Phenol-formaldehyde resin, pyrolysis

A hard carbon with high capacity can be made from epoxy novolac resin [12]. The epoxy resins used cost about US 2.50 per pound and give pyrolysis yields between 20 and 30%. However, it is well known that phenolic (or phenol-formaldehyde) resins can be pyrolyzed to give hard carbons with a yield of over 50% [42]. In addition, these resins cost about USSl.OO per pound. Phenolic resins therefore offer significant cost advantages over epoxy resins, so we... 

Finally, it is important to note that it is possible to produce carbon sorbents with dehganding properties from different materials. In Table 29.4 this is demonstrated for granulated activated carbon Novocarb (MAST Carbon International, US Patent 20020176840A1, Nov. 2002) prepared by pyrolysis of phenol-formaldehyde resins, and coconut shell derived activated carbon ZL-150 (Huzhou Beigang Enterprises Group Corp., P.R. China). 

Glass-like carbons (glassy carbons) are produced by the pyrolysis of different precursors, such as phenol-formaldehyde resin, poly(furfuryl alcohol), cellulose, etc., through an exact control of the heating process [88,89], They are characterized by an amorphous structure and also by... 

There is a common feature of the polymer composition in PC, PPO, epoxy and phenol-formaldehyde resin, all contain phenoxy moieties in their repeating unit. Hence, it is not unexpected that the major pyrolysis products of these plastics are phenols. The reason of the production of phenolic compounds is the higher bonding energy of the C-0 linkage in the phenoxy moiety related to that of other bonds along the polymer chain. 

Pyrolysis Products of Cured Phenol-Formaldehyde Resin... 

Carbonaceous materials (CMs) are sometimes also named polymeric carbons. They are mostly prepared by thermal decomposition of organic precursors. One strategy is pyrolysis of gaseous or vaporized hydrocarbons at the surface of heated substrates, a second is heating (pyrolysis) of natural or synthetic polymers, both in an inert atmosphere. The latter is of special interest, and according to Miyabayashi et al. [374], precursors such as condensed polycyclic hydrocarbons, polymeric heterocyclic compounds, phenol-formaldehyde resins, polyacrylonitrile or polyphenylene are heated to 300-3000 °C for 0.15-20 h. Sometimes, a temperature/time profile is run. The temperature range must be divided into two domains, namely... 

The carbonaceous products were obtained by pyrolysis at temperature of AN Tp (acenaphthene) and PH (phenol-formaldehyde resin) those from were nongraphitizable. 

The same kinds of highly symmetric carbon systems for ECDLCs are also known for activated carbons [15, 249, 385], carbon blacks [33, 249], carbonaceous materials ( aerogels ) from phenol-formaldehyde resins via pyrolysis [18], and pyrolyzed PAN [430]. Another system, but with a rather low s,th> was built with two activated glassy carbon plates [240, 434] (cf. Section 7, group 6). 

ABSTRACT In cooperation with several companies different biomass waste such as wood waste, fibre sludge, cocoa shell and panel boards with a high content of phenol-formaldehyde resin have been decomposed by flash pyrolysis into small molecules. 

The mixture of organic compounds in bio oil from pyrolysis of different feedstock is shown in Table 5. It can be seen that the amount of phenols is very high in HPL-oil in comparison to others. More than 97 wt, /o of these phenols originate from phenol-formaldehyde resins from the HPL production process. Normally the phenol components have an amount below 1 wt.% in the oil. On the other hand Table 5 demonstrates a large variation in the total amount of each chemical class. 

Kelley, S. S., Wang, X.-M., Myers, M. D., Johnson, D. K., Scahill, J. W. (1997) Use of biomass pyrolysis oils for preparation of modified phenol formaldehyde resins. In Development in Thermochemical Biomass Conversion, (Ed. By... 

Carbon molecular sieves, or carbogoric sieves are amorphous materials made by pyrolyz-ing coal, coconut shells, pitch, phenol-formaldehyde resin, or other polymers. EKslocations of aromatic microdomains in a glassy matrix give their porosity. Pores are slit-shaped. Pore structure is controlled by the temperature of the pyrolysis. Pore widths range from 3 A to 10 A. Acarbogenic sieve made from polyfurfuryl alcohol and combined with silica-alumina was selective for monomethylamine production from methanol and ammonia [54]. 

Phenol-formaldehyde resins are relatively resistant to heat. They start decomposing at about 250° C still maintaining some mechanical resistance, the decomposition rate increasing significantly around 300° C. In an inert atmosphere at 750° C, phenol-formaldehyde resins form more than 50% char [2, 3]. The volatile materials consist of xylene (76%). traces of phenol, cresol, and benzene [4]. The heating in air above 300° C leads to the oxidation of the carbonaceous char and complete volatilization of the polymer [5], More information regarding pyrolysis products of phenol-formaldehyde... 

Figure 8.3.1. Pyrogram of a crosslinked phenol-formaldehyde resin sample. Pyrolysis done on 0.4 mg material at 60(f C in He, with the separation on a Carbowax type column.

FIGURE 1. Schematic representation of the pyrolysis of a phenol-formaldehyde resin, showing possible fragmentation sites leading to simple aromatic products... 

Experimental attempts to synthesize any of the polymers described above have not been successful except a preliminary preparation of poly-perylene (Murakami and Yoshimura, 1984). Alternative efforts are currently being made to obtain polyacenic material through pyrolysis of various organic polymers such as phenol-formaldehyde resin (Yamabe et al., 1983 Tanaka et al., 1984b), polyacrylonitrile (Teoh et al., 1982, 1983), and poly(p-phenylene-1,3,4-oxadiazole) (Murakami et al., 1983). The group of these pyrolytic polymers behaves rather like amorphous semiconductors and is considered to be composed of fragments of polyacene to graphite, that is, a sort of coke, coal, and so on. 

It should be emphasized that Py-GC is often very sensitive to structural differences in polymers. Depending on the similarity of the chemical structure and selection of the pyrolysis and chromatographic separation conditions, the chromatograms of the pyrolysis products (pyrograms) from test substances may feature qualitative and in some instances only quantitative differences. For example, pyrograms of phenol—formaldehyde resins obtained on the basis of 3-methylphenol and 3,5-dimethylphenol differed widely in the qualitative composition of the pyrolysis products [19], whereas with low-density (Marlex 6002) and high-density (Okiten G-03) polycthylenes, only quantitative differences in the ratios of individual products were found [20]. 

Py-GC has also been applied in studying the structures of some phenol—formaldehyde resins. The main pyrolysis products were found to correspond to individual fragments of the initial polymer molecule [254]. 

Combustion Energy Alkaline Hydrolysis or Direct AoDlications Phenol-Formaldehyde Resins, Epoxy-modified lignin, Aminated Lignin, Sulfonated Lignin, Cement, Ceramics, Emulsions, Fertilisers, Silicon Carbide Pyrolysis CO, H2, Methane, Phenol, Ethene, Benzene Alkaline Melt or Hvdroaenoivsis Phenols... 

During the thermal decomposition of phenol-formaldehyde resins, considerable quantities of volatiles (up to 50% of the initial mass) having a rather diverse composition are liberated. At temperatures up to 360 °C one may observe release of considerable quantities of propanols (up to 11% mass), acetone (6.7% mass), propylene (4.0% mass) and butanols (3.0% (mass). The non-volatile products of decomposition at temperatures up to 400 °C cause an increase in the quantity of acetone (17.6% mass) while, carbon dioxide, carbon monoxide and methane which are the major products of decomposition also begin to be released. The quantity of non-volatile pyrolysis products (molecular mass about 350) is gradually reduced to about 37% (mass) at elevated temperatures. 

Prokai [2] used pulse probe mass spectroscopy (MS) and pyrolysis-gas chromatography-mass spectroscopy (Py-GC-MS) to study the thermal decomposition of high molecular weight phenol-formaldehyde resins. He showed that degradation occurred by cleavage of the phenol-methylene bond and subsequent hydrogen abstraction to form phenol and methyl substituted phenols. 

Information about the composition of the sample material can be significantly increased if the paints have been derivatized during pyrolysis. Tetramethyl-ammonium hydroxide (TMAH) is used as a derivat-izing reagent for structure elucidation of alkyd, unsaturated polyester, epoxy, and phenol-formaldehyde resins. The derivatization of paints, whose pyrolysis products elute at very low retention times (such as formulations based on polyvinylacetate... 

TABLE 22. Composition of Gaseous Products of the Pyrolysis of Hardened Phenol-Formaldehyde Resin... 

The representative carbon precursor is the phenol formaldehyde resin, polyacrylonitrile, pitch, coke, coconut shell, wood, etc. In most cases, these precursors are activated after carbonizing (pyrolysis in inert gas). The activation process for preparing the activated carbons is classified as gas activation (physical activation) and chemical activation. These activation characteristics are summarized in Table 1. In the former, the starting carbon materials are gasified using steam or carbon dioxide gas at... 

Specifically in phenol-formaldehyde resins [100]. Polymers have been separated using pyrolysis-GC. This approach, which yields an identifiable pyro-gram suitable of being further characterised by mass spectrometry, has been successful in the separation of acrylic plastics [101], phenol-formaldehyde polycondensate [102], vulcanised elastomers [103], silane coupling agents [104], polyquinones [105], polyester, polyamide and polyethylene fibres [106], styrene-butadiene rubbers [107] and in the classification of PVC tape [108]. 

Phenol-formaldehyde resins Pulsed mode pyrolysis - Phenol, methyl-substituted phenols Cleavage of phenol-methylene bond and subsequent hydrogen abstraction [85]... 

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