Polyurethanes PUR

Because polyurethane is a polar material, it is resistant to nonpolar organic fluids such as oils, fuels, and greases, but it will be readily attacked and even dissolved by polar organic fluids such as dimethylformamide and dimethyl sulfoxide. 

Polyurethanes are used where the properties of good abrasion resistance and low coefficient of friction are required. They are also used 

The chemicals listed are in the pure state or in a saturated solution unless otherwise indicated. Compatibility at 90°F/32°C is shown by an R. incompatibility is shown by an X. 

It is obtained through a reaction between di-isocyanates and glycols, that are supplied as polyesters or polyethers. It was developed by Bayer in Germany in 1937, and later in the United States (1953). 

This is an addition reaction that proceeds via a mechanism of step growth (stagewise) polymerization. The most common isocyanates are toluene diisocyanate (TDI) and methylene bis 4-phenylisocyanate (MDI). TDI is cheaper and is mostly used for flexible foams, but MDI competes because of its lower vapor pressure and reduced sensitivity in handling. Polyfunctional isocyanates are added for cross-linking. The interesting reaction between isocyanate 

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Poly(propylene oxide) [25322-69-4] may be abbreviated PPO and copolymers of PO and ethylene oxide (EO) are referred to as EOPO. Diol poly(propylene oxide) is commonly referred to by the common name poly(propylene glycol) (PPG). Propylene oxide [75-56-9] and poly(propylene oxide) and its copolymers, with ethylene oxide, have by far the largest volume and importance in the polyurethane (PUR) and surfactant industry compared to all other polyepoxides. Articles reviewing propylene oxide (1), poly(propylene oxide) (2—4), other poly(aIkylene oxides) (4), and polyurethanes (5—7) are cited to lead the interested reader to additional detail not in the scope of this article. 

The tendency of aliphatic ethers toward oxidation requires the use of antioxidants such as hindered phenoHcs (eg, BHT), secondary aromatic amines, and phosphites. This is especially tme in polyether polyols used in making polyurethanes (PUR) because they may become discolored and the increase in acid number affects PUR production. The antioxidants also reduce oxidation during PUR production where the temperature could reach 230°C. A number of new antioxidant products and combinations have become available (115,120,124—139) (see Antioxidants). 

Thin coatings consist of paints and varnishes, which are applied as liquids or powdered resin with a thickness of about 0.5 mm [e.g., epoxy resin (EP) [2]]. Typical thick coatings are bituminous materials [3] and polyolefins [e.g., polyethylene (PE) [4]], thick coating resin combinations [e.g., EP tar and polyurethane (PUR) tar [2]] as well as heat-shrinkable sleeves and tape systems [5]. 

Different materials can be used such as nylon, polyester (TS), and epoxy, but TS polyurethane (PUR) is predominantly used. Almost no other plastic has the range of properties of PUR. Modulus of elasticity range in bending is 200 to 1,400 MPa (29,000-203,000 psi) and heat resistance from 90 to over 200°C (122-392°F). The higher values are for chopped glass-fiber-reinforced RIM (RRIM). 

Polyurethanes (PURs) are usually described as being prepared by the reaction of diols with diisocyanates. However, this is an oversimplification because often water is deliberately added in the production of flexible polyurethane foams. Unreacted isocyanate groups react with water to form carbon dioxide and urea groups in the polymer chain. The carbon dioxide acts as a blowing agent in the production of PUR foams. Also, polyurethanes can be formed by the reaction of bischloroformates with diamines. 

In order to validate sliding spark spectrometry results, plastic material was collected and the element concentration was determined via AAS after digestion. The samples were used as calibration standards. Additional standards were obtained by manufacturing known amounts of additives in the polymer matrix. Calibrations were made for Cd, Cr, Pb, Zn, Sb, Si and Ti in chlorine-free polymers Al, Ba, Ca, Cd, Pb, Sn, Ti, Zn in PVC chlorine (as PVC) and bromine in polyurethane (PUR). A calibration curve for Br as a flame retardant in PUR is shown in Figure 8.5. 

Polyurethane (PUR) is one of the most versatile plastics, due to the wide variation of the starting materials and by the use of practically all processing methods known in the plastics sector. Basically, what has been said in relation to the plastics considered so far can be applied to coloring PUR. 

The reactor is an aerobic, plug flow, packed-bed biofihn reactor. Reticulated polyurethane (PUR), a foam with large surface area, is used as the substrate for microorganisms. The substantial area available on the PUR for contact results in a high biomass concentration and thus high reaction rates at short retention times. Biopur can be used in conjunction with soil vapor extraction technology. 

Dentures acrylic, ultrahigh molecular weight polyethylene (UHMWPE), epoxy Facial prosthesis acrylic, PVC, polyurethane (PUR)... 

PBDEs are used in different resins, polymers, and substrates at levels ranging from 5 to 30% by weight (EU 2001). Plastic materials that utilize PBDEs as flame retardants include ABS polyacrylonitrile (PAN) polyamide(PA) polybutylene terephthalate (PBT) polyethylene (PE) cross-linked polyethylene (XPE) polyethylene terephthalate (PET) polypropylene (PP) polystyrene (PS) high-impact polystyrene (HIPS) polyvinyl chloride (PVC) polyurethane (PUR) and unsaturated polyester (UPE). These polymers and examples of their final products are summarized inTable 5-2 (Hardy 2002 WHO 1994a). 

Example 12.10. Polyurethane (PUR) foams are widely used in the building industry. The name refers to the fact that its monomer contains urethane ( 0-CO-NH ) as a functional group. The polymer is usually made from diisocyanates. Isocyanates are molecules which have a N=C=0 group attached. Upon addition of water the reaction shown in Fig. 12.16 starts. 

The temperatures used in RIM are also significantly lower. With polyurethanes (PURs), the intermediates normally are processed at temperatures between 75 and 120F and the mold is usually between 130 and 170F (266 to 338F). These lower temperatures obviously require significantly less energy consumption than competitive processes. 

AMS 3569A-88 Foam, Flexible Polyurethane (PUR), Open Pore, Polyvinylchloride Coated, 9 pp... 

BS 4840 1985 Specification for Rigid Polyurethan (PUR) Foam in Slab Form... 

BS 5241 Specification iot Rigid Polyurethane (PUR) and Polyisocyanu-rate (PIR) Foam When Dispensed or Sprayed on a Construction Site... 

BS 6586 1985 Bigid Polyurethane (PUR) Foam Produced by the Press Injection Method... 

The Danish minister of environment in 1988 announced that within a few years the manufacture and use of polyvinyl chloride (PVC) products had to be reduced as much as technically and economically possible due to their environmental impacts of production, use, and disposal. This preventive environmental policy was mainly based on the emission of hydrogen chloride and dioxins from waste incineration. A study of the technical, economic, and environmental consequences of a substitution was initiated by the National Agency of Environmental Protection. The goal was to collect background data for the upcoming negotiations between the environmental authorities and PVC-industry and manufacturers of PVC products in Denmark. The environmental assessment focused on PVC and 11 alternative materials, such as polyethylene (PE), polypropylene (PP), polyethylene terephtalate (PET), polystyrene (PS), polyurethane (PUR), synthetic rubbers (EPDM, CR and SBR), paper, impregnated wood, and aluminum. ... 

Plastics with a carbonyl group can be converted to monomers by hydrolysis or glycolysis. Condensation polymers such as polyesters and nylons can be depolymerized to form monomers. For Polyurethanes (PURs), what is obtained is not the initial monomer, but a reaction product of the monomer diamine, which can be converted to diisocyanate. For PURs. hydrolysis is attractive as they can be easily broken down to polyols and diamines. The only issue is to separate them later. Steam-assisted hydrolysis has been shown to yield 60 to 80 percent recovery of polyols from PUR foam products. A twin screw extruder can be used as a reactor for hydrolysis. Glycolysis of PURS, yields mixture of polyols that can be reused directly. 

Polyurethane PUR Good NVH dampening, good elasticity, low heat conductivity Seat upholstery, jounce bumpers, dash and roof padding, exterior elements... 

The annual capacity of the United States to manufacture phosgene is about 2 billion lb, and the unit price is 0.55 (per pound 1993). The gas is packaged in 1-ton returnable containers that cost about 3,000 each. Most of the demand of about 1.6 billion lb is consumed in the production of polyurethane (PUR) followed by the production of polycarbonates (PC) [85]. 

Most of the current demand of 1.6 billion lb of phosgene is used by the polyurethane (PUR) industry, and most of it is produced for captive use because of its hazardous nature and the consequently high shipping and insurance costs [85]. 

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