Kinetics of the thermal degradation of anhydrous bisphenol‐A polycarbonate/alkali metal arylcarboxylate systems in the melt

Bailly, Christian; Daumerie, M.; Legras, Roger; Mercier, Jean‐Pierre

doi:10.1002/macp.1986.021870517

Cited by 10 publications

(17 citation statements)

References 14 publications

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“…For that composition, the sulfonation levels used in this study, ca. 4-13 mol %, correspond to about 0.1-0.2 wt % zinc sulfonate, which is comparable to the 0.1-1 wt % SOCB and SOCP (see Introduction) used by Legras and co-workers [7][8][9][10][11][12][13] in their work on chemical nucleation of PC.…”

Section: Resultssupporting

confidence: 58%

“…The authors called the nucleation of PC by SOCB and SOCP "chemical nucleation" to distinguish it from conventional heterogeneous nucleation where no chemical reaction occurs. [7][8][9][10][11][12][13] Lightly sulfonated polystyrene ionomers (SPS) are miscible with PC for a range of sulfonation level that depends on the cation used, and the blends exhibit upper critical solution temperature (UCST) phase behavior. [14][15][16] Weiss and co-workers 16,17 reported that the PC in PC/SPS blends crystallized when the blend was cooled from the melt, but the phenomenon was not well characterized in those papers.…”

Section: Introductionmentioning

confidence: 99%

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Melt Crystallization of Bisphenol A Polycarbonate in Blends of Polycarbonate with Zinc Salts of Sulfonated Polystyrene Ionomers

Weiß

2003

Macromolecules

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The addition of zinc salts of sulfonated polystyrene ionomers (ZnSPS) to bisphenol A polycarbonate (PC) induced melt crystallization of the PC. This phenomenon was investigated using differential scanning calorimetry and wide-angle X-ray diffraction. Gel permeation chromatography was used to monitor changes in molecular weight to assess whether polymer degradation was responsible for the melt crystallization. Fourier transform infrared spectroscopy and small-angle X-ray scattering were used to evaluate specific interaction and the microstructure of the blends. Melt crystallization of PC at 190 °C was accelerated in both single-phase and phase-separated blends. The crystallization induction time ranged from 1 to 42 h depending on the sulfonation level of the ionomer, and crystallinities of 20%−28% were achieved. An Avrami analysis of the crystallization kinetics indicated that the crystallization was a nucleated process. Although some molecular weight reduction of the PC did occur during thermal annealing at elevated temperatures, it was not considered responsible for the crystallization. Unlike previous work where melt crystallization of PC was induced by a “chemical nucleation” with alkali salts of aromatic carboxylic acids, crystallization in the PC−ZnSPS blends was reversible. Although the origin of the crystallization was not determined, it appeared that the nanometer-sized ionic aggregates associated with the ionomer, which were present even in the single-phase blends, contributed to the crystal nucleation.

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Section: Resultssupporting

confidence: 58%

Section: Introductionmentioning

confidence: 99%

Melt Crystallization of Bisphenol A Polycarbonate in Blends of Polycarbonate with Zinc Salts of Sulfonated Polystyrene Ionomers

Weiß

2003

Macromolecules

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“…To understand the action of alkalis, considerable efforts have been devoted to investigating the thermal degradation of polymers or biomass in the presence or absence of alkalis. Significant progress has been made in the clarification of the degradation products or intermediate structures, and the action of alkali ions on the primary reactions such as dehydration, esterification, and decarboxylation in early degradation stages have been well documented [9,10,11,12,13]. However, the use of complex raw materials might confound the alkalis’ roles in the later aromatization process.…”

Section: Introductionmentioning

confidence: 99%

On the Origin of Alkali-Catalyzed Aromatization of Phenols

Yao

Zhao

et al. 2019

Polymers

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To gain an insight of the chemistry in the alkali-promoted aromatization of oxygen-containing heavily aromatic polymers or biomass; thermal degradations of sodium phenolates with different substituents have been investigated. The -ONa group strongly destabilizes the phenolates. The thermal stability of phenolates is largely in parallel with bond strengths of Ar substituents. De-substituents and the removal of aromatic hydrogens are dominant reactions in the main degradation step. CO is formed only at a very late stage. This degradation pattern is completely different from that of phenol. To account for this distinctive decomposition; a mechanism involving an unprecedented formation of an aromatic carbon radical anion generated from the homolytic cleavage of Ar substituent (or Ar–H) in keto forms has been proposed. The homolytic cleavage of Ar substituent (or Ar–H) is facilitated by the strong electron-donating ability of the oxygen anion. A set of free-radical reactions involved in the alkali-catalyzed aromatization have been established.

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“…6 The crystallization of PC is increased by several orders of magnitude by the presence of alkali metal aryl carbonates such as sodium benzoate, and this has been attributed to the formation of NaOPh chain ends that catalyze a fast transesterification reaction. 9 The polymerization of macrocyclic oligomers of BPA-PC has been initiated by numerous ions, and the reaction of LiOPh with the cyclic tetramer is unusual, since it has no measurable exotherm (enthalpy less than 0.3 kcal/ mol) 10 and must be entropy driven. Experimental studies on a number of functionalized bisphenols using a variety of catalysts showed that the carbonate group provided the site for ringopening polymerization in all cases.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Reactions of Living Polymers: Density Functional Study of Reactivity of Phenol and Phenoxides with the Cyclic Tetramer of Polycarbonate

2000

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The reactivity of phenol, lithium phenoxide (LiOPh), and sodium phenoxide (NaOPh) with the cyclic tetramer of bisphenol A polycarbonate (BPA-PC) has been investigated using density functional calculations. The potential energy of the system is computed using a suitable reaction coordinate and relaxing all other degrees of freedom by Car-Parrinello molecular dynamics. Both LiOPh and NaOPh catalyze ring opening with small energy barriers (∆E ) 4.0, 2.5 kcal/mol, respectively) to a chain with a phenyl carbonate at one end and a phenoxide at the other, a "living polymer". The barrier is large for phenol (∆E > 40 kcal/mol), but the total energy differences between the reactants and the chain are very small in all three molecules. We discuss the balance between changes in entropy and energy, and we compute the vibrational properties of metastable intermediate species.

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Kinetics of the thermal degradation of anhydrous bisphenol‐A polycarbonate/alkali metal arylcarboxylate systems in the melt

Cited by 10 publications

References 14 publications

Melt Crystallization of Bisphenol A Polycarbonate in Blends of Polycarbonate with Zinc Salts of Sulfonated Polystyrene Ionomers

Melt Crystallization of Bisphenol A Polycarbonate in Blends of Polycarbonate with Zinc Salts of Sulfonated Polystyrene Ionomers

On the Origin of Alkali-Catalyzed Aromatization of Phenols

Catalytic Reactions of Living Polymers: Density Functional Study of Reactivity of Phenol and Phenoxides with the Cyclic Tetramer of Polycarbonate

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