Novel Method for Quantifying Molecular Orientation by Polarized Raman Spectroscopy: A Comparative Simulations Study

Richard‐Lacroix, Marie; Pellerin, Christian

doi:10.1366/12-06879

Cited by 31 publications

(44 citation statements)

References 24 publications

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“…HDPE with low crystallinity exhibits larger 〈P 4 〉, which indicates a broader distribution of molecular orientation. These peculiar behaviors of 〈P 4 〉 are highlighted by considering the most probable distribution function 〈P 4 〉 mp [22,28,29,45]. In Fig.…”

Section: Resultsmentioning

confidence: 97%

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

Kida

Oku

Hiejima

et al. 2015

Polymer

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Semi-crystalline polymers such as polyethylene (PE) and polypropylene (PP) show complicated morphologies composed of a mixture of crystalline and amorphous phases. The diversity in the structure with a wide range of length scales is responsible for the durability or high toughness of semi-crystalline polymers [1,2].When a high-density polyethylene (HDPE) specimen is uniaxially drawn, the elastic deformation is followed by double yield points referred to as the first and the second yields. 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]. It has also been demonstrated that the orientation proceeds rapidly after the first yield, and gradually in the neck-propagation and the strain-hardening regions.However, the IR spectroscopy gives one orientation parameter 〈P 2 〉 which corresponds to the averaged orientation. For PE, the vibrations of the side chains, such as CH 2 twisting and wagging, are IR-active, and the skeletal vibrations of the C-C bonds are IR-inactive, then the load sharing on the polymer chains could not be directly observed with the IR spectroscopy.Raman spectroscopy has several advantages to investigate the deformation behavior of polymeric materials [18][19][20][21][22][23][24]: it is applicable to opaque and thick samples, and molecular environments can be separately detected for both the crystalline and the amorphous phases. Raman scattering is an optical technique that provides a complementary approach to IR absorption when transparent and very thin (typically <100 µm thickness) films are required. In addition, it is advantageous to use Raman spectroscopy because the vibrations of the skeletal C-C bonds in main chains are directly observed [20,25]. Because the C-C stretching vibration is strongly Raman active, microenvironments of the polymer chains are probed by the spectral shifts [26,27]. Polarized Raman spectroscopy gives not only a measure of the average orientation, which is obtained by the usual spectroscopies such as birefringence and IR dichrom, but also the orientation distribution function (ODF, N(θ)) [28][29][30]. In the yielding region where the neck of the specimen is formed, complicated deformation mechanism is expect...

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Section: Resultsmentioning

confidence: 97%

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

Kida

Oku

Hiejima

et al. 2015

Polymer

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“…The orientation parameters were obtained from the intensities of the polarized Raman spectra as defined by Equations (3)- (6) [15,19,[22][23][24]: (6) where I ij denotes the integrated intensity for the i-polarized excitation and j-polarized scattered light. The terms a and b were associated with the principal elements of the Raman tensor [15,22].…”

Section: Orientation Parametersmentioning

confidence: 99%

“…Thus, the forms of the Raman tensor were classified mainly as type A or E [15]. Raman bands classified as type A can be used to calculate the orientation parameters [13,[22][23][24], so the Raman bands at 809 and 975 cm -1 were used. Both of these are classified as type A, and were sufficiently strong to calculate the orientation parameters.…”

Section: Orientation Parametersmentioning

confidence: 99%

Molecular orientation behavior of isotactic polypropylene under uniaxial stretching by rheo-Raman spectroscopy

Kida¹,

Hiejima

Nitta³

2016

Express Polym. Lett.

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“…Moreover, there has been recent evidence that in structured materials, the use of the depolarization ratio is not always accurate for the quantification of fiber orientation. 41 Each spectrum consisted of five accumulations of 10-s integration time to yield a high signal-to-noise ratio (SNR) from 300 to 1800 cm −1 (Hydroxyproline SNR in excess of 25:1). Spectra were processed via least squares modified polynomial fit 42 and smoothed for noise using a second-order Savitsky-Golay filter.…”

Section: Raman Spectroscopymentioning

confidence: 99%

Polarization in Raman spectroscopy helps explain bone brittleness in genetic mouse models

et al. 2014

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Abstract. Raman spectroscopy (RS) has been extensively used to characterize bone composition. However, the link between bone biomechanics and RS measures is not well established. Here, we leveraged the sensitivity of RS polarization to organization, thereby assessing whether RS can explain differences in bone toughness in genetic mouse models for which traditional RS peak ratios are not informative. In the selected mutant miceactivating transcription factor 4 (ATF4) or matrix metalloproteinase 9 (MMP9) knock-outs-toughness is reduced but differences in bone strength do not exist between knock-out and corresponding wild-type controls. To incorporate differences in the RS of bone occurring at peak shoulders, a multivariate approach was used. Full spectrum principal components analysis of two paired, orthogonal bone orientations (relative to laser polarization) improved genotype classification and correlation to bone toughness when compared to traditional peak ratios. When applied to femurs from wild-type mice at 8 and 20 weeks of age, the principal components of orthogonal bone orientations improved age classification but not the explanation of the maturation-related increase in strength. Overall, increasing polarization information by collecting spectra from two bone orientations improves the ability of multivariate RS to explain variance in bone toughness, likely due to polarization sensitivity to organizational changes in both mineral and collagen.

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Novel Method for Quantifying Molecular Orientation by Polarized Raman Spectroscopy: A Comparative Simulations Study

Cited by 31 publications

References 24 publications

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

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

Molecular orientation behavior of isotactic polypropylene under uniaxial stretching by rheo-Raman spectroscopy

Polarization in Raman spectroscopy helps explain bone brittleness in genetic mouse models

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