Nucleation of poly(ethylene terephthalate) by sodium compounds: a unique mechanism

Dekoninck, Jm.; Legras, Roger; Mercier, Jean‐Pierre

doi:10.1016/0032-3861(89)90191-2

Cited by 58 publications

(44 citation statements)

References 10 publications

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“…Using IR spectroscopy, Dekoninck tion. The following salts were reported 46 to have et al 38 were able to confirm the suggestions of decomposition (d.) temperatures near, slightly chemical nucleation by using sodium o-chlorobenabove, or below the 300ЊC mark: MgCO 3 (d. zoate and identifying chains having sodium car-350ЊC), ZnCO 3 (d. 300ЊC), PbCO 3 (d. 315ЊC), and boxylate ends. The authors also showed that these NaHCO 3 (d. 285ЊC).…”

Section: Characteristicsmentioning

confidence: 66%

Effects of carbonate salts on crystallization kinetics and properties of recycled poly(ethylene terephthalate)

Xanthos

Baltzis

Hsu

1997

J. Appl. Polym. Sci.

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ABSTRACT:In this study, thermal and microscopic analyses were used to evaluate a variety of carbonate and bicarbonate salts (alkali, alkaline-earth, and other metals), having different thermal stability within the range of poly(ethylene terephthalate) (PET) processing temperatures, as nucleating agents for recycled bottle PET. In addition, the effects of the salts on the melt viscosity and MW of the resin after melt processing were investigated in attempts to determine their overall relative performance as potential nucleating agents during injection molding. It was found that among the additives tried sodium salts are the most effective nucleating agents for recycled PET crystallization with a concomitant relatively small reduction in molecular weight. All other salts were less effective nucleating agents and, in some cases, caused also significant resin degradation. Mechanisms explaining the behavior of the different salts are proposed. With regard to processability of recycled PET in injection molding, it was found that for certain additives temperatures below 100ЊC could be effectively used, resulting in short cycles that produced crystalline products with satisfactory mechanical properties.

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Section: Characteristicsmentioning

confidence: 66%

Effects of carbonate salts on crystallization kinetics and properties of recycled poly(ethylene terephthalate)

Xanthos

Baltzis

Hsu

1997

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 shear and fountain flows occurring during cavity filling actually induce a well-known multilayer structure with skin layers showing a fibre orientation in the flow direction and a core layer where the fibres are oriented transversally to the flow [10,11,24].…”

Section: Figure 2 Location Of Test Samples In the Platementioning

confidence: 99%

“…Besides, nucleating agents (e.g. most commonly carboxylate or phosphate ester salts, and sorbitol acetals) are often added to semi-crystalline polymers such as PET [24][25][26][27] or PP [28,29] in order to modify the crystallisation kinetics and mechanism (increase of the crystallisation rate, leading to a faster polymer solidification), consequently leading to injection moulding cycle time reduction. In particular, PET is characterised by a very slow crystallisation and nucleating agents are often added to control a more homogeneous structure through a uniform spherulite size more than to increase the degree of crystallinity of the polymer.…”

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confidence: 99%

“…The sodium salts usually used as nucleating agent do not act as nucleation centres themselves but interact with the PET molecules to give sodium terephtalate chains that are the effective nucleating species. These nucle-ophilic substitution chemical reactions induce a global molecular weight decrease of the polymer [24][25][26]. Sodium benzoate nucleating agent is wellknown to substantially increase the crystallization rate of poly(ethylene terephtalate) at higher temperature and to accelerate crystallization even more at lower temperature with an additional improvement of molecular mobility of PET chains, but the increase of crystallization rate is limited by the fact that sodium benzoate may be only partially soluble in PET matrix [26,27].…”

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confidence: 99%

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Injection moulding of long glass fibre reinforced poly(ethylene terephtalate): Influence of carbon black and nucleating agents on impact properties

Cilleruelo¹,

Lafranche²,

Krawczak³

et al. 2012

Express Polym. Lett.

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This paper aims at highlighting the influence of different additives (carbon black and nucleating agents) on both the notched and unnotched Charpy impact properties of long glass fibre reinforced poly(ethylene terephtalate) injection mouldings. The relationship with the polymer matrix and composite microstructure modifications (variations of crystalline morphology and local fibre content) was investigated. Adding carbon black alone decreases the impact performances. This highly conductive additive actually increases the cooling rate, and therefore the fibre ‘frettage’ effect (higher internal stresses). It also acts as filler, which increases the material brittleness. The nucleating agents allow reducing the mould temperature, but their effect on the impact strength may be favourable or not depending on the processing temperatures. The addition of such additives induces perturbations of the polymer melt rheology in the mould cavity and of the cooling kinetics of the part, which both act on the fibre distribution during mould filling and on the degree of crystallinity of the composite parts

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Nucleation of poly(ethylene terephthalate) by sodium compounds: a unique mechanism

Cited by 58 publications

References 10 publications

Effects of carbonate salts on crystallization kinetics and properties of recycled poly(ethylene terephthalate)

Effects of carbonate salts on crystallization kinetics and properties of recycled poly(ethylene terephthalate)

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

Injection moulding of long glass fibre reinforced poly(ethylene terephtalate): Influence of carbon black and nucleating agents on impact properties

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