Commercial foamed plastics polyurethane

Foamed plastics (qv) were developed in Europe and the United States in the mid-to-late 1930s. In the mid-1940s, extmded foamed polystyrene (XEPS) was produced commercially, foUowed by polyurethanes and expanded (molded) polystyrene (EPS) which were manufactured from beads (1,2). In response to the requirement for more fire-resistant ceUular plastics, polyisocyanurate foams and modified urethanes containing additives were developed in the late 1960s urea—formaldehyde, phenoHc, and other foams were also used in Europe at this time. 

Another area in which 1,4-cyclohexanedimethanol is commercially important is in the manufacture of polyurethane foams (see Foamed plastics). 

Unique Properties of Foamed Plastics Structural Features of Foamed Plastics Leading Commercial Polymers Polyurethane Polystyrene Poly(vinyl chloride)... 

Polyurethanes can trace their commercial origin to the development work undertaken by Otto Bayer et al in the 1930 s Since then, this family of products has adapted extremely well for use in a wide variety of applications, such as fibres, foams, plastics, adhesives, textiles and coatings to name but a few. 

Commercial Construction. The same attributes desirable on residential constmction appHcations hold for commercial constmction as weU but insulation quaHty, permanence, moisture insensitivity, and resistance to free2e—thaw cycling in the presence of water are of greater significance. For this reason ceUular plastics have greater appHcation here. Both polystyrene and polyurethane foams are highly desirable roof insulations in commercial as in residential constmction. 

Some other groups such as ester, ether, amide, or urea are present in the Polymer chain of commercial polymers. In 1937, O. Bayer found that reaction of diisocyanates with glycols fields polyurethanes which are useful as plastics, fibres, adhesives, rigid foams and surface coatings. 

While unaffected by water, styrofoam is dissolved by many organic solvents and is unsuitable for high-temperature applications because its heat-distortion temperature is around 77°C. Molded styrofoam objects are produced commercially from expandable polystyrene beads, but this process does not appear attractive for laboratory applications because polyurethane foams are much easier to foam in place. However, extruded polystyrene foam is available in slabs and boards which may be sawed, carved, or sanded into desired shapes and may be cemented. It is generally undesirable to join expanded polystyrene parts with cements that contain solvents which will dissolve the plastic and thus cause collapse of the cellular structure. This excludes from use a large number of cements which contain volatile aromatic hydrocarbons, ketones, or esters. Some suitable cements are room-temperature-vulcanizing silicone rubber (see below) and solvent-free epoxy cements. When a strong bond is not necessary, polyvinyl-acetate emulsion (Elmer s Glue-All) will work. 

Thermal degradation of foams is not different from that of the solid polymer, except in that the foam structure imparts superior thermal insulation properties, so that the decomposition of the foam will be slower than that of the solid polymer. Almost every plastic can be produced with a foam structure, but only a few are commercially significant. Of these flexible and rigid polyurethane (PU) foams, those which have urethane links in the polymer chain are the most important. The thermal decomposition products of PU will depend on its composition that can be chemically complex due to the wide range of starting materials and combinations, which can be used to produce them and their required properties. Basically, these involve the reaction between isocyanates, such as toluene 2,4- and 2,6-diisocyanate (TDI) or diphenylmethane 4,3-diisocyanate (MDI), and polyols. If the requirement is for greater heat stability and reduced brittleness, then MDI is favored over TDI. 

All available methods of preparing reticulated plastic foams are divided into chemical and physical methods In the chemical methods, a finished plastic foam is subjected either to alkaline or acid hydrolysis which destroys the walls more rapidly than the thicker struts. This method has been commercially utilized for the production of reticulated polyurethane foams from polyesters. 

BDE-153 occurs primarily in the commercial Octa and Penta BDE mixtures. The Octamix contains approximately 10-12% hexabrominated diphenyl ethers. Penta generally contained about 4-8% hexabrominated diphenyl ethers including BDE-153. Typical analysis shows that the Penta mix contains an equal distribution of BDE-153 and BDE-154. The commercial Penta mix was typically used in flexible polyurethane foam for furniture and cushions. It was also used in polyesters, and epoxy and phenolic resins. Octa is used primarily in rigid plastics for housing electronics. 

Methylene chloride is a volatile, colorless, nonflammable liquid. It is slightly soluble in water and miscible with many other solvents, such as acetone, chloroform, carbon tetrachloride, and alcohol. Under speciflc conditions it may burn. Its commercial formulations for paint stripping are particularly flammable. Methylene chloride is a widely used solvent where quick drying (i.e., high volatility) is required. Such application areas include adhesives, cellulose acetate flber production, blowing of polyurethane foams, and metal and textile treatment. It dissolves oils, fats, waxes, many plastics, bitumen, and rubber. This property is used in paint stripper formulations. It is used as an aerosol solvent, and for extraction operations in the pharmaceutical industry. It was previously used in fire-extinguishing products. ... 

Foams can be made with both thermoplastic and thermosetting plastics. The well known commercial thermoplastic foams are polystyrene, PVC, polyethylene, polypropylene, ABS copolymer, cellulose acetate. The thermosetting plastics which may be mentioned, among others, are phenol-formaldehyde, urea-formaldehyde, polyurethane, epoxy, and silicone. The methods of manufacture of some of these polymeric foams are given below. 

Use of this plasticizer, which is commercially available (Fyrolflex RDP) permits to obtain, non-fogging, flame retarded polyurethane foam. Incorporation of halide (preferably chlorine) in trialkyl plasticizer results in an ignition resistant, UV stable plasticizer. Effect of a plasticizer on heat stability of PVC, flexibility of plasticized material at room and low temperatures is usually balanced by the selection of a required proportion between aryl and alkyl components. Low temperature properties can be improved by alkylphettylation with special attention to isopropyl substituents. Also haze can be eliminated in PVC composition by use of alkylated derivatives (e.g., methylphosphonate). Matty efforts were made by international groups of specialists to analyze reasons for increased toxicity of some phosphates such as tricresyl and triphenyl phosphates. Their extensive findings are reported elsewhere. ... 

Commercial preparation of ceramic foam starts with a foamed organic precursor having the same porosity as the desired final product [14-19]. The most common organic precursor is polyurethane, which is available m the form of flexible, open cell foams with pore sizes ranpng from 4 to 30 pores cm (10 to 80 pores inch" ). However, other organic plastics, such as polyolefins, are equally suitable. The pores of the organic precursor are then filled with an aqueous slurry of the desired ceramic. This typically... 

The first cellular synthetic plastic was an unwanted cellular phenol-formaldehyde resin produced by early workers in this field. The elimination of cell formation in these resins, as given by Baekeland in his 1909 heat and pressure patent (2), is generally considered the birth of the plastics industry. The first commercial cellular polymer was sponge rubber, introduced between 1910 and 1920 (3). Most plastic polymers can be foamed. However, a relative few have commercial significance, such as polystyrene, polyolefins, poly(vinyl chloride), polyimides, and polyurethanes. 

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