Structure and physical properties of biaxially stretched polyethylene terephthalate sheets under different heat‐set and stretch conditions

Maruhashi, Yoshitsugu

doi:10.1002/pen.10914

Cited by 8 publications

(5 citation statements)

References 30 publications

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“…8,19,24 Studies on the effect of biaxial deformation on PET structure are less numerous and have tended to focus on the development of constitutive models to describe the biaxial drawing of amorphous PET. [25][26][27][28][29][30][31][32][33][34] Most recently, Buckley and Lew provided further insight into the response of PET upon biaxial stretching across a range of strain rates and temperatures. 29 The authors identified four regimes in describing the biaxial hot-drawing behaviour of PET and used the data obtained to further refine their constitutive model for PET.…”

Section: Introductionmentioning

confidence: 99%

Quasi-solid state uniaxial and biaxial deformation of PET/MWCNT composites: structural evolution, electrical and mechanical properties

Mayoral¹,

Hornsby²,

McNally³

et al. 2013

RSC Adv.

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Composites of multi-walled carbon nanotubes (MWCNTs) and a poly(ethylene terephthalate)(PET), prepared by melt mixing, were uniaxially and biaxially deformed at 100 uC using a strain rate of 2 s 21 and at stretch ratios (SR) up to 2. A hierarchical organization of randomly well dispersed and distributed agglomerates, smaller bundles and individual MWCNTs was identified in the as extruded composite from extensive microscopic examination across the length scales using polarised optical microscopy (POM), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). Evidence from X-ray diffraction (XRD) and differential scanning calorimetry (DSC) confirmed the MWCNTs induced crystallization via a heterogeneous mechanism and altered the crystallization behaviour of PET. Uniaxial deformation of the composite materials resulted in orientation of the MWCNTs in the direction parallel to the applied strain and for biaxial deformation at an angle approaching 45u to the vertical axis (extrusion direction), evidence for the latter obtained by HRTEM and from small angle X-ray scattering experiments (SAXS). In both instances, XRD and DSC confirmed the occurrence of significant strain induced crystallization resulting in large increases in tensile mechanical properties. Evidence from wide angle X-ray scattering experiments (WAXS), supported by XRD and DSC showed the overall crystalline content and degree of long-range ordering increased with MWCNT addition. The decrease in diffraction (SAXS) associated with lamella spacing implies the MWCNTs disrupt formation of lamella and reside in the inter-lamellar spacing. Annealing the composites, particularly at T m 250 uC, results in an increase in PET crystalline content. Prior to deformation the MWCNTs formed an electrically conducting interconnected network throughout the PET matrix, however, this was partially destroyed when the composite was uniaxially or biaxially deformed, as the probability of conductor-conductor contacts decreased. It was possible to restore a MWCNT conducting network similar to that achieved prior to uniaxial deformation only by annealing the sample at T m 250 uC.

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Section: Introductionmentioning

confidence: 99%

Quasi-solid state uniaxial and biaxial deformation of PET/MWCNT composites: structural evolution, electrical and mechanical properties

Mayoral¹,

Hornsby²,

McNally³

et al. 2013

RSC Adv.

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“…A semicrystalline PET can be obtained by a cold‐crystallization (or annealing) at above the glass transition temperature from the amorphous glass or by a melt‐crystallization (nonisothermal or isothermal) from the melt. As the properties of PET depend very much on the crystallinity and morphology, the crystallization and melting behavior of PET have always drawn attention to investigate 2–21. In these many studies, the crystallinity and morphology of PET are clearly seen to be influenced by various factors such as orientation, thermal history, and crystallization conditions which include temperature, time, heating and cooling rates, isothermal and nonisothermal processes, pretreatment conditions, and so forth.…”

Section: Introductionmentioning

confidence: 99%

Effect of crystallinity on enthalpy recovery peaks and cold‐crystallization peaks in PET via TMDSC and DMA studies

Shieh

Lin

Twu

et al. 2009

J of Applied Polymer Sci

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Poly(ethylene terephthalate) (PET) sheets of different crystallinity were obtained by annealing the amorphous PET (aPET) sheets at 110 C for various times. The peaks of enthalpy recovery and double cold-crystallization in the annealed aPET samples with different crystallinity were investigated by a temperature-modulated differential scanning calorimeter (TMDSC) and a dynamic mechanical analyzer (DMA). The enthalpy recovery peak around the glass transition temperature was pronounced in TMDSC nonreversing heat flow curves and was found to shift to higher temperatures with higher degrees of crystallinity. The magnitudes of the enthalpy recovery peaks were found to increase with annealing times for samples annealed 30 min but to decrease with annealing times for samples annealed !40 min. The nonreversing curves also found that the samples annealed short times ( 40 min) having low crystallinity exhibited double cold-crystallization peaks (or a major peak with a shoulder) in the region of 108-130 C. For samples annealed long times (!50 min), the cold-crystallization peaks were reduced to one small peak or disappeared because of high crystallinity in these samples. The double cold-crystallization exotherms in samples of low crystallinity could be attributed to the superposition of the melting of crystals, formed by the annealing pretreatments, and the cold-crystallizations occurring during TMDSC heating. The ongoing crystallization after the cold crystallization was clearly seen in the TMDSC nonreversing heat flow curves. DMA data agreed with TMDSC data on the origin of the double cold-crystallization peaks.

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“…The crystallization of PET is influenced by various factors, such as molecular weight, orientation, annealing, and crystallization conditions 5. For example, the orientation can cause stress‐induced crystallization and influence the crystallinity 5–9. PET is a semirigid crystalline polymer with slow crystallization behavior; this usually leads to the presence of a large amount of metastable crystals or imperfect crystals that are not at thermodynamic equilibrium.…”

Section: Introductionmentioning

confidence: 99%

Glass transition and cold crystallization in carbon dioxide treated poly(ethylene terephthalate)

Shieh

Lin

2009

J of Applied Polymer Sci

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An amorphous poly(ethylene terephthalate) (aPET) and a semicrystalline poly(ethylene terephthalate) obtained through the annealing of aPET at 110 C for 40 min (aPET-110-40) were treated in carbon dioxide (CO 2 ) at 1500 psi and 35 C for 1 h followed by treatment in a vacuum for various times to make samples containing various amount of CO 2 residues in these two CO 2 -treated samples. Glass transition and cold crystallization as a function of the amount of CO 2 residues in these two CO 2 -treated samples were investigated by temperature-modulated differential scanning calorimetry (TMDSC) and dynamic mechanical analysis (DMA). The CO 2 residues were found to not only depress the glass-transition temperature (T g ) but also facilitate cold crystallization in both samples. The depressed T g in both CO 2 -treated poly(ethylene terephthalate) samples was roughly inversely proportional to amount of CO 2 residues and was independent of the crystallinity of the poly(-ethylene terephthalate) sample. The nonreversing curves of TMDSC data clearly indicated that both samples exhibited a big overshoot peak around the glass transition. This overshoot peak occurred at lower temperatures and was smaller in magnitude for samples containing more CO 2 residues. The TMDSC nonreversing curves also indicated that aPET exhibited a clear cold-crystallization exotherm at 120.0 C, but aPET-110-40 exhibited two cold-crystallization exotherms at 109.2 and 127.4C. The two cold crystallizations in the CO 2 -treated aPET-110-40 became one after vacuum treatment. The DMA data exhibited multiple tan d peaks in both CO 2 -treated poly-(ethylene terephthalate) samples. These multiple tan d peaks, attributed to multiple amorphous phases, tended to shift to higher temperatures for longer vacuum times.

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Structure and physical properties of biaxially stretched polyethylene terephthalate sheets under different heat‐set and stretch conditions

Cited by 8 publications

References 30 publications

Quasi-solid state uniaxial and biaxial deformation of PET/MWCNT composites: structural evolution, electrical and mechanical properties

Quasi-solid state uniaxial and biaxial deformation of PET/MWCNT composites: structural evolution, electrical and mechanical properties

Effect of crystallinity on enthalpy recovery peaks and cold‐crystallization peaks in PET via TMDSC and DMA studies

Glass transition and cold crystallization in carbon dioxide treated poly(ethylene terephthalate)

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