Polymer dust

Dust control is a major problem in corrosion control by silicone polymers. Dust particles which may bridge, or meerly lay upon conductors will absorb moisture diffusing through the silicone and result in a localized site of corrosion. We found this to be the case in a number of our early saunples. Following the results of this study, all of our encapsulated assemblies will be cleaned and encapsulated in a clean room which is serviced by HEPA filters. 

In the late 1980s, environmental concerns led to the development of photo-degradable resins being incorporated in the polymer mix. Methyl isopropenyl ketone (MIPK) at a level of 5 % was found to be effective in making the loose-fill pieces photodegrade to polymer dust with 10-12 months of exposure to sunlight [134]. 

Antistatic Properties Since EVAL EVOH resin is a highly antistatic polymer, dust is prevented from building up on the package when used as a surface... 

One of the hazards uniquely associated with the production of methacrylic powders and sheets is explosion of polymer dust. These materials are flammable and must be treated with care to avoid static discharges which can serve as ignition sources. Poly(methyl methacrylate) is widely used in buildings imder codes which limit the fire hazards associated with this material. Solution polymers of methacrylic esters are considered flammable while latex emulsion polymers are nonflammable because of the aqueous continuous phase. 

Before polyacrylamides are sold, the amount of residual acrylamide is determined. In one method, the monomer is extracted from the polymer and the acrylamide content is determined by hplc (153). A second method is based on analysis by cationic exchange chromatography (154). For dry products the particle si2e distribution can be quickly determined by use of a shaker and a series of test sieves. Batches with small particles can present a dust ha2ard. The percentage of insoluble material is determined in both dry and emulsion products. 

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 different types of furniture pohshes include hquid or paste solvent waxes, clear oil pohshes, emulsion oil pohshes, emulsion wax pohshes, and aerosol or spray pohshes (3). Nonwoven wipes impregnated with pohsh ingredients have been targeted at consumers who do not wish to expend the time to dust before polishing (11). Compilations of representative formulas are given in References 3, 4, 12, and 13. Paste waxes contain ca 25 wt % wax, the remainder being solvent. Clear oil pohshes contain 10—15 wt % oil and a small amount of wax, the rest being solvent. Aerosol or spray products may contain 2—5 wt % of a sihcone polymer, 1—3 wt % wax, 0—30 wt % hydrocarbon solvent, and ca 1 wt % emulsifier. The remainder is water. 

Antistatic polystyrenes have been developed in terms of additives or coatings to minimise primarily dust collecting problems in storage (see Antistatic agents). Large Hsts of commercial antistatic additives have been pubhshed (41). For styrene-based polymers, alkyl and/or aryl amines, amides, quaternary ammonium compounds, anionics, etc, are all used. 

Polyurethanes. These polymers can be considered safe for human use. However, exposure to dust, generated in finishing operations, should be avoided. Ventilation, dust masks, and eye protection are recommended in foam fabrication operations. Polyurethane or polyisocyanurate dust may present an explosion risk under certain conditions. Airborne concentrations of 25—30 g/m are required before an explosion occurs. Inhalation of thermal decomposition products of polyurethanes should be avoided because carbon monoxide and hydrogen cyanide are among the many products present. 

Products are granular, free-flowing, and dust-free by nature, since no flow conditioner dust is used as with sulfur-coated fertilizers. They possess excellent abrasion resistance and handling integrity. Since the outer coating is a hard polymer, the products do not leave waxy residues on material handling and apphcation equipment. 

Hard rubber presents a fire hazard when reduced on steam-heated rolls (see subsection Organic Polymers ). Its dust is explosive [Twiss and McGowan, India Rtwber]., 107, 292 (1944)]. 

Benzene m air (porous polymer diffusion samplers, thermal desoiption and gas chromatography) Quartz in respirable airborne dusts (X-ray diffraction)... 

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