Crystallization of oriented amorphous poly(ethylene terephthalate) as revealed by X-ray diffraction and microhardness

Asano, Tsutomu; Calleja, F. J. Baltá; Flores, A.; Tanigaki, Motonori; Mina, Md. Forhad; Sawatari, Chie; Itagaki, Hideyuki; Takahashi, Hiroshi; Hatta, Ichiro

doi:10.1016/s0032-3861(98)00839-8

Cited by 127 publications

(148 citation statements)

References 22 publications

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“…the decrease of the value of H // . Similar behaviour was observed above T g for PET in an earlier study [12].…”

Section: Influence Of Temperature On Indentation Anisotropysupporting

confidence: 88%

“…The first finding in Fig. 4 is the unusually high ΔH values for the samples investigated compared to those reported for PET in earlier studies [12]. However, in those experiments all the measurements were made at room temperature after annealing the samples at certain temperatures.…”

Section: Development Of Microhardness In Oriented Petmentioning

confidence: 51%

“…Microindentation hardness has been shown to be a valuable tool capable of distinguishing between the amorphous, smectic and crystalline structure of annealed cold drawn PET films after cooling the sample at room temperature [12] as well as unoriented PET and PEN samples [19,20]. What we are interested in now is to perform the experiments in real time as a function of temperature and time so that we understand the effect of the intermediate liquid crystalline mesophase on the crystallization process.…”

Section: Resultsmentioning

confidence: 99%

“…Two well-defined hardness values can be defined due to orientation [12,13]. One value, maximum (H // ), derived from the indentation diagonal parallel to the fibre axis (d // ), the second one, minimum (H ?…”

Section: Microhardness Of Oriented Polymersmentioning

confidence: 99%

“…Asano et al [12] have used hardness measurements to distinguish between the different phases occurring during the crystallization of oriented PET. In their experiments all measurements have been done at room temperature and it showed that the hardness of PET increased by increasing the annealing temperature and that the indentation anisotropy decreases when PET samples are annealed at temperatures above glass transition (T g ).…”

Section: Introductionmentioning

confidence: 99%

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Microindentation technique as a tool for investigating the development of order in PET under uniaxial stress

Abou-Kandil¹,

Flores²,

Calleja³

et al. 2008

J Polym Res

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The development of microhardness during annealing was used as a tool to follow the development of the liquid crystalline transient mesophase during the crystallization of uniaxially oriented polyethylene terephthalate (PET). 2D X-ray diffraction was used to characterize the different stages of the crystallization process. We were able to separate those stages by quenching into air. Microindentation hardness experiments were done in real time where samples were heated with their ends fixed on a specially developed stage and microhardness was measured simultaneously. The oriented samples examined exhibit a clear difference in behavior from isotropic samples that mainly lack the existence of such an ordered mesophase. The mesophase clearly has a reinforcement effect on the whole polymer matrix that leads to an increase in hardness value with annealing of the oriented PET films. Microindentation hardness is shown to be a versatile tool to detect the existence of the liquid crystalline transient mesophase. It is also efficient in comparing and explaining results obtained by wide angle X-ray scattering.

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“…the decrease of the value of H // . Similar behaviour was observed above T g for PET in an earlier study [12].…”

Section: Influence Of Temperature On Indentation Anisotropysupporting

confidence: 88%

Section: Development Of Microhardness In Oriented Petmentioning

confidence: 51%

Section: Resultsmentioning

confidence: 99%

Section: Microhardness Of Oriented Polymersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Microindentation technique as a tool for investigating the development of order in PET under uniaxial stress

Abou-Kandil¹,

Flores²,

Calleja³

et al. 2008

J Polym Res

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Hardness

Calleja¹,

Flores²

2001

Encyclopedia of Polymer Science and Technology

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Hardness is related to the resistance to local deformation of a material surface when indented, drilled, sawed, or abraded. Hardness is shown to be a mechanical property that provides a rapid evaluation of variations in polymer microstructure and morphology. Recent results concerning the microhardness of semicrystalline polymers and amorphous polymers relating to their structure are reviewed. The hardness of polymer glasses is first discussed in relation to their glass‐transition temperature. The development of structure during crystallization of glassy polymers as revealed by microhardness is brought up, and the hardness dependence on structural parameters such as the degree of crystallinity and the crystalline lamellar thickness is discussed. The close existing relationship between crystal hardness and melting temperature is presented. The correlation between microhardness of polymers and macroscopic mechanical properties (yield stress and Young's modulus) is highlighted. Some applications of the microhardness technique to polymer blends are also illustrated. In case of uniaxially oriented polymers, the indentation anisotropy is shown to provide information of the elastic response of the material along chain direction. Finally, the present review presents a comprehensive summary of the different methods used for the determination of hardness numbers, stressing the correlation between the hardness values resulting from different indenter geometries.

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Hardness

Calleja

Flores

2011

Encyclopedia of Polymer Science and Technology

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A description of the hardness technique and its application to polymer systems is presented. The method is based on the local deformation produced on a material surface by an indenter upon application of a given load. Conventional methods based on the optical measure of the residual impression left behind upon load release represent a rather simple technique for a rapid evaluation of the surface mechanical properties. In the past two decades, depth‐sensing indentation devices based on the monitoring of the load and displacement throughout an indentation have progressively substituted traditional testers. Smaller loads can be applied capable of producing penetration depths in the nanoscale. Indentation hardness has nowadays gained widespread application in polymer science. Besides its aforementioned technical advantages, one has to add its extreme sensitivity to detect nanostructural changes occurring in polymer materials. Behind this ability is the intimate correlation between the mechanisms of local deformation and the polymer basic nanostructural entities. The present contribution intends to provide the reader a general overview of the state of the art of indentation hardness in relation to nanostructure and morphology in glassy and semicrystalline polymers including blends.

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Crystallization of oriented amorphous poly(ethylene terephthalate) as revealed by X-ray diffraction and microhardness

Cited by 127 publications

References 22 publications

Microindentation technique as a tool for investigating the development of order in PET under uniaxial stress

Microindentation technique as a tool for investigating the development of order in PET under uniaxial stress

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