Sequential reordering in condensation copolymers, 4. Crystallization-induced sequential reordering in poly(ethylene terephthalate)/polycarbonate copolymers as revealed by the behavior of the amorphous phases

Denchev, Z.; Sarkissova, Marianna; Radusch, Hans‐Joachim; Luepke, Thomas; Fakirov, S.

doi:10.1002/(sici)1521-3935(19980201)199:2<215::aid-macp215>3.3.co;2-k

Cited by 5 publications

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“…As the reactions proceed, the sequence distribution in the copolyesters becomes statistically random, eventually providing a single‐phase material. Several examples of blends between polyesters and between a polyester and a polycarbonate (PC), which are characterized by this behavior, can be mentioned: poly(butylene terephthalate) (PBT)/poly(ethylene terephthalate) (PET),1 PBT/PC,2–5 PET/PC,6–9 and PBT/polyarylate10, 11 have been extensively studied for both industrial applications and academic purposes.…”

Section: Introductionmentioning

confidence: 99%

Relationships between the molecular architecture, crystallization capacity, and miscibility in poly(butylene terephthalate)/polycarbonate blends: A comparison with poly(ethylene terephthalate)/polycarbonate blends

Marchese¹,

Celli²,

Fiorini³

2004

J Polym Sci B Polym Phys

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Poly(butylene terephthalate) (PBT)/polycarbonate (PC) samples, prepared via reactive blending in the presence of Ti-and Sm-based catalysts, resulted in block copolymers whose block length decreased as the mixing time increased. A single homogeneous amorphous phase occurred when the blocks had monomeric sequences shorter than 10 units. Otherwise, a crystalline phase of PBT developed. Also, in poly(ethylene terephthalate) (PET)/PC blends previously studied, the miscibility was strictly correlated with the crystallizability of the system. Therefore, the miscibility of the PBT/PC and PET/PC blends was compared with respect to the tendency of the PBT and PET blocks to crystallize under isothermal conditions. The crystallization rate of the PBT/PC copolymers was faster than that of the PET/PC copolymers with similar block lengths. Accordingly, the minimum crystallizable sequence length of the PBT blocks was shorter than that of the PET blocks (18 vs 31 monomeric unit sequences). This behavior was interpreted as an effect of the more flexible PBT units, which had a greater tendency to fold and crystallize than the PET units. Therefore, PBT, the blocks of which tended to crystallize even if they were very short and phase-separated, was characterized by a poorer compatibility with PC than that of PET. As a result, the block size had a fundamental role in determining the crystallizability and, therefore, phase behavior of the semicrystalline block copolymers.

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Section: Introductionmentioning

confidence: 99%

Relationships between the molecular architecture, crystallization capacity, and miscibility in poly(butylene terephthalate)/polycarbonate blends: A comparison with poly(ethylene terephthalate)/polycarbonate blends

Marchese¹,

Celli²,

Fiorini³

2004

J Polym Sci B Polym Phys

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“…Bisphenol A polycarbonate (PC)/polyester blends are among the most widely studied polymer blend systems industrially and academically. PC/poly(ethylene terephthalate) (PET),13–28 PC/poly(butylene terephthalate) (PBT),29–36 PC/poly(ϵ‐caprolactone) (PCL),37–43 and PC/thermotropic liquid‐crystalline polyesters44–56 are some examples of PC/polyester blends. Many interdisciplinary blends, such as PET/nylon‐6,57 PCL/polyanhydrides,58 PBT/polysiloxanes,59 and biodegradable polyester blends,60 have also very recently been reported.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic aspects of ester–carbonate exchange in polycarbonate/cycloaliphatic polyester with model reactions

Jayakannan

Anilkumar

2004

J. Polym. Sci. A Polym. Chem.

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The reactive blending of bisphenol A polycarbonate (PC) with poly(1,4cyclohexanedimethylene-1,4-cyclohexanedicarboxylate) (PCCD) was investigated with a new high-temperature solution-blending methodology. The ester-carbonate exchange reaction (transesterification) in the blends was studied with NMR and Fourier transform infrared. The composition analysis of the PC/PCCD blends was performed with 1 H NMR, and the molecular weights were determined with viscosity methods. 1,4-Dimethylcyclohexanedicarboxylate, 1,4-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedimethanol were reacted with PC to study the tendency of polyester chain-end reactions such as transesterification, acidolysis, and alcoholysis. These model reactions revealed that the reactive blending was affected by both alcoholysis and transesterification, whereas acidolysis was absent. The model reaction products were used to study the mechanistic aspects of PC/PCCD reactive blending, which indicated the formation of three stable triads; two corresponded to symmetrical and unsymmetrical aromaticcycloaliphatic esters, and the other corresponded to aromatic-cycloaliphatic ethers. The composition analysis confirmed that in PC/PCCD reactive blending, the exchange reaction predominantly occurred in the polymer main chains, and the influence of the end groups was insignificant. The effect of the catalyst concentration and PC/PCCD composition on the extent of the exchange reaction was also investigated. Thermal analysis by differential scanning calorimetry revealed that the ester-carbonate exchange enhanced the compatibilization of PC/PCCD, and a single glass-transition temperature was observed for the miscible blends.

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“…These processes also alter morphology significantly as random copolymers are less prone to crystallize. On the other hand, when transesterification-formed random copolyesters are annealed at temperature lower than the melting temperature of one of the homopolyesters, transesterification reactions can promote the formation of block copolyesters via crystallization induced sequential reordering. − In some applications, e.g., polymer functionalization or in situ compatibization of polymer blends, interchange reactions are highly welcome provided they are carefully controlled. One necessary condition to achieve this is a better understanding of the basic processes occurring in melts of polycondensates, therefore a better knowledge of interchange reaction kinetics.…”

Section: Introductionmentioning

confidence: 99%

Kinetics and Mechanisms of Poly(poly(ethylene terephthalate)-co-poly(ε-caprolactone)) Catalyzed Randomization: Influence of End Groups

et al. 2010

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Hydroxy-ester interchanges were found to be the predominant reactions involved in poly-(ethylene terephthalate)-poly(ε-caprolactone) copolyester randomization. Even for high molar-mass copolyesters having low hydroxyl end group concentration, kinetic studies show that ester-ester interchanges play a minor role. Reaction rate was almost proportional to hydroxyl end groups concentration. The randomization kinetics was studied by 1 H NMR on copolyesters obtained in situ by reacting a series of poly(ethylene terephthalate)s of various molar masses and end groups with ε-caprolactone, in the molten state and in the presence of Ti(OBu) 4 catalyst. A mechanism involving parallel catalyzed second-order hydroxy-ester and ester-ester interchanges is proposed for the randomization step and perfectly fits experimental data. This study clearly shows that the nature and concentration of hydroxyl end groups must be carefully controlled for reliable synthesis of copolyesters by homopolyester melt blending.

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Sequential reordering in condensation copolymers, 4. Crystallization-induced sequential reordering in poly(ethylene terephthalate)/polycarbonate copolymers as revealed by the behavior of the amorphous phases

Cited by 5 publications

References 0 publications

Relationships between the molecular architecture, crystallization capacity, and miscibility in poly(butylene terephthalate)/polycarbonate blends: A comparison with poly(ethylene terephthalate)/polycarbonate blends

Relationships between the molecular architecture, crystallization capacity, and miscibility in poly(butylene terephthalate)/polycarbonate blends: A comparison with poly(ethylene terephthalate)/polycarbonate blends

Mechanistic aspects of ester–carbonate exchange in polycarbonate/cycloaliphatic polyester with model reactions

Kinetics and Mechanisms of Poly(poly(ethylene terephthalate)-co-poly(ε-caprolactone)) Catalyzed Randomization: Influence of End Groups

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