Comparison of polarized fluorescence with polarized raman and infrared dichroism measures of orientation in uniaxially drawn poly(ethylene terephthalate)

Abstract

In a number of previous papers the results of studies of molecular orientation in poly(ethylene terephthalate) (PET) by means of refractive index measurements and infrared, Raman and fluorescence spectroscopy have been presented. The present paper attempts to correlate the results of these studies and, in particular, to explain the observation that the fluorescent molecules appear to be more highly oriented than the polymer chains. Of the two explanations considered, that which assumes that the fluorescent molecules align themselves preferentially parallel to those segments of polymer chain in which the glycol residues are in the trans conformation is the more successful. It is also shown that the development of orientation in PET can be described well in terms of a simple modification of the rubber‐network model even for large deformations.

Molecular orientation in hot-drawn poly(ethylene terephthalate) films as determined from the intrinsic polarized fluorescence

“…The angle o = 14 o would indicate that the polarization in plane of the terephthalate ring is dominant; there may exist only a small charge-transfer contribution which is polarized perpendicularly to the plane of the aromatic rings. The relationship between f2 F and/A which is linear even in the case of high orientation, differs from the behaviour of incorporated probe molecules [2]; in the case of probes, the factor f~ is larger in the initial state of orientation but tends to zero in the range of An > 0.10 (see Fig. 3).…”

“…From this it follows directly that one can compare the orientation measured by use of the intrinsic polymer fluorescence with the results obtained with physically incorporated fluorescent probes [2,3] and with bireffingence. Thus, additional information about the discussed PET deformation models [2,4,5] should be obtainable. Therefore, PET film was uniaxially hotdrawn and analyzed by the fluorescence technique.…”

Deformation mechanism of high-density polyethylene probed by in situ Raman spectroscopy

“…During such dual plastic deformations, large-scale transformation of the semi-crystalline morphology takes place, and collapse of the spherulite structures, necking of the sample specimens, and rearrangement of the lamellar crystals and the polymer chains have been observed [1][2][3][4][5][6]. Although various models, such as the lamellar local-melting and recrystallization model [4,7], and the lamellar cluster model [3,[8][9][10], have been proposed for the deformation mechanism, such complicated changes in the hierarchical structures of semicrystalline polymers are still controversial.Spectroscopic techniques have been applied for the orientational behavior of PE during elongation [11][12][13][14][15][16][17]. The infrared (IR) spectroscopy has been applied intensively, and it has been established that the molecular chains in the crystalline and amorphous phases orientate toward the draw direction [11][12][13][14].…”

“…Spectroscopic techniques have been applied for the orientational behavior of PE during elongation [11][12][13][14][15][16][17]. The infrared (IR) spectroscopy has been applied intensively, and it has been established that the molecular chains in the crystalline and amorphous phases orientate toward the draw direction [11][12][13][14].…”

Elasticity and photoelasticity relationships for polyethylene terephthalate fiber networks by molecular simulation

“…15, 25 Stepto and co-workers [15][16][17]20,21 have proposed a derivativemodified Gaussian molecular elasticity model to analyze the stress-optical behavior of a network of RIS-MC chains under deformation. Ward et al 16 recommended such a RIS-MC approach because of the inadequacies of the random-flight chain approaches in describing the deformation behavior of polyethylene terephthalate ͑PET͒ fibers and films.…”