End-group characterization of homo- and copolyesters of cyclohexane-1,4-dimethanol

Amari, Toru; Nishimura, Kumiko; Minou, Kimiko; Kawabata, Akira; Ozaki, Yukihiro

doi:10.1002/1099-0518(20010301)39:5<665::aid-pola1038>3.0.co;2-8

Cited by 24 publications

(32 citation statements)

References 20 publications

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“…[ 37,38 ] Content values between 2-4 meq kg -1 measured by NMR, very close to the ones determined by titration, have been reported for PET samples coming from different sources. [ 37 ] It should be noted however that Samperi et al [ 39 ] were unable to detect vinyl end groups by 1 H NMR in thermally degraded samples of PET. In view of these results and on the basis of data obtained by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry, these authors postulated a different mechanism for the thermal degradation of PET in which cyclic oligomers formed at lower temperatures decomposed upon heating with generation of acetaldehyde and anhydride containing oligomers.…”

Section: End Groupssupporting

confidence: 79%

“…The vinyl end groups of PET are identifi ed in the 1 H NMR spectrum by two signals appearing at 5.22 and 7.36 ppm (Figure 3 ), which may be quantifi ed by integration. [ 37,38 ] Content values between 2-4 meq kg -1 measured by NMR, very close to the ones determined by titration, have been reported for PET samples coming from different sources. [ 37 ] It should be noted however that Samperi et al [ 39 ] were unable to detect vinyl end groups by 1 H NMR in thermally degraded samples of PET.…”

Section: End Groupssupporting

confidence: 67%

“…Although the content of vinyl groups in PET is usually very low, its control is of extreme importance because they act as intermediates in the formation of highly undesirable volatile compounds such as acetaldehyde and others. The vinyl end groups of PET are identified in the 1 H NMR spectrum by two signals appearing at 5.22 and 7.36 ppm (Figure ), which may be quantified by integration . Content values between 2–4 meq kg –1 measured by NMR, very close to the ones determined by titration, have been reported for PET samples coming from different sources …”

Section: Petmentioning

confidence: 56%

“…The vinyl end groups of PET are identified in the 1 H NMR spectrum by two signals appearing at 5.22 and 7.36 ppm (Figure ), which may be quantified by integration . Content values between 2–4 meq kg –1 measured by NMR, very close to the ones determined by titration, have been reported for PET samples coming from different sources …”

Section: Petmentioning

confidence: 56%

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Chemical Structure and Microstructure of Poly(alkylene terephthalate)s, their Copolyesters, and their Blends as Studied by NMR

Ilarduya

Muñoz‐Guerra

2014

Macro Chemistry & Physics

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The use of NMR spectroscopy in solution to investigate the chemical structure of engineering poly(alkylene terephthalate)s such as poly(ethylene terephthalate) (PET), poly(trimethylene terephthalate) (PTT), and poly(butylene terephthalate) (PBT) is reviewed. Chemical defects present in the polyester chain, such as oxydialkylene units, as well as accompanying side products such as cyclic oligomers generated in the polycondensation, are well detected in 1H NMR spectra. The technique is also demonstrated to be effective for identifying, and even for quantifying in certain cases, the end groups of these polyterephthalates, including those that are generated in small amounts as a consequence of thermal degradation. The application of NMR to the study of the chemical microstructure of copolyesters derived from such polyterephthalates is also reviewed for its unique ability to determine comonomeric sequence lengths and degree of randomness (R). Copolyesters synthesized by either melt polycondensation or entropically driven ring opening polymerization, in addition to those prepared by solid‐state modification or melt blending, are the object of this review.

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Section: End Groupssupporting

confidence: 79%

Section: End Groupssupporting

confidence: 67%

Section: Petmentioning

confidence: 56%

Section: Petmentioning

confidence: 56%

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Chemical Structure and Microstructure of Poly(alkylene terephthalate)s, their Copolyesters, and their Blends as Studied by NMR

Ilarduya

Muñoz‐Guerra

2014

Macro Chemistry & Physics

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“…As it can be seen in Table 2, the thermal stability of coPExCyT decreased steadily in a range of 20ºC as the content in CT units in the copolymer increased with the maximum and minimum values corresponding to the parent homopolymers PET and PCT, respectively. This pattern of behavior is in agreement with preceding work published by Amari et al, [31] in which the thermal degradation of these copolymers was studied by analyzing by NMR, the end groups present in the degraded products. They showed that thermal decomposition evolved with releasing of unsaturated compounds that generated by cis-β-elimination and found that CT units were less stable to heating than the ET ones because the ester link between terephthalic acid and CHDM is thermally weaker than that between terephthalic acid and EG.…”

Section: Thermal Properties Of Copexcyt Copolyestersmentioning

confidence: 99%

Poly(ethylene‐co‐1,4‐cyclohexylenedimethylene terephthalate) copolyesters obtained by ring opening polymerization

González-Vidal

Ilarduya

Muñoz‐Guerra

2009

J. Polym. Sci. A Polym. Chem.

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Cyclic oligomer fractions of ethylene terephthalate c(ET)n and 1,4-cyclohexylenedimethylene terephthalate c(CT)n were obtained by yclodepolymerization of their respective polyesters, the former containing around 80 mol % of trimer and the latter with around 70 mol % of trimer to pentamer. Mixtures of these fractions at selected compositions were subjected to ring opening copolymerization to give a series of poly(ethylene-cocyclohexylenedimethylene terephthalate) copolyesters with ET/CT comonomer ratios ranging from 90/10 to 10/90. The copolyesters were characterized by GPC and NMR, and their thermal properties were evaluated by DSC and TGA. They had essentially the same composition as the feed from which they were produced and had an average-weight molecular weights between 30,000 and 40,000 g/mol with polydispersities between 2 and 2.7. The distribution of the monomeric units in these copolyesters was essentially at random although it evolved to be a blocky microstructure as the contents in the two comonomers became more dissimilar. Their thermal behavior was the expected one for these types of copolyesters with crystallinity and heating stability decreasing with the content in CT units.

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Molecular Weight Determination

Cooper

2004

Encyclopedia of Polymer Science and Technology

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Methods to determine molecular weight averages and distributions of polymeric and oligomeric materials have been devised and developed over many decades. Most of the early classical techniques were primary methods which usually yield only a single molecular weight average, based on theory and measurable constants. Of the classical methods only ultracentrifugation can determine a molecular weight distribution. Secondary methods, which depend on the availability of calibration materials, have largely supplanted the older classical techniques. Methods based on fractionation, with molecular weight characterization of the fractions, or chromatography, with continuous determination of molecular weight, are currently used to generate molecular weight distributions. Newer methods based on dynamic light scattering and viscoelastic measurements are available to determine the molecular weight distribution of difficulty soluble materials. Development of methods to describe the molecular weight and compositional distribution of multimer polymers continues to be a vibrant research area.

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End-group characterization of homo- and copolyesters of cyclohexane-1,4-dimethanol

Cited by 24 publications

References 20 publications

Chemical Structure and Microstructure of Poly(alkylene terephthalate)s, their Copolyesters, and their Blends as Studied by NMR

Chemical Structure and Microstructure of Poly(alkylene terephthalate)s, their Copolyesters, and their Blends as Studied by NMR

Poly(ethylene‐co‐1,4‐cyclohexylenedimethylene terephthalate) copolyesters obtained by ring opening polymerization

Molecular Weight Determination

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