame-retarding properties. They were found in an emission test of a television set with a maximum concentration of 2.2 tgm-3 after 220 h of operation (Wensing, 2003). CP are used as a substitute for PCBs, which have been prohibited worldwide since 2001. The detection of CP in indoor air needs a complex analytical procedure because the amount of single compounds in a CP mixture is high. Therefore, this class is seldom found during standard TD-GC-MS analysis. 

Triphenylphosphate is a colorless, odorless, crystalline solid (mp, 49°C bp, 245°C). It is moderately toxic. A similar, but much more toxic, compound is tri-o-cresyl-phosphate (TOCP), an aryl phosphate ester with a notorious record of poisonings.3 Before its toxicity was fully recognized, TOCP was a common contaminant of commercial tricresylphosphate. Tricresylphos-phate is an industrial chemical with numerous applications and consists of a mixture of phosphate esters in which the hydrocarbon moieties are meta and para cresyl substituents. It has been used as a lubricant, gasoline additive, flame retardant, solvent for nitrocellulose, plasticizer, and even a cooling fluid for machine guns. Although modem commercial tricresylphosphate contains less than 1% TOCP, contaminant levels of up to 20% in earlier products have resulted in severe poisoning incidents. 

R.E. Lyon, R.N. Walters, M. Beach, and F.R Schall, Flammability screening of plastics containing flame retardant additives, ADDITIVES 2007, 16th International Conference, San Antonio, TX, 2007. 

Still, some harmful compounds can appear in waste plastics, e.g. additives containing antimony, cadmium, lead, zinc, or hexavalent chromium, and plasticizers. Brominated flame retardants spreading into the environment is another reason for concern and a rational argument for dealing with WEEE and ASR-plastics [37]. 

PBBs and PBDEs belong to a group of brominated organic compounds which are used as flame retardants. Flame retardants are valued for their ability to inhibit combustion in plastics, textiles, electric, and other materials. There are different groups of flame retardants inorganic and organic chemicals. Usually they are divided into reactive and additive flame retardants. 

Recycling of plastics is difficult, because of the content of the additives PBBs and PBDEs [27]. Pyrolysis of flame retardant material of printed circuit board and electronics components (laboratory scale) produces high amounts of brominated dioxins and furans (2,3,7,8-TeBDF, 29 pg/kg residue after quarts flask pyrolysis in N2/H2 atomosphere at 1100 °C) located in the condensed material. It was known that these plastics contain flame retardants to a maximum of 20 wt%. PBDEs can be extracted from plastics based on propyl-carbonate. The origin of brominated dioxins and furans detectable in propyl-carbonate extract is still to be investigated. Further recycling activities which process flame retarded plastics might produce hazardous products, an aspect that has to be investigated more closely [27]. 

The gas composition of smoke depends on the chemical composition, the molecular structure and polymer formulation of the burning material, which may include a variety of additives, plasticizers, stabilizers, flame retardants, cross-linking agents, fillers, and blowing agents. In addition, the conditions of... 

Chloroparaffines are used, for instance, in coolants and lubricants in the metalworking industry and as additives in paints, plastics and rubber. They fulfil the function of plasticizer and flame retardant. 

This standard is for polymers, blends of polymers, copolymers, terpolymers and alloys. It considers plastic parts that have been produced under a material identity control system. Molders/fabricators are required not to employ such additives/flame retardants that would adversely affect critical material properties. A detailed discussion on national and international fire protection regulations and test methods for plastics is presented by Troitzsch [1983]. 

The organophosphorus esters represent another class of environmental chemicals that are hydrolyzed by nucleophilic substitution reactions. These chemicals comprise one of the most important classes of agrochemicals with insecticidal activity (Fest and Schmidt, 1983). The organophosphorus esters also have important industrial uses such as oil additives, flame retardants, and plasticizers (Muir, 1988). The wide range of biological activity that this class of chemicals exhibits is due to the variety of substituents that can be attached to the central phosphorus atom. 

Of the compounding ingredients, fillers and plasticizers are more important in terms of quantities used. Other additives used in smaller quantities are antioxidants, stabilizers, colorants, flame retardants, etc. The ingredients used as antioxidants and light stabilizers, and their effect have been discussed previously. Fillers, plasticizers and flame retardants are described next. 

PVC is one of the most flame resistant pol5uners but only in rigid formulations which do not contain many other additives. Addition of other polymers or additives decreases its flame resistance to the point that it frequently requires addition of special plasticizers, organic flame retardants, or special fillers. Plasticized PVC must contain at least 20% flame retarding plasticizer to be self-extinguishing. 

It is clearly a truism that for reducing the fire risk in the applications of plastics, their flammability should be diminished. This is achieved either by reactive flame-retardants incorporated during the preparation (polymerization, polyaddition, polycondensation) of the polymer or by additive flame-retardants admixed in the course of plastics processing. The flammability of plastics is sometimes reduced by surface protection. The most recent methods of reducing flammability are the modification of the macromolecular structure and the development of thermally resistant polymers (high-temperature plastics). 

The flammability of plastics can be reduced by chemical or physical methods. The latter approach involves protective coatings on the surface of plastics while the chemical approach has a great many variants, from the incorporation of reactive or additive flame-retardant additives up to fundamental structural modifications of the material. 

Among phosphorus-containing additive flame-retardants, phosphates are mostly applied as secondary plasticizers in formulations of flame-retarded plasticized PVC. Other additive agents are admixed with natural and synthetic rubbers, polyester and epoxy resins, polyurethane foams, polystyrenes and polyethylenes, etc. 

Saturated halogenated phosphoric esters can be admixed to polyacrylates as additive flame-retardants in a proportion of 30 to 40 per cent, or 12 to 15 per cent when chlorinated (such as tris(chloroethyl) or bis(chloroethyl) phosphates) or brominated (as with tris(bromoethyl) phosphate) agents are used. These additives also act as plasticizers. 

Additive flame-retardants, however, may also be suitable, for example ammonium polyphosphate, tris(2-chloroethyl) phosphate, or other phosphorus-containing plasticizers. 

A 2011 study by Lithner et al. (2011) assessed the environmental and health hazards posed by plastics, based on the toxicity of their monomers. The classification is not inherent to the polymer as it is based primarily on residual monomer (with selected additives, plasticizer, and flame retardants). The ranking (see Table 8.8) can have relevance only for occupational exposures and in some food-contact uses of plastics. Also, future advances in residual monomer reduction technology and green substitution of additives can change the status of a polymer in this assessment. Where recyclabihty" is used as a ranking criterion, it generally refers to technical recyclabihty that has little to do with if the resin will in fact be recycled in practice. 

Method of Use. Compounders add flame retardants to the finished polymer these additive flame-retardants are 87 percent of the market. The other 13 percent of reactive flame-retardants are built into the polymer molecule, either during polymerization or in the curing agents added to thermosetting plastics. 

GC combined with different extraction and detection techniques, such as Py-GC, Py-GC/MS, SFE-GC, thermodesorption cooled injection system (TD-CIS)-GC/MS among others, has been widely applied to the analysis of many additives. The use of Py-GC and Py-GC/MS in the determination of lubricants, antioxidants, plasticizers, and flame retardants was discussed in depth by Wang and CO workers. In the case of antioxidants, Py-GC... 

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