Polymeric materials polyurethanes

ISO 5999 2007 Flexible cellular polymeric materials—Polyurethane foam for load-bearing applications excluding carpet underlay—Specification... 

About 2 X 10 Ib/year of 1 2 epoxypropane is produced in the United States as an intermediate in the preparation of various polymeric materials including polyurethane plastics and foams and polyester resins A large fraction of the 1 2 epoxypropane is made from propene by way of its chlorohydrm... 

Thermoplastic polyurethane (TPU) is a type of synthetic polymer that has properties between the characteristics of plastics and rubber. It belongs to the thermoplastic elastomer group. The typical procedure of vulcanization in rubber processing generally is not needed for TPU instead, the processing procedure for normal plastics is used. With a similar hardness to other elastomers, TPU has better elasticity, resistance to oil, and resistance to impact at low temperatures. TPU is a rapidly developing polymeric material. 

History. The first attempts to desensitize RDX were reported by Frankel and Carle ton (Refs 1 thru 5) who made use of polymeric materials such as polyurethanes to coat expl crysts by means of emulsion or soln techniques. The first true PB-RDX was developed in 1952 at the Univ of Califs Los Alamos Lab and consisted of RDX coated with polystyrene plasticized with DOP (Refs 6 21). Since then the Lawrence Livermore Lab has evolved a series of PBX formulations, many of which are listed in Tables 3,4 5. These compns are described in Ref 77... 

Thermal and thermomechanical analyses44 are very important for determining die upper and lower usage temperature of polymeric materials as well as showing how they behave between diose temperature extremes. An especially useful thermal technique for polyurethanes is dynamic mechanical analysis (DMA).45 Uiis is used to study dynamic viscoelastic properties and measures die ability to... 

The most common methods for trapping pesticide vapors from air use adsorbents. Common air sampling adsorbents include charcoal (derived from petroleum or coconut) and synthetic polymeric materials, such as cross-linked polystyrene and open-cell polyurethane foam. Charcoal has been used for the cumulative sampling of volatile... 

Various polymeric materials were tested statically with both gaseous and liquefied mixtures of fluorine and oxygen containing from 50 to 100% of the former. The materials which burned or reacted violently were phenol-formaldehyde resins (Bakelite) polyacrylonitrile-butadiene (Buna N) polyamides (Nylon) polychloroprene (Neoprene) polyethylene polytriflu-oropropylmethylsiloxane (LS63) polyvinyl chloride-vinyl acetate (Tygan) polyvinylidene fluoride-hexafluoropropylene (Viton) polyurethane foam. Under dynamic conditions of flow and pressure, the more resistant materials which binned were chlorinated polyethylenes, polymethyl methacrylate (Perspex) polytetraflu-oroethylene (Teflon). 

Polymeric materials used as fuel components of pyrolants are classified into two types active polymers and inert polymers. Typical active polymers are nitropoly-mers, composed of nitrate esters containing hydrocarbon and oxidizer structures, and azide polymers, containing azide chemical bonds. Hydrocarbon polymers such as polybutadiene and polyurethane are inert polymers. When both active and inert polymers are mixed with crystalline oxidizers, polymeric pyrolants are formed. 

Plastics are by far the largest group of polymeric materials being processed by electron beam irradiation. Cross-linking of polyolefins, PVC, polyesters, polyurethanes, fluoropolymers, and fiber-reinforced composites is a common practice. 

Amino-1,2,4-thiadiazoles79 and their 3-alkoxy-, 3-alkylmercapto-, and 3-dialkylamino derivatives84 have been claimed to be useful intermediates in the manufacture of dyes,84 pharmaceuticals,84 and materials valuable in pest control.79 Mono-azo dyes derived from diazotized 5-amino-l,2,4-thiadiazoles and coupling components of the benzene series are especially suitable for dyeing polymeric materials such as acetate rayon, polyamides, polyurethanes, polyesters, and... 

Figure 4. Microencapsulated Flavobacterium cells. The bead (10 gm diameter) is composed of alginate. Similar beads can be prepared for agar, polyurethane, and other polymeric materials. From Stormo Crawford (1992). Reprinted with permission of the American Society for Microbiology.

Syntactic foamed plastics (from the Greek ovvxa C, to put together) or spheroplastics are a special kind of gas filled polymeric material. They consist of a polymer matrix, called the binder, and a filler of hollow spherical particles, called microspheres, microcapsules, or microballoons, distributed within the binder. Expoxy and phenolic resins, polyesters, silicones, polyurethanes, and several other polymers and oligomers are used as binders, while the fillers have been made of glass, carbon, metal, ceramics, polymers, and resins. The foamed plastic is formed by the microcapsular method, i.e. the gas-filled particles are inserted into the polymer binder1,2). 

Aziridines represent another group of cyclic monomers that are capable of copolymerizing with C02 to potentially provide useful polymeric materials, namely polyurethanes. Early studies of the reactions of aziridines with C02 led to the production of cyclic urethanes [72] and polymers [73, 74], but the polymeric product was shown to consist of both urethane and amine linkages, as depicted in Equation 8.7. However, because the rate of homopolymerization of aziridines is similar to that of the copolymerization of aziridines and C02, the urethane linkages were limited to -30%. 

The results of calculations for two values of the initial temperature of the reactive mass To are shown in Fig. 4.17. For To = 70°C, the curves are practically insensitive to the value of to. This is explained by the fact that the mold temperature is lower than the initial temperature of the reactive mass (polyurethane composition) and therefore the layers of polymeric material close to the surface of the mold cool rapidly down to the temperature Ts, because this temperature is strictly constant. 

As already mentioned, there has been renewed interest for using carbohydrates as a source of chemicals since the 1980s with the development of the chemistry of furanic compounds, particularly for the preparation of nonpetroleum derived polymeric materials, such as polyesters, polyamides and polyurethanes.[17,19]... 

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