Styrene copolymers pyrolysis

Combination techniques such as microscopy—ftir and pyrolysis—ir have helped solve some particularly difficult separations and complex identifications. Microscopy—ftir has been used to determine the composition of copolymer fibers (22) polyacrylonitrile, methyl acrylate, and a dye-receptive organic sulfonate trimer have been identified in acryHc fiber. Both normal and grazing angle modes can be used to identify components (23). Pyrolysis—ir has been used to study polymer decomposition (24) and to determine the degree of cross-linking of sulfonated divinylbenzene—styrene copolymer (25) and ethylene or propylene levels and ratios in ethylene—propylene copolymers (26). 

T. Bhaskar, K. Murai, T. Matsui, M.A. Brebu, M.A. Uddin, A. Muto, Y. Sakata, and K. Murata, Studies on thermal degradation of acrylonitrile-butadiene-styrene copolymer (ABS-br) containing brominated flame retardant, J. Anal. Appl. Pyrolysis, 70(2) 369-381, December 2003. 

Thermoset plastics have also been pyrolysed with a view to obtain chemicals for recycling into the petrochemical industry. Pyrolysis of a polyester/styrene copolymer resin composite produced a wax which consisted of 96 wt% of phthalic anhydride and an oil composed of 26 wt% styrene. The phthalic anhydride is used as a modifying agent in polyester resin manufacture and can also be used as a cross-linking agent for epoxy resins. Phthalic anhydride is a characteristic early degradation product of unsaturated thermoset polyesters derived from orf/io-phthalic acid [56, 57]. Kaminsky et al. [9] investigated the pyrolysis of polyester at 768°C in a fiuidized-bed reactor and reported 18.1 wt% conversion to benzene. 

The actual temperature acquired by the sample during pyrolysis can be monitored using optical pyrometry or can be standardized between different pyrolyzers using a model compound. The procedure is based on the dependence of the composition of the pyrolysis products on temperature. One such compound chosen as a standard is an isoprene/styrene copolymer, trade name Kraton 1107 [15] (see Section 4.2). 

Numerous other copolymers of styrene are known, such as poly(acrylonitrile-co-styrene-co-ethylene), or poly(methyl methacrylate-co-butadiene-co-styrene), which is utilized in making blister-packaging, disposable medical instruments, containers, etc. The frequent utilization of styrene copolymers in practice has been associated with a considerable number of studies regarding pyrolysis and thermal behavior of these copolymers [68-86]. Some of these studies are summarized in Table 6.2.3. 

Polymers like polyoxymethylene (POM) and polyethylene terephthalate (PTFE, Teflon), do not form hydrocarbon compounds during combustion and do not exhibit an inclination towards formation of soot. Polyolefins, which form predominantly aliphatic hydrocarbons during pyrolysis, are less inclined to form soot than others like PS, styrene copolymers or ABS, which produce aromatic hydrocarbon [131]. 

METHOD 95 - DETERMINATION OF STYRENE AND METHACRYLATE UNITS IN STYRENE-METHYL MET ACRYLATE AND STYRENE N-BUTYL METHACRYLATE COPOLYMERS. PYROLYSIS - GAS CHROMATOGRAPHY... 

Determination of styrene and methacrylate units in styrene-methyl methacrylate and styrene n-butyl methacrylate copolymers. Pyrolysis-gas chromatography 415... 

Zaikin, V.G., Mardanov, R.G. etal. (1990) Pyrolysis-gas chromatographic/mass spectrometric behaviour of polyvinylcy-clohexane and vinylcyclohexane-styrene copolymers. /. Anal Appl Pyrolysis, 17, 291. 

Products obtained by pyrolysis of other polymers is reviewed in Table 4.5. Some specific applications of the chromatography-MS technique to various types of polymers include the following PE [34,35], poly(l-octene) [29], poly(l-decene) [29], poly(l-dodecene) [29], CPE [36], polyolefins [37, 38], acrylic acid-methacrylic acid copolymers [39, 40], polyacrylate [41], nitrile rubber [42], natural rubbers [43, 44], chlorinated natural rubber [45, 46], polychloroprene [47], PVC [48-50], polysilicones [51, 52, 53], polycarbonates [54], styrene-isoprene copolymers [55], substituted olystyrene [56], PP carbonate [57], ethylene-vinyl acetate [58], Nylon 66 [59], polyisopropenyl cyclohexane-a-methyl styrene copolymers [60], cresol-novolac epoxy resins [61], polymeric flame retardants [62], poly(4-N-alkyl styrenes) [63], polyvinyl pyrrolidone [64], polybutyl-cyanoacrylate [65], polysulfides [66], poly(diethyl-2-methacryl-oxy) ethyl phosphate [67, 68], polyetherimide [69], bisphenol-A [70], polybutadiene [71], polyacenaphthalene [72], poly(l-lactide) [73], polyesterimide [74], polyphenylene triazine [75], poly-4-N-vinyl pyridine [76], diglycidylether-bisphenol-A epoxy resins [77], polyvinylidene chloride [78] and poly-p-chloromethyl styrene [79]. 

Figure 12.8 Mia ocolumn size exclusion chromatogram of a styrene-aaylonitrile copolymer sample fractions ti ansfeired to the pyrolysis system are indicated 1-6. Conditions fused-silica column (50 cm X 250 p.m i.d.) packed with Zorbax PSM-1000 (7p.m 4f) eluent, THF flow rate, 2.0 p.L/min detector, Jasco Uvidec V at 220 nm injection size, 20 nL. Reprinted from Analytical Chemistry, 61, H. J. Cortes et al, Multidimensional chromatography using on-line microcolumn liquid chromatography and pyrolysis gas chromatography for polymer characterization , pp. 961 -965, copyright 1989, with peimission from the American Chemical Society.

Figure 12.9 Typical pyrolysis chromatogram of fraction from a styrene-acTylonitiile copolymer sample obtained from a miciocolumn SEC system 1, acrylonitrile 2, styrene. Conditions 5 % Phenylmetliylsilicone (0.33 p.m df) column (50 m X 0.2 mm i.d.) oven temperature, 50 to 240 °C at 10 °C/min carrier, gas, helium at 60 cm/s flame-ionization detection at 320 °C make-up gas, nitrogen at a rate of 20 mL/min. P indicates tlie point at which pyrolysis was made. Reprinted from Analytical Chemistry, 61, H. J. Cortes et ai, Multidimensional cliromatography using on-line microcolumn liquid cliromatography and pyrolysis gas cliromatography for polymer characterization , pp. 961-965, copyright 1989, with permission from tlie American Chemical Society.

F.C. Y.Wang and P.B. Smith, Quantitative analysis and structure determination of styrene/ methyl methacrylate copolymers by pyrolysis gas chromatography, Anal. Chem., 68, 3033 3037(1996). 

Typical chromatograms were observed when polystyrene was py-rolyzed in air and the pyrolytic products were analyzed by gas chromatography. A characteristic peak which was observed on the chromatograms obtained by the pyrolysis of maleic anhydride and the alternating styrene maleic anhydride copolymer but not with polystyrene was used as a reference peak. As shown in Table II, the ratio of the area under... 

It has been reported that pyrolysis gas chromatographic techniques could be used to differentiate between block and random copolymers (18). However, it was not possible to distinguish between the block copolymers and mixtures of polystyrene and the alternating copolymers of styrene and maleic anhydride by the PGC technique used in this investigation. However, differences were noted in the DTA thermograms of the alternating copolymer, the block copolymer, and the mixture of polystyrene and the alternating copolymer. 

In a typical reaction, initial concentrations of NIPAM, styrene, CTAB, KPS, and TMEDA are 0.16 M, 5.24 mM, 17.3 mM, 0.34 mM, 0.67 mM, respectively. The styrene content (3.9 mol %) of the resultant segmented PNIPAM-seg-St copolymer can be determined by pyrolysis gas chromatography. The average degree of polymerization between two styrene segments can be over a wide range, mainly depending on the initial NIPAM/styrene ratio. The resultant copolymer can be purified and fractionated by a number of successive dissolution-and- precipitation cycles in a mixture of extremely dried... 

Pyrolysis gas chromatography can be used to determine the acrylonitrile content of the SAN copolymer [7-9]. It is a method that heats the polymer above the decomposition temperature, then separates and identifies the low molecular weight compounds formed. The primary decomposition products are styrene, acrylonitrile, and propionitrile, and the styrene content of the copolymer is directly proportional to the styrene yield from pyrolysis [8]. 

Vukovic R and Gnjatovic V (1970) Characterization of styrene-acrylonitrile copolymer by pyrolysis gas chromatography. J Polym Sci, Part A-l 8 139-46. 

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