Caprolactone Copolyesters Research Articles

Transesterifications of poly(bisphenol A carbonate) with aromatic and aliphatic segments in ethylene terephthalate–caprolactone copolyester

AbstractIn this article, transesterification of poly(bisphenol A carbonate) (PC) with a ethylene terephthalate–caprolactone copolyester at a weight ratio 50/50 (TCL50) was investigated by infrared spectroscopy (IR), proton nuclear magnetic resonance spectroscopy (1H‐NMR), and a model compound. The IR and 1H‐NMR results showed that transesterification occurred between PC and ethylene terephthalate (ET) segments in TCL50 and resulted in the formation of bisphenol A–terephthalate ester units as in the annealed blend of PC with the PET homopolyester. By comparison with a model compound, the new signal at 2.55 ppm in the 1H‐NMR spectrum confirmed the appearance of bisphenol A–caprolactone ester units resulting from the exchange reaction of PC with caprolactone (CL) segments. The 1H‐NMR analysis of the transesterification rates revealed that the reactions of PC with aromatic and aliphatic segments in TCL50 proceeded in a random or free manner. In addition, we separately examined the interchange reaction between a PC and poly(ε‐caprolactone) (PCL) homopolyester in an annealed blend. It was found that in the presence of a Ti compound catalyst the predominant reaction was a transesterification rather than a thermooxidative branching reaction. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1558–1565, 2001

Crystallization behavior and spherulite morphology of hard and soft segments in butylene terephthalate-?-caprolactone copolyesters

The crystallization behaviors and spherulite morphology of a series of butylene terephthalate–ϵ-caprolactone (BCL) copolyesters were explored with differential scanning calorimetry, polarized light microscopy, and wide-angle X-ray diffraction. The crystallization characteristics reflecting the segmented properties of BCL copolyesters are discussed. For BCL copolyesters with low or high hard-segment contents, the ϵ-caprolactone segments or butylene terephthalate segments are long enough to crystallize and even grow spherulites under appropriate conditions, and the crystallizability strengthens with increases in the corresponding segment sequence length. In BCL copolyesters, the crystallization of the soft segments requires a considerably long sequence length, whereas the hard segments even containing only one structural unit can still crystallize and even grow spherulites. The hard segments can grow the usual spherulites at a higher temperature like the poly(butylene terephthalate) homopolymer. The crystallizabilities of hard segments and soft segments for BCL and ethylene terephthalate–ϵ-caprolactone copolyesters are compared and discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 634–644, 2001

Transesterifications of poly(bisphenol A carbonate) with caprolactone segments in copolyester and poly(ε-caprolactone) homopolymer

Transesterification of poly(bisphenol A carbonate) with caprolactone segments in ethylene terephthalate–caprolactone copolyester was investigated using 1H and 1H– 1H nuclear magnetic resonance (NMR) spectroscopy and a model compound. It was found that during annealing process, transesterification took place between poly(bisphenol A carbonate) and caprolactone segments and resulted in the formation of bisphenol A-caprolactone ester unit. On the basis of the results, we separately examined the interchange reaction of poly(bisphenol A carbonate) with poly(ε-caprolactone) homopolymer by 1H and 13C nuclear magnetic resonance spectroscopy. It was shown that in the presence of Ti compound catalyst, transesterification mainly occurred and gave rise to three different kinds of linkage patterns: bisphenol A-caprolactone ester unit, bisphenol A-caprolactone carbonate unit and caprolactone–caprolactone carbonate unit. However, the resultant aliphatic carbonate units were stable under the reaction conditions; the evidence of decarboxylation was not obtained from NMR measurements. The characteristics of the transesterification behavior will be discussed in this paper.

Proton NMR characterization of chain structure in butylene terephthalate-?-caprolactone copolyesters

A series of butylene terephthalate-ϵ-caprolactone copolyesters (BCL) with different hard-segment content were synthesized and their chain structures were carefully investigated by high resolution 1H-NMR spectroscopy. The analysis from 1H-NMR spectra of samples reveals that BCL chain chemical and sequence structure is specific and complicated because of the unavoidable transesterification between BT and CL segments during synthesis process and so BCL copolyesters are segmented copolyesters with certain random property as confirmed by DSC measurements. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3770–3777, 1999

Crystallization behavior and spherulite morphology of soft and hard segments in ethylene terephthalate-?-caprolactone copolyesters

Crystallization behavior and spherulite morphology of soft and hard segments in ethylene terephthalate-?-caprolactone copolyesters

Synthesis and chain structure of ethylene terephthalate-?-caprolactone copolyesters

A series of ethylene terephthalate–e-caprolactone copolyesters (TCL) with different hard segment contents were synthesized and characterized by GPC, NMR, and DSC. The analysis from high-field 1H-NMR reveals that the transesterification between ET and CL segments during synthesis is unavoidable, so TCL copolyesters are segmented copolyesters with certain random properties, as shown by the specific chemical and sequence structure of TCL copolyester chains and as confirmed by their crystallization behavior. The stress–strain test shows that TCL copolyesters with different hard segment contents may possess rubberlike or toughening plastic mechanical properties. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2961–2969, 1998

Miscibility and transesterification in bisphenol‐a polycarbonate/ethylene terephthalate–caprolactone copolyester blends

AbstractThe miscibility and microstructure of blends of bisphenol‐A polycarbonate (PC) with ethylene terephthalate (ET)‐caprolactone (CL) copolyesters (TCL) were studied by differential scanning calorimetry (DSC), infrared spectroscopy (IR) and phase contrast microscopy (PCM). The DSC results showed that PC were immiscible or partially miscible with the copolyesters having ethylene terephthatate contents higher than 60 (wt %), and miscible with the copolyesters having ET contents lower than 60(wt %). After annealing at elevated temperature, homogenization will take place in the immiscible or partially miscible blends of PC with higher ET‐content copolyesters. The IR and PCM results revealed that the homogenization of the blend are caused by the transesterification between the PC and copolyesters. © 1995 John Wiley & Sons, Inc.

Multiple melting endotherms from ethylene terephthalate—caprolactone copolyesters

The melting behaviour of ethylene terephthalate (ET)—caprolactone (CL) random block copolyesters (TCLs) crystallized from the melt were studied by differential scanning calorimetry (d.s.c.). The TCLs with high ET contents showed three melting endotherms. Peaks I and II can be attributed to the melting of crystallites formed during primary and secondary crystallization processes respectively, and peak III is the fusion of crystals recrystallized during the d.s.c. heating scan process. For TCL having relatively lower ET content, another melting endotherm, corresponding to the fusion of crystallites of the CL segments, was observed, which indicated that the segregation occurred during the annealing process because of the non-uniformity of the chemical composition and sequence length distribution of the ET and CL segments in TCL copolyesters.