Pyrolysis rubber

Rubber recycling has been extended to the use of mbber in asphalt (qv), scrap mbber as fuel, mbber pyrolysis, tine spHtting, and other uses. 

IRB 7, N-234, Ensaco250 Used to rubber industry PFO Pyrolysis fuel oil 4. Conclusion... 

An assortment of small corks for closing small bore tubing can, in addition, be very useful. If the flame is to come near to a cork or a rubber stopper it is best to wrap either in thin asbestos paper before inserting into the tube. When pyrolysis of the cork or rubber stopper seems probable it is best to use a cork and not a rubber stopper, because the pyrolysis products from a cork can be cleaned olf more easily than those from rubber. Sometimes a plug made from damp asbestos paper is adequate for closing a tube of small bore, and this plug can be heated quite strongly. 

Analysis of natural rubber Analysis of synthetic mbber Oils-characterisation-CC Rubber chemicals-Infrared Rubber chemicals-Ultraviolet Antidegradant-TLC Rubber-Pyrolysis GC Rubber identification by IR spectrophotometry Ct2, Br2, I2 by oxygen flask... 

Conventional rubber compound analysis requires several instrumental techniques, in addition to considerable pretreatment of the sample to isolate classes of components, before these selected tests can be definitive. Table 2.5 lists some general analytical tools. Spectroscopic methods such as FTIR and NMR often encounter difficulties in the analysis of vulcanised rubbers since they are insoluble and usually contain many kinds of additives such as a curing agent, plasticisers, stabilisers and fillers. Pyrolysis is advantageous for the practical analysis of insoluble polymeric materials. 

Table 2.7 lists techniques used to characterise carbon-blacks. Analysis of CB in rubber vulcanisates requires recovery of CB by digestion of the matrix followed by filtration, or by nonoxidative pyrolysis. Dispersion of CB within rubber products is usually assessed by the Cabot dispersion test, or by means of TEM. Kruse [46] has reviewed rubber microscopy, including the determination of the microstructure of CB in rubber compounds and vulcanisates and their qualitative and quantitative determination. Analysis of free CB features measurements of (i) particulate and aggregate size (SEM, TEM, XRD, AFM, STM) (ii) total surface area according to the BET method (ISO 4652), iodine adsorption (ISO 1304) or cetyltrimethylammonium bromide (CTAB) adsorption (ASTM D 3765) and (iii) external surface area, according to the dibutylphthalate (DBP) test (ASTM D 2414). TGA is an excellent technique for the quantification of CB in rubbers. However, it is very limited in being able to distinguish the different types of... 

Scheme 2.1 BFGoodrich rubber separation and analysis scheme. After Lattimer [76]. Reprinted from Journal of Analytical and Applied Pyrolysis, 26, R.P. Lattimer, 65-92, Copyright (1993), with permission from Elsevier...

Okumoto [89] has reported an analytical scheme (Scheme 2.8) for automotive rubber products (ENB-EPDM vulcanisates). For high-resolution PyGC analysis, organic additives are first removed from the rubber/(CB, inorganics) formulation. Carbon-black and inorganic material hardly interfere with pyrolysis. For the analysis of the additives the extracted soluble... 

Alternative approaches consist in heat extraction by means of thermal analysis, thermal volatilisation and (laser) desorption techniques, or pyrolysis. In most cases mass spectrometric detection modes are used. Early MS work has focused on thermal desorption of the additives from the bulk polymer, followed by electron impact ionisation (El) [98,100], Cl [100,107] and field ionisation (FI) [100]. These methods are limited in that the polymer additives must be both stable and volatile at the higher temperatures, which is not always the case since many additives are thermally labile. More recently, soft ionisation methods have been applied to the analysis of additives from bulk polymeric material. These ionisation methods include FAB [100] and LD [97,108], which may provide qualitative information with minimal sample pretreatment. A comparison with FAB [97] has shown that LD Fourier transform ion cyclotron resonance (LD-FTTCR) is superior for polymer additive identification by giving less molecular ion fragmentation. While PyGC-MS is a much-used tool for the analysis of rubber compounds (both for the characterisation of the polymer and additives), as shown in Section 2.2, its usefulness for the in situ in-polymer additive analysis is equally acknowledged. 

If additional information pertaining to the rubber composition were sought, FTIR analysis of the pyrolysis products would have been performed. Even more detailed analysis can be obtained by gas chromatography (GC) separation of the multiple pyrolysis products followed by mass spectrometric (MS) detection. The gas chromatography-mass spectrometry (GC-MS) method is well suited to deformulation and contaminant analysis. 

GC is used in rubber analysis to obtain polymer type information by use of a pyrolysis approach, also to identify some additives. 

Membranes with extremely small pores ( < 2.5 nm diameter) can be made by pyrolysis of polymeric precursors or by modification methods listed above. Molecular sieve carbon or silica membranes with pore diameters of 1 nm have been made by controlled pyrolysis of certain thermoset polymers (e.g. Koresh, Jacob and Soffer 1983) or silicone rubbers (Lee and Khang 1986), respectively. There is, however, very little information in the published literature. Molecular sieve dimensions can also be obtained by modifying the pore system of an already formed membrane structure. It has been claimed that zeolitic membranes can be prepared by reaction of alumina membranes with silica and alkali followed by hydrothermal treatment (Suzuki 1987). Very small pores are also obtained by hydrolysis of organometallic silicium compounds in alumina membranes followed by heat treatment (Uhlhom, Keizer and Burggraaf 1989). Finally, oxides or metals can be precipitated or adsorbed from solutions or by gas phase deposition within the pores of an already formed membrane to modify the chemical nature of the membrane or to decrease the effective pore size. In the last case a high concentration of the precipitated material in the pore system is necessary. The above-mentioned methods have been reported very recently (1987-1989) and the results are not yet substantiated very well. 

Not only hydrocarbon systems, but also silicon rubbers (Lee 1986), can be pyrolyzed to obtain silicon-based membranes. Details of the pyrolysis are mainly reported for nonmembrane applications. A recent example is the paper of Boutique (1986) for the preparation of carbon fibers used in aeronautical or automobile constructions. 

Lee, K. H. and S. J. Khang. 1986. A new silicon-based material formed by pyrolysis of silicon rubber and its properties as a membrane. Chem, Eng. Common. 44 121-32. 

Prior to the discovery of the vulcanization or cross-linking of hevea rubber with sulfur by Goodyear in 1838, Faraday has shown that the empirical formula of this elastomer is CsHg making it a member of the terpene family. The product obtained by pyrolysis of rubber was named isoprene by Williams in 1860 and converted to a solid (polymerized) by Bouchardat in 1879. 

Gas chromatography (GC) and mass spectrometry (MS) can be coupled to the TGA instrument for online identification of the evolved gases during heating pyrolysis-GC/MS is a popular technique for the evaluation of the mechanism and the kinetics of thermal decomposition of polymers and rubbers. Moreover, it allows a reliable detection and (semi)quantitative analysis of volatile additives present in an unknown polymer sample. 

Enerco, Inc. (Yardley, Pennsylvania) has a 600 tire/d demonstration pyrolysis plant located in Indiana, Pennsylvania. The facility operated 8 h/d, 5 d/wk for six months. The process involves pyrolysis in a 5.41/d batch-operated retort chamber. The heated tires are broken down to cmde oil, noncondensable gases, pyrolytic filter, steel (qv), and fabric waste. In this process, hot gases are fed direcdy to the rubber rather than using indirect heating as in most other pyrolyses. The pyrolysis plant was not operating as of eady 1996. 

Carbon black is made by the vapour-phase incomplete pyrolysis of hydrocarbons to produce a fluffy fine powder. Worldwide, about 7 million tons a year are produced. It is used as a reinforcing agent in rubber products such as tyres (20-300 nm), as a black pigment (<20 nm) in printing inks, paints, and plastics, in photocopier toner, and in electrodes for batteries and brushes in motors. 

Was first obtained by Moureau (Ref 2). Current methods of prepn include dehydration of S-hydroxypropionitrile or pyrolysis of cyano-ethylacetate(Ref 5). It is somewhat poisonous and sustained exposure to its vapors should be avoided (Refs 4,5,7 8). It is manufd on a large scale for use in making oil-resistant artificial rubber of GR-N type, as well as plastics, etc (Refs 3,4,5 7). Absorption spectra and some other physical props are given in Ref 4 Refs 1)Beil 2,400,(186) [388] 2)... 

The thermal black process, which was developed in the 1930s, is still used for the production of coarse carbon blacks (nonreinforcing carbon blacks) for special applications in the rubber industry. Contrary to the above-described processes, energy generation and the pyrolysis reaction are not carried out simultaneously. Natural gas eventually blended with vaporized oil is used as both a feedstock and a fuel. 

Pyrolysis - [MANGANESE COMPOUNDS] (Vol 15) -in batteries [BATTERIES - PRIMARY CELLS] (Vol 3) -of benzene [BENZENE] (Vol 4) -of esters [ESTERS, ORGANIC] (Vol 9) -of lignite [LIGNITE AND BROWN COAL] (Vol 15) -of scrap tires [RECYCLING - RUBBER] (Vol 21)... 

Recycling. The methods proposed for the recycling of polyurethanes include pyrolysis, hydrolysis, and glycolysis. Regrind from polyurethane RIM elastomers is used as filler in some RIM as well as compression molding applications. The RIM chips are also used in combination with rubber chips in the construction of athletic fields, tennis courts, and pavement of working roads of golf courses. 

From the time that isoprene was isolated from the pyrolysis products of natural mbber (1), scientific researchers have been attempting to reverse the process. In 1879, Bouchardat prepared a synthetic rubbery product by treating isoprene with hydrochloric acid (2). It was not until 1954—1955 that methods were found to prepare a high ar-polyisoprene which duplicates the structure of natural rubber. In one method (3,4) a Ziegler-type catalyst of trialkylaluminum and titanium tetrachloride was used to polymerize isoprene in an air-free, moisture-free hydrocarbon solvent to an all t /s- 1,4-polyisoprene. A polyisoprene with 90% 1,4-units was synthesized with lithium catalysts as early as 1949 (5). 

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