End group modification in poly(ethylene terephthalate)

Kenwright, Alan M.; Peace, S.K.; Richards, Roy J.; Bunn, Alan; MacDonald, William

doi:10.1016/s0032-3861(98)00433-9

Cited by 64 publications

(66 citation statements)

References 12 publications

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“…Alternately, relative molecular weights are examined by comparing the copolymers reduced viscosity in trichloroacetic acid/chloroform mixed solvent. It should be noted that the employment of strong acid such as trichloroacetic acid or trifluoroacetic acid as a mixed solvent for ET-based (co)polymers may result in end-groups modification, as reported by Kenwright and coworkers [22] that these strong acids slowly reacted with hydroxyl end-groups by esterification. The authors, however, observed no polymers degradation when the strong acids were employed.…”

Section: Effect Of Thermo-stabilizersmentioning

confidence: 92%

Effects of synthesis conditions on chemical structures and physical properties of copolyesters from lactic acid, ethylene glycol and dimethyl terephthalate

Opaprakasit

Petchsuk²,

Opaprakasit³

et al. 2009

Express Polym. Lett.

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Lactic acid/ethylene terephthalate copolyesters were synthesized by the standard melt polycondensation of lactic acid (L), ethylene glycol (EG) and dimethyl-terephthalate (DMT). Effects of reaction temperatures and types of catalysts on the structures and properties of the copolymers were examined. In addition, feasibility of promoting the copolymerization process by a novel synthesis step of using thermo-stabilizers was investigated. The results show that a reaction temperature of higher than 180°C is necessary to produce copolymers with appreciable molecular weight. However, degradation was observed when the reaction temperature is higher than 220°C. Triphenyl phosphate (TPP) shows promising results as a potential thermo-stabilizer to minimize this problem. It was found that Sb2O3 and Tin(II) octoate are most effective among 4 types of catalysts employed in this study. 1H-NMR results indicate that copolymers have a random microstructure composed mainly of single L units alternately linked with ET blocks at various sequential lengths. The longer ET sequence in the chain structure leads to the increase in melting temperature of the copolymer. TGA results show that the resulting copolymers possessed greater thermal stability than commercially-available aliphatic PLA, as a result of the inclusion of T (terephthalate) units in the chain structure

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Section: Effect Of Thermo-stabilizersmentioning

confidence: 92%

Effects of synthesis conditions on chemical structures and physical properties of copolyesters from lactic acid, ethylene glycol and dimethyl terephthalate

Opaprakasit

Petchsuk²,

Opaprakasit³

et al. 2009

Express Polym. Lett.

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show abstract

“…1 H NMR spectra were recorded on a Bruker AC300 spectrometer by using 7% wt trifluoroacetic acid/ CDCl 3 mixed solvent. The spectrum was recorded immediately in order to avoid end-group esterification by trifluoroacetic acid [17].…”

Section: Synthesismentioning

confidence: 99%

Synthesis and characterizations of degradable aliphatic-aromatic copolyesters from lactic acid, dimethyl terephthalate and diol: Effects of diol type and monomer feed ratio

Namkajorn¹,

Petchsuk²,

Opaprakasit³

et al. 2010

Express Polym. Lett.

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“…In the spectra of PET recorded in CD 2 Cl 2 /CF 3 CO 2 D, these peaks (a triplet) are shifted to 4.2 ppm due to esterification by trifluoroacetic acid. 409 In unsaturated polyesters, the −OOC−CH=CH−COO methines give resonances close to 6.7 (fumarate units) and 6.3 ppm (maleate units). The assignments of the 1 H NMR spectra of some typical polyesters are given in Table 2.20.…”

Section: H Nmr Spectroscopymentioning

confidence: 99%