Polymers toxicity

Of common interest in this area are predominantly hexafluoroacetone (HFA, a gas), because of its chemical reactivity as an intermediate and the solvent power of its liquid or low melting hydrates, and perfiuoro(methyloxirane) (perfiuoropropylene oxide, HFPO, a gas), used as an intermediate and building block with many applications for functional oils and polymers.1 Hexafluoroacetone is used for the synthesis of 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP), pharmaceuticals, agrochemicals and polymers. Toxic properties of some species are listed in Tabic 10. 

Monolayer cultures of WISH (human amnion) cells were treated with the Indicated concentrations of each polymer. Toxic effects were recorded at the end of 24 hours. 4 = lOOt cell destruction, 3 = 751,... 

Chloroform is a potent volatile anaesthetic, but is little used due to its potential hepato-toxicity. It is used principally for the manufacture of chlorofluorohydrocarbon refrigerants ( Arctons and Freons ) and certain polymers. 

Pure acrylonitrile boils at 78°. Acrylonitrile vapour is highly toxic it should therefore be handled with due caution and all operations with it should be conducted in a fume cupboard provided with an efficient draught. Acrylonitrile forms an azeotropic mixture with water, b.p. 70-5° (12-5 per cent, water). The commercial product may contain tte polymer it should be redistilled before use and the fraction b.p. 76 -5-78° collected separately as a colourless liquid. 

One of the chief uses of chloromethane is as a starting material from which sili cone polymers are made Dichloromethane is widely used as a paint stripper Trichloromethane was once used as an inhalation anesthetic but its toxicity caused it to be replaced by safer materials many years ago Tetrachloromethane is the starting mate rial for the preparation of several chlorofluorocarbons (CFCs) at one time widely used as refrigerant gases Most of the world s industrialized nations have agreed to phase out all uses of CFCs because these compounds have been implicated m atmospheric processes that degrade the Earth s ozone layer... 

Acrylic polymers are considered to be nontoxic. In fact, the FDA allows certain acrylate polymers to be used in the packaging and handling of food. However, care must be exercised because additives or residual monomers present in various types of polymers can display toxicity. For example, some acryflc latex dispersions can be mild skin or eye irritants. This toxicity is usually ascribed to the surfactants in the latex and not to the polymer itself. 

Potential health and safety problems of acryflc polymers occur in their manufacture (159). During manufacture, considerable care is exercised to reduce the potential for violent polymerizations and to reduce exposure to flammable and potentially toxic monomers and solvents. Recent environmental legislation governing air quality has resulted in completely closed ketde processes for most acryflc polymerizations. Acryflc solution polymers are treated as flammable mixtures. Dispersion polymers are nonflammable. 

Solution Casting. The production of unsupported film and sheet by solution casting has generally passed from favor and is used only for special polymers not amenable to melt processes. The use of solvents was generally very hazardous because of their flammabiUty or toxic nature. The cost of recovery and disposal of solvents became prohibitive for many lower price film appHcations. The nature of the drying operations leads to problems with solvent migration and retention that are not problems with melt-processed polymers. 

In the area of municipal and iadustrial wastewater treatment, the principal environmental issue is the toxicity of residual flocculating agents ia the effluent. Laboratory studies have shown that cationic polymers are toxic to fish because of the iateraction of these polymers with giU. membranes. Nonionic and anionic polymers show no toxicity (82,83). Other studies have shown that ia natural systems the suspended inorganic matter and humic substances substantially reduce the toxicity of added cationic polymer, and the polymers have been used successfully ia fish hatcheries (84—86). Based on these results, the EPA has added a protocol for testing these polymers for toxicity toward fish ia the presence of humic acids (87). The addition of anionic polymers to effluent streams containing cationic polymers to reduce their toxicity has been mentioned ia the patent Hterature (83). 

Exposure to PTFE can arise from ingestion, skin contact, or inhalation. The polymer has no irritating effect to the skin, and test animals fed with the sintered polymer have not shown adverse reactions. Dust generated by grinding the resin also has no effect on test animals. Formation of toxic products is unlikely. Only the heated polymer is a source of a possible health hazard (120). 

The self-ignition temperature of PVF film is 390°C. The limiting oxygen iadex (LOI) for PVF is 22.6% (98), which can be raised to 30% ia antimony oxide-modified film (99). Hydrogen fluoride and a mixture of aromatic and aUphatic hydrocarbons (100) are generated from the thermal degradation of PVF. Toxicity studies, ie, survival and time to iacapacitation, of polymers, ceUulosics (101,102), and airplane iaterior materials (103) expose... 

PVDE is not hazardous under typical processing conditions. If the polymer is accidentaky exposed to temperatures exceeding 350°C, thermal decomposition occurs with evolution of toxic hydrogen fluoride (HE). 

Other than fuel, the largest volume appHcation for hexane is in extraction of oil from seeds, eg, soybeans, cottonseed, safflower seed, peanuts, rapeseed, etc. Hexane has been found ideal for these appHcations because of its high solvency for oil, low boiling point, and low cost. Its narrow boiling range minimises losses, and its low benzene content minimises toxicity. These same properties also make hexane a desirable solvent and reaction medium in the manufacture of polyolefins, synthetic mbbers, and some pharmaceuticals. The solvent serves as catalyst carrier and, in some systems, assists in molecular weight regulation by precipitation of the polymer as it reaches a certain molecular size. However, most solution polymerization processes are fairly old it is likely that those processes will be replaced by more efficient nonsolvent processes in time. 

Dyes for WORM-Disks. Regarding their memory layer, dye-in-polymer systems show advantages over metal layers in their higher stabiHty, lower toxicity, lower heat conductivity, lower melting and sublimation temperature, and simpler manufacturing technique (substrate coating by sublimation or spincoating). 

Daylight fluorescent pigments (qv) are considered to be nontoxic. Since they are combinations of polymers and dyestuffs, the combined effect of the ingredients must be taken into account when considering the net toxic effect of these materials. Table 5 gives results of laboratory animal toxicity tests of standard modified melamine—formaldehyde-type pigments, the Day-Glo A Series, and the products recommended for plastic mol ding, Day-Glo Z-series. 

Disadvantages associated with some organic solvents include toxicity flammabiHty and explosion ha2ards sensitivity to moisture uptake, possibly leading to subsequent undesirable reactions with solutes low electrical conductivity relatively high cost and limited solubiHty of many solutes. In addition, the electrolyte system can degrade under the influence of an electric field, yielding undesirable materials such as polymers, chars, and products that interfere with deposition of the metal or alloy. 

Acryhc and methacryhc nonaqueous dispersions (NADs) are primarily utilized by the coatings industry to avoid certain difficulties associated with aqueous dispersion (emulsion) polymers. Water as a suspension medium has numerous practical advantages, but also some inherent difficulties a high heat of evaporation, a low boiling point, and an evaporation rate that depends on the prevailing humidity. Nonaqueous dispersions alleviate these problems, but introduce others such as flammabihty, increased cost, odor, and toxicity. 

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