Physical ageing of amorphous and semicrystalline poly(ethylene terephthalate)

Vigier, G.; Tatibouët, J.

doi:10.1016/0032-3861(93)90186-e

Cited by 68 publications

(35 citation statements)

References 23 publications

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“…Measurements of the glass relaxation not influenced by vitrification require a sufficiently big difference between the time scales of the perturbation and the cooling (or heating) process. This is not only important for temperature modulated differential scanning calorimetric experiments, but also well known for dielectric [22] and mechanical [23] spectroscopy at low frequencies comparable with the time scale of vitrification. As shown in Fig.…”

Section: (5)mentioning

confidence: 98%

Temperature modulated calorimetry and dielectric spectroscopy in the glass transition region of polymers

Hensel

Dobbertin

Schawe

et al. 1996

Journal of Thermal Analysis

122

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The results from temperature modulated DSC in the glass transition region of amorphous and semicrystalline polymers are described with the linear response approach. The real and the imaginary part of the eomplex heat capacity are discussed. The findings are compared with those of dielectric spectroscopy. The frequency dependent glass transition temperature can be fitted with a VFT-equation. The transition frequencies are decreased by 0.5 to 1 orders of magnitude compared to dielectric measurements. Cooling rates from standard DSC are transformed into frequencies. The glass transition temperatures are also approximated by the VFT-fit from the temperature modulated measurements. The differences in the shape of the curves from amorphous and semicrystalline samples are discussed.

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Section: (5)mentioning

confidence: 98%

Temperature modulated calorimetry and dielectric spectroscopy in the glass transition region of polymers

Hensel

Dobbertin

Schawe

et al. 1996

Journal of Thermal Analysis

122

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“…A model based on the assumption that density fluctuation in a glassy polymer can be considered as quasipoint defects, interprets sub-T g aging in terms of diffusion-aided annihilation of such defects until a new thermodynamic (metastable) equilibrium is reached at that temperature. 70 Setting PET fiber at and around T g is believed to result in temporary or semipermanent set, 10 again mainly through free-volume collapse. However, some recent findings on isotropic, amorphous PET have shown 71 that when PET is annealed from the glassy state at 80°C (5°C above T g ), the frozen gauche conformations in the amorphous glassy state begin to transform to the trans conformations.…”

Section: Effect Of Setting Conditions and Fiber Structurementioning

confidence: 99%

Heat setting

Gupta¹

2001

J of Applied Polymer Sci

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As-manufactured polymeric fibers are oriented semi-crystalline structures in which the macromolecules are rarely in their equilibrium state. Further instabilities are imparted when the fibers are converted to yarns and the yarns to fabrics. Heat setting is an important industrial process, since it rids them of their instabilities. This review article first considers aspects that are relevant to the broad area of heat setting, viz., the origin of instability, the durability of set, thermal and dynamic mechanical transitions, thermodynamic basis of setting, shrinkage and shrinkage stress, and characterization of the degree of set. The heat setting of major thermoplastic fibers, viz., polyester, polyamide, polyacrylonitrile, polypropylene, and polyethylene has been described in terms of the conditions of heat setting, the structural and morphological changes that occur on heat setting, and the changes in their physical properties. It is shown that heat setting affects such important properties as stress-strain and recovery behavior, dye-uptake, optical properties, and thermal properties. The structural and morphological changes have been described in terms of changes in crystallinity, crystal size and their size distribution, crystal defects, crystal orientation, the nature of the amorphous phase and its orientation, the coupling of the crystalline and amorphous phases, etc. The structural basis of property changes is then discussed.

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“…Let us for instance mention the study reported by Vigier and Tatibouet [14] in PET (with many references included). They have shown that thermal and micromechanical properties of both amorphous and semi crystalline PET depend on aging effects induced by thermal treatments below T g .…”

Section: Introductionmentioning

confidence: 98%

“…The first investigations were performed in amorphous polymers [13,14]. Let us for instance mention the study reported by Vigier and Tatibouet [14] in PET (with many references included).…”

Section: Introductionmentioning

confidence: 98%