Chemical nucleation, a new concept applied to the mechanism of action of organic acid salts on the crystallization of polyethylene terephthalate and bisphenol—A polycarbonate

Legras, Roger; Bailly, Christian; Daumerie, M.; Dekoninck, Jm.; Mercier, Jean‐Pierre; Zichy, V.; Nield, E.

doi:10.1016/0032-3861(84)90015-6

Cited by 107 publications

(72 citation statements)

References 9 publications

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“…This reduction in impact strength can be attributed to a reduction in molecular weight resulting from reaction of the polymer with sodium stearate as described by Legras et al 18,19 As shown in Table I, the addition of sodium stearate reduced the M n of PPT and PBT by 14.5 and 17.0%, respectively.…”

Section: Mechanical and Thermomechanical Propertiesmentioning

confidence: 85%

“…Nucleation by heterogeneous nucleants occurs by molecular interactions between the polymer and the surface of the nucleant, resulting in a reduction in the free energy needed to form a stable nucleus. 17 Chemical nucleation of condensation polymers such as PET was described by Legras et al 18,19 as occurring by the reaction of alkali metal salts of organic acids with the polymer to produce chains with ionic end-groups. Due to strong electrostatic interactions, these ionic end groups form clusters that reduce the local mobility of the chain, thereby facilitating the formation of stable nuclei.…”

Section: Crystallization and Melting Behaviormentioning

confidence: 99%

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Properties of glass-filled thermoplastic polyesters

Chisholm

Fong

Zimmer

et al. 1999

J. Appl. Polym. Sci.

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ABSTRACT:The thermal, mechanical, and rheological properties of glass-filled poly(propylene terephthalate) (GF PPT) were compared to glass-filled poly(butylene terephthalate) (GF PBT). The impetus for this study was the recent commercial interest in PPT as a new glass-reinforced thermoplastic for injection-molding applications. This article represents the first systematic comparison of the properties of GF PPT and GF PBT in which differences in properties can be attributed solely to differences in the polyester matrices, that is, glass-fiber size and composition, polymer melt viscosity, nucleant content and composition, polymerization catalyst composition and content, and processing conditions were kept constant. Under these controlled conditions, GF PPT showed marginally higher tensile and flexural properties and significantly lower impact strength compared to GF PBT. The crystallization behavior observed by cooling from the melt at a constant rate showed that GF PBT crystallized significantly faster than did GF PPT. Nucleation of GF PPT with either talc or sodium stearate increased the rate of crystallization, but not to the level of GF PBT. The slower crystallization rate of GF PPT was found to strongly affect thermomechanical properties of injection-molded specimens. For example, increasing the polymer molecular weight and decreasing the mold temperature significantly increased the modulus drop associated with the glass transition. In contrast, the modulus-temperature response of GF PBT was just marginally influenced by the polymer molecular weight and was essentially independent of the mold temperature.

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Section: Mechanical and Thermomechanical Propertiesmentioning

confidence: 85%

Section: Crystallization and Melting Behaviormentioning

confidence: 99%

Properties of glass-filled thermoplastic polyesters

Chisholm

Fong

Zimmer

et al. 1999

J. Appl. Polym. Sci.

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“…There has been experimental evidence about ionic groups acting as nucleating sites, thereby accelerating the rate of crystallization. [8][9][10] The higher nucleation densities at low T a may result in the accelerated crystallization rate and the fine crystallite without highly ordered spherulitic structure. Figure 4 shows TEM micrographs for Ion-PET annealed at T a = 120 ºC (a) and 210 ºC (b).…”

Section: Resultsmentioning

confidence: 99%

Morphology Development in a Range of Nanometer to Micrometer in Sulfonated Poly(ethylene terephthalate) Ionomer

2002

Bulletin of the Korean Chemical Society

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We investigated the effect of ionic component on crystalline morphology development during isothermal annealing in a sodium neutralized sulfonated poly(ethylene terephthalate) ionomer (Ion-PET) by time-resolved small-angle x-ray scattering (TR-SAXS) using synchrotron radiation. At early stage in Ion-PET, SAXS intensity at a low annealing temperature (T a = 120 ºC) decreased monotonously with scattering angle for a while. Then SAXS profile showed a peak and the peak position progressively moved to wider angles with isothermal annealing time. Finally, the peak intensity decreased, shifting the peak angle to wider angle. It is revealed that ionic aggregates (multiplets structure) of several nm, calculated by Debye-Bueche plot, are formed at early stage. They seem to accelerate the crystallization rate and make fine crystallites without spherulite formation (supported by optical microscopy observation). From decrease of peak intensity in SAXS, it is suggested that new lamellae are inserted between the preformed lamellae so that the concentration of ionic multiplets in amorphous region decreases to lower the electron density difference between lamellar crystal and amorphous region. In addition, analysis on the annealing at a high temperature (T a = 210 ºC) by optical microscopy, light scattering and transmission electron microscopy shows a formation of spherulite, no ionic aggregates, the retarded crystallization rate and a high level of lamellar orientation.

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“…The formation of comb-like structure can give an explanation for less reduction of molecular weight of PET in the case of PET/S. By means of IR spectroscopy, Legras et al [24][25][26][27] identified the PETCOONa produced by reaction Eq. (1), while we confirmed the formation of PET-R. A 50 wt.…”

Section: Influence Of Nucleating Agents On the Crystallization Of Petmentioning

confidence: 98%

“…A new concept 'chemical nucleation' has been proposed by Legras et al [24][25][26][27] to describe the mechanism of action of organic acid salts on the crystallization of PET. Organic nucleating agents do not behave as inert, heterogeneous substrates in lowering the energy barrier towards nucleation, but dissolve into PET melt and react with PET.…”

Section: Influence Of Nucleating Agents On the Crystallization Of Petmentioning

confidence: 99%

Fast crystallization of poly(ethylene terephthalate)

Wang

Huang

et al. 1996

Journal of Thermal Analysis

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The crystallization of poly(ethylene terephthalate) (PET) was studied in the presence of nucleating agents and promoters. The effect of both by themselves and in concert was investigated using differential scanning calorimetry. The aim of this work is to find conditions of fast crystallization of PET. Sodium benzoate(SB) and Surlyn | (S) substantially increase the crystallization rate of PET at higher temperature owing to a reduction in the energy barrier towards primary nucleation, but they accelerate crystallization even more at lower temperature with an additional improvement of the molecular mobility of PET chains. Chain seission of PET caused by the reaction with the nucleating agents was proven by determination of molecular weight. The addition of S alone led to a lower reduction in molecular weight. A series of N-alkyl-p-toluenesulfonamides (ATSAs) were shown to effectively promote molecular motion of the PET chains, leading to an increase in crsytallization rate at lower temperature. A remarkable acceleration of crystallization of PET was attained at lower temperature when S and ATSA were added together. When the content of ATSA is low, S has the dominant influence due to its dual effect of decreasing energy barrier towards nucleation and promoting molecular motion of PET chains. A further increase of crystallization rate of PET was found only after an addition of ATSA of above 5 wt.%.

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Chemical nucleation, a new concept applied to the mechanism of action of organic acid salts on the crystallization of polyethylene terephthalate and bisphenol—A polycarbonate

Cited by 107 publications

References 9 publications

Properties of glass-filled thermoplastic polyesters

Properties of glass-filled thermoplastic polyesters

Morphology Development in a Range of Nanometer to Micrometer in Sulfonated Poly(ethylene terephthalate) Ionomer

Fast crystallization of poly(ethylene terephthalate)

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