Network formation in poly(ethylene terephthalate) by thermooxidative degradation

Yoda, Kentaro; Tsuboi, Akito; Wada, M.; Yamadera, Reizô

doi:10.1002/app.1970.070140915

Cited by 50 publications

(38 citation statements)

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“…They result in crosslinked products and in the formation of compounds such as aldehydes, carboxylic acids and vinyl esters, as reported in the case of PET. 93,94 On the other hand, the presence of oxygen has little effect on the thermal resistance of wholly aromatic polyesters below 550…”

Section: Thermal and Thermo-oxidative Degradationmentioning

confidence: 99%

Polyesters

Fradet

Tessier

2003

Synthetic Methods in Step‐Growth Polymers

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Section: Thermal and Thermo-oxidative Degradationmentioning

confidence: 99%

Polyesters

Fradet

Tessier

2003

Synthetic Methods in Step‐Growth Polymers

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“…Catalysts (commercially available guaranteed grade) and a radical inhibitor, 1,3,4, Shell Fine Chemicals), were used without further prufication.…”

Section: Methodsmentioning

confidence: 99%

Formation of Aromatic Compounds as Side Reactions in the Polycondensation of Bis(2-hydroxyethyl) Terephthalate

Kamatani

Kuze

1979

Polym J

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ABSTRACT:Studies on the side reactions in the polycondensation of bis(2-hydroxyethyl) terephthalate were performed in the presence of catalysts (Mn, Co, Zn, W). 4,4'-Biphenyldicarboxylic acid, l,2-bis(4-carboxyphenyl)ethane, and 2,4',5-biphenyltricarboxylic acid were found as major aromatic by-products in the reaction. The yield of these by-products was very poor in the absence of these catalysts, and remarkably increased in the presence of catalysts in the following order: Mn< Co< Zn <1; W. This order was in accord with that of the activity of catalysts for polycondensation of bis(2-hydroxyethyl) terephthalate. The side reactions were suppressed with the addition of radical inhibitor, indicating that the side reactions occurred with a radical mechanism; this was supported from ESR studies. The side reactio'ls are probably initiated by the alkyl radical ( -C6 H4 COOC2H4 ·) obtained from the reaction ofbis(2-hydroxyethyl) terephthalate with the metal of catalysts.KEY WORDS Bis(2-hydroxyethyl) Terephthalate / Poly(ethylene terephthalate) / Polycondensation / 4,4'-Biphenyldicarboxylic Acid / l,2-Bis(4-carboxyphenyl)ethane / 2,4',5-Biphenyltricarboxylic Acid / ESR / Free EXPERIMENT A-L MaterialsSeveral side reactions such as etherification 1 · 2 and thermal degradation 3 -6 have been observed in the polycondensation of bis(2-hydroxyethyl) terephthalate (BHET) or its oligomer. We found that 4,4'-biphenyldicarboxylic acid, 2,4' ,5-biphenyltricarboxylic acid, and 1,2-bis( 4-carboxyphenyl)ethane were obtained as by.products in the polycondensation of BHET. The side reactions sometimes lead to the deterioration of the physical and chemical properties of the poly(ethylene terephthalate) (PET) obtained. 2 · 3 · 7 In order to manufacture PET of high quality, details of the side reactions in the polycondensation must be investigated.BHET was prepared by the reaction of terephthalic acid with ethylene oxide. 9One of the present authors previously identified the mechanism of the polycondensation of BHET in the presence of catalysts (Co, Mn, Zn). 8 In this research, aromatic compounds formed by the side reactions in the polycondensation of BHET were determined quantitatively in the presence of a catalyst (Mn, Co, Zn, W); the mechanisms for the side reactions are discussed here.Catalysts (commercially available guaranteed grade) and a radical inhibitor, 1,3,4, Shell Fine Chemicals), were used without further prufication. Polycondensation of BHETPolycondensation ofBHET (1.5 mol) was carried out in a 1.0 dm 3 autoclave in the presence of a catalyst (0.3 mmol) at 273°C under reduced pressure. 8 Samples for the study of by-products were taken out of the autoclave at regular time intervals 8 and were subjected to methanolysis. Thermooxidative Degradation of PETThe polymer containing a polycondensation catalyst was powdered and heated for I h in an oven at 300°C under an air stream 4 -6 and was subjected to 787

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“…Figure 3 shows the thermal degradation reactions that are believed to occur during melt processing of PET. 15 Other degradation mechanisms of PET, namely hydrolytic and thermooxidative, are considered to be negligible under the selected experimental conditions. More details about PET degradation are given by Yoda et al 15 In the case of thermal degradation, at first, random scission of PET chain takes place, initiated by chain cleavage forming carboxylic end groups and vinyl esters, aldehydes, and carbon dioxide.…”

Section: Process Stability Of Pet In a Batch Mixermentioning

confidence: 99%

“…15 Other degradation mechanisms of PET, namely hydrolytic and thermooxidative, are considered to be negligible under the selected experimental conditions. More details about PET degradation are given by Yoda et al 15 In the case of thermal degradation, at first, random scission of PET chain takes place, initiated by chain cleavage forming carboxylic end groups and vinyl esters, aldehydes, and carbon dioxide. 15 Yoda further suggested that vinyl esters accumulate to a certain concentration and then react with polyester chains, resulting in extension/branching/crosslinking and acetaldehyde generation.…”

Section: Process Stability Of Pet In a Batch Mixermentioning

confidence: 99%

“…More details about PET degradation are given by Yoda et al 15 In the case of thermal degradation, at first, random scission of PET chain takes place, initiated by chain cleavage forming carboxylic end groups and vinyl esters, aldehydes, and carbon dioxide. 15 Yoda further suggested that vinyl esters accumulate to a certain concentration and then react with polyester chains, resulting in extension/branching/crosslinking and acetaldehyde generation. Through end-group degradation, additional carboxylic groups may be formed.…”

Section: Process Stability Of Pet In a Batch Mixermentioning

confidence: 99%

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Parameters affecting the chain extension and branching of PET in the melt state by polyepoxides

Dhavalikar

Xanthos

2002

J of Applied Polymer Sci

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This article describes the chemical modification of polyethylene terephthalate (PET) with a variety of compounds containing reactive glycidyl group(s). Four different modifiers, namely, diglycidyl ether of bisphenol-A (DGEBA), N, phenyl] pyromellitimide (BGPM), triglycidyl glycerol (TGG), and triglycidyl isocyanurate (TGIC) were compared for their reactivity toward PET in the melt phase. It was found that the presence of tertiary nitrogen in the structure of the epoxide modifiers plays the role of in-built catalyst for their reaction with the end groups of PET. TGIC as a modifier was selected for the detailed investigation of the simultaneously occurring degradation and chain extension/branching reactions in a batch-melt mixer. The reactions were followed by torque changes, analyzing the products for residual carboxyl content, and by determining insoluble content. It is shown that the rate of the reactive modification of PET melt by TGIC depends upon stoichiometry, temperature, rate of shear, and the chemical composition and the molecular weight (MW) of the PET resin. In general, the results indicate an increase in melt viscosity and insoluble content, whereas an overall decrease in carboxyl content occurs, as defined by the choice of mixing conditions and stoichiometry. Analysis of the batch kinetic data can be useful to define the process requirements for carrying out the reactive modification in continuous extrusion equipment.

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Network formation in poly(ethylene terephthalate) by thermooxidative degradation

Cited by 50 publications

References 4 publications

Polyesters

Polyesters

Formation of Aromatic Compounds as Side Reactions in the Polycondensation of Bis(2-hydroxyethyl) Terephthalate

Parameters affecting the chain extension and branching of PET in the melt state by polyepoxides

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