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Polymers carbon products

The metabohc rate of poly(ester—amide) where x = Q has been studied in rats using carbon-14 labeled polymer. This study indicates that polymer degradation occurs as a result of hydrolysis of the ester linkages whereas the amide linkages remain relatively stable in vivo. Most of the radioactivity is excreted by urine in the form of unchanged amidediol monomer, the polymer hydrolysis product (51). [Pg.192]

Synthetic Resins. Various polymers and resins are utilized to produce some specialty carbon products such as glassy carbon or carbon foam and as treatments for carbon products. Typical resins include phenoHcs, furan-based polymers, and polyurethanes. These materials give good yields of carbon on pyrolysis and generally carbonize directly from the thermoset polymer state. Because they form Httle or no mesophase, the ultimate carbon end product is nongraphitizing. [Pg.498]

Acrolein is immediately passed through a second oxidation reactor to form acrylic acid. The reaction talces place at 475-575 E, over a tin-antimony oxide catalyst. A few by-products form, namely, formic acid (HCOOH), acetic acid (CH3COOH), low molecular weight polymers, carbon monoxide, and dioxide. But overall yields of propylene to acrylic acid are high—85 to 90%. [Pg.285]

For most commercial polymers, carbon and silicon are the two backbone building blocks, and they routinely form chains of like atoms. Generally three types of covalent bonds are associated with carbon in the production of commercial vinyl polymers, as shown in Fig. 2.5 the single, double, and triple carbon-to-carbon bonds. [Pg.31]

Polymer Chain Growth Versus Cyclic Carbonate Production. 5... [Pg.2]

Zipping-up reaction is a well known method for ladder polymer production. The most important from the practical point of view is cyclization and carbonization of polyacrylonitrile. " The mechanism of the thermal conversion of polyacrylonitrile to carbonized product has been intensively studied and it is extremely complex.The reaction can be partially treated as a template polymerization proceeding according to the reaction ... [Pg.115]

Fig. 4.3 Data of Raman spectroscopy (He-Ne laser, A,=632,8 nm) for the following samples 1 - polyvinyl chloride-polyvinylidene chloride composition after chemical dehydrochlorination (80°C, KOH in dimethyl sulfoxide -propan-2-ol 1 1, w/w) 2 - chemically dehydrochlorinated polymer carbonized in CO at 350°C 3 - carbonized product activated in CO at 950°C... Fig. 4.3 Data of Raman spectroscopy (He-Ne laser, A,=632,8 nm) for the following samples 1 - polyvinyl chloride-polyvinylidene chloride composition after chemical dehydrochlorination (80°C, KOH in dimethyl sulfoxide -propan-2-ol 1 1, w/w) 2 - chemically dehydrochlorinated polymer carbonized in CO at 350°C 3 - carbonized product activated in CO at 950°C...
As in the carbon series, this photolytic rearrangement involved a nitrene intermediate. Indeed, in the case of thio phospho-razides, beside the formation of dimers 3 and polymers, the product was characterized and arises from hydrogen abstraction from the solvent by the nitrene intermediate. [Pg.598]

In general, carbocyclic aromatic polymers yield more carbonized products than heterocyclic ones. Susceptibility of polymers to carbonization under pyrolysis conditions is characterized by the so-called coke number Van Krevelen concluded that the tendency for carbonization may be regarded as an additive resultant of the contributions of the individual functional groups in the monomer units. The contribution of a group is expressed in carbon equivalents contributed by each group to the coke residue, CR, per monomer unit ... [Pg.206]

Eliminations and other reactions do not necessarily take place only on the polymeric chain or only on the side groups. Combined reactions may take place, either with a cyclic transition state or with free radical formation. The free radicals formed during polymeric chain scission or during the side chain reactions can certainly interact with any other part of the molecule. Particularly in the case of natural organic polymers, the products of pyrolysis and the reactions that occur can be of extreme diversity. A common result in the pyrolysis of polymers is, for example, the carbonization. The carbonization is the result of a sequence of reactions of different types. This type of process occurs frequently, mainly for natural polymers. An example of combined reactions is shown below for an idealized structure of pectin. Only three units of monosaccharide are shown for idealized pectin, two of galacturonic acid and one of methylated galacturonic acid ... [Pg.25]

The polymer/zeolite host-guest precursor for preparation of porous carbon can also be obtained through direct contact of monomers in a carrier gas with zeolite molecular sieves followed by polymerization. For example, propylene can enter into zeolite Y under the carriage of N2 and polymerize to form polypropylene. After pyrolysis, the polypropylene undergoes carbonization, and the host zeolite framework of the carbonization product can be removed by dissolution in acids, leaving carbon material with characteristic pores.[93] However, the pore-size distribution of the porous carbons obtained through this approach is not uniform, and hence they are hardly used as molecular sieves for sieving small molecules. [Pg.624]


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