Foamed plastics production

Zapp, J.A. (1957). Hazards of isocyanates in polyurethane foam plastic production. Arch. Ind. Health 15 324-30. 

Cups, foeiined plastics Cushions, carpet and rug plastics foam Foamed plastics products Ice chests or eoolers, portable foamed plastics... 

Many different foamed plastic products are produced, and practically all processes reviewed in this book can be used to make them, particularly... 

Compressive strength— ASTM D695. Except for foams, plastic products rarely fail from compression alone. Consequently, the compressive strength is of limited value. The apparatus for this test resembles a C-clamp with the specimen compressed between the jaws of the apparatus, which close at the rate of 0.05 in/min until failure occurs. A wide... 

It must be realized that flcujie properties of this or any other raw material are not intended to reflect the fire hazards presented by any cellular or foamed plastic product containing this raw material. 

TDI has a flash point of 132°C (270°F) and therefore does not constitute a severe fire hazard. However, TDI is an organic material and will bum when exposed to fire. In addition, the flash point of TDI does not reflect the hazards presented by any cellular or foam plastic product that contains TDI. 

Foam-injection molding Foam plastic sheathing Foam products Foam regulators Foam rheology... 

The properties of commercial rigid foamed plastics are presented in Table 2. The properties of commercial flexible foamed plastics are presented in Table 4. The definition of a flexible foamed plastic is that recommended by the ASTM Committee D 11. The data shown demonstrate the broad ranges of properties of commercial products rather than an accurate set of properties on a specific few materials. Specific producers of foamed plastics should be consulted for properties on a particular product (137,138,142). 

A variety of cellular plastics exists for use as thermal iasulation as basic materials and products, or as thermal iasulation systems ia combination with other materials (see Foamed plastics). Polystyrenes, polyisocyanurates (which include polyurethanes), and phenoHcs are most commonly available for general use, however, there is increasing use of other types including polyethylenes, polyimides, melamines, and poly(vinyl chlorides) for specific appHcations. 

Many cellular plastic products are available with different types of protective faces, including composite metal and plastic foils, fiber-reinforced plastic skins, and other coatings. These reduce but do not eliminate the rate of aging. For optimum performance, such membranes must be totally adhered to the foam, and other imperfections such as wrinkles, cuts, holes, and unprotected edges should be avoided because they all contribute to accelerated aging. 

Foam Products. Latices are made into foams for use in cushioning appHcations. The latices are frothed with air and then chemically coagulated for thick appHcations, or heated to induce coagulation for thinner appHcations. The latter method allows for infinite pot life during production (see Foamed plastics). 

Polystyrene. Polystyrene [9003-53-6] is a thermoplastic prepared by the polymerization of styrene, primarily the suspension or bulk processes. Polystyrene is a linear polymer that is atactic, amorphous, inert to acids and alkahes, but attacked by aromatic solvents and chlorinated hydrocarbons such as dry cleaning fluids. It is clear but yellows and crazes on outdoor exposure when attacked by uv light. It is britde and does not accept plasticizers, though mbber can be compounded with it to raise the impact strength, ie, high impact polystyrene (HIPS). Its principal use in building products is as a foamed plastic (see Eoamed plastics). The foams are used for interior trim, door and window frames, cabinetry, and, in the low density expanded form, for insulation (see Styrene plastics). 

They range from structural foam molded products (which come from the mold as completed molded products) incorporating low density cores and high density skins of the same materials to products vacuum formed of a plastics material, the core of which becomes cellular during the heating process (Chapter 8). RP translucent structural panels for curtain wall building construction using... 

In order for such an extensive project to remain manageable, certain requirements were necessary. Initially the data were confined to TPs, TSs, TPEs, and casting plastics. To be included in this group were the TSEs, reinforced plastics, foams, semifinished products, and others. Polymat completed its initial work in 1989. New plastics products on the market and updated additional information on existing products are continually added. Data no longer available are still accessible to the user in a memory file. 

Plastic products are made by a variety of basic manufacturing processes. As an example a major method such as extrusion has subdivisions that include profile, pipe, tube, film, sheet, coating, post forming, etc. equipment In injection molding there are subdivisions such as coinjection, gas assist, foam, inmold decorating, etc. equipment. There are literally hundreds of processes used with only about the dozen, as reviewed in this chapter, that are principally used (2). 

Many plastic products are decorated to make them multi-colored, add distinctive logos, or allow them to imitate wood, metal and other materials. Some plastic products are painted since their as-molded appearance is not satisfactory, as may be the case with reinforced, filled or foamed plastics. Painting or coating is also for product protection. The following section will discuss some of the secondary operations frequently used with plastics. Since plastics vary widely in their ability to be machined and to accept finishes,... 

Genpak, a plastic products manufacturer, and Mobil are in the process of opening and operating one of the first plants to recycle polystyrene foam items such as food containers, cups, and cutlery. The materials are being collected from Massachusetts schools and institutions by New England CRInc, a major reclamation firm and recycled materials end-use manufacturer. The plant has a capacity to recycle 3 million lb per year of polystyrene resin, which will be reused by the companies or sold to producers of insulation, fence posts, and flower pots. The new company is expecting a profit by 1992. 

Uses. Blowing agent in foamed plastics in the production of tetraethyl lead formerly used as an inhalation anesthetic agent... 

Table 16.1 shows the breakdovm in value of shipments in Plastics and Rubber Products and its subdivisions. It is divided into 78.5% Plastics Products and 21.5% Rubber Products. Plastics products are then subdivided into products such as film, sheet, bags, pipe, laminate, foam, bottles, and miscellaneous. While film, sheet, and bags are the largest subdivision of plastics, the large miscellaneous other category demonstrates the breadth and scope of plastics. It cannot be denied that our modem standard of living... 

For the production of foamed plastics two methods can be essentially differentiated. 

Dielectric drying baked goods, breakfast cereals, furniture timber blanks, veneers, plyboard, plasterboard, water-based foam plastic slabs, and some textile products... 

COLLOID SYSTEMS. Colloids are usually defined as disperse systems with at least one characteristic dimension in the range 10 7 lo ll> centimeter. Examples include sals (dispersions or solid in liquid) emulsions (dispersion of liquids in liquids) aerosols (dispersions of liquids or solids in gases) /inum (dispersion of gases in liquids or solids) and gels (system, such as common jelly, in which one component provides a sufficient structural framework for rigidity and other components fill the space between the structural units or spaces). All forms of colloid systems are encountered in nature. Products of a colloidal nature arc commonly found in industry and are notably extensive in the food field. Foams, widely used in industrial products, but also the causes of processing problems are described in entries on Foam and Foamed Plastics. 

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