Application of FTIR-spectroscopy on orientation processes in polyethylene films

Holland-Moritz, K.; Holland-Moritz, I.; Werden, K. van

doi:10.1007/bf01381756

Cited by 26 publications

(7 citation statements)

References 5 publications

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“…Force and displacement were monitored simultaneously by friction-free force transducers and linear-variable differential transformers. The force transducer had a maximum range of 10 kg load such that the applied forces could be reliably measured to the nearest gram (-lo3 dyn) on the digital display and stripchart recorder. The displacements were obtained with an accuracy of f2 x mm.…”

Section: Mechanical Testing Methodsmentioning

confidence: 99%

Infrared and raman spectroscopy of stressed polyethylene

Wool

Bretzlaff

et al. 1986

J Polym Sci B Polym Phys

140

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Polyethylene films were stressed in uniaxial tension at room temperature while the infrared (FTIR) or Raman spectra were simultaneously measured. The purpose of these experiments was to gain an understanding of the molecular origins of the stress‐induced vibrational frequency shifts Δν and determine the mechanisms of molecular deformation and fracture of PE molecules with stress σ. The PE samples consisted of ultradrawn, high‐density, ultrahigh‐molecular‐weight, solid‐state‐extruded films and the stress was applied parallel to the nearly perfectly oriented orthorhombic crystal c‐axis direction. The experimental frequency shifting coefficients α = (∂ν/∂σ)σ→0 were compared with calculated α values determined from a vibrational analysis of an isolated PE chain using conformational energy minimization methods in which both harmonic and anharmonic (Morse) potential energy functions were used for the CC stretching modes in the valence force field. The following α values were obtained and are compared with theory (anharmonic case in parentheses, in cm−1/GPa): CC symmetric stretch, α(1127) = −5.9 (−5.3); CC asymmetric stretch, α(1059) = −11.2 to −5.7 (−5.8); CH2 rock, α(730/720) = −2.0 to −3.0 (−2.2); CH2 scissors, α(1472/1462) = −1.0 to −1.2 (−1.1); CH2 twist, α(1295) ≃ 0(0.8); CH2 wag, α(1370) undetermined owing to weak bands (−4.6); CH2 stretch α(3000) ≈ 0. The largest negative frequency shifts were observed for the CC stretching modes, in agreement with the calculations using the Morse potential. The harmonic potential for CC stretching resulted in small positive α values for both the CC stretching and CH2 wagging modes, while the other modes were unaffected by this choice of potential. The relative contribution of CC bond stretching and CĈC valence angle bending to the c‐axis strain was about 1:1, in agreement with experiment. The Young's tensile modulus of a PE chain was calculated as Ec = 267 GPa.

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Section: Mechanical Testing Methodsmentioning

confidence: 99%

Infrared and raman spectroscopy of stressed polyethylene

Wool

Bretzlaff

et al. 1986

J Polym Sci B Polym Phys

140

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“…This can qualitatively be seen by application of the respective formula for ideal uniaxial orientation (13) which leads to an angle of about 46 ° between the polymer C-axes and the stretching direction. (Comparable experiments on polyethylene result in an angle less then 13 °) (12). On cooling, the dichroic ratios approach 0,5 reflecting a further increase in the orientation with an estimated angle of 39 ° between polymer chain and elongation direction.…”

Section: Discussionmentioning

confidence: 93%

Vibrational spectroscopic studies on different modifications of poly(trans-alkenylene)s

Werden

Holland-Moritz

1981

Colloid & Polymer Sci

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SummaryThe changes in the state of order in poly(trans-octenylene) and poly(trans-dodecenylene) are studied by Raman and FTIR-spectroscopy in dependence of temperature and applied stress. The observed spectral changes are discussed on the basis of a normal coordinate analysis. ZusammenfassungDie _~.nderungen des Ordnungszustandes in Poly(transoctenylen) und Poly(trans-dodecenylen) wurden mittels der Raman-und FTIR-Spektroskopie in Abh~ngigkeit yon Temperatur und Reckgrad untersucht. Die beobachteten spektralen ~.nderungen werden auf der Basis einer Normalkoordinatenanalyse diskutiert.

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“…The 720 cm À1 band dichroic ratio (D 720 ) was then calculated (equation ( 6)) by dividing the parallel absorbance by the perpendicular absorbance The 720 cm À1 band was chosen as it represents both the crystalline and amorphous chain orientation from the CH 2 units. [23][24][25]…”

Section: Macromolecular Orientationmentioning

confidence: 99%

Entanglement density, macromolecular orientation, and their effect on elastic strain recovery of polyolefin films

Traon

Grohens

Corre

2022

Journal of Plastic Film & Sheeting

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For amorphous polymers, restoring forces are generated by the progressive orientation of the macromolecular chains in the stretching direction leading to a decrease in the system entropy. Orienting the chains in the future stretching direction thus reduces the entropy variation induced by the stretching and limits the entropic restoring force magnitude. Entropic restoring forces created during stretching have been correlated to the number of junction points by previous studies. Reducing the entanglement density (i.e., the number of junction points) is supposed to limit the entropic restoring force magnitude. In this study, the influence of blend ratio of low molecular weight wax and orientation level on the mechanical properties of the thin films, especially the elastic recovery, were evaluated. Elastic energy strain recovery was calculated from hysteresis curve obtained during 60% loading (stretch) and unloading (recovery) cycle and compared to rheological and orientation measurement. It has been shown that a decrease in entanglement density can minimize elastic recovery, Nevertheless, a compromise must be found, in order to limit the permanent deformation caused by chain flow. Macromolecular orientation is also a way to adjust the film mechanical properties. A LDPE 3 × 3 biaxial orientation leads to a 25% reduction in transversal direction elastic recovery (compared to MDO cast film) without altering machine direction mechanical behavior. However, for ethylene vinyl acetate, the uniaxial macromolecular orientation seems to impact the film behavior in the transverse direction by causing a smaller inter-atom distance, favoring a higher bond strength. The latter acts as transient physical nodes, increasing entropic restoring forces.

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Application of FTIR-spectroscopy on orientation processes in polyethylene films

Cited by 26 publications

References 5 publications

Infrared and raman spectroscopy of stressed polyethylene

Infrared and raman spectroscopy of stressed polyethylene

Vibrational spectroscopic studies on different modifications of poly(trans-alkenylene)s

Entanglement density, macromolecular orientation, and their effect on elastic strain recovery of polyolefin films

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