Thermal degradation of copolymers based on selected alkyl methacrylates

The thermal stability and thermal degradation of copolymers based on selected alkyl methacrylates at temperatures between 250 and 400?°C have been studied using pyrolysis?Cgas chromatography. The type and composition of thermal degradation products gave useful information about the mechanism of pyrolysis of copolymers synthesized by using typical commercially available alkyl methacrylates. It was observed that the main thermal degradation products from alkyl methacrylate copolymers are monomers of alkyl methacrylates using by synthesis. Other pyrolysis by-products formed during thermal degradation were carbon dioxide, carbon monoxide, methane, ethane, methanol, ethanol, and propanol-1.     

Thermal degradation of butyl acrylate-methyl acrylate-acrylic acid-copolymers

The thermal degradation of copolymers based on butyl acrylate-methyl acrylate-acrylic acid used as acrylic pressure-sensitive adhesives, especially for bonding of plasticizer containing materials, has been investigated using thermogravimetry and pyrolysis-gas chromatography at 250°C. It was observed that during the pyrolysis of butyl acrylate-methyl acrylate-acrylic acid copolymers unsaturated monomers as methyl acrylate, methyl methacrylate, butyl acrylate and butyl methacrylate were formed. During the side-chain butyl acrylate-methyl-acrylate-acrylic acid-copolymer degradation the presence of methyl alcohol and butyl alcohol was observed.     

Thermal degradation of copolymers of 2-hydroxyethyl methacrylate and alkyl methacrylates

Thermal degradation of homopolymers of ethyl methacrylate (I), n-butyl methacrylate (II), 2-hydroxyethyl methacrylate (III), and copolymers of III with I and II were carried out by thermal volatilization analysis (TVA) up to 440°C with subsequent subambient thermal volatilization analysis (SATVA). An on-line mass spectrometry coupled with TVA and SATVA was employed to identify the products of thermal degradations. Isothermal pyrolyses of the polymers were carried out separately at 400°C in vacuum for 30 min and the liquid products of decomposition were collected and analysed by gas chromatography. The relationship between the amounts of I and II obtained from pyrolysis and the amounts of these components actually present in the copolymer samples was determined. Also the amount of III and ethyleneglycol dimethacrylate obtained from pyrolysis increases with the amount of III in the copolymer. The polymers were also characterized by differential thermal analysis.     

Pyrolysis-gas chromatography of some crosslinked copolymers of styrene

The thermal degradation of copolymers of styrene, ethylstyrene and divinylbenzene with acrylonitrile and other acrylic monomers has been studied by pyrolysis-gas chromatography at 420, 570 and 790°. The thermal degradation products were identified and determined at 570°. The thermal degradation of some chloromethylated copolymers with the same composition was also followed. It has been ascertained that the chloromethylated copolymers show characteristic behaviour in thermal degradation. This is explained by modification of the degradation mechanism of the chloromethylated copolymers with respect to the development of crosslinking processes.     

Thermal degradation of poly-2-hydroxyethyl methacrylate by pyrolysis gas chromatography

The thermal degradation of linear poly-2-hydroxyethyl methacrylate and of its acetyl and methoxy derivatives was investigated by the Curie-point pyrolysis gas chromatography. The kinetic parameters of pyrolysis were determined and the formation of crosslinks during degradation, due to the hydroxyl groups present in the polymer, was proved.     

Pyrolysis of poly(2-propylheptyl acrylate)

The thermal destruction processes of poly(2-propylheptyl acrylate) take place at the range of temperature 250–950 °C was investigated using pyrolysis–gas chromatography. Knowledge of the types and amounts of pyrolysis products will provide important information about the thermal degradation of homopolymer poly(2-propylheptyl acrylate) and the mechanisms involved. Unsaturated monomers 2-propylheptyl acrylate and 2-propylheptyl methacrylate, according to by-product alkyl alcohol 2-propylheptylalcohol, alkene 2-propylheptene-1, carbon dioxide, carbon monoxide, methane, and ethane were formed during thermal degradation of poly(2-propylheptyl acrylate).     

Thermal degradation of poly(alkyl methacrylates)

The thermal degradation of selected poly(alkyl methacrylates) at temperatures between 300 and 800 °C was investigated by pyrolysis gas chromatography. Quantitative characterization of the pyrolysis products yields insights into the mechanism for thermal degradation of poly(alkyl methacrylates) under these conditions. Unsaturated monomeric alkyl methacrylates, carbon dioxide, carbon monoxide, methane, ethane, methanol, ethanol, and propanol were formed during thermal degradation of poly(alkyl methacrylates).     

Thermal degradation mechanism of methacrylonitrile-styrene copolymers on flash pyrolysis

The thermal degradation mechanisms of random copolymers of methacrylonitrile (MAN) and styrene (St) have been investigated by pyrolysis gas chromatography in the temperature range of 358 to 920?C using a Curie point pyrolyzer (JHP-2) and comparing results with the results from TG/DTA-FTIR apparatus (SII-6200, JASCO-320). The amount of St monomer from decomposition of the copolymer is higher than that from P(St) alone; whilst that of MAN monomer from copolymer is lower than that from P(MAN). This phenomenon reflects the boundary effect in the pyrolysis of copolymer. The thermal degradation mechanisms of copolymers are discussed in terms of the competition between the depolymerization and the back biting reaction on the basis of bond dissociation energies of C-C and C-H bonds in the copolymer chain.     

Thermal degradation of bromine-containing polymers. Part 9—Copolymers of 2,3-dibromopropyl methacrylate and 2,3-dibromopropyl acrylate with styrene

The products of the thermal degradation of copolymers of styrene (S) with 2,3-dibromopropyl methacrylate (2,3-DBPM) and 2,3-dibromopropyl acrylate (2,3-DBPA) have been analysed quantitatively using thermal analysis, infra-red spectroscopy, mass spectrometry and gas-liquid chromatography. The products are generally similar to those which result from the degradation of the two homopolymers and no significant interaction occurs between the two types of units in the polymer chains. The only abnormal feature is the fact that the yield of 2,3-DBPA increases as the 2,3-DBPA content of copolymers of 2,3-DBPA and S decreases but this is consistent with previous observations in related copolymer systems.     

Thermal degradation mechanisms of liquid crystalline aromatic polyesters studied by pyrolysis–gas chromatography/mass spectrometry

The thermal degradation mechanisms of liquid crystalline aromatic polyesters (LCPs) prepared from p-hydroxybenzoic acid (PHB), biphenol (BP), and terephthalic acid (TA) were studied by pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS). The LCP containing deuterated terephthalate units and the LCPs that have different comonomer ratios were examined. On the basis of the pyrolysis products determined, the origin of the main pyrolysis products (benzene, phenol, biphenyl, phenyl benzoate, etc.) from the corresponding comonomer units were estimated and their thermal degradation mechanisms were eventually discussed in detail.     

Investigation on the thermal degradation of acrylic polymers with fluorinated side-chains

The thermal degradation of poly-2,2′,3,3′,4,4′,5,5′,6,6′,7,7′,7″-tridecafluoroheptylacrylate and poly-2,2′,3,3′,4,4′,5,5′,6,6′,7,7′-dodecafluoroheptylmethacrylate has been studied in isothermal conditions at 450-750 °C using pyrolysis-gas chromatography. The type and composition of the pyrolysis products give useful information about mechanism of thermal degradation. It was shown that the main thermal degradation process for both polymers is random main-chain scission. The major degradation products for fluorinated polyacrylate are monomer, dimer, saturated diester, trimer, and corresponding methacrylate. The fluorinated polymethacrylate gives monomer as the main product of thermal destruction. As a result of side-chain reaction, the thermal degradation of the fluorinated polyacrylate also produces remarkable amounts of alcohol. On the other hand, the respective alcohol is only a minor component among the pyrolysis products of the fluorinated polymethacrylate. For both polymers, the main nontrivial degradation product coming from the alkyl ester decomposition is the corresponding fluorinated cyclohexane. The formation of the fluorinated cyclohexanes may be accounted for a nucleophilic bimolecular substitution pathway.     

Thermal degradation of amphetamine sulphate

The pyrolysis of amphetamine sulphate was studied in a laboratory flow reactor in the range 350–1000°C. The identifications and quantitative determinations of most gaseous and condensed products by means of gas chromatography and mass spectrometry made possible the suggestion of a thermal degradation scheme. The presence of sulphate in the initial molecule led to oxidation reactions in addition to the usual thermal reactions that occur during the pyrolysis of organic materials.     

Calculation of kinetic parameters and sequence distribution from pyrolysis gas chromatographic data of styrene-methyl acrylate copolymers

Styrene-methyl acrylate copolymers have been investigated by pyrolysis gas chromatography. The pyrolysis product distribution, ranging from methyl acrylate monomer to styrene trimer, was measured and introduced into a mathematical model described previously. Applying this model, the sequence distribution and the rate constants of the degradation reactions were obtained. The results show that the sequential arrangement is important in the thermal decomposition of styrene-methyl acrylate copolymers. In most cases the rate constant of a product release reaction depends considerably on the nature and sequence of the monomer units in the product molecule, as well as on the nature of the monomer unit remaining on the macroradical end, from which the molecule was released.     

Characterization of some acrylic anion-exchangers by pyrolysis-gas chromatography

Pyrolysis-gas chromatography was used in the study of the thermal behaviour of some acrylic anion-exchangers for identification of the thermal decomposition products and their percentage estimation. The acrylic anion-exchangers were prepared by aminolysis of cross-linked acrylic ester copolymer with difunctional amines. The pyrolysis-gas chromatography studies, coupled with data obtained by thermogravimetry, showed that the acrylic anion-exchangers first lose the water easily absorbed from the air, and the decomposition starts at temperatures above 100°. The great number of decomposition products identified in the pyrograms on the thermal degradation of acrylic anion-exchangers indicated a complex degradation mechanism, with important variations in the contents of the evolved amine compounds.     

Determination of multipolymer structure using pyrolysis gas chromatography

The thermal degradation of poly(styrene-butadiene-methylmethacrylate-butylacrylate)multipolymers has been investigated by Curie Point pyrolysis gas chromatography (PGC). Small multipolymer samples were pyrolysed in a stream of helium at 600° in a Curie Point pyrolyser directly connected to the gas chromatograph. The pyrolysis products were identified by mass spectrometry. The interpretation of each cluster of dimer and trimer peaks appearing on the chromatogram was carried out by using a statistical method (factor analysis) from which the molecular structure of the multipolymers was inferred.     

Thermal behavior and pyrolysis products of modified organo-layered silicates as intermediates for in situ polymerization

A systematic study on organo-layered silicate intermediates used for preparing in situ polyethylene nanocomposites was performed by pyrolysis–gas chromatography/mass spectrometry and thermogravimetric analysis. The type and composition of the pyrolysis products gave useful information about mechanism of thermal degradation. The combination of pyrolysis and thermal decomposition data allowed us to describe the evolution of the organoclay structure after the reactive pretreatment steps with alkylaluminoxane cocatalyst and zirconocene or bis(imino)pyridine iron precatalyst, respectively. A proof of the formation of heterogeneous organoclay-immobilized catalyst was obtained.     

Degradation thermique des copolymeres methacrylate de methyle-chlorure de vinylidene

The thermal degradation, under inert atmosphere, of a set of methyl-methacrylate-vinylidene chloride copolymers prepared by free radical copolymerization with constant composition conditions, is studied by thermogravimetry coupled with titration of HCl evolved and with gas chromatographic analysis of volatile products (monomers, methyl chloride). Only the formation of methyl methacrylate can be related to the sequence distribution.     

Aromatic polyamides. II. Thermal degradation of some aromatic polyamides and their model diamides

Thermal degradation behavior of poly(1,3-phenylene isophthalamide) and poly(chloro-2,4-phenylene isophthalamide) was investigated with the aid of some appropriate model compounds. The pyrolysis products of these materials were identified by gas chromatography (GC), gas chromatography/Fourier transform infrared spectroscopy (GC/FT-IR), and gas chromatography/mass spectrometry (GC/MS). The residual chars were characterized by IR spectroscopy. Thermogravimetric analysis (TGA) was applied to study the effect of end-group concentration on the degradation characteristics of the two polyamides. Kinetic parameters that describe the thermal degradation of the polyamides were also evaluated by TGA. The results of this investigation suggest that the thermal decomposition of these aromatic polyamides involves homolytic as well as hydrolytic cleavages of the amide units.     

Thermal degradation of phenyl methacrylate-methyl methacrylate copolymers

The degradation behaviours of poly(phenyl methacrylate), four phenyl methacrylate-methyl methacrylate copolymers which span the composition range, and poly(methyl methacrylate) have been compared by using thermogravimetry in dynamic nitrogen and thermal volatilisation analysis (TVA) under vacuum, with programmed heating at 10°C/min. Volatile products have been separated by subambient TVA and identified and the cold ring fraction and partially degraded polymer have been examined by ir spectroscopy. Poly(phenyl methacrylate) resembles poly(methyl methacrylate) in degrading completely to monomer. Copolymers of phenyl methacrylate and methyl methacrylate are more stable than the homopolymers. On degradation, the major products are the two monomers. Minor products from all the copolymers include carbon dioxide, dimethylketene, isobutene and formaldehyde. Copolymers with low and moderate phenyl methacrylate contents show the formation of anhydride ring structures in the cold ring fraction and partially degraded copolymer, together with small amounts of methanol in the volatile products. Carbon dioxide is a more significant product at lower phenyl methacrylate contents.The mechanism of degradation is discussed.     

Pyrolysis–gas chromatography mass spectrometry and field ionization mass spectrometry of polyquinones

Low- and high-molecular mass thermal decomposition products of five polyquinones with different linking aromatic structures have been analyzed by pyrolysis–gas chromatography and by direct (in-source) pyrolysis–field ionization mass spectrometry. The quantity of carboxyl groups present in the polymer is obtained by the amounts of carbon dioxide found by pyrolysis–gas chromatography. Assuming a radical thermal decomposition mechanism the distribution of ketoacidic and quinonoid segments along the macromolecular ladder could be estimated from the high-molecular mass products measured by pyrolysis–field ionization mass spectrometry. A random distribution of the two different segments was found for polyquinones with biphenylene and dibenzofuran subunits, while a structure built up of blocks of two or more identical segments was obtained for polyquinones with dibenzothiophene and diphenylmethane subunits. At the same time the anomalous structural moieties in the polyquinone ladders are also clarified with the help of the identification of the unexpected pyroysis products. Oxidated and bis-dibenzothiophene and bis-diphenylmethane subunits were found. The observed temperature dependence for the appearances of the thermal degradation products indicates that condensation and elimination reactions are taking place under the described pyrolysis conditions. Condensation in the ketoacidic segments forming new quinonoid segments proved to be important in the polymer which was a 100% poly(ketoacid), but negligible in the polyquinones containing ketoacidic segments up to 60%.