The rate acceleration in solid‐state polycondensation of PET by nanomaterials

Yu, Huimin; Han, Keqing; Yu, Miao

doi:10.1002/app.20888

Cited by 23 publications

(15 citation statements)

References 14 publications

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“…From the above analysis, it is suggested that clay influence on SSP rate was attributed to increased chemical reactivity. Even more, this considerable increase in reaction rates could not be attributed to higher by-product diffusivity (physical diffusion) as in a previous work on PET, [14] since clays are known to exert enhanced barrier properties to semi-crystalline polymers such as PAs, [8][9][10] and therefore a lower diffusivity of condensate should be expected. This is valid considering also the low concentration of clay employed and the high temperatures examined.…”

Section: Nanocatalysis Mechanismmentioning

confidence: 71%

“…As a result, the investigation of nanoparticles influence on SSP appears very significant and attractive, also to the polymerization process itself; this interest is even more enhanced due to the fact that published literature on nanocomposites SSP is restricted so far to the case of poly(ethylene terephthalate) (PET). In particular, Yu et al [14] studied the SSP reaction of PET in the presence of 2.5 wt.-% clay. They reported an acceleration effect based on intrinsic viscosity ([h]) measurements, with the pertinent increase ranging from 2 to 8% at 230 8C, for up to 25 h. This rate increase was attributed to clay nucleation action, which led to more amorphous regions both on the surfaces of crystals and between them, and thus to easier by-products diffusion.…”

Section: Introductionmentioning

confidence: 99%

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Nanocatalysis in Polyamide 6.6 Solid‐State Polymerization

Boussia

Konstantakopoulou

Vouyiouka

et al. 2010

Macro Materials & Eng

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Solid‐state polymerization (SSP) of a poly(hexamethyleneadipamide) (PA 6.6)/clay nanocomposite system was studied. SSP runs were performed in a fixed‐bed reactor, at temperatures 160–200 °C and reaction times up to 8 h. The influence of clay presence on the PA 6.6 SSP rate constant was herewith quantified for the first time to prove significant acceleration of the SSP process. A catalysis mechanism was suggested, according to which the positive effect of clay is of a synergistic origin attributed to nucleated crystal morphology, that increased the concentration of reactive end groups in the amorphous regions, to chain extension performed by clay SiOH groups, and to thermal protection of the polyamide matrix due to the presence of the nanoparticles. magnified image

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Section: Nanocatalysis Mechanismmentioning

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Nanocatalysis in Polyamide 6.6 Solid‐State Polymerization

Boussia

Konstantakopoulou

Vouyiouka

et al. 2010

Macro Materials & Eng

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“…During the SSP procedure it is found that montmorillonite can accelerate the increase of IV by acting as a co-catalyst. [17] Another observation that leads to the conclusion that something else is concurrently occurring that obstructs the IV increase is the presence of an 'insoluble residue' in the sample containing 5 wt.-% SiO 2 , which exhibits the lowest IV values over all the reaction temperatures and times examined. From our experience with PET up to now, we are not familiar with any case where an insoluble residue is produced to such an extent, except in cases where multifunctional monomers such as trimethyl trimellitate or other additives such as diepoxides or dianhydrides have been used.…”

Section: Solid-state Polymerizationmentioning

confidence: 99%

A New Approach to Prepare Poly(ethylene terephthalate)/Silica Nanocomposites with Increased Molecular Weight and Fully Adjustable Branching or Crosslinking by SSP

Bikiaris

Karavelidis

Karayannidis

2006

Macromol. Rapid Commun.

102

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Summary: In the present study, it has been unexpectedly found that solid‐state polycondensation (SSP) can act as a facile method to prepare poly(ethylene terephthalate)/silica (PET/SiO2) nanocomposites with high molecular weight and an adjustable degree of branching or crosslinking. Fumed silica, with its surface silanol groups, seems to participate in some kind of reaction, probably esterification with the hydroxy end‐groups of PET, during SSP, to act as a multifunctional chain extender. Differential scanning calorimetry and FT‐IR spectroscopy reveal this ability of the silanol groups. The molecular weight increase depends on the used temperatures of SSP as well as on the amount of SiO2 added. As the amount of silica increases the rate of increase of the intrinsic viscosity slows because of the higher extent of branching. At 5 wt.‐% SiO2 the extensive branching produces a crosslinked polymeric material. Such polyesters with increased molecular weight and low silica content could be suitable for blown bottle production, while the high SiO2 content and adjustable branching or crosslinking could make them ideal high‐melt‐strength resins suitable for the preparation of low‐density closed‐shell foams.Schematic representation of PET/SiO2 crosslinked macromolecules.magnified imageSchematic representation of PET/SiO2 crosslinked macromolecules.

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“…In the nanocomposite literature, the presence of nanoclay in PET has been shown to create smaller crystallites in the melt‐phase heterogeneous nucleation [30]. Yu et al [31] demonstrated that solid‐state polymerization (SSP) of PET in the presence of montmorillonite type nanoclays is feasible and is shown to accelerate the solid‐state polycondensation reaction relative to pure PET. However, the effects of nanoclay dispersion or concentration were not discussed.…”

Section: Introductionmentioning

confidence: 99%

Improved mechanical properties of poly(ethylene terephthalate) nanocomposite fibers

Litchfield

Baird

Rim³

et al. 2010

Polymer Engineering & Sci

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Improvements in Young's modulus and strength (tenacity) of poly(ethylene terephthalate) (PET) fibers were obtained by drawing unoriented nanocomposite filaments containing low concentrations (<3 wt%) of various organically modified montmorillonites (MMTs) in a second step at temperatures above the glass transition. Prior to melt spinning, solid‐state polymerization was used to rebuild lost molecular weight, due to MMT‐induced degradation, to a level suitable for producing high strength fibers. Greater improvements in mechanical properties occurred when the MMT stacks were intercalated with PET. A nominal 1 wt% loading of dimethyl‐dehydrogenated tallow quaternary ammonium surface modified MMT in drawn PET fiber showed a 28% and 63% increase in Young's modulus and strength, respectively. Relative to an unfilled PET fiber, these results surpassed the upper bound of the rule of mixtures estimate and suggested that both the type of surface modification and concentration of MMT affect the degree of PET orientation and crystallinity. Furthermore, drawability above Tg and elongation at break increased upon the addition of organically modified MMT to unoriented PET fibers, which was a key distinction of this work from others examining similar systems. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers

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The rate acceleration in solid‐state polycondensation of PET by nanomaterials

Cited by 23 publications

References 14 publications

Nanocatalysis in Polyamide 6.6 Solid‐State Polymerization

Nanocatalysis in Polyamide 6.6 Solid‐State Polymerization

A New Approach to Prepare Poly(ethylene terephthalate)/Silica Nanocomposites with Increased Molecular Weight and Fully Adjustable Branching or Crosslinking by SSP

Improved mechanical properties of poly(ethylene terephthalate) nanocomposite fibers

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