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The preparation of methacrylate esters by transesterification with ion-exchange resins as acidic catalysts and n-butanol as the reactant alcohol is described. Conventional cellular cation exchangers have been used together with a resin having a solid centre and a reactive outer surface. The latter resin is of lower capacity but the reaction rate compares favourably with that of conventional resins while its performance on repeated use is vastly superior.

An extensive bibliography on the pyrolysis gas chromatography of coating materials is presented. The analysis of homopolymers, copolymers, of microstructure and end groups are included. The two latter tabulations refer to simple polymer systems, but the procedures are applicable to coating materials. References concerning pyrolytic alkylation and reactive degradation are included as separate tabulations.

The review considers the degradative analysis of polymers in association with chromatography. The work indicates very briefly the scope of polymer pyrolysis, the necessary parameters to be controlled and includes some recent advances in polymer pyrolysis with a detailed treatment of the application of chemical degradation to the identification of polymers. Pyrolytic methylation, a newer application which effectively is a combination of the two techniques described, is included. This procedure carries out in situ, part of the derivatization conducted with the chemical degradation procedure.

The analysis of high performance polymers, because of their very properties of thermal stability and insolubility, will always be a difficult task. This analysis is even further complicated by the presence of fillers and other reinforcing materials. This paper describes a relatively simple procedure of preliminary hydrolytic fusion followed by chemical work-up and gas chromatography that enables the analysis of these materials to be successfully achieved. This success was shown by the analysis of a series of filled polyphthalamide samples.

On passe en revue les methodes de decomposition chimique applicables pour l'analyse de systemes de resines reactives utilises dans les revetements : resines alkydes modifiees a l'huile, polyesters silicones, condensats alkyde-aminoplaste, resines et stratifies renforces de fibres de verre, polyurethannes, esters vinyliques, polyamides dimeres, resines epoxydes.

The dispersion and selectivity indices of a series of n-alkyl- and 1-(alkyl)m(alkyl)n benzenes were determined using retention inde values determined on a non-polar (DB-1) and a polar (DB-wax) fused-silica capillary column. The effect of the individual groups and the multiple alkyl substituents and their position on the alkyl chain are discussed in terms of the relevant polar interactions.

An improved design of a reactor for alkaline fusion as a preliminary to chromatographic analysis is described. The reactor allows the use of a significantly reduced sample size, minimizes leakages and facilitates the removal of the reaction products. The use of the reactor is demonstrated by the analysis of several polyester samples exhibiting increased hydrolytic stability.

The preparation and gas chromatographic behaviour of simple alkyl borate and boronate esters is reported. Difficulties with the gas chromatography of some of these esters, the rearrangements that occur with the boronate esters and the formation of cyclic and acyclic boronates were investigated. The effect of the alkyl substituent on retention when adjacent to a boron or oxygen atom has been considered and the effects are discussed in relation to the behaviour of other ester series.

Analyse par fusion alcaline-chromatographie gazeuse d'un copolymere PDMS-polycarbonate du bisphenol A. Apres coupure, les fragments bisphenol A sont identifies sous la forme de diacetate de bisphenol A. Le methane derive des groupes methyl du PDMS est dose par chromatographie gaz-solide. La coupure du copolymere peut aussi etre faite par fusion acide avec un temps de reaction important

The retention behaviour of fourteen solutes, possessing a wide range of polarity, and fiven-alkanes was investigated using various percentage loadings ofpolyethylene glycol 400 as stationary phase on two diatomaceous supports of different adsorptivity. Retentions were measured as Kova´ts retention indices and specific retention volumes, in order to compare the dependences of absolute and relative retentions on phase loading. For all the solutes examined the values of the retention index decrease with a reduction in phase loading, suggesting a decrease in phase polarity. In contrast, the polar test solutes display slight increases in specific retention whereas those of then-alkanes increase enormously as the phase loading is decreased and thereby giving rise to the observed large shifts in retention index. In order to explain the phase loading dependence of retention index with polar stationary phases an elution mechanism involving a significant contribution of gas—liquid interfacial adsorption is proposed.

The major areas of chromatography, both gas (GC) and high-performance liquid chromatography (HPLC), have found little direct application for polymers. Molecular weights and their distributions have been determined by size-exclusion techniques (SEC) but analytical procedures have not been possible. Some condensation polymers have traditionally been analysed by gravimetry after chemical cleavage. Many such polymers are of considerable chemical stability and it has been shown that vigorous chemical reactions will effect cleavage. The products or their derivatives are conveniently estimated using the appropriate chromatographic technique. The degradation reactions used are hydrolysis or ether cleavage, either singly or simultaneously, with strong alkaline and acid reagents.

This work describes the analysis of coating materials using gas chromatography (GC). An element of volatility is necessary for samples to be amenable to the technique and early applications concerned the analysis of solvents and their mixtures. The examination of low molecular weight and volatile components of coatings followed; these included trace or residual products in resins. The resinous or binder components are essentially nonvolatile, and to be amenable to GC a considerable reduction in molecular weight is necessary. This has been achieved by chemical cleavage of condensation systems, with examination of the reconstituted reactants or their derivatives, or by thermal means in the absence of oxygen where pyrolysis provides fragments which may be related to the initial composition. Chemical cleavage was applied to alkyd resins, acrylics, polysiloxanes, polyurethanes and polyethers during the 1960s and while the results were most satisfactory, the time required was considered excessive. Several decades later, some of the problems have been eliminated but the procedures have found little application. Pyrolysis was also introduced at the same time and while the early reports were of low reproducibility, refinements in technique allow reproducible results to be achieved rapidly. The major area of the application of GC to coating materials is pyrolysis, where, in combination with mass spectroscopy (MS), valuable information is achieved in minutes. Other coating applications of GC include inverse chromatography which has found negligible use and headspace chromatography which is widely used in determining the source of odors or taints in coated food packaging. Special applications of GC include use in forensic science where accelerants used by arsonists are readily detected and also examination and identification of paint flakes by pyrolysis GC/MS. Similarly pyrolysis techniques are used in conservation studies, with the analysis of old paints on art works.

A synthesis of 2-methyl-1,3-pentadiene from 4-methyl-4-methoxy-2-pentanol is reported, in which a single reaction produces a pure product in good yield.

The linearity of the relationship between retention data and carbon number for homologous series of oxygn-containing organic compounds has been investigated for the series of Porapak porous polymers in gas chromatography. A marked deviation from linearity occurs with the lower members of normal alcohols, aldehydes, acetates and methyl ketones.

Dead-time have been calculated by an iterative procedure using data for four homologous series of different functional classes each determined on four stationary phases of varying polarity. No statistical difference was found between the mean dead-times calculated from the four homologous series on each stationary phase. The series included the n -alkanes which are the only compounds that have been previously considered for this determination. The dead-time calculated from n -fatty acid esters was computed and its usefulness in the computer processing of data obtained from an automated gas chromatograph described.

Retention indices of halogenated derivatives of cyclohexane, benzene and anisole are reported on the low polarity hydrocarbon stationary phase C87H176 developed by Kovats and on the polar stationary phases, Carbowax 20M and tetrakis(2-cyanoethoxy)butane. Retention increments due to the molecular structure and size of the pendant groups together with the effect of increasing stationary phase polarity and concepts of additivity are discussed and compared with limited earlier reports as available.

Polysiloxane stationary phases developed and used in the Soviet Union are described in detail, probably for the first time in the Western literature. Materials comparable to those produced by Western specialty chromatographic suppliers are included; polysiloxanes particularly suitable for high-temperature use are available in the Soviet Union and comparable materials are not available elsewhere. The effect of adsorption on the determination of McReynolds constants of stationary phases is discussed.

Discussion sur le calcul du temps mort qui mene a des contradictions; on presente deux interpretations

The qualitative analysis of linear silicone polyester resins after alkali fusion is described. The identification of all fragments of the resins i.e. polyol, carboxylic acid, silicate, methane and benzene is achieved by gas chromatography. Polyol, carboxylic acid and silicate fragments are separated simultaneously as their trimethylsilyl derivatives.

The analysis of acetate acrylic and acrylic copolymers systems is described. Much useful information is rapidly obtained by infra‐red spectrophotometry and pyrolysis gas chromatography, however quantitative analyses generally require the polymer material to be cleaved by chemical means with subsequent identification of the fragments by gas chromatography.

The analyses of the alkyd components of cross-linked aminoplast resin systems including urea—formaldehyde have been reported. Chemical cleavage of the ether groups cross-linking the two resins and hydrolytic cleavage of the alkyd was achieved by reaction with p -toluenesulphonic acid—acetic anhydride, orthophosphoric acid or acetic anhydride—acetic acid reagents. The alkyd constituents were identified and the aminoplast remained as insoluble salts. The cleavage is reported here of both the urea—formaldehyde and alkyd components of a cross-linked system by reaction with trifluoroacetic anhydride—trifluoroacetic acid. The reaction products were examined as appropriate derivatives using gas—liquid and gas—solid chromatography.

A series of five simple and inter-related extrathermodynamic relationships developed by Fellous and co-workers with several series of ethers and suggested to be applicable to homologous series of any functional class have been examined with an extensive series of alkyl esters. The low-polarity esters with alkyl substituents which are not equivalent as are those the ethers, present a more realistic series to determine general application.

A general procedure for the rapid analysis of resinous polyamides is reported. The various acidic and amine fragments are identified after cleavage with molten alkali. Mono- and dicarboxylic acids are analysed as methyl esters and the diamines either in the free state or as trifluoroacetyl derivatives.

An analytical procedure is described for the rapid qualitative analysis of polyurethane elastomers, based on polycaprolactonediols (CAPA). These thermoplastic polyurethanes are a complex reaction product of an isocyanate-terminated linear CAPA-based polyester prepolymer, extended with a 1,4-butanediol chain extender. The polymer is cleaved into the corresponding diamine, polyether, 6-hydroxycaproic acid, and 1,4-butanediol fragments by alkali fusion at high temperature. The fragments formed were analysed by gas and size-exclusion chromatography, after separation and derivatization. The polyethers were further cleaved into the corresponding polyol acetates by using a mixed anhydride reagent, before the gas chromatographic analysis.

The values of substance polarity factors for several series of homologous compounds have been reported. These factors have previously only been considered in the introductory work of Rohrschneider, where with thirty compounds selected to cover a wide range of functional classes it was not apparent if the values had any real significance. The calculations here include the mathematical corrections of Leary and of Souter and the values of the various terms in relation to the various structures are discussed.

An examination of the hydrocarbon C87H176 (24,24-diethyl-19,29-dioctadecylheptatetracontane) developed by Kovats as a standard stationary phase is reported. The hydrocarbon is compared with squalane and dimethylpolysiloxane and a thermal stability equal to that of the siloxane is apparent at both 120° and 180° determined by repetitive measurement of McReynolds constants. Some discussion is also included of a further recently described hydrocarbon produced by exhaustive hydrogenation of Apiezon M, which exhibits McReynolds constants substantially identical to those of squalane, is apparently thermal stable to 200° and may well be of lower cost.

The pyrolytic degradation of copolymers and homopolymer mixtures of styrene, methyl acrylate, α-methylstyrene, and methyl methacrylate has been examined using a Curie Point pyrolysis system. The pyrolysis behaviour at several temperatures allows copolymers and mixtures to be distinguished. The essentially individual behaviour of homopolymers is observed and the concept of fragmentation indices as proposed for acrylic systems is considered.

This work reports the analysis of crosslinked aminoplast alkyd and epoxy amine systems and their components particularly the silicone polyesters. Aminoplast alkyd systems have been cleaved by reaction with an acetic anhydride/paratoluene sulphonic acid reagent with simultaneous hydrolysis of the alkyd resin. The use of trifluoroacetic anhydride/trifluoroacetic acid allowed both cleavage of the alkyd and of the butylated urea-formaldehyde resin. Silicone-modified polyesters containing vegetable oil and oil-free types have been hydrolysed using acidic degradation. The reaction products were analysed both after separation into dicarboxylic and hydroxylic functional classes and in admixture. The silicon in the polysiloxane intermediate may be identified as the trimethylsilylether derivative. The results of continuing studies on epoxy resins and epoxy amine systems are discussed.

The linearity of the relationship between the logarithm of the corrected retention time and the carbon number of C1C7 n-alkanes is examined using gas—liquid and gas—solid chromatography. The effective carbon number of methane is shown to be variable but in most instances is substantially closer to unity than the value of 0.5 reported previously.

The analyses of resinous polyamides has been very limited; the sole available work would appear to be a cooperative IUPAC study where the overall results were generally poor, particularly considering the effort devoted to the study. The examinations reported employed chemical analyses of the samples as received and after hydrolysis, together with instrumental analyses using IR and NMR spectroscopy and gas and gel permeation chromatography. A successful procedure for the rapid analyses of these IUPAC polyamides has been developed in which cleavage is carried out using alkali fusion rather than the prolonged acidic hydrolysis procedures previously used. The various acidic and amine fragments produced have been identified after formation of methyl esters of the dicarboxylic acids and trifluoracetyl derivatives of the diamines using gas and gel permeation chromatography. The limitations of examination of the free diamines is described.

On passe en revue la degradation chimique simple et les reactions de fusion d'un grand nombre de polymeres industriels