Thermally stimulated current studies on molecular relaxation and blow moulding of poly(ethylene terephthalate)

Satoto, Rahmat; Morikawa, Junko; Hashimoto, Toshimasa

doi:10.1002/(sici)1097-0126(199906)48:6<509::aid-pi183>3.0.co;2-w

Cited by 7 publications

(9 citation statements)

References 44 publications

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“…In these studies, 5,43,48 T c is between 5-30°C above T g , as in our samples, and the decrease in t c with increasing crystallinity/orientation, that also occurs with our samples, was interpreted as a decrease of the size of the moving units. 43 In fact, the practical significance of the compensation parameters is difficult to interpret and, to date, no consistent theory has offered an unambiguous explanation for their physical origin. Some authors have argued that this phenomenon does not have a true physical origin but rather it is a result of statistical error propagation.…”

Section: Differential Scanning Calorimetry and Dynamic Mechanical Anasupporting

confidence: 80%

“…4 These parameters are 119°C and 0·3 s for the film and 100°C and 2 s for the bar. U noriented and biaxially oriented films of PET have been compared for exploring the influence of molecular orientation and crystallinity 5,43,48 in the compensation parameters. H owever, the results are not conclusive because in some studies there seems to be a variation 43,48 with these factors but in another study 5 the influence was not significant.…”

Section: Differential Scanning Calorimetry and Dynamic Mechanical Anamentioning

confidence: 99%

“…U noriented and biaxially oriented films of PET have been compared for exploring the influence of molecular orientation and crystallinity 5,43,48 in the compensation parameters. H owever, the results are not conclusive because in some studies there seems to be a variation 43,48 with these factors but in another study 5 the influence was not significant. In these studies, 5,43,48 T c is between 5-30°C above T g , as in our samples, and the decrease in t c with increasing crystallinity/orientation, that also occurs with our samples, was interpreted as a decrease of the size of the moving units.…”

Section: Differential Scanning Calorimetry and Dynamic Mechanical Anamentioning

confidence: 99%

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Study of the viscoelastic properties of PET by thermally stimulated recovery

Alves¹,

Ribelles²,

Mano³

2003

Plastics, Rubber and Composites

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The conformational chain mobility of semi-crystalline poly(ethylene terephthalate), PET, is studied in the glass transition region by thermally stimulated recovery (TSR ). The thermal sampling (TS) experiments are analysed according to a simple Voigt-Kelvin model. Both the activation energy (E a ) and the pre-exponential factor follow the usual trends with temperature and present the compensation behaviour, that is discussed in this work. The influence of crystallinity and orientation on the glass transition dynamics is analysed. In particular, the profile of variation of E a with temperature is found to be very sensitive to these two effects. TSR results are compared with the results obtained by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). In addition, this technique was successfully applied to the study of the structural relaxation process of semi-crystalline PET and it was found that the characteristic parameters of the TSR curves vary with the ageing temperature and ageing time. These variations are explained on the basis of the changes verified on the distribution of characteristic times with ageing. PRC/2025 N. M. Alves et al. viscoelastic properties of PET by thermally stimulated recovery 283 1 Thermograms obtained on heating scans at 10°C min -1 for the as-received PET film and for the asreceived and annealed (165°C for 1 h) PET bar. For the as-received film, the derivative of the heat flow curve between 50-150°C is also shown

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Section: Differential Scanning Calorimetry and Dynamic Mechanical Anasupporting

confidence: 80%

Section: Differential Scanning Calorimetry and Dynamic Mechanical Anamentioning

confidence: 99%

Section: Differential Scanning Calorimetry and Dynamic Mechanical Anamentioning

confidence: 99%

See 1 more Smart Citation

Study of the viscoelastic properties of PET by thermally stimulated recovery

Alves¹,

Ribelles²,

Mano³

2003

Plastics, Rubber and Composites

View full text Add to dashboard Cite

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“…T g is not affected by the changes in the mold temperature. T g was found to increase, and the transition magnitude to decrease, with increasing degrees of crystallinity because the crystalline entities geometrically constrain the amorphous phase, inhibiting the segmental motions (26). In this context, a more precise treatment was performed where DSC results for PET with different degrees of crystallinity were analyzed with a model based on the configurational entropy concept (14).…”

Section: Waxs Characterizationmentioning

confidence: 99%

Morphology and mechanical properties of injection molded poly(ethylene terephthalate)

Viana

Alves

Mano

2004

Polymer Engineering & Sci

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This work reports on the relationships between processing, the morphology and the mechanical properties of an injection molded poly(ethylene terephthalate), PET. Specimens were injection molded with different mold temperatures of 30°C, 50°C, 80°C, 100°C, 120°C, 150°C, while maintaining constant the other operative processing parameters. The thermomechanical environment imposed during processing was estimated by computer simulations of the mold‐filling phase, which allow the calculation of two thermomechanical indices indicative of morphological development (degree of crystallinity and level of molecular orientation). The morphology of the moldings was characterized by differential scanning calorimetry (DSC) and by hot recoverable strain tests. The mechanical behavior was assessed in tensile testing at 5 mm/min and 23°C. A strong thermal and mechanical coupling is evidenced in the injection molding process, significantly influencing morphology development. An increase in the mold temperature induces a decrease of the level of molecular orientation (decrement in the hot recoverable strain) and an increment in the initial crystallinity of the moldings (decrement in the enthalpy of cold crystallization), also reflected in the variations of the computed thermomechanical indices. The initial modulus is mainly dependent upon the level of molecular orientation. The yield stress is influenced by both the degree of crystallinity and the level of molecular orientation of the moldings, but more significantly by the former. The strain at break was not satisfactorily linked directly to the initial morphological state because of the expected morphology changes occurring during deformation. Polym. Eng. Sci. 44:2174–2184, 2004. © 2004 Society of Plastics Engineers.

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“…In Table 1 PET2 is a biaxially oriented and semi-crystalline film (crystallinity degree X c ¼ 36%) whereas PET3 is an isotropic semi-crystalline material (X c ¼ 29%). Unoriented and biaxially oriented films of PET have been compared for exploring the influence of molecular orientation and crystallinity on the compensation parameters (8,(52)(53)(54). However the results are not conclusive.…”

Section: Molecular Mobility In Polymersmentioning

confidence: 99%

Study of the Molecular Mobility in Polymers with the Thermally Stimulated Recovery Technique—A Review

Alves

Ribelles

Mano

2005

Journal of Macromolecular Science, Part C: Polymer Reviews

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Thermally stimulated recovery (TSR) is a non-conventional mechanical spectroscopy technique that allows to analyse in detail the relaxation processes of polymeric systems in the low frequency region. This work reviews the main aspects and potentialities of this technique. The different kinds of TSR experiments that can be performed, global and thermal sampling (TS) experiments, are described and illustrated with several examples. Also, the different methods for the determination of the thermokinetic parameters (activation energy and pre-exponential factor) of the thermal sampling (TS) procedure are explained and compared. In this context, the compensation phenomenon, which always appears in TSR results when the studies are performed in the glass transition region of a given system, is discussed. Examples of the application of this technique to different polymeric systems during the last 20 years are provided. An emphasis will be made on the analysis of the effect of crystallinity degree and crosslink density on the TSR response. A comparison between the results (characteristic times and activation energies) obtained by different techniques, namely TSR, dynamic mechanical analysis (DMA), and differential scanning calorimetry (DSC), is made.

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Thermally stimulated current studies on molecular relaxation and blow moulding of poly(ethylene terephthalate)

Cited by 7 publications

References 44 publications

Study of the viscoelastic properties of PET by thermally stimulated recovery

Study of the viscoelastic properties of PET by thermally stimulated recovery

Morphology and mechanical properties of injection molded poly(ethylene terephthalate)

Study of the Molecular Mobility in Polymers with the Thermally Stimulated Recovery Technique—A Review

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